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256-color CBitmapButton

srantala
srantala asked
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Medium Priority
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Last Modified: 2013-11-20
How I can use more than 20-color bitmapbutton in 8bit-mode? In better than 8bit everything works fine. MFC seems to reduce colours when I start application.
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Commented:
MFC don't reduce colours. It may be Windows does. To remove any problems convert your image to standard 256 palette.

Author

Commented:
All the pictures have been made with the standard 256-palette. BitmapButton just doesn't show all of them.

Author

Commented:
All the pictures have been make with the standard 256-colour-palette. BitmapButton just doesn't show all of them.

Commented:
Do you use bitmaps with compression? If yes try to save bitamps without compression.
Commented:
CBitmapButton does not support 256 colors because it uses ::LoadBitmap() to load the bitmaps, which converts a DIB to a DDB without the palette. So, you have to write your own 256 colors version CBitmapButton. You can refer to MFC source code about CBitmapButton to write your own class. You have to load the 256 colors bitmap as a DIB and whenever the frame window receives WM_QUERYNEWPALETTE and WM_PALETTECHANGED, you should direct them to your button so that it processes the messages.

By the way, there is no standard 256 colors palette in fact.

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Commented:
To chensu:
  Why do you think that there is no standard 256 colors palette? You can choose 16 colors palette from 64 available colors and you can choose 256 colors palette from (don't remember how much) available colors too.

Commented:
To AVaulin:
Windows reserves standard 20 colors for system use (window titles, menus, ...) in a palette. The other colors are arbitrary. If an application has its own 256 colors palette, it must process WM_QUERYNEWPALETTE and WM_PALETTECHANGED messages.
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