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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