On 08/17/2018 02:36 PM, Bill Crocker wrote:
Hello:
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
From some experimentation it appears that the CPU time required by the
QPainterPath system is quite non-linear in the number of control points.
So, if I break my one long path up into a number of shorter paths, it
draws MUCH faster.
I use the QPainterPath because I have a dotted-line option and it knows
how to handle the corners.
Bill
Am I using some fancy, expensive feature
that I should turn off.
Thanks.
Bill
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