[Qt-interest] Using OpenGL to render and transform a SVG in a QDialog

[Andre Somers]

  Op 18-10-2010 22:08, Sven Grunewaldt schreef:
> Thanks for your reply Max,
>
> rotating before rendering did indeed work:
(...)
> The image does rotate now but it keeps the top left corner of the SVG in
> the top left corner of the QGLWidget:
> http://dl.dropbox.com/u/256059/tmp/qglwidget.png
>
> I guess it is my responsibility to recalculate the position and "center"
> the SVG again... I can't see how I'm supposed to do that with QTransform
> or QPainter other than moving the ViewPort - is this correct?
Yes. And it is not that hard. The easiest way is to do it in a few 
steps: first, create a transformation that represents the translation. 
You just make sure that you translate the centre of your needle to the 
origin of your painter. Create the inverted transformation too, so you 
can translate back. Then, create your total matrix by multiplying the 
transformation matrices: TM = translate center to origin * rotation * 
translate back. This matrix should do what you want.

André