GMIC in Krita

[Boudewijn Rempt]

On Sun, 14 Apr 2013, Lukast dev wrote:

>>> So my approach will be:
>>> a) convert layer actual color-space to FLOAT32 RGB(A), relayout pixel
>>> format (Krita uses bgrbgrbgrbgr, GMIC rrrrbbbbgggg)
>>
>>
>> Hm, I don't think so. Specially for float32 I created KoRgbF32Traits --
>> this means that the f32 and f16 colorspaces layout the pixel as rgba:
>>
>>    addChannel(new KoChannelInfo(i18n("Red")  , 0 * sizeof(float), 0,
>> KoChannelInfo::COLOR, KoChannelInfo::FLOAT32, 4, QColor(255, 0, 0)));
>>     addChannel(new KoChannelInfo(i18n("Green"), 1 * sizeof(float), 1,
>> KoChannelInfo::COLOR, KoChannelInfo::FLOAT32, 4, QColor(0, 255, 0)));
>>     addChannel(new KoChannelInfo(i18n("Blue") , 2 * sizeof(float), 2,
>> KoChannelInfo::COLOR, KoChannelInfo::FLOAT32, 4, QColor(0, 0, 255)));
>>     addChannel(new KoChannelInfo(i18n("Alpha"), 3 * sizeof(float), 3,
>> KoChannelInfo::ALPHA, KoChannelInfo::FLOAT32, 4));
>>
>> So not much conversion needed, I think
>
> Well, it still layout pixels in 2x2 image like this:
>
> rgbargbargbargba
>
> but GMIC asks for
>
> rrrrggggbbbbaaaa
>

Ah! Now I get you. But that is already provided for, too, by:

     /**
      * Copy the bytes in the paint device into a vector of arrays of 
bytes,
      * where the number of arrays is the number of channels in the
      * paint device. If the specified area is larger than the paint
      * device's extent, the default pixel will be read.
      */
     QVector<quint8*> readPlanarBytes(qint32 x, qint32 y, qint32 w, qint32 
h);

     /**
      * Write the data in the separate arrays to the channes. If there
      * are less vectors than channels, the remaining channels will not
      * be copied. If any of the arrays points to 0, the channel in
      * that location will not be touched. If the specified area is
      * larger than the paint device, the paint device will be
      * extended. There are no guards: if the area covers more pixels
      * than there are bytes in the arrays, krita will happily fill
      * your paint device with areas of memory you never wanted to be
      * read. Krita may also crash.
      *
      * XXX: what about undo?
      */
     void writePlanarBytes(QVector<quint8*> planes, qint32 x, qint32 y, 
qint32 w, qint32 h);


Not absolutely completely efficient, of course, but this is the right 
thing to do. And I should spell-check the apidox and remove that XXX
:-).

Boud