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# Source code for pyqtgraph.graphicsItems.GridItem

    import numpy as np

    from .. import functions as fn
    from .. import getConfigOption
    from ..Point import Point
    from ..Qt import QtCore, QtGui
    from .UIGraphicsItem import UIGraphicsItem

    __all__ = ['GridItem']

    class GridItem(UIGraphicsItem):
        """
        **Bases:** :class:`UIGraphicsItem <pyqtgraph.UIGraphicsItem>`

        Displays a rectangular grid of lines indicating major divisions within a coordinate system.
        Automatically determines what divisions to use.
        """

        def __init__(self, pen='default', textPen='default'):
            UIGraphicsItem.__init__(self)
            #QtWidgets.QGraphicsItem.__init__(self, *args)
            #self.setFlag(QtWidgets.QGraphicsItem.GraphicsItemFlag.ItemClipsToShape)
            #self.setCacheMode(QtWidgets.QGraphicsItem.CacheMode.DeviceCoordinateCache)

            self.opts = {}

            self.setPen(pen)
            self.setTextPen(textPen)
            self.setTickSpacing(x=[None, None, None], y=[None, None, None])

        def setPen(self, *args, **kwargs):
            """Set the pen used to draw the grid."""
            if kwargs == {} and (args == () or args == ('default',)):
                self.opts['pen'] = fn.mkPen(getConfigOption('foreground'))
            else:
                self.opts['pen'] = fn.mkPen(*args, **kwargs)

            self.picture = None
            self.update()

        def setTextPen(self, *args, **kwargs):
            """Set the pen used to draw the texts."""
            if kwargs == {} and (args == () or args == ('default',)):
                self.opts['textPen'] = fn.mkPen(getConfigOption('foreground'))
            else:
                if args == (None,):
                    self.opts['textPen'] = None
                else:
                    self.opts['textPen'] = fn.mkPen(*args, **kwargs)

            self.picture = None
            self.update()

        def setTickSpacing(self, x=None, y=None):
            """
            Set the grid tick spacing to use.

            Tick spacing for each axis shall be specified as an array of
            descending values, one for each tick scale. When the value
            is set to None, grid line distance is chosen automatically
            for this particular level.

            Example:
                Default setting of 3 scales for each axis:
                setTickSpacing(x=[None, None, None], y=[None, None, None])

                Single scale with distance of 1.0 for X axis, Two automatic
                scales for Y axis:
                setTickSpacing(x=[1.0], y=[None, None])

                Single scale with distance of 1.0 for X axis, Two scales
                for Y axis, one with spacing of 1.0, other one automatic:
                setTickSpacing(x=[1.0], y=[1.0, None])
            """
            self.opts['tickSpacing'] = (x or self.opts['tickSpacing'][0],
                                        y or self.opts['tickSpacing'][1])

            self.grid_depth = max([len(s) for s in self.opts['tickSpacing']])

            self.picture = None
            self.update()

        def viewRangeChanged(self):
            UIGraphicsItem.viewRangeChanged(self)
            self.picture = None
            #UIGraphicsItem.viewRangeChanged(self)
            #self.update()

        def paint(self, p, opt, widget):
            #p.setPen(QtGui.QPen(QtGui.QColor(100, 100, 100)))
            #p.drawRect(self.boundingRect())
            #UIGraphicsItem.paint(self, p, opt, widget)
            ### draw picture
            if self.picture is None:
                #print "no pic, draw.."
                self.generatePicture()
            p.drawPicture(QtCore.QPointF(0, 0), self.picture)
            #p.setPen(QtGui.QPen(QtGui.QColor(255,0,0)))
            #p.drawLine(0, -100, 0, 100)
            #p.drawLine(-100, 0, 100, 0)
            #print "drawing Grid."

        def generatePicture(self):
            self.picture = QtGui.QPicture()
            p = QtGui.QPainter()
            p.begin(self.picture)

            vr = self.getViewWidget().rect()
            unit = self.pixelWidth(), self.pixelHeight()
            dim = [vr.width(), vr.height()]
            lvr = self.boundingRect()
            ul = np.array([lvr.left(), lvr.top()])
            br = np.array([lvr.right(), lvr.bottom()])

            texts = []

            if ul[1] > br[1]:
                x = ul[1]
                ul[1] = br[1]
                br[1] = x

            lastd = [None, None]
            for i in range(self.grid_depth - 1, -1, -1):
                dist = br-ul
                nlTarget = 10.**i
                d = 10. ** np.floor(np.log10(np.abs(dist/nlTarget))+0.5)
                for ax in range(0,2):
                    ts = self.opts['tickSpacing'][ax]
                    try:
                        if ts[i] is not None:
                            d[ax] = ts[i]
                    except IndexError:
                        pass
                    lastd[ax] = d[ax]

                ul1 = np.floor(ul / d) * d
                br1 = np.ceil(br / d) * d
                dist = br1-ul1
                nl = (dist / d) + 0.5
                for ax in range(0,2):  ## Draw grid for both axes
                    if i >= len(self.opts['tickSpacing'][ax]):
                        continue
                    if d[ax] < lastd[ax]:
                        continue

                    ppl = dim[ax] / nl[ax]
                    c = int(fn.clip_scalar(5 * (ppl-3), 0, 50))

                    linePen = self.opts['pen']
                    lineColor = self.opts['pen'].color()
                    lineColor.setAlpha(c)
                    linePen.setColor(lineColor)

                    textPen = self.opts['textPen']
                    if textPen is not None:
                        textColor = self.opts['textPen'].color()
                        textColor.setAlpha(c * 2)
                        textPen.setColor(textColor)

                    bx = (ax+1) % 2
                    for x in range(0, int(nl[ax])):
                        linePen.setCosmetic(True)
                        p.setPen(linePen)
                        p1 = np.array([0.,0.])
                        p2 = np.array([0.,0.])
                        p1[ax] = ul1[ax] + x * d[ax]
                        p2[ax] = p1[ax]
                        p1[bx] = ul[bx]
                        p2[bx] = br[bx]
                        ## don't draw lines that are out of bounds.
                        if p1[ax] < min(ul[ax], br[ax]) or p1[ax] > max(ul[ax], br[ax]):
                            continue
                        p.drawLine(QtCore.QPointF(p1[0], p1[1]), QtCore.QPointF(p2[0], p2[1]))
                        if i < 2 and textPen is not None:
                            if ax == 0:
                                x = p1[0] + unit[0]
                                y = ul[1] + unit[1] * 8.
                            else:
                                x = ul[0] + unit[0]*3
                                y = p1[1] + unit[1]
                            texts.append((QtCore.QPointF(x, y), "%g"%p1[ax]))
            tr = self.deviceTransform()
            p.setWorldTransform(fn.invertQTransform(tr))

            if textPen is not None and len(texts) > 0:
                # if there is at least one text, then c is set
                textColor.setAlpha(c * 2)
                p.setPen(QtGui.QPen(textColor))
                for t in texts:
                    x = tr.map(t[0]) + Point(0.5, 0.5)
                    p.drawText(x, t[1])

            p.end()