Comment 2 for bug 981210

The attached patch solves the problem ont the device of #0.

I have changed drawPixamp to drawImage.

There is still a Pixamp version of the bitmap in Memory, to easy test the the performance on other Systems.
The patch includes the results from tests on #0 Netbook with Qt 4.6 and Intel GPU and a ubuntu desktop box with Qt 4.8 and Radeon driver.

It turns out that although we can read this:
http://qt-project.org/doc/qt-4.8/qimage.html
"QImage is designed and optimized for I/O, and for direct pixel access and manipulation, while QPixmap is designed and optimized for showing images on screen."

.. the drawImage version is significant faster and not at least Intel Qt 4.6 compatible.

If we find systems, where this is not the case we can include conditions for using drawPixamp. But for the moment this version is just fine. Or we may remove the Pixamp copys from memory later.

This patch works also on ubuntu 64 and 32 with nvidia driver and on WinXp in a Virtual Box.