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Examples: fix touch handling in painting examples

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On macOS, we don't deliver a press event for the first press on the
track pad (Qt::WA_TouchPadAcceptSingleTouchEvents is not set by default,
so Qt doesn't deliver a single-press on the track pad as a touch event -
that makes some sense or at least maintains compatibility). Because of
that, point 0 is never added to the finger-mapping hash.

When point 0 is then released, we didn't check if we found a valid
iterator for that point ID, and the example crashed.

Fix this by checking that we have a valid iterator before dereferencing,
and by handling Stationary events in the same way as pressed (add the
point to the mapping if it's not already there).

Pick-to: 6.5
Fixes: QTBUG-110266
Change-Id: I32337b801aaabf9b821a97ddc15ad78747b5e6a2
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>
(cherry picked from commit 9d8473cdf63537dee65e9c235249b4e4901baa1a)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit 7378c709f527749493bc15e66a566e1bdfc09fd3)
This commit is contained in:
Volker Hilsheimer 2023-12-12 12:25:11 +01:00 committed by Qt Cherry-pick Bot
parent d19037271c
commit acfe26b167
1 changed files with 6 additions and 3 deletions
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9
examples/widgets/painting/shared/hoverpoints.cpp
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@ -131,6 +131,7 @@ bool HoverPoints::eventFilter(QObject *object, QEvent *event)
const int id = point.id(); const int id = point.id();
switch (point.state()) { switch (point.state()) {
case QEventPoint::Pressed: case QEventPoint::Pressed:
case QEventPoint::Stationary:
{ {
// find the point, move it // find the point, move it
const auto mappedPoints = m_fingerPointMapping.values(); const auto mappedPoints = m_fingerPointMapping.values();
@ -155,7 +156,7 @@ bool HoverPoints::eventFilter(QObject *object, QEvent *event)
} }
} }
if (activePoint != -1) { if (activePoint != -1) {
m_fingerPointMapping.insert(point.id(), activePoint); m_fingerPointMapping.insert(id, activePoint);
movePoint(activePoint, point.position()); movePoint(activePoint, point.position());
} }
} }
@ -164,8 +165,10 @@ bool HoverPoints::eventFilter(QObject *object, QEvent *event)
{ {
// move the point and release // move the point and release
const auto it = m_fingerPointMapping.constFind(id); const auto it = m_fingerPointMapping.constFind(id);
movePoint(it.value(), point.position()); if (it != m_fingerPointMapping.constEnd()) {
m_fingerPointMapping.erase(it); movePoint(it.value(), point.position());
m_fingerPointMapping.erase(it);
}
} }
break; break;
case QEventPoint::Updated: case QEventPoint::Updated: