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Toolbar's images not showing in 256 color mode

Posted on 2002-03-27
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Last Modified: 2013-12-03
Hello!

Hello!

Using plain Win32 Api
...I have an app with a  toolbar with bitmap images in 256
colors indexed . The
toolbar displays well in W2K 24-bit True Color graphics mode. But when I
changed
W2k's graphics mode to 256 colors, the toolbar was created and displayed
sans the images.

How do I solve the mystery of the disappearing images?
What guidelines should I follow so bitmaps for toolbars(or any other window
using bitmaps)
will display properly?

How do I create bitmaps to display properly in all color modes? And how do I insert them into a toolbar, using CreateToolbarEx using whole bitmaps  and CreateWindowEx using imagelists?

I'll add another 100 points to the one who gives the suitable solution to the problem!

Thanks in advance!

Maimee Arai


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Question by:RolandAZ
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7 Comments
 
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Expert Comment

by:robpitt
ID: 6900517
You've discovered a fundamental problem with the toolbar control. I ran into this ages ago back when supporting 256 colour displays mattered. Obviously a lot of people don't care about 256 colour users any more ... but since I know the solution here goes...

The problem lies in the fact that the toolbar doesn't select or realise a palette before drawing itself. Thus when running on a palettised display it attempts to draw using the default 16 standard colours (which usually doesn't work very well).


The solution is to subclass the toolbar control and then replace the WM_PAINT handler with something like the following:

          BeginPaint(hWnd,&ps);

          hopal=SelectPalette(ps.hdc,hPalette,TRUE);
          RealizePalette(ps.hdc);
         
          flags=PRF_CHECKVISIBLE|PRF_CLIENT;
          if (ps.fErase) flags|=PRF_ERASEBKGND;
          SendMessage(hWnd,WM_PRINT,(WPARAM)ps.hdc,flags);

          SelectPalette(ps.hdc,hopal,TRUE);
          EndPaint(hWnd,&ps);
          return 0;


The above selects and realises a palette before using WM_PRINT to get the control to draw itself using the newly selected palette.



Rob

PS For those extra 100 pts, I'll send you a full working example - post your email here.
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Expert Comment

by:robpitt
ID: 6900522
PPS

An alternative to subclassing the window is you use the NM_CUSTOMDRAW (CDDS_PREPAINT) notification and select the palette here. Note this feature is only supported on ComCtl32.dll v4.7 and later... then again most people do have this now as its included with Internet Explorer.
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LVL 5

Expert Comment

by:robpitt
ID: 6900543
PPS

An alternative to subclassing the window is you use the NM_CUSTOMDRAW (CDDS_PREPAINT) notification and select the palette here. Note this feature is only supported on ComCtl32.dll v4.7 and later... then again most people do have this now as its included with Internet Explorer.
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Author Comment

by:RolandAZ
ID: 6902328
Thanks, Rob, for the tip!

Could you please send me your working example that used "subclassing" the toolbar and one using NM_CUSTOMDRAW in Win32 API C, or in non-MFC C++ ?

Send it to rolandaz@hotmail.com

Thanks again!

I'm increasing the points by 100...
another 100, when I have incorporated your solution and satisfied my program's need. I hope it will...
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Accepted Solution

by:
robpitt earned 300 total points
ID: 6904745
Can't send it, your mailbox is full.

Get it from : http://63.144.255.25/downloads/misc/TB256.zip
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Author Comment

by:RolandAZ
ID: 6904845

Great programming!
Thanks, Rob!


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