I'm running Qt 4.5.3 (on Ubuntu Karmic -- yes old school)
I had to comment out a recent optimization since I could not compile with it set. I just wanted to make certain we were planning on upping the baseline Qt to 4.6
Relevant commit info:
* Enable QGraphicsView::IndirectPainting mode on Panner.
Why? Because we have our own implementation of drawItems() which uses
a pixmap cache to avoid having to redraw the whole scene every time you
scroll or zoom. And, to quote the bit of Qt documentation that I've
only just discovered, "Since Qt 4.6, this function is not called
anymore unless the QGraphicsView::IndirectPainting flag is given as
an Optimization flag." So we were using the default method which is
to redraw the whole scene, instead.
Thanks, guys. No really, _thanks_. No, thank _you_.
--- trunk/rosegarden/src/gui/widgets/Panner.cpp 2010-11-10 07:22:51 UTC (rev 12130)
+++ trunk/rosegarden/src/gui/widgets/Panner.cpp 2010-11-10 20:36:48 UTC (rev 12131)
@@ -41,7 +41,8 @@
+ setOptimizationFlags(QGraphicsView::DontSavePainterState |