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several TImages, 1 hPalette -> problem

Posted on 1997-10-20
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Last Modified: 2012-08-13
I use several TImages to display data. They all need the same colours, so I made 1 logical palette and 1 hPalette, which I assigned to the Picture.Bitmap.Palette property of all TImages. I use CopyRect to copy part of a memory bitmap to the TImages. This goes OK, unless I mirror the data in the CopyRect. (by passing for the source rect: Bounds(width-1, 0, -width, height-1)). Then the TImage stays black. If I give every TImage its own hPalette, the mirroring goes fine.

My questions:
1- is what I try at all posiible, or do all TImages always need  a unique hPalette?
2- if it is possible, what should I change to make it work?

thanks,

Wim
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Question by:cadenza
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Author Comment

by:cadenza
ID: 1348435
Edited text of question
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Accepted Solution

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jorgen.hojdmo earned 150 total points
ID: 1348436
Hi!

I have had the same problem, but could not make it work properly by assigning the palette property. A workaround is to use the WinAPI. Before you draw on the bitmap call:

SelectPalette(Bitmap.Canvas.Handle,YourHPalette,false);
RealizePalette(Bitmap.Canvas.Handle);

This will work fine if you do not assign the Palette.

Call the select and realize everytime your app gets focus.


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Expert Comment

by:mirek071497
ID: 1348437
This is fine however better way is to remember the hPalette in your program and use SelectPalette( savedpalette .....
at the end of pgm you must delete this object.

BTW SelectPalette  returns previous palette so you must save this and then restore. You can loose resources if this will not be done !.

prevpal := SelectPalette( ...
...
any code
...
SlelectPalette( prevpal

this is good idea to save resources without loose.

sorry for my english.
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Author Comment

by:cadenza
ID: 1348438
Thanks for the answer and valuable comment. This not only will save me time, but, as I understand from Mirek's comment, resources as well !!!

Wim
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