Which format to use for efficient QImage to QPixmap conversion?

[Simmania]

Hi,
I would like to create an QImage from scratch and convert it to a QPixmap to show it on screen.
Which QImage format should I use to make the conversion to QPixmap fast?
I guess I need to use the native screen format. But how can I find that out?

[SGaist]

Hi,

Which operations will you be doing to your QImage ? Depending on that, it might be possible to do them directly on the pixmap.

[Simmania]

I want to fill in the pixels with some algorithm. It must be pixel accurate. And then draw the resulting image (possibly stretched) onto the screen.
I prefere not to use painter functions for this to get maximum speed. Unless the transfer from image to pixelmap takes a lot of time, then maybe drawing to pixmap is faster. But I have to fill in the pixels one by one. So writing to a char array will be faster.

And I had problems painting to the screen directly before (see some other posts). To avoid this kind of problems (like scaling) I think it is better to not paint to a pixmap because that probably adapts to the screen too.