Hi all,
A while back I promised an example of using the wx.Overlay to assist
with drawing temporary things like rubber-band boxes over the top of
something else. I finally did that this morning and I've attached the
result. Basically instead of using the wx.INVERT or wx.XOR trick of
drawing a 2nd time to "erase" the rectangle, you can draw whatever you
want, in any colour you want, and you don't have to rely on a
side-effect of the logical op to make it work.
--
Robin Dunn
Software Craftsman
http://wxPython.org Java give you jitters? Relax with wxPython!
"""
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()
app = wx.App(redirect=False)
frm = wx.Frame(None, title="wx.Overlay Test", size=(450,450))
pnl = TestPanel(frm)
frm.Show()
app.MainLoop()
