[Pkg-pascal-devel] Change xcf2png -> ImageMagick breaks images with alpha channel

[Paul Gevers]

Hi Michalis,

Thanks for jumping in. I'm a novice in graphics, I checked one icon
where I first had issues with transparency, which I was able to fix.

On 11-02-2021 13:46, Michalis Kamburelis wrote:
> I checked the last change, to use ImageMagick to convert some XCF to
> PNG within Castle Game Engine in Debian, and I don't think the command
> works correctly.
> 
> Testcase:
> 
> cd src/ui/opengl/gui-images/
> convert -layers flatten -background transparent FrameYellow.xcf
> NewFrameYellow.png
> 
> You can now compare NewFrameYellow.png (which will be in Debian
> package) vs FrameYellow.png in original CGE sources (attaching). The
> former looks like it lost alpha channel, i.e. it is all yellow. while
> it should be only a yellow frame with transparent area in the middle.
> 
> How can we fix it? In upstream, we use (obviously) jump GIMP to
> convert XCF to PNG. I know that pulling GIMP as build-dependency of
> CGE feels "heavy", but it seems like the most reliable solution.

I don't care pulling in gimp if it produces better pics, so if you're
able to provide a command line way to instruct gimp to convert the
icons, I'll upload straight away.

Paul

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