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# Source code for pyqtgraph.graphicsItems.ArrowItem

    from math import hypot

    from .. import functions as fn
    from ..Qt import QtGui, QtWidgets

    __all__ = ['ArrowItem']

    class ArrowItem(QtWidgets.QGraphicsPathItem):
        """
        For displaying scale-invariant arrows.
        For arrows pointing to a location on a curve, see CurveArrow

        """

        def __init__(self, parent=None, **opts):
            """
            Arrows can be initialized with any keyword arguments accepted by
            the setStyle() method.
            """
            self.opts = {}
            QtWidgets.QGraphicsPathItem.__init__(self, parent)

            if 'size' in opts:
                opts['headLen'] = opts['size']
            if 'width' in opts:
                opts['headWidth'] = opts['width']
            pos = opts.pop('pos', (0, 0))

            defaultOpts = {
                'pxMode': True,
                'angle': -150,   ## If the angle is 0, the arrow points left
                'headLen': 20,
                'headWidth': None,
                'tipAngle': 25,
                'baseAngle': 0,
                'tailLen': None,
                'tailWidth': 3,
                'pen': (200,200,200),
                'brush': (50,50,200),
            }
            defaultOpts.update(opts)

            self.setStyle(**defaultOpts)

            # for backward compatibility
            self.setPos(*pos)

        def setStyle(self, **opts):
            """
            Changes the appearance of the arrow.
            All arguments are optional:

            ======================  =================================================
            **Keyword Arguments:**
            angle                   Orientation of the arrow in degrees. Default is
                                    0; arrow pointing to the left.
            headLen                 Length of the arrow head, from tip to base.
                                    default=20
            headWidth               Width of the arrow head at its base. If
                                    headWidth is specified, it overrides tipAngle.
            tipAngle                Angle of the tip of the arrow in degrees. Smaller
                                    values make a 'sharper' arrow. default=25
            baseAngle               Angle of the base of the arrow head. Default is
                                    0, which means that the base of the arrow head
                                    is perpendicular to the arrow tail.
            tailLen                 Length of the arrow tail, measured from the base
                                    of the arrow head to the end of the tail. If
                                    this value is None, no tail will be drawn.
                                    default=None
            tailWidth               Width of the tail. default=3
            pen                     The pen used to draw the outline of the arrow.
            brush                   The brush used to fill the arrow.
            pxMode                  If True, then the arrow is drawn as a fixed size
                                    regardless of the scale of its parents (including
                                    the ViewBox zoom level).
            ======================  =================================================
            """
            arrowOpts = ['headLen', 'tipAngle', 'baseAngle', 'tailLen', 'tailWidth', 'headWidth']
            allowedOpts = ['angle', 'pen', 'brush', 'pxMode'] + arrowOpts
            needUpdate = False
            for k,v in opts.items():
                if k not in allowedOpts:
                    raise KeyError('Invalid arrow style option "%s"' % k)
                if self.opts.get(k) != v:
                    needUpdate = True
                self.opts[k] = v

            if not needUpdate:
                return

            opt = dict([(k,self.opts[k]) for k in arrowOpts if k in self.opts])
            tr = QtGui.QTransform()
            tr.rotate(self.opts['angle'])
            self.path = tr.map(fn.makeArrowPath(**opt))

            self.setPath(self.path)

            self.setPen(fn.mkPen(self.opts['pen']))
            self.setBrush(fn.mkBrush(self.opts['brush']))

            if self.opts['pxMode']:
                self.setFlags(self.flags() | self.GraphicsItemFlag.ItemIgnoresTransformations)
            else:
                self.setFlags(self.flags() & ~self.GraphicsItemFlag.ItemIgnoresTransformations)

        def paint(self, p, *args):
            p.setRenderHint(QtGui.QPainter.RenderHint.Antialiasing)
            super().paint(p, *args)

            #p.setPen(fn.mkPen('r'))
            #p.setBrush(fn.mkBrush(None))
            #p.drawRect(self.boundingRect())

        def shape(self):
            #if not self.opts['pxMode']:
                #return QtWidgets.QGraphicsPathItem.shape(self)
            return self.path

        ## dataBounds and pixelPadding methods are provided to ensure ViewBox can
        ## properly auto-range
        def dataBounds(self, ax, frac, orthoRange=None):
            pw = 0
            pen = self.pen()
            if not pen.isCosmetic():
                pw = pen.width() * 0.7072
            if self.opts['pxMode']:
                return [0,0]
            else:
                br = self.boundingRect()
                if ax == 0:
                    return [br.left()-pw, br.right()+pw]
                else:
                    return [br.top()-pw, br.bottom()+pw]

        def pixelPadding(self):
            pad = 0
            if self.opts['pxMode']:
                br = self.boundingRect()
                pad += hypot(br.width(), br.height())
            pen = self.pen()
            if pen.isCosmetic():
                pad += max(1, pen.width()) * 0.7072
            return pad