1 files changed, 40 insertions, 3 deletions

diff --git a/src/gui/kernel/qwindowsysteminterface.cpp b/src/gui/kernel/qwindowsysteminterface.cpp
index bb778bc5fc7..ecc84e73d74 100644
--- a/src/gui/kernel/qwindowsysteminterface.cpp
+++ b/src/gui/kernel/qwindowsysteminterface.cpp
@@ -460,9 +460,40 @@ void QWindowSystemInterface::handleTouchEvent(QWindow *w, QTouchDevice *device,
 handleTouchEvent(w, time, device, points, mods);
 }

+static int g_nextPointId = 1;
+
+// map from device-independent point id (arbitrary) to "Qt point" ids
+typedef QMap<quint64, int> PointIdMap;
+Q_GLOBAL_STATIC(PointIdMap, g_pointIdMap)
+
+/*!
+ This function maps potentially arbitrary point ids \a pointId in the 32 bit
+ value space to start from 1 and increase incrementally for each touch point
+ held down. If all touch points are released it will reset the id back to 1
+ for the following touch point.
+
+ We can then assume that the touch points ids will never become too large,
+ and it will then put the device identifier \a deviceId in the upper 8 bits.
+ This leaves us with max 255 devices, and 16.7M taps without full release
+ before we run out of value space.
+*/
+static int acquireCombinedPointId(quint8 deviceId, int pointId)
+{
+ quint64 combinedId64 = (quint64(deviceId) << 32) + pointId;
+ auto it = g_pointIdMap->constFind(combinedId64);
+ int uid;
+ if (it == g_pointIdMap->constEnd()) {
+ uid = g_nextPointId++;
+ g_pointIdMap->insert(combinedId64, uid);
+ } else {
+ uid = *it;
+ }
+ return (deviceId << 24) + uid;
+}
+
 QList<QTouchEvent::TouchPoint>
 QWindowSystemInterfacePrivate::fromNativeTouchPoints(const QList<QWindowSystemInterface::TouchPoint> &points,
- const QWindow *window,
+ const QWindow *window, quint8 deviceId,
 QEvent::Type *type)
 {
 QList<QTouchEvent::TouchPoint> touchPoints;
@@ -473,7 +504,7 @@ QList<QTouchEvent::TouchPoint>
 QList<QWindowSystemInterface::TouchPoint>::const_iterator point = points.constBegin();
 QList<QWindowSystemInterface::TouchPoint>::const_iterator end = points.constEnd();
 while (point != end) {
- p.setId(point->id);
+ p.setId(acquireCombinedPointId(deviceId, point->id));
 if (point->uniqueId >= 0)
 p.setUniqueId(point->uniqueId);
 p.setPressure(point->pressure);
@@ -506,6 +537,11 @@ QList<QTouchEvent::TouchPoint>
 *type = QEvent::TouchEnd;
 }

+ if (states == Qt::TouchPointReleased) {
+ g_nextPointId = 1;
+ g_pointIdMap->clear();
+ }
+
 return touchPoints;
 }

@@ -540,7 +576,8 @@ void QWindowSystemInterface::handleTouchEvent(QWindow *tlw, ulong timestamp, QTo
 return;

 QEvent::Type type;
- QList<QTouchEvent::TouchPoint> touchPoints = QWindowSystemInterfacePrivate::fromNativeTouchPoints(points, tlw, &type);
+ QList<QTouchEvent::TouchPoint> touchPoints =
+ QWindowSystemInterfacePrivate::fromNativeTouchPoints(points, tlw, QTouchDevicePrivate::get(device)->id, &type);

 QWindowSystemInterfacePrivate::TouchEvent *e =
 new QWindowSystemInterfacePrivate::TouchEvent(tlw, timestamp, type, device, touchPoints, mods);