# Source code for guiqwt.image

    # -*- coding: utf-8 -*-
    #
    # Copyright © 2009-2010 CEA
    # Pierre Raybaut
    # Licensed under the terms of the CECILL License
    # (see guiqwt/__init__.py for details)

    # pylint: disable=C0103

    """
    guiqwt.image
    ------------

    The `image` module provides image-related objects and functions:

        * :py:class:`guiqwt.image.ImagePlot`: a 2D curve and image plotting widget,
          derived from :py:class:`guiqwt.curve.CurvePlot`
        * :py:class:`guiqwt.image.ImageItem`: simple images
        * :py:class:`guiqwt.image.TrImageItem`: images supporting arbitrary
          affine transform
        * :py:class:`guiqwt.image.XYImageItem`: images with non-linear X/Y axes
        * :py:class:`guiqwt.image.Histogram2DItem`: 2D histogram
        * :py:class:`guiqwt.image.ImageFilterItem`: rectangular filtering area
          that may be resized and moved onto the processed image
        * :py:func:`guiqwt.image.assemble_imageitems`
        * :py:func:`guiqwt.image.get_plot_source_rect`
        * :py:func:`guiqwt.image.get_image_from_plot`

    ``ImageItem``, ``TrImageItem``, ``XYImageItem``, ``Histogram2DItem`` and
    ``ImageFilterItem`` objects are plot items (derived from QwtPlotItem) that
    may be displayed on a :py:class:`guiqwt.image.ImagePlot` plotting widget.

    .. seealso::

        Module :py:mod:`guiqwt.curve`
            Module providing curve-related plot items and plotting widgets

        Module :py:mod:`guiqwt.plot`
            Module providing ready-to-use curve and image plotting widgets and
            dialog boxes

    Examples
    ~~~~~~~~

    Create a basic image plotting widget:

        * before creating any widget, a `QApplication` must be instantiated (that
          is a `Qt` internal requirement):

    >>> import guidata
    >>> app = guidata.qapplication()

        * that is mostly equivalent to the following (the only difference is that
          the `guidata` helper function also installs the `Qt` translation
          corresponding to the system locale):

    >>> from PyQt5.QtGui import QApplication
    >>> app = QApplication([])

        * now that a `QApplication` object exists, we may create the plotting
          widget:

    >>> from guiqwt.image import ImagePlot
    >>> plot = ImagePlot(title="Example")

    Generate random data for testing purpose:

    >>> import numpy as np
    >>> data = np.random.rand(100, 100)

    Create a simple image item:

        * from the associated plot item class (e.g. `XYImageItem` to create
          an image with non-linear X/Y axes): the item properties are then
          assigned by creating the appropriate style parameters object
          (e.g. :py:class:`guiqwt.styles.ImageParam`)

    >>> from guiqwt.curve import ImageItem
    >>> from guiqwt.styles import ImageParam
    >>> param = ImageParam()
    >>> param.label = 'My image'
    >>> image = ImageItem(param)
    >>> image.set_data(data)

        * or using the `plot item builder` (see :py:func:`guiqwt.builder.make`):

    >>> from guiqwt.builder import make
    >>> image = make.image(data, title='My image')

    Attach the image to the plotting widget:

    >>> plot.add_item(image)

    Display the plotting widget:

    >>> plot.show()
    >>> app.exec_()

    Reference
    ~~~~~~~~~

    .. autoclass:: ImagePlot
       :members:
       :inherited-members:
    .. autoclass:: BaseImageItem
       :members:
       :inherited-members:
    .. autoclass:: RawImageItem
       :members:
       :inherited-members:
    .. autoclass:: ImageItem
       :members:
       :inherited-members:
    .. autoclass:: TrImageItem
       :members:
       :inherited-members:
    .. autoclass:: XYImageItem
       :members:
       :inherited-members:
    .. autoclass:: RGBImageItem
       :members:
       :inherited-members:
    .. autoclass:: MaskedImageItem
       :members:
       :inherited-members:
    .. autoclass:: ImageFilterItem
       :members:
       :inherited-members:
    .. autoclass:: XYImageFilterItem
       :members:
       :inherited-members:
    .. autoclass:: Histogram2DItem
       :members:
       :inherited-members:

    .. autofunction:: assemble_imageitems
    .. autofunction:: get_plot_qrect
    .. autofunction:: get_image_from_plot
    """

    import sys
    import os
    import os.path as osp
    from math import fabs

    import numpy as np

    from qtpy.QtGui import QColor, QImage
    from qtpy.QtCore import QRectF, QPointF, QRect

    from guidata.utils.misc import assert_interfaces_valid
    from guidata.dataset import update_dataset

    # Local imports
    from guiqwt.transitional import QwtPlotItem, QwtInterval
    from guiqwt.config import _
    from guiqwt.interfaces import (
        IBasePlotItem,
        IBaseImageItem,
        IHistDataSource,
        IImageItemType,
        ITrackableItemType,
        IColormapImageItemType,
        IVoiImageItemType,
        ISerializableType,
        ICSImageItemType,
        IExportROIImageItemType,
        IStatsImageItemType,
    )
    from guiqwt.curve import CurvePlot, CurveItem, PolygonMapItem
    from guiqwt.colormap import FULLRANGE, get_cmap, get_cmap_name
    from guiqwt.styles import (
        ImageParam,
        ImageAxesParam,
        TrImageParam,
        RGBImageParam,
        MaskedImageParam,
        XYImageParam,
        RawImageParam,
    )
    from guiqwt.shapes import RectangleShape
    from guiqwt import io
    from guiqwt.geometry import translate, scale, rotate, colvector
    from guiqwt.baseplot import canvas_to_axes, axes_to_canvas

    stderr = sys.stderr
    try:
        from guiqwt.histogram2d import histogram2d, histogram2d_func
        from guiqwt._scaler import (
            _histogram,
            _scale_tr,
            _scale_xy,
            _scale_rect,
            _scale_quads,
            INTERP_NEAREST,
            INTERP_LINEAR,
            INTERP_AA,
        )
    except ImportError:
        print(("Module 'guiqwt.image': missing C extension"), file=sys.stderr)
        print(
            ("try running :" "python setup.py build_ext --inplace -c mingw32"),
            file=sys.stderr,
        )
        raise

    LUT_SIZE = 1024
    LUT_MAX = float(LUT_SIZE - 1)

    def _nanmin(data):
        if isinstance(data, np.ma.MaskedArray):
            data = data.data
        if data.dtype.name in ("float32", "float64", "float128"):
            return np.nanmin(data)
        else:
            return data.min()

    def _nanmax(data):
        if isinstance(data, np.ma.MaskedArray):
            data = data.data
        if data.dtype.name in ("float32", "float64", "float128"):
            return np.nanmax(data)
        else:
            return data.max()

    def pixelround(x, corner=None):
        """
        Return pixel index (int) from pixel coordinate (float)
        corner: None (not a corner), 'TL' (top-left corner),
        'BR' (bottom-right corner)
        """
        assert corner is None or corner in ("TL", "BR")
        if corner is None:
            return np.floor(x)
        elif corner == "BR":
            return np.ceil(x)
        elif corner == "TL":
            return np.floor(x)

    # ==============================================================================
    # Base image item class
    # ==============================================================================

    class BaseImageItem(QwtPlotItem):
        __implements__ = (
            IBasePlotItem,
            IBaseImageItem,
            IHistDataSource,
            IVoiImageItemType,
            ICSImageItemType,
            IStatsImageItemType,
            IExportROIImageItemType,
        )
        _can_select = True
        _can_resize = False
        _can_move = False
        _can_rotate = False
        _readonly = False
        _private = False

        def __init__(self, data=None, param=None):
            super(BaseImageItem, self).__init__()

            self.bg_qcolor = QColor()

            self.bounds = QRectF()

            # BaseImageItem needs:
            # param.background
            # param.alpha_mask
            # param.alpha
            # param.colormap
            if param is None:
                param = self.get_default_param()
            self.imageparam = param

            self.selected = False

            self.data = None

            self.min = 0.0
            self.max = 1.0
            self.cmap_table = None
            self.cmap = None
            self.colormap_axis = None

            self._offscreen = np.array((1, 1), np.uint32)

            # Linear interpolation is the default interpolation algorithm:
            # it's almost as fast as 'nearest pixel' method but far smoother
            self.interpolate = None
            self.set_interpolation(INTERP_LINEAR)

            x1, y1 = self.bounds.left(), self.bounds.top()
            x2, y2 = self.bounds.right(), self.bounds.bottom()
            self.border_rect = RectangleShape(x1, y1, x2, y2)
            self.border_rect.set_style("plot", "shape/imageborder")
            # A, B, Background, Colormap
            self.lut = (1.0, 0.0, None, np.zeros((LUT_SIZE,), np.uint32))

            self.set_lut_range([0.0, 255.0])
            self.setItemAttribute(QwtPlotItem.AutoScale)
            self.setItemAttribute(QwtPlotItem.Legend, True)
            self._filename = None  # The file this image comes from

            self.histogram_cache = None
            if data is not None:
                self.set_data(data)
            self.imageparam.update_image(self)

        # ---- Public API ----------------------------------------------------------

        def get_default_param(self):
            """Return instance of the default imageparam DataSet"""
            raise NotImplementedError

        def set_filename(self, fname):
            self._filename = fname

        def get_filename(self):
            fname = self._filename
            if fname is not None and not osp.isfile(fname):
                other_try = osp.join(os.getcwd(), osp.basename(fname))
                if osp.isfile(other_try):
                    self.set_filename(other_try)
                    fname = other_try
            return fname

        def get_filter(self, filterobj, filterparam):
            """Provides a filter object over this image's content"""
            raise NotImplementedError

        def get_pixel_coordinates(self, xplot, yplot):
            """
            Return (image) pixel coordinates
            Transform the plot coordinates (arbitrary plot Z-axis unit)
            into the image coordinates (pixel unit)

            Rounding is necessary to obtain array indexes from these coordinates
            """
            return xplot, yplot

        def get_plot_coordinates(self, xpixel, ypixel):
            """
            Return plot coordinates
            Transform the image coordinates (pixel unit)
            into the plot coordinates (arbitrary plot Z-axis unit)
            """
            return xpixel, ypixel

        def get_closest_indexes(self, x, y, corner=None):
            """
            Return closest image pixel indexes
            corner: None (not a corner), 'TL' (top-left corner),
            'BR' (bottom-right corner)
            """
            x, y = self.get_pixel_coordinates(x, y)
            i_max = self.data.shape[1] - 1
            j_max = self.data.shape[0] - 1
            if corner == "BR":
                i_max += 1
                j_max += 1
            i = max([0, min([i_max, int(pixelround(x, corner))])])
            j = max([0, min([j_max, int(pixelround(y, corner))])])
            return i, j

        def get_closest_index_rect(self, x0, y0, x1, y1):
            """
            Return closest image rectangular pixel area index bounds
            Avoid returning empty rectangular area (return 1x1 pixel area instead)
            Handle reversed/not-reversed Y-axis orientation
            """
            ix0, iy0 = self.get_closest_indexes(x0, y0, corner="TL")
            ix1, iy1 = self.get_closest_indexes(x1, y1, corner="BR")
            if ix0 > ix1:
                ix1, ix0 = ix0, ix1
            if iy0 > iy1:
                iy1, iy0 = iy0, iy1
            if ix0 == ix1:
                ix1 += 1
            if iy0 == iy1:
                iy1 += 1
            return ix0, iy0, ix1, iy1

        def align_rectangular_shape(self, shape):
            """Align rectangular shape to image pixels"""
            ix0, iy0, ix1, iy1 = self.get_closest_index_rect(*shape.get_rect())
            x0, y0 = self.get_plot_coordinates(ix0, iy0)
            x1, y1 = self.get_plot_coordinates(ix1, iy1)
            shape.set_rect(x0, y0, x1, y1)

        def get_closest_pixel_indexes(self, x, y):
            """
            Return closest pixel indexes
            Instead of returning indexes of an image pixel like the method
            'get_closest_indexes', this method returns the indexes of the
            closest pixel which is not necessarily on the image itself
            (i.e. indexes may be outside image index bounds: negative or
            superior than the image dimension)

            .. note::

                This is *not* the same as retrieving the canvas pixel coordinates
                (which depends on the zoom level)
            """
            x, y = self.get_pixel_coordinates(x, y)
            i = int(pixelround(x))
            j = int(pixelround(y))
            return i, j

        def get_x_values(self, i0, i1):
            return np.arange(i0, i1)

        def get_y_values(self, j0, j1):
            return np.arange(j0, j1)

        def get_data(self, x0, y0, x1=None, y1=None):
            """
            Return image data
            Arguments: x0, y0 [, x1, y1]
            Return image level at coordinates (x0,y0)

            If x1,y1 are specified:

              Return image levels (np.ndarray) in rectangular area (x0,y0,x1,y1)
            """
            i0, j0 = self.get_closest_indexes(x0, y0)
            if x1 is None or y1 is None:
                return self.data[j0, i0]
            else:
                i1, j1 = self.get_closest_indexes(x1, y1)
                i1 += 1
                j1 += 1
                return (
                    self.get_x_values(i0, i1),
                    self.get_y_values(j0, j1),
                    self.data[j0:j1, i0:i1],
                )

        def get_closest_coordinates(self, x, y):
            """Return closest image pixel coordinates"""
            return self.get_closest_indexes(x, y)

        def get_coordinates_label(self, xc, yc):
            title = self.title().text()
            z = self.get_data(xc, yc)
            return "%s:<br>x = %d<br>y = %d<br>z = %g" % (title, xc, yc, z)

        def set_background_color(self, qcolor):
            # mask = np.uint32(255*self.imageparam.alpha+0.5).clip(0,255) << 24
            self.bg_qcolor = qcolor
            a, b, _bg, cmap = self.lut
            if qcolor is None:
                self.lut = (a, b, None, cmap)
            else:
                self.lut = (a, b, np.uint32(QColor(qcolor).rgb() & 0xFFFFFF), cmap)

        def set_color_map(self, name_or_table):
            if name_or_table is self.cmap_table:
                # This avoids rebuilding the LUT all the time
                return
            if isinstance(name_or_table, str):
                table = get_cmap(name_or_table)
            else:
                table = name_or_table
            self.cmap_table = table
            self.cmap = table.colorTable(FULLRANGE)
            cmap_a = self.lut[3]
            alpha = self.imageparam.alpha
            alpha_mask = self.imageparam.alpha_mask
            for i in range(LUT_SIZE):
                if alpha_mask:
                    pix_alpha = alpha * (i / float(LUT_SIZE - 1))
                else:
                    pix_alpha = alpha
                alpha_channel = max(min(np.uint32(255 * pix_alpha + 0.5), 255), 0) << 24
                cmap_a[i] = (
                    np.uint32((table.rgb(FULLRANGE, i / LUT_MAX)) & 0xFFFFFF)
                    | alpha_channel
                )
            plot = self.plot()
            if plot:
                plot.update_colormap_axis(self)

        def get_color_map(self):
            return self.cmap_table

        def get_color_map_name(self):
            return get_cmap_name(self.get_color_map())

        def set_interpolation(self, interp_mode, size=None):
            """
            Set image interpolation mode

            interp_mode: INTERP_NEAREST, INTERP_LINEAR, INTERP_AA
            size (integer): (for anti-aliasing only) AA matrix size
            """
            if interp_mode in (INTERP_NEAREST, INTERP_LINEAR):
                self.interpolate = (interp_mode,)
            if interp_mode == INTERP_AA:
                aa = np.ones((size, size), self.data.dtype)
                self.interpolate = (interp_mode, aa)

        def get_interpolation(self):
            """Get interpolation mode"""
            return self.interpolate

        def set_lut_range(self, lut_range):
            """
            Set LUT transform range
            *lut_range* is a tuple: (min, max)
            """
            self.min, self.max = lut_range
            _a, _b, bg, cmap = self.lut
            if self.max == self.min:
                self.lut = (LUT_MAX, self.min, bg, cmap)
            else:
                fmin, fmax = float(self.min), float(self.max)  # avoid overflows
                self.lut = (
                    LUT_MAX / (fmax - fmin),
                    -LUT_MAX * fmin / (fmax - fmin),
                    bg,
                    cmap,
                )

        def get_lut_range(self):
            """Return the LUT transform range tuple: (min, max)"""
            return self.min, self.max

        def get_lut_range_full(self):
            """Return full dynamic range"""
            return _nanmin(self.data), _nanmax(self.data)

        def get_lut_range_max(self):
            """Get maximum range for this dataset"""
            kind = self.data.dtype.kind
            if kind in np.typecodes["AllFloat"]:
                info = np.finfo(self.data.dtype)
            else:
                info = np.iinfo(self.data.dtype)
            return info.min, info.max

        def update_border(self):
            """Update image border rectangle to fit image shape"""
            bounds = self.boundingRect().getCoords()
            self.border_rect.set_rect(*bounds)

        def draw_border(self, painter, xMap, yMap, canvasRect):
            """Draw image border rectangle"""
            self.border_rect.draw(painter, xMap, yMap, canvasRect)

        def draw_image(self, painter, canvasRect, src_rect, dst_rect, xMap, yMap):
            """
            Draw image with painter on canvasRect

            .. warning::

                `src_rect` and `dst_rect` are coordinates tuples
                (xleft, ytop, xright, ybottom)
            """
            dest = _scale_rect(
                self.data, src_rect, self._offscreen, dst_rect, self.lut, self.interpolate
            )
            qrect = QRectF(QPointF(dest[0], dest[1]), QPointF(dest[2], dest[3]))
            painter.drawImage(qrect, self._image, qrect)

        def export_roi(
            self,
            src_rect,
            dst_rect,
            dst_image,
            apply_lut=False,
            apply_interpolation=False,
            original_resolution=False,
        ):
            """Export Region Of Interest to array"""
            if apply_lut:
                a, b, _bg, _cmap = self.lut
            else:
                a, b = 1.0, 0.0
            interp = self.interpolate if apply_interpolation else (INTERP_NEAREST,)
            _scale_rect(self.data, src_rect, dst_image, dst_rect, (a, b, None), interp)

        # ---- QwtPlotItem API -----------------------------------------------------
        def draw(self, painter, xMap, yMap, canvasRect):
            x1, y1, x2, y2 = canvasRect.getCoords()
            i1, i2 = xMap.invTransform(x1), xMap.invTransform(x2)
            j1, j2 = yMap.invTransform(y1), yMap.invTransform(y2)

            xl, yt, xr, yb = self.boundingRect().getCoords()
            dest = (
                xMap.transform(xl),
                yMap.transform(yt),
                xMap.transform(xr) + 1,
                yMap.transform(yb) + 1,
            )

            W = canvasRect.right()
            H = canvasRect.bottom()
            if self._offscreen.shape != (H, W):
                self._offscreen = np.empty((H, W), np.uint32)
                self._image = QImage(self._offscreen, W, H, QImage.Format_ARGB32)
                self._image.ndarray = self._offscreen
                self.notify_new_offscreen()
            self.draw_image(painter, canvasRect, (i1, j1, i2, j2), dest, xMap, yMap)
            self.draw_border(painter, xMap, yMap, canvasRect)

        def boundingRect(self):
            return self.bounds

        def notify_new_offscreen(self):
            # callback for those derived classes who need it
            pass

        def setVisible(self, enable):
            if not enable:
                self.unselect()  # when hiding item, unselect it
            if enable:
                self.border_rect.show()
            else:
                self.border_rect.hide()
            QwtPlotItem.setVisible(self, enable)

        # ---- IBasePlotItem API ----------------------------------------------------
        def types(self):
            return (
                IImageItemType,
                IVoiImageItemType,
                IColormapImageItemType,
                ITrackableItemType,
                ICSImageItemType,
                IExportROIImageItemType,
                IStatsImageItemType,
                IStatsImageItemType,
            )

        def set_readonly(self, state):
            """Set object readonly state"""
            self._readonly = state

        def is_readonly(self):
            """Return object readonly state"""
            return self._readonly

        def set_private(self, state):
            """Set object as private"""
            self._private = state

        def is_private(self):
            """Return True if object is private"""
            return self._private

        def select(self):
            """Select item"""
            self.selected = True
            self.border_rect.select()

        def unselect(self):
            """Unselect item"""
            self.selected = False
            self.border_rect.unselect()

        def is_empty(self):
            """Return True if item data is empty"""
            return self.data is None or self.data.size == 0

        def set_selectable(self, state):
            """Set item selectable state"""
            self._can_select = state

        def set_resizable(self, state):
            """Set item resizable state
            (or any action triggered when moving an handle, e.g. rotation)"""
            self._can_resize = state

        def set_movable(self, state):
            """Set item movable state"""
            self._can_move = state

        def set_rotatable(self, state):
            """Set item rotatable state"""
            self._can_rotate = state

        def can_select(self):
            return self._can_select

        def can_resize(self):
            return self._can_resize

        def can_move(self):
            return self._can_move

        def can_rotate(self):
            return self._can_rotate

        def hit_test(self, pos):
            plot = self.plot()
            ax = self.xAxis()
            ay = self.yAxis()
            return self.border_rect.poly_hit_test(plot, ax, ay, pos)

        def update_item_parameters(self):
            pass

        def get_item_parameters(self, itemparams):
            itemparams.add("ShapeParam", self, self.border_rect.shapeparam)

        def set_item_parameters(self, itemparams):
            self.border_rect.set_item_parameters(itemparams)

        def move_local_point_to(self, handle, pos, ctrl=None):
            """Move a handle as returned by hit_test to the new position pos
            ctrl: True if <Ctrl> button is being pressed, False otherwise"""
            pass

        def move_local_shape(self, old_pos, new_pos):
            """Translate the shape such that old_pos becomes new_pos
            in canvas coordinates"""
            pass

        def move_with_selection(self, delta_x, delta_y):
            """
            Translate the shape together with other selected items
            delta_x, delta_y: translation in plot coordinates
            """
            pass

        # ---- IBaseImageItem API --------------------------------------------------
        def can_setfullscale(self):
            return True

        def can_sethistogram(self):
            return False

        def get_histogram(self, nbins):
            """interface de IHistDataSource"""
            if self.data is None:
                return [
                    0,
                ], [0, 1]
            if self.histogram_cache is None or nbins != self.histogram_cache[0].shape[0]:
                if True:
                    res = np.histogram(self.data[~np.isnan(self.data)], nbins)
                else:
                    # TODO: _histogram is faster, but caching is buggy
                    # in this version
                    _min = _nanmin(self.data)
                    _max = _nanmax(self.data)
                    if self.data.dtype in (np.float64, np.float32):
                        bins = np.unique(
                            np.array(
                                np.linspace(_min, _max, nbins + 1), dtype=self.data.dtype
                            )
                        )
                    else:
                        bins = np.arange(_min, _max + 2, dtype=self.data.dtype)
                    res2 = np.zeros((bins.size + 1,), np.uint32)
                    _histogram(self.data.flatten(), bins, res2)
                    res = res2[1:-1], bins
                self.histogram_cache = res
            else:
                res = self.histogram_cache
            return res

        def __process_cross_section(self, ydata, apply_lut):
            if apply_lut:
                a, b, bg, cmap = self.lut
                return (ydata * a + b).clip(0, LUT_MAX)
            else:
                return ydata

        def get_stats(self, x0, y0, x1, y1):
            """Return formatted string with stats on image rectangular area
            (output should be compatible with AnnotatedShape.get_infos)"""
            ix0, iy0, ix1, iy1 = self.get_closest_index_rect(x0, y0, x1, y1)
            data = self.data[iy0:iy1, ix0:ix1]
            xfmt = self.imageparam.xformat
            yfmt = self.imageparam.yformat
            zfmt = self.imageparam.zformat
            return "<br>".join(
                [
                    "<b>%s</b>" % self.imageparam.label,
                    "%sx%s %s"
                    % (self.data.shape[1], self.data.shape[0], str(self.data.dtype)),
                    "",
                    "%s ≤ x ≤ %s" % (xfmt % x0, xfmt % x1),
                    "%s ≤ y ≤ %s" % (yfmt % y0, yfmt % y1),
                    "%s ≤ z ≤ %s" % (zfmt % data.min(), zfmt % data.max()),
                    "‹z› = " + zfmt % data.mean(),
                    "σ(z) = " + zfmt % data.std(),
                ]
            )

        def get_xsection(self, y0, apply_lut=False):
            """Return cross section along x-axis at y=y0"""
            _ix, iy = self.get_closest_indexes(0, y0)
            return (
                self.get_x_values(0, self.data.shape[1]),
                self.__process_cross_section(self.data[iy, :], apply_lut),
            )

        def get_ysection(self, x0, apply_lut=False):
            """Return cross section along y-axis at x=x0"""
            ix, _iy = self.get_closest_indexes(x0, 0)
            return (
                self.get_y_values(0, self.data.shape[0]),
                self.__process_cross_section(self.data[:, ix], apply_lut),
            )

        def get_average_xsection(self, x0, y0, x1, y1, apply_lut=False):
            """Return average cross section along x-axis"""
            ix0, iy0, ix1, iy1 = self.get_closest_index_rect(x0, y0, x1, y1)
            ydata = self.data[iy0:iy1, ix0:ix1].mean(axis=0)
            return (
                self.get_x_values(ix0, ix1),
                self.__process_cross_section(ydata, apply_lut),
            )

        def get_average_ysection(self, x0, y0, x1, y1, apply_lut=False):
            """Return average cross section along y-axis"""
            ix0, iy0, ix1, iy1 = self.get_closest_index_rect(x0, y0, x1, y1)
            ydata = self.data[iy0:iy1, ix0:ix1].mean(axis=1)
            return (
                self.get_y_values(iy0, iy1),
                self.__process_cross_section(ydata, apply_lut),
            )

    assert_interfaces_valid(BaseImageItem)

    # ==============================================================================
    # Raw Image item (image item without scale)
    # ==============================================================================

    class RawImageItem(BaseImageItem):
        """
        Construct a simple image item

            * data: 2D NumPy array
            * param (optional): image parameters
              (:py:class:`guiqwt.styles.RawImageParam` instance)
        """

        __implements__ = (
            IBasePlotItem,
            IBaseImageItem,
            IHistDataSource,
            IVoiImageItemType,
            ISerializableType,
        )
        # ---- BaseImageItem API ---------------------------------------------------

        def get_default_param(self):
            """Return instance of the default imageparam DataSet"""
            return RawImageParam(_("Image"))

        # ---- Serialization methods -----------------------------------------------
        def __reduce__(self):
            fname = self.get_filename()
            if fname is None:
                fn_or_data = self.data
            else:
                fn_or_data = fname
            state = self.imageparam, self.get_lut_range(), fn_or_data, self.z()
            res = (self.__class__, (), state)
            return res

        def __setstate__(self, state):
            param, lut_range, fn_or_data, z = state
            self.imageparam = param
            if isinstance(fn_or_data, str):
                self.set_filename(fn_or_data)
                self.load_data()
            elif fn_or_data is not None:  # should happen only with previous API
                self.set_data(fn_or_data)
            self.set_lut_range(lut_range)
            self.setZ(z)
            self.imageparam.update_image(self)

        def serialize(self, writer):
            """Serialize object to HDF5 writer"""
            fname = self.get_filename()
            load_from_fname = fname is not None
            data = None if load_from_fname else self.data
            writer.write(load_from_fname, group_name="load_from_fname")
            writer.write(fname, group_name="fname")
            writer.write(data, group_name="Zdata")
            writer.write(self.get_lut_range(), group_name="lut_range")
            writer.write(self.z(), group_name="z")
            self.imageparam.update_param(self)
            writer.write(self.imageparam, group_name="imageparam")

        def deserialize(self, reader):
            """Deserialize object from HDF5 reader"""
            lut_range = reader.read(group_name="lut_range")
            if reader.read(group_name="load_from_fname"):
                self.set_filename(reader.read(group_name="fname", func=reader.read_unicode))
                self.load_data()
            else:
                data = reader.read(group_name="Zdata", func=reader.read_array)
                self.set_data(data)
            self.set_lut_range(lut_range)
            self.setZ(reader.read("z"))
            self.imageparam = self.get_default_param()
            reader.read("imageparam", instance=self.imageparam)
            self.imageparam.update_image(self)

        # ---- Public API ----------------------------------------------------------

        def load_data(self, lut_range=None):
            """
            Load data from *filename* and eventually apply specified lut_range
            *filename* has been set using method 'set_filename'
            """
            data = io.imread(self.get_filename(), to_grayscale=True)
            self.set_data(data, lut_range=lut_range)

        def set_data(self, data, lut_range=None):
            """
            Set Image item data

                * data: 2D NumPy array
                * lut_range: LUT range -- tuple (levelmin, levelmax)
            """
            if lut_range is not None:
                _min, _max = lut_range
            else:
                _min, _max = _nanmin(data), _nanmax(data)

            self.data = data
            self.histogram_cache = None
            self.update_bounds()
            self.update_border()
            self.set_lut_range([_min, _max])

        def update_bounds(self):
            if self.data is None:
                return
            self.bounds = QRectF(0, 0, self.data.shape[1], self.data.shape[0])

        # ---- IBasePlotItem API ---------------------------------------------------
        def types(self):
            return (
                IImageItemType,
                IVoiImageItemType,
                IColormapImageItemType,
                ITrackableItemType,
                ICSImageItemType,
                ISerializableType,
                IExportROIImageItemType,
                IStatsImageItemType,
            )

        def update_item_parameters(self):
            self.imageparam.update_param(self)

        def get_item_parameters(self, itemparams):
            BaseImageItem.get_item_parameters(self, itemparams)
            self.update_item_parameters()
            itemparams.add("ImageParam", self, self.imageparam)

        def set_item_parameters(self, itemparams):
            update_dataset(self.imageparam, itemparams.get("ImageParam"), visible_only=True)
            self.imageparam.update_image(self)
            BaseImageItem.set_item_parameters(self, itemparams)

        # ---- IBaseImageItem API --------------------------------------------------
        def can_setfullscale(self):
            return True

        def can_sethistogram(self):
            return True

    assert_interfaces_valid(RawImageItem)

    # ==============================================================================
    # Image item
    # ==============================================================================

    class ImageItem(RawImageItem):
        """
        Construct a simple image item

            * data: 2D NumPy array
            * param (optional): image parameters
              (:py:class:`guiqwt.styles.ImageParam` instance)
        """

        __implements__ = (
            IBasePlotItem,
            IBaseImageItem,
            IHistDataSource,
            IVoiImageItemType,
            IExportROIImageItemType,
        )

        def __init__(self, data=None, param=None):
            self.xmin = None
            self.xmax = None
            self.ymin = None
            self.ymax = None
            super(ImageItem, self).__init__(data=data, param=param)

        # ---- BaseImageItem API ---------------------------------------------------

        def get_default_param(self):
            """Return instance of the default imageparam DataSet"""
            return ImageParam(_("Image"))

        # ---- Serialization methods -----------------------------------------------
        def __reduce__(self):
            fname = self.get_filename()
            if fname is None:
                fn_or_data = self.data
            else:
                fn_or_data = fname
            (xmin, xmax), (ymin, ymax) = self.get_xdata(), self.get_ydata()
            state = (
                self.imageparam,
                self.get_lut_range(),
                fn_or_data,
                self.z(),
                xmin,
                xmax,
                ymin,
                ymax,
            )
            res = (self.__class__, (), state)
            return res

        def __setstate__(self, state):
            param, lut_range, fn_or_data, z, xmin, xmax, ymin, ymax = state
            self.set_xdata(xmin, xmax)
            self.set_ydata(ymin, ymax)
            self.imageparam = param
            if isinstance(fn_or_data, str):
                self.set_filename(fn_or_data)
                self.load_data()
            elif fn_or_data is not None:  # should happen only with previous API
                self.set_data(fn_or_data)
            self.set_lut_range(lut_range)
            self.setZ(z)
            self.imageparam.update_image(self)

        def serialize(self, writer):
            """Serialize object to HDF5 writer"""
            super(ImageItem, self).serialize(writer)
            (xmin, xmax), (ymin, ymax) = self.get_xdata(), self.get_ydata()
            writer.write(xmin, group_name="xmin")
            writer.write(xmax, group_name="xmax")
            writer.write(ymin, group_name="ymin")
            writer.write(ymax, group_name="ymax")

        def deserialize(self, reader):
            """Deserialize object from HDF5 reader"""
            super(ImageItem, self).deserialize(reader)
            for attr in ("xmin", "xmax", "ymin", "ymax"):
                # Note: do not be tempted to write the symetric code in `serialize`
                # because calling `get_xdata` and `get_ydata` is necessary
                setattr(self, attr, reader.read(attr, func=reader.read_float))

        # ---- Public API ----------------------------------------------------------

        def get_xdata(self, aligned=True):
            """Return (xmin, xmax)"""
            xmin, xmax = self.xmin, self.xmax
            if xmin is None:
                xmin = 0.0
            if xmax is None:
                xmax = self.data.shape[1]
            if aligned:
                dx = 0.5 * (xmax - xmin) / self.data.shape[1]
                xmin -= dx
                xmax -= dx
            return xmin, xmax

        def get_ydata(self, aligned=True):
            """Return (ymin, ymax)"""
            ymin, ymax = self.ymin, self.ymax
            if ymin is None:
                ymin = 0.0
            if ymax is None:
                ymax = self.data.shape[0]
            if aligned:
                dy = 0.5 * (ymax - ymin) / self.data.shape[0]
                ymin -= dy
                ymax -= dy
            return ymin, ymax

        def set_xdata(self, xmin=None, xmax=None):
            self.xmin, self.xmax = xmin, xmax

        def set_ydata(self, ymin=None, ymax=None):
            self.ymin, self.ymax = ymin, ymax

        def update_bounds(self):
            if self.data is None:
                return
            (xmin, xmax), (ymin, ymax) = self.get_xdata(), self.get_ydata()
            self.bounds = QRectF(QPointF(xmin, ymin), QPointF(xmax, ymax))

        # ---- BaseImageItem API ---------------------------------------------------

        def get_pixel_coordinates(self, xplot, yplot):
            """Return (image) pixel coordinates (from plot coordinates)"""
            (xmin, xmax), (ymin, ymax) = self.get_xdata(), self.get_ydata()
            xpix = self.data.shape[1] * (xplot - xmin) / float(xmax - xmin)
            ypix = self.data.shape[0] * (yplot - ymin) / float(ymax - ymin)
            return xpix, ypix

        def get_plot_coordinates(self, xpixel, ypixel):
            """Return plot coordinates (from image pixel coordinates)"""
            (xmin, xmax), (ymin, ymax) = self.get_xdata(), self.get_ydata()
            xplot = xmin + (xmax - xmin) * xpixel / float(self.data.shape[1])
            yplot = ymin + (ymax - ymin) * ypixel / float(self.data.shape[0])
            return xplot, yplot

        def get_x_values(self, i0, i1):
            xmin, xmax = self.get_xdata()
            xfunc = lambda index: xmin + (xmax - xmin) * index / float(self.data.shape[1])
            return np.linspace(xfunc(i0), xfunc(i1), i1 - i0)

        def get_y_values(self, j0, j1):
            ymin, ymax = self.get_ydata()
            yfunc = lambda index: ymin + (ymax - ymin) * index / float(self.data.shape[0])
            return np.linspace(yfunc(j0), yfunc(j1), j1 - j0)

        def get_closest_coordinates(self, x, y):
            """Return closest image pixel coordinates"""
            xmin, xmax = self.get_xdata(aligned=False)
            ymin, ymax = self.get_ydata(aligned=False)
            i, j = self.get_closest_indexes(x, y)
            xpix = np.linspace(xmin, xmax, self.data.shape[1] + 1)
            ypix = np.linspace(ymin, ymax, self.data.shape[0] + 1)
            return xpix[i], ypix[j]

        def _rescale_src_rect(self, src_rect):
            sxl, syt, sxr, syb = src_rect
            xl, yt, xr, yb = self.boundingRect().getCoords()
            H, W = self.data.shape[:2]
            x0 = W * (sxl - xl) / (xr - xl)
            x1 = W * (sxr - xl) / (xr - xl)
            y0 = H * (syt - yt) / (yb - yt)
            y1 = H * (syb - yt) / (yb - yt)
            return x0, y0, x1, y1

        def draw_image(self, painter, canvasRect, src_rect, dst_rect, xMap, yMap):
            if self.data is None:
                return
            src2 = self._rescale_src_rect(src_rect)
            dst_rect = tuple([int(i) for i in dst_rect])
            try:
                dest = _scale_rect(
                    self.data, src2, self._offscreen, dst_rect, self.lut, self.interpolate
                )
            except ValueError:
                # This exception is raised when zooming unreasonably inside a pixel
                return
            qrect = QRectF(QPointF(dest[0], dest[1]), QPointF(dest[2], dest[3]))
            painter.drawImage(qrect, self._image, qrect)

        def export_roi(
            self,
            src_rect,
            dst_rect,
            dst_image,
            apply_lut=False,
            apply_interpolation=False,
            original_resolution=False,
        ):
            """Export Region Of Interest to array"""
            if apply_lut:
                a, b, _bg, _cmap = self.lut
            else:
                a, b = 1.0, 0.0
            interp = self.interpolate if apply_interpolation else (INTERP_NEAREST,)
            _scale_rect(
                self.data,
                self._rescale_src_rect(src_rect),
                dst_image,
                dst_rect,
                (a, b, None),
                interp,
            )

    assert_interfaces_valid(ImageItem)

    # ==============================================================================
    # QuadGrid item
    # ==============================================================================
    class QuadGridItem(RawImageItem):
        """
        Construct a QuadGrid image

            * X, Y, Z: A structured grid of quadrilaterals
              each quad is defined by (X[i], Y[i]), (X[i], Y[i+1]),
              (X[i+1], Y[i+1]), (X[i+1], Y[i])
            * param (optional): image parameters (ImageParam instance)
        """

        __implements__ = (IBasePlotItem, IBaseImageItem, IHistDataSource, IVoiImageItemType)

        def __init__(self, X, Y, Z, param=None):
            assert X is not None
            assert Y is not None
            assert Z is not None
            self.X = X
            self.Y = Y
            assert X.shape == Y.shape
            assert Z.shape == X.shape
            super(QuadGridItem, self).__init__(Z, param)
            self.set_data(Z)
            self.grid = 1
            self.interpolate = (0, 0.5, 0.5)
            self.imageparam.update_image(self)

        # ---- BaseImageItem API ---------------------------------------------------
        def get_default_param(self):
            """Return instance of the default imageparam DataSet"""
            return QuadGridParam(_("Quadrilaterals"))

        def types(self):
            return (
                IImageItemType,
                IVoiImageItemType,
                IColormapImageItemType,
                ITrackableItemType,
            )

        def update_bounds(self):
            xmin = self.X.min()
            xmax = self.X.max()
            ymin = self.Y.min()
            ymax = self.Y.max()
            self.bounds = QRectF(xmin, ymin, xmax - xmin, ymax - ymin)

        def set_data(self, data, X=None, Y=None, lut_range=None):
            """
            Set Image item data

                * data: 2D NumPy array
                * lut_range: LUT range -- tuple (levelmin, levelmax)
            """
            if lut_range is not None:
                _min, _max = lut_range
            else:
                _min, _max = _nanmin(data), _nanmax(data)

            self.data = data
            self.histogram_cache = None
            if X is not None:
                assert Y is not None
                self.X = X
                self.Y = Y
            self.update_bounds()
            self.update_border()
            self.set_lut_range([_min, _max])

        def draw_image(self, painter, canvasRect, src_rect, dst_rect, xMap, yMap):
            self._offscreen[...] = np.uint32(0)
            dest = _scale_quads(
                self.X,
                self.Y,
                self.data,
                src_rect,
                self._offscreen,
                dst_rect,
                self.lut,
                self.interpolate,
                self.grid,
            )
            qrect = QRectF(QPointF(dest[0], dest[1]), QPointF(dest[2], dest[3]))
            painter.drawImage(qrect, self._image, qrect)
            xl, yt, xr, yb = dest
            self._offscreen[yt:yb, xl:xr] = 0

        def notify_new_offscreen(self):
            # we always ensure the offscreen is clean before drawing
            self._offscreen[...] = 0

    assert_interfaces_valid(QuadGridItem)

    # ==============================================================================
    # Image with a custom linear transform
    # ==============================================================================

    class TrImageItem(RawImageItem):
        """
        Construct a transformable image item

            * data: 2D NumPy array
            * param (optional): image parameters
              (:py:class:`guiqwt.styles.TrImageParam` instance)
        """

        __implements__ = (IBasePlotItem, IBaseImageItem, IExportROIImageItemType)
        _can_select = True
        _can_resize = True
        _can_rotate = True
        _can_move = True

        def __init__(self, data=None, param=None):
            self.tr = np.eye(3, dtype=float)
            self.itr = np.eye(3, dtype=float)
            self.points = np.array([[0, 0, 2, 2], [0, 2, 2, 0], [1, 1, 1, 1]], float)
            super(TrImageItem, self).__init__(data, param)

        # ---- BaseImageItem API ---------------------------------------------------

        def get_default_param(self):
            """Return instance of the default imageparam DataSet"""
            return TrImageParam(_("Image"))

        # ---- Public API ----------------------------------------------------------
        def set_transform(self, x0, y0, angle, dx=1.0, dy=1.0, hflip=False, vflip=False):
            self.imageparam.set_transform(x0, y0, angle, dx, dy, hflip, vflip)
            if self.data is None:
                return
            ni, nj = self.data.shape
            rot = rotate(-angle)
            tr1 = translate(nj / 2.0 + 0.5, ni / 2.0 + 0.5)
            xflip = -1.0 if hflip else 1.0
            yflip = -1.0 if vflip else 1.0
            sc = scale(xflip / dx, yflip / dy)
            tr2 = translate(-x0, -y0)
            self.tr = tr1 * sc * rot * tr2
            self.itr = self.tr.I
            self.compute_bounds()

        def get_transform(self):
            return self.imageparam.get_transform()

        def debug_transform(self, pt):
            x0, y0, angle, dx, dy, _hflip, _vflip = self.get_transform()
            ni, nj = self.data.shape
            rot = rotate(-angle)
            tr1 = translate(ni / 2.0 + 0.5, nj / 2.0 + 0.5)
            sc = scale(dx, dy)
            tr2 = translate(-x0, -y0)
            p1 = tr1.I * pt
            p2 = rot.I * pt
            p3 = sc.I * pt
            p4 = tr2.I * pt
            print("src=", pt.T)
            print("tr1:", p1.T)
            print("tr1+rot:", p2.T)
            print("tr1+rot+sc:", p3.T)
            print("tr1+rot+tr2:", p4.T)

        def set_crop(self, left, top, right, bottom):
            self.imageparam.set_crop(left, top, right, bottom)

        def get_crop(self):
            return self.imageparam.get_crop()

        def get_crop_coordinates(self):
            """Return crop rectangle coordinates"""
            tpos = np.array(np.dot(self.itr, self.points))
            xmin, ymin, _ = tpos.min(axis=1).flatten()
            xmax, ymax, _ = tpos.max(axis=1).flatten()
            left, top, right, bottom = self.imageparam.get_crop()
            return (xmin + left, ymin + top, xmax - right, ymax - bottom)

        def compute_bounds(self):
            x0, y0, x1, y1 = self.get_crop_coordinates()
            self.bounds = QRectF(QPointF(x0, y0), QPointF(x1, y1))
            self.update_border()

        # --- RawImageItem API -----------------------------------------------------

        def set_data(self, data, lut_range=None):
            RawImageItem.set_data(self, data, lut_range)
            ni, nj = self.data.shape
            self.points = np.array([[0, 0, nj, nj], [0, ni, ni, 0], [1, 1, 1, 1]], float)
            self.compute_bounds()

        # --- BaseImageItem API ----------------------------------------------------

        def get_filter(self, filterobj, filterparam):
            """Provides a filter object over this image's content"""
            raise NotImplementedError

            # TODO: Implement TrImageFilterItem

        #        return TrImageFilterItem(self, filterobj, filterparam)

        def get_pixel_coordinates(self, xplot, yplot):
            """Return (image) pixel coordinates (from plot coordinates)"""
            v = self.tr * colvector(xplot, yplot)
            xpixel, ypixel, _ = v[:, 0]
            return xpixel, ypixel

        def get_plot_coordinates(self, xpixel, ypixel):
            """Return plot coordinates (from image pixel coordinates)"""
            v0 = self.itr * colvector(xpixel, ypixel)
            xplot, yplot, _ = v0[:, 0].A.ravel()
            return xplot, yplot

        def get_x_values(self, i0, i1):
            v0 = self.itr * colvector(i0, 0)
            x0, _y0, _ = v0[:, 0].A.ravel()
            v1 = self.itr * colvector(i1, 0)
            x1, _y1, _ = v1[:, 0].A.ravel()
            return np.linspace(x0, x1, i1 - i0)

        def get_y_values(self, j0, j1):
            v0 = self.itr * colvector(0, j0)
            _x0, y0, _ = v0[:, 0].A.ravel()
            v1 = self.itr * colvector(0, j1)
            _x1, y1, _ = v1[:, 0].A.ravel()
            return np.linspace(y0, y1, j1 - j0)

        def get_closest_coordinates(self, x, y):
            """Return closest image pixel coordinates"""
            xi, yi = self.get_closest_indexes(x, y)
            v = self.itr * colvector(xi, yi)
            x, y, _ = v[:, 0].A.ravel()
            return x, y

        def update_border(self):
            tpos = np.dot(self.itr, self.points)
            self.border_rect.set_points(tpos.T[:, :2])

        def draw_border(self, painter, xMap, yMap, canvasRect):
            self.border_rect.draw(painter, xMap, yMap, canvasRect)

        def draw_image(self, painter, canvasRect, src_rect, dst_rect, xMap, yMap):
            W = canvasRect.width()
            H = canvasRect.height()
            if W <= 1 or H <= 1:
                return

            x0, y0, x1, y1 = src_rect
            cx = canvasRect.left()
            cy = canvasRect.top()
            sx = (x1 - x0) / (W - 1)
            sy = (y1 - y0) / (H - 1)
            # tr1 = tr(x0,y0)*scale(sx,sy)*tr(-cx,-cy)
            tr = np.matrix([[sx, 0, x0 - cx * sx], [0, sy, y0 - cy * sy], [0, 0, 1]], float)
            mat = self.tr * tr

            dst_rect = tuple([int(i) for i in dst_rect])
            dest = _scale_tr(
                self.data, mat, self._offscreen, dst_rect, self.lut, self.interpolate
            )
            qrect = QRectF(QPointF(dest[0], dest[1]), QPointF(dest[2], dest[3]))
            painter.drawImage(qrect, self._image, qrect)

        def export_roi(
            self,
            src_rect,
            dst_rect,
            dst_image,
            apply_lut=False,
            apply_interpolation=False,
            original_resolution=False,
        ):
            """Export Region Of Interest to array"""
            if apply_lut:
                a, b, _bg, _cmap = self.lut
            else:
                a, b = 1.0, 0.0

            xs0, ys0, xs1, ys1 = src_rect
            xd0, yd0, xd1, yd1 = dst_rect

            if original_resolution:
                _t1, _t2, _t3, xscale, yscale, _t4, _t5 = self.get_transform()
            else:
                xscale, yscale = (
                    (xs1 - xs0) / float(xd1 - xd0),
                    (ys1 - ys0) / float(yd1 - yd0),
                )

            mat = self.tr * (translate(xs0, ys0) * scale(xscale, yscale))

            x0, y0, x1, y1 = self.get_crop_coordinates()
            xd0 = max([xd0, xd0 + int((x0 - xs0) / xscale)])
            yd0 = max([yd0, yd0 + int((y0 - ys0) / xscale)])
            xd1 = min([xd1, xd1 + int((x1 - xs1) / xscale)])
            yd1 = min([yd1, yd1 + int((y1 - ys1) / xscale)])
            dst_rect = xd0, yd0, xd1, yd1

            interp = self.interpolate if apply_interpolation else (INTERP_NEAREST,)
            _scale_tr(self.data, mat, dst_image, dst_rect, (a, b, None), interp)

        # ---- IBasePlotItem API ---------------------------------------------------

        def move_local_point_to(self, handle, pos, ctrl=None):
            """Move a handle as returned by hit_test to the new position pos
            ctrl: True if <Ctrl> button is being pressed, False otherwise"""
            x0, y0, angle, dx, dy, hflip, vflip = self.get_transform()
            nx, ny = canvas_to_axes(self, pos)
            handles = self.itr * self.points
            p0 = colvector(nx, ny)
            # self.debug_transform(p0)
            center = handles.sum(axis=1) / 4
            vec0 = handles[:, handle] - center
            vec1 = p0 - center
            a0 = np.arctan2(vec0[1, 0], vec0[0, 0])
            a1 = np.arctan2(vec1[1, 0], vec1[0, 0])
            if self.can_rotate():
                # compute angles
                angle += a1 - a0
            if self.can_resize():
                # compute pixel size
                zoom = np.linalg.norm(vec1) / np.linalg.norm(vec0)
                dx = zoom * dx
                dy = zoom * dy
            self.set_transform(x0, y0, angle, dx, dy, hflip, vflip)
            if self.plot():
                self.plot().SIG_ITEM_HANDLE_MOVED.emit(self)

        def move_local_shape(self, old_pos, new_pos):
            """Translate the shape such that old_pos becomes new_pos
            in canvas coordinates"""
            x0, y0, angle, dx, dy, hflip, vflip = self.get_transform()
            nx, ny = canvas_to_axes(self, new_pos)
            ox, oy = canvas_to_axes(self, old_pos)
            self.set_transform(x0 + nx - ox, y0 + ny - oy, angle, dx, dy, hflip, vflip)
            if self.plot():
                self.plot().SIG_ITEM_MOVED.emit(self, ox, oy, nx, ny)

        def move_with_selection(self, delta_x, delta_y):
            """
            Translate the shape together with other selected items
            delta_x, delta_y: translation in plot coordinates
            """
            x0, y0, angle, dx, dy, hflip, vflip = self.get_transform()
            self.set_transform(x0 + delta_x, y0 + delta_y, angle, dx, dy, hflip, vflip)

    assert_interfaces_valid(TrImageItem)

    def assemble_imageitems(
        items,
        src_qrect,
        destw,
        desth,
        align=None,
        add_images=False,
        apply_lut=False,
        apply_interpolation=False,
        original_resolution=False,
    ):
        """
        Assemble together image items in qrect (`QRectF` object)
        and return resulting pixel data

        .. warning::

            Does not support `XYImageItem` objects
        """
        # align width to 'align' bytes
        if align is not None:
            print(
                "guiqwt.image.assemble_imageitems: since v2.2, "
                "the `align` option is ignored",
                file=sys.stderr,
            )
        align = 1  # XXX: byte alignment is disabled until further notice!
        aligned_destw = int(align * ((int(destw) + align - 1) / align))
        aligned_desth = int(desth * aligned_destw / destw)

        try:
            output = np.zeros((aligned_desth, aligned_destw), np.float32)
        except ValueError:
            raise MemoryError
        if not add_images:
            dst_image = output

        dst_rect = (0, 0, aligned_destw, aligned_desth)

        src_rect = list(src_qrect.getCoords())
        # The source QRect is generally coming from a rectangle shape which is
        # adjusted to fit a given ROI on the image. So the rectangular area is
        # aligned with image pixel edges: to avoid any rounding error, we reduce
        # the rectangle area size by one half of a pixel, so that the area is now
        # aligned with the center of image pixels.
        pixel_width = src_qrect.width() / float(destw)
        pixel_height = src_qrect.height() / float(desth)
        src_rect[0] += 0.5 * pixel_width
        src_rect[1] += 0.5 * pixel_height
        src_rect[2] -= 0.5 * pixel_width
        src_rect[3] -= 0.5 * pixel_height

        for it in sorted(items, key=lambda obj: -obj.z()):
            if it.isVisible() and src_qrect.intersects(it.boundingRect()):
                if add_images:
                    dst_image = np.zeros_like(output)
                it.export_roi(
                    src_rect=src_rect,
                    dst_rect=dst_rect,
                    dst_image=dst_image,
                    apply_lut=apply_lut,
                    apply_interpolation=apply_interpolation,
                    original_resolution=original_resolution,
                )
                if add_images:
                    output += dst_image
        return output

    def get_plot_qrect(plot, p0, p1):
        """
        Return `QRectF` rectangle object in plot coordinates
        from top-left and bottom-right `QPointF` objects in canvas coordinates
        """
        ax, ay = plot.X_BOTTOM, plot.Y_LEFT
        p0x, p0y = plot.invTransform(ax, p0.x()), plot.invTransform(ay, p0.y())
        p1x, p1y = plot.invTransform(ax, p1.x() + 1), plot.invTransform(ay, p1.y() + 1)
        return QRectF(p0x, p0y, p1x - p0x, p1y - p0y)

    def get_items_in_rectangle(plot, p0, p1, item_type=None):
        """Return items which bounding rectangle intersects (p0, p1)
        item_type: default is `IExportROIImageItemType`"""
        if item_type is None:
            item_type = IExportROIImageItemType
        items = plot.get_items(item_type=item_type)
        src_qrect = get_plot_qrect(plot, p0, p1)
        return [it for it in items if src_qrect.intersects(it.boundingRect())]

    def compute_trimageitems_original_size(items, src_w, src_h):
        """Compute `TrImageItem` original size from max dx and dy"""
        trparams = [item.get_transform() for item in items if isinstance(item, TrImageItem)]
        if trparams:
            dx_max = max([dx for _x, _y, _angle, dx, _dy, _hf, _vf in trparams])
            dy_max = max([dy for _x, _y, _angle, _dx, dy, _hf, _vf in trparams])
            return src_w / dx_max, src_h / dy_max
        else:
            return src_w, src_h

    def get_image_from_qrect(
        plot,
        p0,
        p1,
        src_size=None,
        adjust_range=None,
        item_type=None,
        apply_lut=False,
        apply_interpolation=False,
        original_resolution=False,
        add_images=False,
    ):
        """Return image array from `QRect` area (p0 and p1 are respectively the
        top-left and bottom-right `QPointF` objects)

        adjust_range: None (return raw data, dtype=np.float32), 'original'
        (return data with original data type), 'normalize' (normalize range with
        original data type)"""
        assert adjust_range in (None, "normalize", "original")
        items = get_items_in_rectangle(plot, p0, p1, item_type=item_type)
        if not items:
            raise TypeError(_("There is no supported image item in current plot."))
        if src_size is None:
            _src_x, _src_y, src_w, src_h = get_plot_qrect(plot, p0, p1).getRect()
        else:
            # The only benefit to pass the src_size list is to avoid any
            # rounding error in the transformation computed in `get_plot_qrect`
            src_w, src_h = src_size
        destw, desth = compute_trimageitems_original_size(items, src_w, src_h)
        data = get_image_from_plot(
            plot,
            p0,
            p1,
            destw=destw,
            desth=desth,
            apply_lut=apply_lut,
            add_images=add_images,
            apply_interpolation=apply_interpolation,
            original_resolution=original_resolution,
        )
        if adjust_range is None:
            return data
        dtype = None
        for item in items:
            if dtype is None or item.data.dtype.itemsize > dtype.itemsize:
                dtype = item.data.dtype
        if adjust_range == "normalize":
            from guiqwt import io

            data = io.scale_data_to_dtype(data, dtype=dtype)
        else:
            data = np.array(data, dtype=dtype)
        return data

    def get_image_in_shape(
        obj, norm_range=False, item_type=None, apply_lut=False, apply_interpolation=False
    ):
        """Return image array from rectangle shape"""
        x0, y0, x1, y1 = obj.get_rect()
        (x0, x1), (y0, y1) = sorted([x0, x1]), sorted([y0, y1])
        xc0, yc0 = axes_to_canvas(obj, x0, y0)
        xc1, yc1 = axes_to_canvas(obj, x1, y1)
        adjust_range = "normalize" if norm_range else "original"
        return get_image_from_qrect(
            obj.plot(),
            QPointF(xc0, yc0),
            QPointF(xc1, yc1),
            src_size=(x1 - x0, y1 - y0),
            adjust_range=adjust_range,
            item_type=item_type,
            apply_lut=apply_lut,
            apply_interpolation=apply_interpolation,
            original_resolution=True,
        )

    def get_image_from_plot(
        plot,
        p0,
        p1,
        destw=None,
        desth=None,
        add_images=False,
        apply_lut=False,
        apply_interpolation=False,
        original_resolution=False,
    ):
        """
        Return pixel data of a rectangular plot area (image items only)
        p0, p1: resp. top-left and bottom-right points (`QPointF` objects)
        apply_lut: apply contrast settings
        add_images: add superimposed images (instead of replace by the foreground)

        .. warning::

            Support only the image items implementing the `IExportROIImageItemType`
            interface, i.e. this does *not* support `XYImageItem` objects
        """
        if destw is None:
            destw = p1.x() - p0.x() + 1
        if desth is None:
            desth = p1.y() - p0.y() + 1
        items = plot.get_items(item_type=IExportROIImageItemType)
        qrect = get_plot_qrect(plot, p0, p1)
        return assemble_imageitems(
            items,
            qrect,
            destw,
            desth,  # align=4,
            add_images=add_images,
            apply_lut=apply_lut,
            apply_interpolation=apply_interpolation,
            original_resolution=original_resolution,
        )

    # ==============================================================================
    # Image with custom X, Y axes
    # ==============================================================================
    def to_bins(x):
        """Convert point center to point bounds"""
        bx = np.zeros((x.shape[0] + 1,), float)
        bx[1:-1] = (x[:-1] + x[1:]) / 2
        bx[0] = x[0] - (x[1] - x[0]) / 2
        bx[-1] = x[-1] + (x[-1] - x[-2]) / 2
        return bx

    class XYImageItem(RawImageItem):
        """
        Construct an image item with non-linear X/Y axes

            * x: 1D NumPy array, must be increasing
            * y: 1D NumPy array, must be increasing
            * data: 2D NumPy array
            * param (optional): image parameters
              (:py:class:`guiqwt.styles.XYImageParam` instance)
        """

        __implements__ = (IBasePlotItem, IBaseImageItem, ISerializableType)

        def __init__(self, x=None, y=None, data=None, param=None):
            # if x and y are not increasing arrays, sort them and data accordingly
            if not np.all(np.diff(x) >= 0):
                x_idx = np.argsort(x)
                x = x[x_idx]
                data = data[:, x_idx]
            if not np.all(np.diff(y) >= 0):
                y_idx = np.argsort(y)
                y = y[y_idx]
                data = data[y_idx, :]
            super(XYImageItem, self).__init__(data, param)
            self.x = None
            self.y = None
            if x is not None and y is not None:
                self.set_xy(x, y)

        # ---- BaseImageItem API ---------------------------------------------------

        def get_default_param(self):
            """Return instance of the default imageparam DataSet"""
            return XYImageParam(_("Image"))

        # ---- Pickle methods ------------------------------------------------------
        def __reduce__(self):
            fname = self.get_filename()
            if fname is None:
                fn_or_data = self.data
            else:
                fn_or_data = fname
            state = (
                self.imageparam,
                self.get_lut_range(),
                self.x,
                self.y,
                fn_or_data,
                self.z(),
            )
            res = (self.__class__, (), state)
            return res

        def __setstate__(self, state):
            param, lut_range, x, y, fn_or_data, z = state
            self.imageparam = param
            if isinstance(fn_or_data, str):
                self.set_filename(fn_or_data)
                self.load_data(lut_range)
            elif fn_or_data is not None:  # should happen only with previous API
                self.set_data(fn_or_data, lut_range=lut_range)
            self.set_xy(x, y)
            self.setZ(z)
            self.imageparam.update_image(self)

        def serialize(self, writer):
            """Serialize object to HDF5 writer"""
            super(XYImageItem, self).serialize(writer)
            writer.write(self.x, group_name="Xdata")
            writer.write(self.y, group_name="Ydata")

        def deserialize(self, reader):
            """Deserialize object from HDF5 reader"""
            super(XYImageItem, self).deserialize(reader)
            x = reader.read(group_name="Xdata", func=reader.read_array)
            y = reader.read(group_name="Ydata", func=reader.read_array)
            self.set_xy(x, y)

        # ---- Public API ----------------------------------------------------------
        def set_xy(self, x, y):
            ni, nj = self.data.shape
            x = np.array(x, float)
            y = np.array(y, float)
            if not np.all(np.diff(x) >= 0):
                raise ValueError("x must be an increasing 1D array")
            if not np.all(np.diff(y) >= 0):
                raise ValueError("y must be an increasing 1D array")
            if x.shape[0] == nj:
                self.x = to_bins(x)
            elif x.shape[0] == nj + 1:
                self.x = x
            else:
                raise IndexError("x must be a 1D array of length %d or %d" % (nj, nj + 1))
            if y.shape[0] == ni:
                self.y = to_bins(y)
            elif y.shape[0] == ni + 1:
                self.y = y
            else:
                raise IndexError("y must be a 1D array of length %d or %d" % (ni, ni + 1))
            self.bounds = QRectF(
                QPointF(self.x[0], self.y[0]), QPointF(self.x[-1], self.y[-1])
            )
            self.update_border()

        # --- BaseImageItem API ----------------------------------------------------

        def get_filter(self, filterobj, filterparam):
            """Provides a filter object over this image's content"""
            return XYImageFilterItem(self, filterobj, filterparam)

        def draw_image(self, painter, canvasRect, src_rect, dst_rect, xMap, yMap):
            xytr = (self.x, self.y, src_rect)
            dst_rect = tuple([int(i) for i in dst_rect])
            dest = _scale_xy(
                self.data, xytr, self._offscreen, dst_rect, self.lut, self.interpolate
            )
            qrect = QRectF(QPointF(dest[0], dest[1]), QPointF(dest[2], dest[3]))
            painter.drawImage(qrect, self._image, qrect)

        def get_pixel_coordinates(self, xplot, yplot):
            """Return (image) pixel coordinates (from plot coordinates)"""
            return self.x.searchsorted(xplot), self.y.searchsorted(yplot)

        def get_plot_coordinates(self, xpixel, ypixel):
            """Return plot coordinates (from image pixel coordinates)"""
            return self.x[int(pixelround(xpixel))], self.y[int(pixelround(ypixel))]

        def get_x_values(self, i0, i1):
            return self.x[i0:i1]

        def get_y_values(self, j0, j1):
            return self.y[j0:j1]

        def get_closest_coordinates(self, x, y):
            """Return closest image pixel coordinates"""
            i, j = self.get_closest_indexes(x, y)
            return self.x[i], self.y[j]

        # ---- IBasePlotItem API ---------------------------------------------------
        def types(self):
            return (
                IImageItemType,
                IVoiImageItemType,
                IColormapImageItemType,
                ITrackableItemType,
                ISerializableType,
                ICSImageItemType,
            )

        # ---- IBaseImageItem API --------------------------------------------------
        def can_setfullscale(self):
            return True

        def can_sethistogram(self):
            return True

    assert_interfaces_valid(XYImageItem)

    # ==============================================================================
    # RGB Image with alpha channel
    # ==============================================================================

    class RGBImageItem(ImageItem):
        """
        Construct a RGB/RGBA image item

            * data: NumPy array of uint8 (shape: NxMx[34] -- 3: RGB, 4: RGBA)
              (last dimension: 0: Red, 1: Green, 2: Blue {, 3:Alpha})
            * param (optional): image parameters
              (:py:class:`guiqwt.styles.RGBImageParam` instance)
        """

        __implements__ = (IBasePlotItem, IBaseImageItem, ISerializableType)

        def __init__(self, data=None, param=None):
            self.orig_data = None
            super(RGBImageItem, self).__init__(data, param)
            self.lut = None

        # ---- BaseImageItem API ---------------------------------------------------

        def get_default_param(self):
            """Return instance of the default imageparam DataSet"""
            return RGBImageParam(_("Image"))

        # ---- Public API ----------------------------------------------------------
        def recompute_alpha_channel(self):
            data = self.orig_data
            if self.orig_data is None:
                return
            H, W, NC = data.shape
            R = data[..., 0].astype(np.uint32)
            G = data[..., 1].astype(np.uint32)
            B = data[..., 2].astype(np.uint32)
            use_alpha = self.imageparam.alpha_mask
            alpha = self.imageparam.alpha
            if NC > 3 and use_alpha:
                A = data[..., 3].astype(np.uint32)
            else:
                A = np.zeros((H, W), np.uint32)
                A[:, :] = int(255 * alpha)
            self.data[:, :] = (A << 24) + (R << 16) + (G << 8) + B

        # --- BaseImageItem API ----------------------------------------------------
        # Override lut/bg handling

        def set_lut_range(self, range):
            pass

        def set_background_color(self, qcolor):
            self.lut = None

        def set_color_map(self, name_or_table):
            self.lut = None

        # ---- RawImageItem API ----------------------------------------------------

        def load_data(self):
            """
            Load data from *filename*
            *filename* has been set using method 'set_filename'
            """
            data = io.imread(self.get_filename(), to_grayscale=False)
            self.set_data(data)

        def set_data(self, data):
            H, W, NC = data.shape
            self.orig_data = data
            self.data = np.empty((H, W), np.uint32)
            self.recompute_alpha_channel()
            self.update_bounds()
            self.update_border()
            self.lut = None

        # ---- IBasePlotItem API ---------------------------------------------------
        def types(self):
            return (IImageItemType, ITrackableItemType, ISerializableType)

        # ---- IBaseImageItem API --------------------------------------------------
        def can_setfullscale(self):
            return True

        def can_sethistogram(self):
            return False

    assert_interfaces_valid(RGBImageItem)

    # ==============================================================================
    # Masked Image
    # ==============================================================================
    class MaskedArea(object):
        """Defines masked areas for a masked image item"""

        def __init__(self, geometry=None, x0=None, y0=None, x1=None, y1=None, inside=None):
            self.geometry = geometry
            self.x0 = x0
            self.y0 = y0
            self.x1 = x1
            self.y1 = y1
            self.inside = inside

        def __eq__(self, other):
            return (
                self.geometry == other.geometry
                and self.x0 == other.x0
                and self.y0 == other.y0
                and self.x1 == other.x1
                and self.y1 == other.y1
                and self.inside == other.inside
            )

        def serialize(self, writer):
            """Serialize object to HDF5 writer"""
            for name in ("geometry", "inside", "x0", "y0", "x1", "y1"):
                writer.write(getattr(self, name), name)

        def deserialize(self, reader):
            """Deserialize object from HDF5 reader"""
            self.geometry = reader.read("geometry")
            self.inside = reader.read("inside")
            for name in ("x0", "y0", "x1", "y1"):
                setattr(self, name, reader.read(name, func=reader.read_float))

    class MaskedImageItem(ImageItem):
        """
        Construct a masked image item

            * data: 2D NumPy array
            * mask (optional): 2D NumPy array
            * param (optional): image parameters
              (:py:class:`guiqwt.styles.MaskedImageParam` instance)
        """

        __implements__ = (IBasePlotItem, IBaseImageItem, IHistDataSource, IVoiImageItemType)

        def __init__(self, data=None, mask=None, param=None):
            self.orig_data = None
            self._mask = mask
            self._mask_filename = None
            self._masked_areas = []
            super(MaskedImageItem, self).__init__(data, param)

        # ---- BaseImageItem API ---------------------------------------------------

        def get_default_param(self):
            """Return instance of the default imageparam DataSet"""
            return MaskedImageParam(_("Image"))

        # ---- Pickle methods -------------------------------------------------------
        def __reduce__(self):
            fname = self.get_filename()
            if fname is None:
                fn_or_data = self.data
            else:
                fn_or_data = fname
            state = (
                self.imageparam,
                self.get_lut_range(),
                fn_or_data,
                self.z(),
                self.get_mask_filename(),
                self.get_masked_areas(),
            )
            res = (self.__class__, (), state)
            return res

        def __setstate__(self, state):
            param, lut_range, fn_or_data, z, mask_fname, old_masked_areas = state
            if old_masked_areas and isinstance(old_masked_areas[0], MaskedArea):
                masked_areas = old_masked_areas
            else:
                # Compatibility with old format
                masked_areas = []
                for geometry, x0, y0, x1, y1, inside in old_masked_areas:
                    area = MaskedArea(
                        geometry=geometry, x0=x0, y0=y0, x1=x1, y1=y1, inside=inside
                    )
                    masked_areas.append(area)
            self.imageparam = param
            if isinstance(fn_or_data, str):
                self.set_filename(fn_or_data)
                self.load_data(lut_range)
            elif fn_or_data is not None:  # should happen only with previous API
                self.set_data(fn_or_data, lut_range=lut_range)
            self.setZ(z)
            self.imageparam.update_image(self)
            if mask_fname is not None:
                self.set_mask_filename(mask_fname)
                self.load_mask_data()
            elif masked_areas and self.data is not None:
                self.set_masked_areas(masked_areas)
                self.apply_masked_areas()

        def serialize(self, writer):
            """Serialize object to HDF5 writer"""
            super(MaskedImageItem, self).serialize(writer)
            writer.write(self.get_mask_filename(), group_name="mask_fname")
            writer.write_object_list(self._masked_areas, "masked_areas")

        def deserialize(self, reader):
            """Deserialize object from HDF5 reader"""
            super(MaskedImageItem, self).deserialize(reader)
            mask_fname = reader.read(group_name="mask_fname", func=reader.read_unicode)
            masked_areas = reader.read_object_list("masked_areas", MaskedArea)
            if mask_fname:
                self.set_mask_filename(mask_fname)
                self.load_mask_data()
            elif masked_areas and self.data is not None:
                self.set_masked_areas(masked_areas)
                self.apply_masked_areas()

        # ---- Public API -----------------------------------------------------------
        def update_mask(self):
            if isinstance(self.data, np.ma.MaskedArray):
                self.data.set_fill_value(self.imageparam.filling_value)

        def set_mask(self, mask):
            """Set image mask"""
            self.data.mask = mask

        def get_mask(self):
            """Return image mask"""
            return self.data.mask

        def set_mask_filename(self, fname):
            """
            Set mask filename

            There are two ways for pickling mask data of `MaskedImageItem` objects:

                1. using the mask filename (as for data itself)
                2. using the mask areas (`MaskedAreas` instance, see set_mask_areas)

            When saving objects, the first method is tried and then, if no
            filename has been defined for mask data, the second method is used.
            """
            self._mask_filename = fname

        def get_mask_filename(self):
            return self._mask_filename

        def load_mask_data(self):
            data = io.imread(self.get_mask_filename(), to_grayscale=True)
            self.set_mask(data)
            self._mask_changed()

        def set_masked_areas(self, areas):
            """Set masked areas (see set_mask_filename)"""
            self._masked_areas = areas

        def get_masked_areas(self):
            return self._masked_areas

        def add_masked_area(self, geometry, x0, y0, x1, y1, inside):
            area = MaskedArea(geometry=geometry, x0=x0, y0=y0, x1=x1, y1=y1, inside=inside)
            for _area in self._masked_areas:
                if area == _area:
                    return
            self._masked_areas.append(area)

        def _mask_changed(self):
            """Emit the :py:data:`guiqwt.baseplot.BasePlot.SIG_MASK_CHANGED` signal"""
            plot = self.plot()
            if plot is not None:
                plot.SIG_MASK_CHANGED.emit(self)

        def apply_masked_areas(self):
            """Apply masked areas"""
            for area in self._masked_areas:
                if area.geometry == "rectangular":
                    self.mask_rectangular_area(
                        area.x0,
                        area.y0,
                        area.x1,
                        area.y1,
                        area.inside,
                        trace=False,
                        do_signal=False,
                    )
                else:
                    self.mask_circular_area(
                        area.x0,
                        area.y0,
                        area.x1,
                        area.y1,
                        area.inside,
                        trace=False,
                        do_signal=False,
                    )
            self._mask_changed()

        def mask_all(self):
            """Mask all pixels"""
            self.data.mask = True
            self._mask_changed()

        def unmask_all(self):
            """Unmask all pixels"""
            self.data.mask = np.ma.nomask
            self.set_masked_areas([])
            self._mask_changed()

        def mask_rectangular_area(
            self, x0, y0, x1, y1, inside=True, trace=True, do_signal=True
        ):
            """
            Mask rectangular area
            If inside is True (default), mask the inside of the area
            Otherwise, mask the outside
            """
            ix0, iy0, ix1, iy1 = self.get_closest_index_rect(x0, y0, x1, y1)
            if inside:
                self.data[iy0:iy1, ix0:ix1] = np.ma.masked
            else:
                indexes = np.ones(self.data.shape, dtype=bool)
                indexes[iy0:iy1, ix0:ix1] = False
                self.data[indexes] = np.ma.masked
            if trace:
                self.add_masked_area("rectangular", x0, y0, x1, y1, inside)
            if do_signal:
                self._mask_changed()

        def mask_circular_area(
            self, x0, y0, x1, y1, inside=True, trace=True, do_signal=True
        ):
            """
            Mask circular area, inside the rectangle (x0, y0, x1, y1), i.e.
            circle with a radius of ``.5\*(x1-x0)``
            If inside is True (default), mask the inside of the area
            Otherwise, mask the outside
            """
            ix0, iy0, ix1, iy1 = self.get_closest_index_rect(x0, y0, x1, y1)
            xc, yc = 0.5 * (x0 + x1), 0.5 * (y0 + y1)
            radius = 0.5 * (x1 - x0)
            xdata, ydata = self.get_x_values(ix0, ix1), self.get_y_values(iy0, iy1)
            for ix in range(ix0, ix1):
                for iy in range(iy0, iy1):
                    distance = np.sqrt(
                        (xdata[ix - ix0] - xc) ** 2 + (ydata[iy - iy0] - yc) ** 2
                    )
                    if inside:
                        if distance <= radius:
                            self.data[iy, ix] = np.ma.masked
                    elif distance > radius:
                        self.data[iy, ix] = np.ma.masked
            if not inside:
                self.mask_rectangular_area(x0, y0, x1, y1, inside, trace=False)
            if trace:
                self.add_masked_area("circular", x0, y0, x1, y1, inside)
            if do_signal:
                self._mask_changed()

        def is_mask_visible(self):
            """Return mask visibility"""
            return self.imageparam.show_mask

        def set_mask_visible(self, state):
            """Set mask visibility"""
            self.imageparam.show_mask = state
            plot = self.plot()
            if plot is not None:
                plot.replot()

        # ---- BaseImageItem API ----------------------------------------------------

        def draw_image(self, painter, canvasRect, src_rect, dst_rect, xMap, yMap):
            ImageItem.draw_image(self, painter, canvasRect, src_rect, dst_rect, xMap, yMap)
            if self.data is None:
                return
            if self.is_mask_visible():
                _a, _b, bg, _cmap = self.lut
                alpha_masked = (
                    np.uint32(255 * self.imageparam.alpha_masked + 0.5).clip(0, 255) << 24
                )
                alpha_unmasked = (
                    np.uint32(255 * self.imageparam.alpha_unmasked + 0.5).clip(0, 255) << 24
                )
                cmap = np.array(
                    [
                        np.uint32(0x000000 & 0xFFFFFF) | alpha_unmasked,
                        np.uint32(0xFFFFFF & 0xFFFFFF) | alpha_masked,
                    ],
                    dtype=np.uint32,
                )
                lut = (1, 0, bg, cmap)
                shown_data = np.ma.getmaskarray(self.data)
                src2 = self._rescale_src_rect(src_rect)
                dst_rect = tuple([int(i) for i in dst_rect])
                dest = _scale_rect(
                    shown_data, src2, self._offscreen, dst_rect, lut, (INTERP_NEAREST,)
                )
                qrect = QRectF(QPointF(dest[0], dest[1]), QPointF(dest[2], dest[3]))
                painter.drawImage(qrect, self._image, qrect)

        # ---- RawImageItem API -----------------------------------------------------

        def set_data(self, data, lut_range=None):
            """
            Set Image item data

                * data: 2D NumPy array
                * lut_range: LUT range -- tuple (levelmin, levelmax)
            """
            ImageItem.set_data(self, data, lut_range)
            self.orig_data = data
            self.data = data.view(np.ma.MaskedArray)
            self.set_mask(self._mask)
            self._mask = None  # removing reference to this temporary array
            if self.imageparam.filling_value is None:
                self.imageparam.filling_value = self.data.get_fill_value()
            #        self.data.harden_mask()
            self.update_mask()

    # ==============================================================================
    # Image filter
    # ==============================================================================
    # TODO: Implement get_filter methods for image items other than XYImageItem!

    class ImageFilterItem(BaseImageItem):
        """
        Construct a rectangular area image filter item

            * image: :py:class:`guiqwt.image.RawImageItem` instance
            * filter: function (x, y, data) --> data
            * param: image filter parameters
              (:py:class:`guiqwt.styles.ImageFilterParam` instance)
        """

        __implements__ = (IBasePlotItem, IBaseImageItem)
        _can_select = True
        _can_resize = True
        _can_move = True

        def __init__(self, image, filter, param):
            self.use_source_cmap = None
            self.image = None  # BaseImageItem constructor will try to set this
            # item's color map using the method 'set_color_map'
            super(ImageFilterItem, self).__init__(param=param)
            self.border_rect.set_style("plot", "shape/imagefilter")
            self.image = image
            self.filter = filter

            self.imagefilterparam = param
            self.imagefilterparam.update_imagefilter(self)

        # ---- Public API -----------------------------------------------------------

        def set_image(self, image):
            """
            Set the image item on which the filter will be applied

                * image: :py:class:`guiqwt.image.RawImageItem` instance
            """
            self.image = image

        def set_filter(self, filter):
            """
            Set the filter function

                * filter: function (x, y, data) --> data
            """
            self.filter = filter

        # ---- QwtPlotItem API ------------------------------------------------------

        def boundingRect(self):
            x0, y0, x1, y1 = self.border_rect.get_rect()
            return QRectF(x0, y0, x1 - x0, y1 - y0)

        # ---- IBasePlotItem API ----------------------------------------------------
        def update_item_parameters(self):
            BaseImageItem.update_item_parameters(self)
            self.imagefilterparam.update_param(self)

        def get_item_parameters(self, itemparams):
            BaseImageItem.get_item_parameters(self, itemparams)
            self.update_item_parameters()
            itemparams.add("ImageFilterParam", self, self.imagefilterparam)

        def set_item_parameters(self, itemparams):
            update_dataset(
                self.imagefilterparam, itemparams.get("ImageFilterParam"), visible_only=True
            )
            self.imagefilterparam.update_imagefilter(self)
            BaseImageItem.set_item_parameters(self, itemparams)

        def move_local_point_to(self, handle, pos, ctrl=None):
            """Move a handle as returned by hit_test to the new position pos
            ctrl: True if <Ctrl> button is being pressed, False otherwise"""
            npos = canvas_to_axes(self, pos)
            self.border_rect.move_point_to(handle, npos)
            if self.plot():
                self.plot().SIG_ITEM_HANDLE_MOVED.emit(self)

        def move_local_shape(self, old_pos, new_pos):
            """Translate the shape such that old_pos becomes new_pos
            in canvas coordinates"""
            old_pt = canvas_to_axes(self, old_pos)
            new_pt = canvas_to_axes(self, new_pos)
            self.border_rect.move_shape(old_pt, new_pt)
            if self.plot():
                self.plot().SIG_ITEM_MOVED.emit(self, *(old_pt + new_pt))

        def move_with_selection(self, delta_x, delta_y):
            """
            Translate the shape together with other selected items
            delta_x, delta_y: translation in plot coordinates
            """
            self.border_rect.move_with_selection(delta_x, delta_y)

        def set_color_map(self, name_or_table):
            if self.use_source_cmap:
                if self.image is not None:
                    self.image.set_color_map(name_or_table)
            else:
                BaseImageItem.set_color_map(self, name_or_table)

        def get_color_map(self):
            if self.use_source_cmap:
                return self.image.get_color_map()
            else:
                return BaseImageItem.get_color_map(self)

        def get_lut_range(self):
            if self.use_source_cmap:
                return self.image.get_lut_range()
            else:
                return BaseImageItem.get_lut_range(self)

        def set_lut_range(self, lut_range):
            if self.use_source_cmap:
                self.image.set_lut_range(lut_range)
            else:
                BaseImageItem.set_lut_range(self, lut_range)

        # ---- IBaseImageItem API ---------------------------------------------------
        def types(self):
            return (
                IImageItemType,
                IVoiImageItemType,
                IColormapImageItemType,
                ITrackableItemType,
            )

        def can_setfullscale(self):
            return False

        def can_sethistogram(self):
            return True

    class XYImageFilterItem(ImageFilterItem):
        """
        Construct a rectangular area image filter item

            * image: :py:class:`guiqwt.image.XYImageItem` instance
            * filter: function (x, y, data) --> data
            * param: image filter parameters
              (:py:class:`guiqwt.styles.ImageFilterParam` instance)
        """

        def __init__(self, image, filter, param):
            ImageFilterItem.__init__(self, image, filter, param)

        def set_image(self, image):
            """
            Set the image item on which the filter will be applied

                * image: :py:class:`guiqwt.image.XYImageItem` instance
            """
            ImageFilterItem.set_image(self, image)

        def draw_image(self, painter, canvasRect, src_rect, dst_rect, xMap, yMap):
            bounds = self.boundingRect()

            filt_qrect = bounds & self.image.boundingRect()
            x0, y0, x1, y1 = filt_qrect.getCoords()
            i0, i1 = xMap.transform(x0), xMap.transform(x1)
            j0, j1 = yMap.transform(y0), yMap.transform(y1)

            dstRect = QRect(int(i0), int(j0), int(i1 - i0), int(j1 - j0))
            if not dstRect.intersects(canvasRect):
                return

            x, y, data = self.image.get_data(x0, y0, x1, y1)
            new_data = self.filter(x, y, data)
            self.data = new_data
            if self.use_source_cmap:
                lut = self.image.lut
            else:
                lut = self.lut
            dest = _scale_xy(
                new_data,
                (x, y, src_rect),
                self._offscreen,
                dstRect.getCoords(),
                lut,
                self.interpolate,
            )
            qrect = QRectF(QPointF(dest[0], dest[1]), QPointF(dest[2], dest[3]))
            painter.drawImage(qrect, self._image, qrect)

    assert_interfaces_valid(ImageFilterItem)

    # ==============================================================================
    # 2-D Histogram
    # ==============================================================================

    class Histogram2DItem(BaseImageItem):
        """
        Construct a 2D histogram item

            * X: data (1-D array)
            * Y: data (1-D array)
            * param (optional): style parameters
              (:py:class:`guiqwt.styles.Histogram2DParam` instance)
        """

        __implements__ = (
            IBasePlotItem,
            IBaseImageItem,
            IHistDataSource,
            IVoiImageItemType,
        )

        def __init__(self, X, Y, param=None, Z=None):
            if param is None:
                param = ImageParam(_("Image"))
            self._z = Z  # allows set_bins to
            super(Histogram2DItem, self).__init__(param=param)

            # Set by parameters
            self.nx_bins = 0
            self.ny_bins = 0
            self.logscale = None

            # internal use
            self._x = None
            self._y = None

            # Histogram parameters
            self.histparam = param
            self.histparam.update_histogram(self)

            self.set_lut_range([0, 10.0])
            self.set_data(X, Y, Z)

        # ---- Public API -----------------------------------------------------------

        def set_bins(self, NX, NY):
            """Set histogram bins"""
            self.nx_bins = NX
            self.ny_bins = NY
            self.data = np.zeros((self.ny_bins, self.nx_bins), float)
            if self._z is not None:
                self.data_tmp = np.zeros((self.ny_bins, self.nx_bins), float)

        def set_data(self, X, Y, Z=None):
            """Set histogram data"""
            self._x = X
            self._y = Y
            self._z = Z
            self.bounds = QRectF(QPointF(X.min(), Y.min()), QPointF(X.max(), Y.max()))
            self.update_border()

        # ---- QwtPlotItem API ------------------------------------------------------
        fill_canvas = True

        def draw_image(self, painter, canvasRect, src_rect, dst_rect, xMap, yMap):
            computation = self.histparam.computation
            i1, j1, i2, j2 = src_rect
            if computation == -1 or self._z is None:
                self.data[:, :] = 0.0
                nmax = histogram2d(
                    self._x, self._y, i1, i2, j1, j2, self.data, self.logscale
                )
            else:
                self.data_tmp[:, :] = 0.0
                if computation in (2, 4):  # sum, avg
                    self.data[:, :] = 0.0
                elif computation in (1, 5):  # min, argmin
                    val = np.inf
                    self.data[:, :] = val
                elif computation in (0, 6):  # max, argmax
                    val = -np.inf
                    self.data[:, :] = val
                elif computation == 3:
                    self.data[:, :] = 1.0
                histogram2d_func(
                    self._x,
                    self._y,
                    self._z,
                    i1,
                    i2,
                    j1,
                    j2,
                    self.data_tmp,
                    self.data,
                    computation,
                )
                if computation in (0, 1, 5, 6):
                    self.data[self.data == val] = np.nan
                else:
                    self.data[self.data_tmp == 0.0] = np.nan
            if self.histparam.auto_lut:
                nmin = _nanmin(self.data)
                nmax = _nanmax(self.data)
                self.set_lut_range([nmin, nmax])
                self.plot().update_colormap_axis(self)
            src_rect = (0, 0, self.nx_bins, self.ny_bins)
            drawfunc = lambda *args: BaseImageItem.draw_image(self, *args)
            if self.fill_canvas:
                x1, y1, x2, y2 = canvasRect.getCoords()
                drawfunc(painter, canvasRect, src_rect, (x1, y1, x2, y2), xMap, yMap)
            else:
                drawfunc(painter, canvasRect, src_rect, dst_rect, xMap, yMap)

        # ---- IBasePlotItem API ---------------------------------------------------
        def types(self):
            return (
                IColormapImageItemType,
                IImageItemType,
                ITrackableItemType,
                IVoiImageItemType,
                IColormapImageItemType,
                ICSImageItemType,
            )

        def update_item_parameters(self):
            BaseImageItem.update_item_parameters(self)
            self.histparam.update_param(self)

        def get_item_parameters(self, itemparams):
            BaseImageItem.get_item_parameters(self, itemparams)
            itemparams.add("Histogram2DParam", self, self.histparam)

        def set_item_parameters(self, itemparams):
            update_dataset(
                self.histparam, itemparams.get("Histogram2DParam"), visible_only=True
            )
            self.histparam = itemparams.get("Histogram2DParam")
            self.histparam.update_histogram(self)
            BaseImageItem.set_item_parameters(self, itemparams)

        # ---- IBaseImageItem API --------------------------------------------------
        def can_setfullscale(self):
            return True

        def can_sethistogram(self):
            return True

        def get_histogram(self, nbins):
            """interface de IHistDataSource"""
            if self.data is None:
                return [
                    0,
                ], [0, 1]
            _min = _nanmin(self.data)
            _max = _nanmax(self.data)
            if self.data.dtype in (np.float64, np.float32):
                bins = np.unique(
                    np.array(np.linspace(_min, _max, nbins + 1), dtype=self.data.dtype)
                )
            else:
                bins = np.arange(_min, _max + 2, dtype=self.data.dtype)
            res2 = np.zeros((bins.size + 1,), np.uint32)
            _histogram(self.data.flatten(), bins, res2)
            # toc("histo2")
            res = res2[1:-1], bins
            return res

    assert_interfaces_valid(Histogram2DItem)

    # ==============================================================================
    # Image Plot Widget
    # ==============================================================================

    class ImagePlot(CurvePlot):
        """
        Construct a 2D curve and image plotting widget
        (this class inherits :py:class:`guiqwt.curve.CurvePlot`)

            * parent: parent widget
            * title: plot title (string)
            * xlabel, ylabel, zlabel: resp. bottom, left and right axis titles
              (strings)
            * xunit, yunit, zunit: resp. bottom, left and right axis units
              (strings)
            * yreverse: reversing y-axis direction of increasing values (bool)
            * aspect_ratio: height to width ratio (float)
            * lock_aspect_ratio: locking aspect ratio (bool)
        """

        DEFAULT_ITEM_TYPE = IImageItemType
        AUTOSCALE_TYPES = (CurveItem, BaseImageItem, PolygonMapItem)
        AXIS_CONF_OPTIONS = ("image_axis", "color_axis", "image_axis", None)

        def __init__(
            self,
            parent=None,
            title=None,
            xlabel=None,
            ylabel=None,
            zlabel=None,
            xunit=None,
            yunit=None,
            zunit=None,
            yreverse=True,
            aspect_ratio=1.0,
            lock_aspect_ratio=True,
            gridparam=None,
            section="plot",
        ):

            self.lock_aspect_ratio = lock_aspect_ratio

            if zlabel is not None:
                if ylabel is not None and not isinstance(ylabel, str):
                    ylabel = ylabel[0]
                ylabel = (ylabel, zlabel)
            if zunit is not None:
                if yunit is not None and not isinstance(yunit, str):
                    yunit = yunit[0]
                yunit = (yunit, zunit)
            super(ImagePlot, self).__init__(
                parent=parent,
                title=title,
                xlabel=xlabel,
                ylabel=ylabel,
                xunit=xunit,
                yunit=yunit,
                gridparam=gridparam,
                section=section,
            )

            self.colormap_axis = self.Y_RIGHT
            axiswidget = self.axisWidget(self.colormap_axis)
            axiswidget.setColorBarEnabled(True)
            self.enableAxis(self.colormap_axis)
            self.__aspect_ratio = None
            self.set_axis_direction("left", yreverse)
            self.set_aspect_ratio(aspect_ratio, lock_aspect_ratio)
            self.replot()  # Workaround for the empty image widget bug

        # ---- QwtPlot API ---------------------------------------------------------

        def showEvent(self, event):
            """Override BasePlot method"""
            if self.lock_aspect_ratio:
                self._start_autoscaled = True
            CurvePlot.showEvent(self, event)

        # ---- CurvePlot API -------------------------------------------------------

        def do_zoom_view(self, dx, dy):
            """Reimplement CurvePlot method"""
            CurvePlot.do_zoom_view(self, dx, dy, lock_aspect_ratio=self.lock_aspect_ratio)

        def do_zoom_rect_view(self, start, end):
            """Reimplement CurvePlot method"""
            CurvePlot.do_zoom_rect_view(self, start, end)
            if self.lock_aspect_ratio:
                self.apply_aspect_ratio()

        # ---- Levels histogram-related API ----------------------------------------

        def update_lut_range(self, _min, _max):
            """update the LUT scale"""
            # self.set_items_lut_range(_min, _max, replot=False)
            self.updateAxes()

        # ---- Image scale/aspect ratio -related API -------------------------------
        def set_full_scale(self, item):
            if item.can_setfullscale():
                bounds = item.boundingRect()
                self.set_plot_limits(
                    bounds.left(), bounds.right(), bounds.top(), bounds.bottom()
                )

        def get_current_aspect_ratio(self):
            """Return current aspect ratio"""
            dx = self.axisScaleDiv(self.X_BOTTOM).range()
            dy = self.axisScaleDiv(self.Y_LEFT).range()
            h = self.canvasMap(self.Y_LEFT).pDist()
            w = self.canvasMap(self.X_BOTTOM).pDist()
            return fabs((h * dx) / (w * dy))

        def get_aspect_ratio(self):
            """Return aspect ratio"""
            return self.__aspect_ratio

        def set_aspect_ratio(self, ratio=None, lock=None):
            """Set aspect ratio"""
            if ratio is not None:
                self.__aspect_ratio = ratio
            if lock is not None:
                self.lock_aspect_ratio = lock
            self.apply_aspect_ratio()

        def apply_aspect_ratio(self, full_scale=False):
            if not self.isVisible():
                return
            ymap = self.canvasMap(self.Y_LEFT)
            xmap = self.canvasMap(self.X_BOTTOM)
            h = ymap.pDist()
            w = xmap.pDist()
            dx1, dy1 = xmap.sDist(), fabs(ymap.sDist())
            x0, y0 = xmap.s1(), ymap.s1()
            x1, y1 = xmap.s2(), ymap.s2()
            if x0 > x1:
                x0, x1 = x1, x0
            if y0 > y1:
                y0, y1 = y1, y0
            if full_scale:
                if w == 0:
                    return  # avoid division by zero
                dy2 = (h * dx1) / (w * self.__aspect_ratio)
                fix_yaxis = dy2 > dy1
            else:
                fix_yaxis = True
            if fix_yaxis:
                if w == 0:
                    return  # avoid division by zero
                dy2 = (h * dx1) / (w * self.__aspect_ratio)
                delta_y = 0.5 * (dy2 - dy1)
                y0 -= delta_y
                y1 += delta_y
            else:
                if h == 0:
                    return  # avoid division by zero
                dx2 = (w * dy1 * self.__aspect_ratio) / h
                delta_x = 0.5 * (dx2 - dx1)
                x0 -= delta_x
                x1 += delta_x
            self.set_plot_limits(x0, x1, y0, y1)

        # ---- LUT/colormap-related API --------------------------------------------

        def notify_colormap_changed(self):
            """Levels histogram range has changed"""
            item = self.get_last_active_item(IColormapImageItemType)
            if item is not None:
                self.update_colormap_axis(item)
            self.replot()
            self.SIG_LUT_CHANGED.emit(self)

        def update_colormap_axis(self, item):
            if IColormapImageItemType not in item.types():
                return
            zaxis = self.colormap_axis
            axiswidget = self.axisWidget(zaxis)
            self.setAxisScale(zaxis, item.min, item.max)
            # XXX: the colormap can't be displayed if min>max, to fix this
            # we should pass an inverted colormap along with _max, _min values
            axiswidget.setColorMap(QwtInterval(item.min, item.max), item.get_color_map())
            self.updateAxes()

        # ---- QwtPlot API ---------------------------------------------------------

        def resizeEvent(self, event):
            """Reimplement Qt method to resize widget"""
            CurvePlot.resizeEvent(self, event)
            if self.lock_aspect_ratio:
                self.apply_aspect_ratio()
            self.replot()

        # ---- BasePlot API --------------------------------------------------------

        def add_item(self, item, z=None, autoscale=True):
            """
            Add a *plot item* instance to this *plot widget*

                * item: :py:data:`qwt.QwtPlotItem` object implementing the
                  :py:data:`guiqwt.interfaces.IBasePlotItem` interface
                * z: item's z order (None -> z = max(self.get_items())+1)
                  autoscale: True -> rescale plot to fit image bounds
            """
            CurvePlot.add_item(self, item, z)
            if isinstance(item, BaseImageItem):
                parent = self.parent()
                if parent is not None:
                    parent.setUpdatesEnabled(False)
                self.update_colormap_axis(item)
                if autoscale:
                    self.do_autoscale()
                if parent is not None:
                    parent.setUpdatesEnabled(True)

        def set_active_item(self, item):
            """Override base set_active_item to change the grid's
            axes according to the selected item"""
            old_active = self.active_item
            CurvePlot.set_active_item(self, item)
            if item is not None and old_active is not item:
                self.update_colormap_axis(item)

        def disable_unused_axes(self):
            """Disable unused axes"""
            CurvePlot.disable_unused_axes(self)
            self.enableAxis(self.colormap_axis)

        def do_autoscale(self, replot=True, axis_id=None):
            """Do autoscale on all axes"""
            CurvePlot.do_autoscale(self, replot=False, axis_id=axis_id)
            self.updateAxes()
            if self.lock_aspect_ratio:
                self.replot()
                self.apply_aspect_ratio(full_scale=True)
            if replot:
                self.replot()
            self.SIG_PLOT_AXIS_CHANGED.emit(self)

        def get_axesparam_class(self, item):
            """Return AxesParam dataset class associated to item's type"""
            if isinstance(item, BaseImageItem):
                return ImageAxesParam
            else:
                return CurvePlot.get_axesparam_class(self, item)

        def edit_axis_parameters(self, axis_id):
            """Edit axis parameters"""
            # XXX: removed the following workaround as the associated bug can't be
            # reproduced anymore with guiqwt 3. However, keeping the workaround
            # here (commented) as it could become useful eventually.
            # -----
            #        #FIXME: without the following workaround, aspect ratio is changed
            #        # when applying axis parameters
            #        # (see also guiqwt.styles.ItemParameters.update)
            #        ratio = self.get_current_aspect_ratio()
            # -----
            if axis_id != self.colormap_axis:
                CurvePlot.edit_axis_parameters(self, axis_id)

            # -----

    #        self.set_aspect_ratio(ratio=ratio)
    #        self.replot()
    # -----