+ // scan the bitmap for the transparent colour and set
+ // the corresponding pixels in the mask to BLACK and
+ // the rest to WHITE
+ COLORREF maskColour = RGB(colour.Red(), colour.Green(), colour.Blue());
+ m_maskBitmap = (WXHBITMAP) ::CreateBitmap(
+ bitmap.GetWidth(),
+ bitmap.GetHeight(),
+ 1, 1, 0
+ );
+ HDC srcDC = ::CreateCompatibleDC(0);
+ ::SelectObject(srcDC, (HBITMAP) bitmap.GetHBITMAP());
+ HDC destDC = ::CreateCompatibleDC(0);
+ ::SelectObject(destDC, (HBITMAP) m_maskBitmap);
+
+ // this is not very efficient, but I can't think
+ // of a better way of doing it
+ for (int w = 0; w < bitmap.GetWidth(); w++)
+ {
+ for (int h = 0; h < bitmap.GetHeight(); h++)
+ {
+ COLORREF col = GetPixel(srcDC, w, h);
+ if (col == maskColour)
+ {
+ ::SetPixel(destDC, w, h, RGB(0, 0, 0));
+ }
+ else
+ {
+ ::SetPixel(destDC, w, h, RGB(255, 255, 255));
+ }
+ }
+ }
+ ::SelectObject(srcDC, 0);
+ ::DeleteDC(srcDC);
+ ::SelectObject(destDC, 0);
+ ::DeleteDC(destDC);
+ return TRUE;