Capture mouse event speed in GraphicsView should not depend on paint performance.

STEPS LEADING TO PROBLEM:
1. Create a full screen empty QGraphicsWidget, capture all mouse move events.
3. Always capture 128 mouse events in 1 second with no paint.
4. Always capture 50~70 mouse events in 1 second with empty paint.

EXPECTED OUTCOME:
The mouse event generate speed should be independent.

ACTUAL OUTCOME:
The mouse event capture speed is depend on
paint speed.

FREQUENCY OF OCCURRENCE:
always

[reply] [-] Comment 1 Tan Roy (Ixonos) 2011-01-10 15:06:09 EET

test code attached.

[reply] [-] Comment 2 Tan Roy (Ixonos) 2011-01-10 15:11:18 EET

the demo code is a full testing code for sketch performance.
there are some macro for different test purpose. And all kinds of test result
are stored in sketchQtOds.ods and sketchQt.xls, please check it out.

BTW, current QGraphicsView full screen paint is so slow. Even i use empty paint
function, its only 50~ fps. If i add paint Qt line to screen, it go down to 30~
FPS.

[reply] [-] Comment 3 Tan Roy (Ixonos) 2011-01-10 15:36:34 EET

Created attachment 126506 [details]
sketchQtOds.ods

attach the test result

[reply] [-] Comment 4 Tan Roy (Ixonos) 2011-01-10 15:58:24 EET

4.7.2~git20101209/git20101231-0maemo1+0m6
translucent=false translucent=false translucent=true translucent=true
cache Qimage cache Qpixmap cache Qimage cache Qpixmap
<1> M=127 FPS=0 M=128 FPS=0 M=127 FPS=0 M=128 FPS=0
<2> M=71 FPS=55 M=68 FPS=56 M=59 FPS=50 M=52 FPS=50

<1> = Only capture mouse
<2> = Only capture mouse and empty paint

This apart diagram show the different whether call the empty paint. Even i set
my HandSketchWidget paint function doing nothing, the mouse event i got and the
FPS are both pretty low.

Then it seems impossible to add my own sketch trace and paint logic base on
such low performance.

and i try ui->graphicsView->setViewport(new GLWidget), it is much slower.

Also, i tried other ways to improve my sketchWidget performance: use small item
cache, focus partial repaint; use QtConcurrent do all my logic and cache paint
in another thread. All things i have done was useless.

I think current the problem is the basic paint performance is low, especially
when background is full translucent.