test_overlay.py

#!/usr/bin/env python
"""
A simple sample of using a wx.Overlay to draw a rubberband effect
"""

import wx
print(wx.version())


class TestPanel(wx.Panel):
    def __init__(self, *args, **kw):
        wx.Panel.__init__(self, *args, **kw)

        self.Bind(wx.EVT_PAINT, self.OnPaint)
        self.Bind(wx.EVT_LEFT_DOWN, self.OnLeftDown)
        self.Bind(wx.EVT_LEFT_UP, self.OnLeftUp)
        self.Bind(wx.EVT_MOTION, self.OnMouseMove)

        self.startPos = None
        self.overlay = wx.Overlay()


    def OnPaint(self, evt):
        # Just some simple stuff to paint in the window for an example
        dc = wx.PaintDC(self)
        coords = ((40, 40), (200, 220), (210, 120), (120, 300))
        dc.SetBackground(wx.Brush("sky blue"))
        dc.Clear()
        dc.SetPen(wx.Pen("red", 2))
        dc.SetBrush(wx.CYAN_BRUSH)
        dc.DrawPolygon(coords)
        dc.DrawLabel("Draw the mouse across this window to see \n"
                    "a rubber-band effect using wx.Overlay",
                    (140, 50, -1, -1))

    def OnLeftDown(self, evt):
        # Capture the mouse and save the starting posiiton for the
        # rubber-band
        self.CaptureMouse()
        self.startPos = evt.GetPosition()

    def OnMouseMove(self, evt):
        if evt.Dragging() and evt.LeftIsDown():
            rect = wx.RectPP(self.startPos, evt.GetPosition())

            # Draw the rubber-band rectangle using an overlay so it
            # will manage keeping the rectangle and the former window
            # contents separate.
            dc = wx.ClientDC(self)
            odc = wx.DCOverlay(self.overlay, dc)
            odc.Clear()

            dc.SetPen(wx.Pen("black", 2))
            if 'wxMac' in wx.PlatformInfo:
                dc.SetBrush(wx.Brush(wx.Colour(0xC0, 0xC0, 0xC0, 0x80)))
            else:
                dc.SetBrush(wx.TRANSPARENT_BRUSH)
            dc.DrawRectangleRect(rect)

            del odc # work around a bug in the Python wrappers to make
                    # sure the odc is destroyed before the dc is.

    def OnLeftUp(self, evt):
        if self.HasCapture():
            self.ReleaseMouse()
        self.startPos = None

        # When the mouse is released we reset the overlay and it
        # restores the former content to the window.
        dc = wx.ClientDC(self)
        odc = wx.DCOverlay(self.overlay, dc)
        odc.Clear()
        del odc
        self.overlay.Reset()


if __name__ == '__main__':
    app = wx.App(redirect=False)
    frm = wx.Frame(None, title="wx.Overlay Test", size=(450, 450))
    pnl = TestPanel(frm)
    frm.Show()
    app.MainLoop()