[REG 5.2->5.3] Windows: Drawing rotated ellipses is very slow with QPainter in QPrinter environment.

There are some performance issues with QPainter printing to some device (large plotter).

Paper size: A0
Resolution: 600 DPI

We set clip area with setClipRect() and than we set transformation which translates and rotates coordinate system according to ellipses major and minor axes. We draw some ellipses with above options and this is very slow because it creating temporary clipping region out of our initial rectangle and this clipping region made out of 27000 clipping sub-rectangles and it looks like they are created and destroyed for every single ellipse.

We are using QPainter::drawPath(), QPainterPath::arcMoveTo() and QPainterPath::arcTo() functions. It was working fast in Qt 4.7.4 environment.

Please see the attached printerperformancetest_v1.zip test program.

Qt 4.8.6

Printing ellipses: 2073ms
Printing ellipses: 330ms
Subsequent results: ~ 250ms

Qt 5.3

Debug
Printing ellipses: 34269ms
Printing ellipses: 34528ms
Printing ellipses: 34788ms

Subsequent results: ~ 34000ms

Release
Printing ellipses: 14933ms
Printing ellipses: 16016ms
Printing ellipses: 15683ms

Subsequent results: ~ 15000ms

Noticeable for paper size A4 already, only in Native/PS format (-0). It is fast when using PDF (-p).