[wxDFB] wxBitmap swaps R and B colours in certain situations

[alarsen]

wxBitmap displays with R and B colours swapped IFF the wxBitmap does NOT have an alpha channel, as can be demonstrated by the attached patch to the old wxDFB test-bitmap sample.

If the sample function LoadBitmap() is modified to not convert the bitmap to and from a wxImage, the leftmost image is shown with interchanged colours, otherwise it's the rightmost one that's displayed wrong.
If the body of DrawRedEffectsOnBitmap() is commented out completely, both images are displayed identically (as expected).

Text colours are always correct, only wxBitmaps get their colours swapped.

I'm using DirectFB c59be091ecbd83bfcc1535c934bbaf1305b5feac from Wed Jun 4 23:00:39 2008 +0200 plus a VT-switch patch from Vaclav;
the framebuffer is 240x320 RGB16.
(This used to work on an older system with an older DirectFB version; the problem manifests itself on new hardware with newer compiler (4.2.4 vs 3.4.4), newer Linux kernel/framebuffer driver, newer wxWidgets and newer DirectFB...)

[alarsen]

Modification of testbitmap.cpp

[alarsen]

original sample

[vaclavslavik]

As far as I can tell, this is a bug in DirectFB -- the wx code looks innocent and I was able to reproduce the bug in pure DirectFB code. Removing Bop_rgb24_to_Aop_rgb16_LE() helps, presumably it didn't yet exist in the version that worked for you (see the details here:  http://mail.directfb.org/pipermail/directfb-dev/2010-September/005820.html).

[alarsen]

Patch against DirectFB git master

[alarsen]

Replying to vaclavslavik:
The attached patch 0001-Remove-the-BGR-RGB-conversion-from-Bop_rgb24_to_Aop.patch seems to solve my original wxBitmap problem.
Could you please check if the df_porter example behaves correctly with the patch applied before submitting it upstream?

BTW what exactly do you mean by "removing Bop_rgb24_to_Aop_rgb16_LE()"?

(Too bad your report didn't prompt more reaction upstream)

Thanks for looking into it!
Anders

[vaclavslavik]

Works for my pure-DFB example too, thanks! Will you submit your patch to DFB developers or should I?

[alarsen]

Replying to vaclavslavik:

Will you submit your patch to DFB developers or should I?

Well, since you obviously already have posting rights to the DFB list...

Thanks again,
Anders