Loading transparent pictures > background color?

[AmigoJack]

I've searched numerous topics and have not found one useful example (code language does not matter) on how to avoid a black background when loading a picture which supports transparence. It happens with GIFs, PNGs and ICOs at least.

Can anybody give an example on how to set/define a background color to be used when loading the picture? Can be Delphi, C++, VB... anything. Thanks.

What I use so far:

Code: Select all

var
  vFileInfo: GFL_FILE_INFORMATION;
  vLoadParam: GFL_LOAD_PARAMS;
  pBmp: PGFL_BITMAP;
  iError: GFL_ERROR;
begin
  gflGetDefaultLoadParams( vLoadParam );
  vLoadParam.ColorModel:= GFL_BGR;
  vLoadParam.LinePadding:= 4;
  iError:= gflLoadBitmap( 'file.ico', @pBmp, @vLoadParam, vFileInfo );

[xnview]

You have the transparency index in GFL_BITMAP

[AmigoJack]

You have the transparency index in GFL_BITMAP

Yes, you answered the same in a couple of threads. But not more. It seems obvious to you what to do with it, but not to me.

What should I do with it? I suspect it's an index on the color palette - should I directly modify this color on the palette into RGBA white? It's a SmallInt - that makes its highest value 32767 - pretty low for all colors used on a palette, or am I missing something here?

Also: when loading my transparent ICOs, CURs or GIFs GFL_BITMAP.TransparentIndex is always -1.

[xnview]

What should I do with it? I suspect it's an index on the color palette - should I directly modify this color on the palette into RGBA white? It's a SmallInt - that makes its highest value 32767 - pretty low for all colors used on a palette, or am I missing something here?

Yes it's the index of colormap

Also: when loading my transparent ICOs, CURs or GIFs GFL_BITMAP.TransparentIndex is always -1.

Could you send me a GIF sample?

[AmigoJack]

Could you send me a GIF sample?

Several.

[xnview]

Could you send me a GIF sample?

Several.

For .ico/cur GFL doesn't support mask so TransparentIndex is always -1
For the GIF, the problem is 1bit, if you convert it in 4bits for example, there is no problem...

[AmigoJack]

For .ico/cur GFL doesn't support mask so TransparentIndex is always -1

Ok - but how to avoid a black background color when loading?

For the GIF, the problem is 1bit, if you convert it in 4bits for example, there is no problem...

Ok, but how?

[xnview]

For .ico/cur GFL doesn't support mask so TransparentIndex is always -1

Ok - but how to avoid a black background color when loading?

Currently there is no way

For the GIF, the problem is 1bit, if you convert it in 4bits for example, there is no problem...

Ok, but how?

I means, if you have a 4bits GIF file