wxPython/demo/AlphaDrawing.py

   1
   2 import wx
   3
   4 #----------------------------------------------------------------------
   5
   6 class TestPanel(wx.Panel):
   7     def __init__(self, parent, log):
   8         self.log = log
   9         wx.Panel.__init__(self, parent, -1)
  10         self.Bind(wx.EVT_PAINT, self.OnPaint)
  11
  12         txt = """\
  13 If this build of wxPython includes the new wx.GCDC class (which
  14 provides the wx.DC API on top of the new wx.GraphicsContext class)
  15 then these squares should be transparent.
  16 """
  17         wx.StaticText(self, -1, txt, (20, 20))
  18
  19
  20     def OnPaint(self, evt):
  21         pdc = wx.PaintDC(self)
  22         try:
  23             dc = wx.GCDC(pdc)
  24         except:
  25             dc = pdc
  26         rect = wx.Rect(0,0, 100, 100)
  27         for RGB, pos in [((178,  34,  34), ( 50,  90)),
  28                          (( 35, 142,  35), (110, 150)),
  29                          ((  0,   0, 139), (170,  90))
  30                          ]:
  31             r, g, b = RGB
  32             penclr   = wx.Colour(r, g, b, wx.ALPHA_OPAQUE)
  33             brushclr = wx.Colour(r, g, b, 128)   # half transparent
  34             dc.SetPen(wx.Pen(penclr))
  35             dc.SetBrush(wx.Brush(brushclr))
  36             rect.SetPosition(pos)
  37             dc.DrawRoundedRectangleRect(rect, 8)
  38
  39
  40 #----------------------------------------------------------------------
  41
  42 def runTest(frame, nb, log):
  43     win = TestPanel(nb, log)
  44     return win
  45
  46 #----------------------------------------------------------------------
  47
  48
  49
  50 overview = """<html><body>
  51 <h2><center>Alpha Drawing</center></h2>
  52
  53 The wx.GCDC class is a class that implemented the wx.DC API using the
  54 new wx.GraphicsContext class, and so it supports anti-aliased drawing
  55 using pens and brushes, that can optionally also be drawn using an
  56 alpha transparency.  (On the Mac all the DC classes are using this new
  57 implementation.)  This is accomplished by enabling the wx.Colour class
  58 to have a fourth component for the alpha value, where 0 is fully
  59 transparent, and 255 is fully opaque.
  60
  61 </body></html>
  62 """
  63
  64
  65
  66 if __name__ == '__main__':
  67     import sys,os
  68     import run
  69     run.main(['', os.path.basename(sys.argv[0])] + sys.argv[1:])
  70