On 11/22/19 2:14 PM, Roland Hughes wrote:
There have been many requests over the years to allow QPainter
operations outside of the primary thread. In particular for running
graphs like heart rate monitors which are just a brick on the screen the
user generally cannot interact with.
With X11 it is at least possible to draw outside of the paint event -
see Qt::WA_PaintOutsidePaintEvent. This type of operation is used in the
Qwt plot package for exactly the use case you have mentioned.
I'm not 100% sure if it wouldn't be possible to the same in an extra thread.
With Qt3 it was even possible to draw in XOR mode, what was at that time
the way how rubberbands were implemented. This was an operation where
you could erase content without having to repaint from scratch. But this
one seems to be gone forever.
Uwe
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