Author Topic: qimage to sf::image conversion (Read 8213 times)

Alia5 · « **on:** May 25, 2011, 09:22:46 pm »

hi
i need help to convert a qimage to an sf::image...
i just cant get it to work...

yeah, i can read and set every pixel, but you cant read the alpha of an pixel from an qimage :O

Laurent · « **Reply #1 on:** May 25, 2011, 10:05:46 pm »

You must convert the image to ARGB32 (QImage::convertToFormat), get the pixels (QImage::bits), and play with bitwise operators to convert from ARGB to RGBA.

Lokk · « **Reply #2 on:** May 25, 2011, 10:09:49 pm »

Take a look at here :
http://doc.qt.nokia.com/latest/qglwidget.html#convertToGLFormat

So, maybe something like this...

Code: [Select]

QImage source;
...

QImage converted = QGLWidget::convertToGLFormat(source);
sf::Image final;
final.LoadFromPixels(source.width(), source.height(), reinterpret_cast<const sf::Uint8*>(converted.bits()));

Alia5 · « **Reply #3 on:** May 25, 2011, 10:34:35 pm »

@Lokk
With your method i have to include the whole qt-opengl-library...

instead i convert using qimage.convertToFormat(QImage::Format_ARGB32);
like laurent said...

works like a charm <3

Code: [Select]

qimage.convertToFormat(QImage::Format_ARGB32);
image.LoadFromPixels(qimage.width(), qimage.height(), reinterpret_cast<const sf::Uint8*>(qimage.bits()));

much thanks to both of you

Laurent · « **Reply #4 on:** May 25, 2011, 10:55:28 pm »

Really? SFML wants RGBA, not ARGB. Colors should be wrong in the final texture.

Lokk · « **Reply #5 on:** May 25, 2011, 11:15:08 pm »

Yeah, it's really weird lol...

Alia5 · « **Reply #6 on:** May 25, 2011, 11:16:58 pm »

I only tested it with an black/transparent image....

will try...

edit: your right... :/

edit2: OpenGLWidget conversion keeps the colours but flips the y of my image xD not that big deal, but kinda sucks

Lokk · « **Reply #7 on:** May 25, 2011, 11:52:48 pm »

Quote

i can read and set every pixel, but you cant read the alpha of an pixel from an qimage :O

In fact, it is possible :

Code: [Select]

QImage image;
...
QRgb pixel = image.pixel(x, y);
int alpha = qAlpha(pixel); // return your alpha component

Alia5 · « **Reply #8 on:** May 26, 2011, 02:23:32 pm »

woot? why i didn't find the qAlpha function in the doc? :O

caracal · « **Reply #9 on:** January 02, 2012, 06:33:16 am »

Not to be a necromancer on this topic but I just ran into the same problem
here is how I solved it.

Code: [Select]


     QImage res = QImage(320, 320, QImage::Format_ARGB32);
     res.load("test.png");
     res = res.rgbSwapped();


     sf::Image image;
     image.Create(res.width(), res.height(), reinterpret_cast<const sf::Uint8*>(res.bits()));