[Interest] Drawing slow.

[Giuseppe D'Angelo]

Hi,

Il 17/08/2018 20:36, Bill Crocker ha scritto:
> My newer, Qt based drawing program takes orders of magnitude longer to draw lines
> than my good old plain X-Windows based drawing program.
> 
> The Qt call stack, as revealed by VTune, is:
> 
> QPainterPath::draw
> QPaintEngineEx::draw
> QRasterPaintEngine::stroke
> QPaintEngineEx::stroke
> QRasterPaintEngine::fill
> QRasterizer::rasterize
> QScanConverter::end
> 
> Am I using some fancy, expensive feature
> that I should turn off.

How are you measuring the time / framerate / CPU usage for the 
XWindows-based one? Note that when using X11 some rendering may happen 
"server side", therefore it's not accounted for in your application's 
CPU time.

It would also be great if you had testcases.

HTH,

-- 
Giuseppe D'Angelo | giuseppe.dangelo at kdab.com | Senior Software Engineer
KDAB (France) S.A.S., a KDAB Group company
Tel. France +33 (0)4 90 84 08 53, http://www.kdab.com
KDAB - The Qt, C++ and OpenGL Experts

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