wxPython/demo/ImageAlpha.py

   1
   2 import wx                  # This module uses the new wx namespace
   3 from Main import opj
   4
   5
   6 #----------------------------------------------------------------------
   7
   8 msg = "Some text will appear mixed in the image's shadow..."
   9
  10 class TestPanel(wx.Panel):
  11     def __init__(self, parent, log):
  12         self.log = log
  13         wx.Panel.__init__(self, parent, -1)
  14
  15         self.Bind(wx.EVT_PAINT, self.OnPaint)
  16
  17
  18     def OnPaint(self, evt):
  19         dc = wx.PaintDC(self)
  20         dc.SetBackground(wx.Brush("WHITE"))
  21         dc.Clear()
  22
  23         dc.SetFont(wx.Font(16, wx.SWISS, wx.NORMAL, wx.BOLD, True))
  24         dc.DrawText("Bitmap alpha blending (on all ports but gtk+ 1.2)",
  25                     25,25)
  26
  27         bmp = wx.Bitmap(opj('bitmaps/toucan.png'))
  28         if "gtk1" in wx.PlatformInfo:
  29             # Try to make up for lack of alpha support in wxGTK (gtk+
  30             # 1.2) by converting the alpha blending into a
  31             # transparency mask.
  32
  33             # first convert to a wx.Image
  34             img = bmp.ConvertToImage()
  35
  36             # Then convert the alpha channel to a mask, specifying the
  37             # threshold below which alpha will be made fully
  38             # transparent
  39             img.ConvertAlphaToMask(220)
  40
  41             # convert back to a wx.Bitmap
  42             bmp = img.ConvertToBitmap()
  43
  44
  45         dc.DrawBitmap(bmp, 25,100, True)
  46
  47         dc.SetFont(self.GetFont())
  48         y = 75
  49         for line in range(10):
  50             y += dc.GetCharHeight() + 5
  51             dc.DrawText(msg, 200, y)
  52         dc.DrawBitmap(bmp, 250,100, True)
  53
  54
  55
  56 #----------------------------------------------------------------------
  57
  58 def runTest(frame, nb, log):
  59     win = TestPanel(nb, log)
  60     return win
  61
  62 #----------------------------------------------------------------------
  63
  64
  65
  66 overview = """<html><body>
  67 <h2><center>Images with Alpha</center></h2>
  68
  69 wxMSW and wxMac now support alpha channels of supported image
  70 types, and will properly blend that channel when drawing a
  71 bitmap.  It is not supported yet on wxGTK, (if you would like to
  72 change that please submit a patch!)
  73
  74 <p>On wxGTK this demo turns the alpha channel into a 1-bit mask, so
  75 yes, it looks like crap.  Please help us fix it!
  76
  77 </body></html>
  78 """
  79
  80
  81
  82 if __name__ == '__main__':
  83     import sys,os
  84     import run
  85     run.main(['', os.path.basename(sys.argv[0])] + sys.argv[1:])
  86