[Qt-interest] Why doesn't the X11 paint engine support QPaintEngine::PixmapTransform? (Re-post due to missing line-breaking)

[Michael T]

Dear List,
 
I hope that this is the right place to ask this, as ideally one of the developers
working on that code would be best placed to answer.  I noticed that when using the
Qt X11 paint engine backend (src/gui/painting/qpaintengine_x11.cpp), if one tries to
do a drawPixmap operation with a transformation more complex than a simple
translation, the pixmap will be copied over to a QImage, the transformation done
there in software, and the result copied back to the X server.  This is even if
XRENDER is in use.  It seems to me that one could do the transformation on the
server at painting time (in the XRENDER case of course) using
XRenderSetPictureTransform(3) to rather increase the efficiency of the operation.
I have trouble believing though that the developers, who surely understand XRENDER
much better than I do, didn't think of that, so I am wondering why they chose not to
do this.
 
Thanks in advance for any answer.
 
Regards,
 
Michael 		 	   		  
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