Masked bitmap from bitmap

[Gandalf]

Hi Gurus! Here is a problem with wxPython. I would like to load bitmaps 
and create a mask
for them at once. Here is my idea: the mask colour for the bitmap should 
be the colour of
the pixel in the top left  corner. (The same way Delphi does with 
TImageList.) E.g. the
bitmap should be transparent everywhere with the same colour. I read the 
documentation,
and I could not find an easy way to do this. Here is what I have tried:

1. Create a wxIcon directly (which is a wxBitmap, I only need a masked 
wxBitmap.)

This does not suit for me, since I need to load bitmaps on all 
platforms. wxIcon cannot handle the BMP format on all platforms.
This is from the docs (about the type parameter of wx.Icon):

 >wxBITMAP_TYPE_ICO  Load a Windows icon file.
 >wxBITMAP_TYPE_ICO_RESOURCE  Load a Windows icon from the resource 
database.
 >wxBITMAP_TYPE_GIF  Load a GIF bitmap file.
 >wxBITMAP_TYPE_XBM  Load an X bitmap file.
 >wxBITMAP_TYPE_XPM  Load an XPM bitmap file.
 >
 >The validity of these flags depends on the platform and wxWindows 
configuration. If all possible wxWindows settings are used, the Windows 
platform supports ICO file, ICO resource, XPM data, and XPM file. Under 
wxGTK, the available formats are BMP file, XPM data, XPM file, and PNG 
file. Under wxMotif, the available formats are XBM data, XBM file, XPM 
data, XPM file.

wxIcon cannot handle BMP on the Windows platform so I cannot use wxIcon.

2. Load wxBitmap and use wxIcon.CopyFromBitmap.

Is not okay. This is from the docs:

 >Copies bmp bitmap to this icon. Under MS Windows the bitmap must have 
mask colour set.

Back to the stove: once I have a bitmap with a mask, I do not really 
need a wxIcon. :-( For most platforms, this solution would be fine but 
not on M$ Windows.

3. Load a bitmap and specify the mask by hand. That would be great. 
Unfortunately, I cannot get the colour of the top left pixel. There is 
no such method, or I could not find it :-/ Even if there were one, I 
would had created the mask by hand, in Python. I cannot set pixels' 
colours (no method for that). And of course, this would be very slow.

4. Load the bitmap in PIL, create the mask by hand, save the mask into a 
different file/object, load the bitmap and the saved mask into different 
objects, finally combine them. Oh yeah, I can imagine this would work. 
But it is too difficult and it would be very very very slow. There must 
be a better way.

Please note that I do not want to use C/SWIG or any external tool. I 
would like to use pure Python with wxPython if possible. Can somebody 
help me?
A code fragment or a link would be great.

Thanks in advance,

  Gandalf


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