[Digikam-devel] [Bug 276096] PGF images not shown if zoom is set to 100%

[Marcel Wiesweg]

https://bugs.kde.org/show_bug.cgi?id=276096





--- Comment #13 from Marcel Wiesweg <marcel wiesweg gmx de>  2011-07-11 17:03:45 ---
This one was difficult to debug. 

At the root, there is a libpgf regression: When the image has no alpha 
channel, the alpha byte is set to 0, instead of 255.
(we initialize the memory with 0xFF, which seems unnecessary, given that 
libpgf seems to fully write the memory including the alpha byte).

Afterwards, the story goes so that we see the problem only in a very specific 
case:
Whenever we scale, the alpha byte is ignored because hasAlpha is false, so all 
is well. At 100%, no scaling is done, and we pass the data as is to QImage and 
then to QPixmap. QPixmap sees transparent pixels and produces a transparent 
pixmap.

I will commit an optimization which as a side-effect fixes the problem here - 
if alpha is false, the image is RGB32 and not ARGB32, which frees QPixmap from 
scanning the image for transparent pixels.

but I think the underlying regression must be fixed in libpgf, it should 
preferably write 255 to the alpha channel, or not touch the alpha channel (and 
say so in the API docs)

-- 
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.