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IDProjectCategoryView StatusLast Update
0002135JEDI VCL00 JVCL Componentspublic2005-02-03 04:33
ReporterchddvAssigned Toobones 
Status resolvedResolutionfixed 
Product Version 
Target VersionFixed in Version3.00 
Summary0002135: JvGif could render some part of a gif tranparently but should not
DescriptionJvGif seems using the pixel color to know if a pixel is transparent instead of using the pallette number of this pixel. (In additionnal information I have copy a post of Remko Bonte clearer about the problem (date: 09/09/2004 23:37).)
Steps To ReproduceCreate a new project, add a TImage. In the TImage load the Image linked, and set the property transparent of TImage to true. The image appears transparent but should not.
Additional InformationOBones wrote:

> AFAIK, the transparent property works exactly like a TImage:
> Every pixel that is the same colour as the bottom left one is transparent. If your bottom left pixel is white, then every white pixel will be considered as transpare,t.

The GIF format has a Transparent Color Index field that specifies what the transparent color should be.

GIF pictures work with palettes. In the example gif picture given by Chris, the palette consist out of 64 colors. The color of the palette index 10 is white ($FFFFFF). The color of the palette index 42 is also white ($FFFFFF). Furthermore the image specifies that palette index 42 should be transparent. The white area on the picture has palette index 10. There is no pixel on the picture with palette index 42.

This confuses the component somehow.

The attached optimized gif image has that problem not.

Remko Bonte (Team JVCL)
TagsNo tags attached.


2004-09-10 12:13


logo.gif (1,802 bytes)
logo.gif (1,802 bytes)


2005-02-03 04:33

administrator   ~0006359

This is now fixed in CVS. Please use file version 1.28

Issue History

Date Modified Username Field Change
2004-09-10 12:13 chddv New Issue
2004-09-10 12:13 chddv File Added: logo.gif
2004-10-01 00:20 obones Status new => assigned
2004-10-01 00:20 obones Assigned To => obones
2005-02-03 04:33 obones Status assigned => resolved
2005-02-03 04:33 obones Fixed in Version => 3.00
2005-02-03 04:33 obones Resolution open => fixed
2005-02-03 04:33 obones Note Added: 0006359