Hi,
Your workaround looks safe enough. Ideally we’d want a situation where
sendUpdateRequest results in the same callback from the OS as
handleExposeEvent, so that the two are coalesced, but the machinery for that Is
not in place yet.
Tor Arne
On 22 Feb 2023, at 03:44, sivan nanthiran <nanthiran2...@gmail.com> wrote:
Hi,
I noticed that when a native widget(Qt::WA_NativeWindow) with WA_PaintOnScreen
is added into a vertical splitter, and when the splitter is moved, 2 paint
events will be received for one mouse move.
One paint event is scheduled through QWidgetRepaintManager::sendUpdateRequest
which is from the code path of processMouseEvent. While another paint event is
called straight from NSView::displayLayer -> handleExposeEvent.
The handleExposeEvent will eventually call QWidget::syncBackingStore while the
posted event of UpdateRequest will also call QWidget::syncBackingStore. And
both of these calls will end up calling PaintOnScreen. Thus 2 paintEvents, for
one mouse action.
The problem with this is that since I am handling my own pipeline for native
widget rendering, frequent paint calls within a vsync interval is exhausting
the rendering resources.
I was wondering if I could do something like this. So far this works well for
me. But I would like to know if there is any issue with this approach. Thanks
in advance.
void QWidgetPrivate::syncBackingStore()
{
+ if (shouldPaintOnScreen())
+ {
+ Q_Q(QWidget);
+ qApp->removePostedEvents(q, QEvent::UpdateRequest);
+ }
+
if (QWidgetRepaintManager *repaintManager = maybeRepaintManager()) {
repaintManager->sync();
}
if (shouldPaintOnScreen()) {
paintOnScreen(dirty);
dirty = QRegion();
}
}
void QWidgetPrivate::syncBackingStore(const QRegion ®ion)
{
if (shouldPaintOnScreen()) {
+ Q_Q(QWidget);
+ qApp->removePostedEvents(q, QEvent::UpdateRequest);
+
if (QWidgetRepaintManager *repaintManager = maybeRepaintManager()) {
repaintManager->sync();
}
- paintOnScreen(region);
+ paintOnScreen(region + dirty);
+ dirty = QRegion();
}
else if (QWidgetRepaintManager *repaintManager = maybeRepaintManager()) {
repaintManager->sync(q_func(), region);
}
}
Regards,
Sivan
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