Review Request 110649: add kimgio WebP image format plugin

[Fredrik Höglund]

> On May 26, 2013, 2:15 p.m., Fredrik Höglund wrote:
> > kimgio/webp.cpp, line 58
> > <http://git.reviewboard.kde.org/r/110649/diff/1/?file=146351#file146351line58>
> >
> >     This is not particularly efficient. WebPDecodeBGRAInto() can decode directly into a QImage without using an intermediate buffer.
> 
> Martin Koller wrote:
>     As far as I understand the QImage documentation, I can not use this: "You cannot use the uchar* pointer directly, because the pixel format depends on the byte order on the underlying platform. Use qRed(), qGreen(), qBlue(), and qAlpha() to access the pixels."
>     
>     I understood it as: WebPDecodeRGBA() delivers always 4 consecutive bytes as RGBA, regardless of the endianess of the platform, but QImage::bits() returns a pointer to the data which contains the bytes in the order of the platform, which might be different than what WebPDecodeRGBA() delivers.

QImage uses a packed-pixel format where the components are packed in 32-bit words in ARGB order. It thus follows that the byte order is BGRA on little-endian, and ARGB on big-endian.

The WebP functions are array-based, so you have to use WebPDecodeBGRAInto() on little-endian and WebPDecodeARGBInto() on big-endian.


- Fredrik


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On May 30, 2013, 10:11 a.m., Martin Koller wrote:
> 
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> http://git.reviewboard.kde.org/r/110649/
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> 
> (Updated May 30, 2013, 10:11 a.m.)
> 
> 
> Review request for KDE Runtime.
> 
> 
> Description
> -------
> 
> This patch adds support for the new Google invented WebP image format. See https://developers.google.com/speed/webp/?hl=ru
> 
> This is what was submitted before in https://git.reviewboard.kde.org/r/106300/ but it was suggested to move it to kde-runtime
> 
> 
> Diffs
> -----
> 
>   CMakeLists.txt 9f1f886 
>   kimgio/CMakeLists.txt PRE-CREATION 
>   kimgio/webp.cpp PRE-CREATION 
>   kimgio/webp.desktop PRE-CREATION 
>   kimgio/webp.h PRE-CREATION 
>   kimgio/webp.xml PRE-CREATION 
> 
> Diff: http://git.reviewboard.kde.org/r/110649/diff/
> 
> 
> Testing
> -------
> 
> some KDE apps, including read/write with a modified kolourpaint (to be able to change the quality)
> 
> 
> Thanks,
> 
> Martin Koller
> 
>

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