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Bug 1766 - no colorkey in surfaces loaded from *.png
Summary: no colorkey in surfaces loaded from *.png
Status: RESOLVED FIXED
Alias: None
Product: SDL_image
Classification: Unclassified
Component: misc (show other bugs)
Version: unspecified
Hardware: x86_64 All
: P2 minor
Assignee: Sam Lantinga
QA Contact: Sam Lantinga
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2013-03-21 08:41 UTC by Peter Kosyh
Modified: 2013-03-24 12:58 UTC (History)
0 users

See Also:

Attachments
indexed png (289 bytes, image/png)
2013-03-21 08:41 UTC, Peter Kosyh 		Details
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Description Peter Kosyh 2013-03-21 08:41:07 UTC 
Created attachment 1075 [details]
indexed png

While linking with SDL 2.0 (taken from hg) i got a problem.

After loading indexed (not RGB!) png, i found, that SDL_GetColorKey is always returns -1. I attached png, that gives the problem. Just load it and do SDL_GetColorKey. So, while blitting such Surface we will get black background, instead of transparency.

I tried to debug SDL_image, but all what i got is no SDL_COPY_COLORKEY in surface->map->info.flags just after loading from png.

Of course, if i manually set colorkey with SDL_SetColorKey (for example, taking pixel from 0,0), all is fine, but without knowing png structure i can not found what color key is transparent.

I have no problem with SDL 1.2. Hope, my report will help.
Comment 1 Sam Lantinga 2013-03-23 16:40:02 UTC 
I think this is fixed, can you check it?
http://hg.libsdl.org/SDL_image/rev/326a602521f2

Thanks!
Comment 2 Peter Kosyh 2013-03-24 01:37:44 UTC 
Thank you! I have pulled from hg and found, that image is transparent now, but, currently only white color is visible. I do not see black borders in image that i attached. 

Just see image in gimp, there are two colors (black, white) and transparent. While blitting i see only white. I am not sure if it is another bug?
Comment 3 Sam Lantinga 2013-03-24 11:53:57 UTC 
It's because there are three entries in the palette and only two distinct RGB colors. I'll have to think about the best fix for this.
Comment 4 Sam Lantinga 2013-03-24 12:58:27 UTC 
Okay, this is fixed! This required changes both in SDL and SDL_image.
Thanks!