Avoid reentering processMouseEvents on embedded

Task-number: QTBUG-38597
Change-Id: I168c9401863bace711d0d8409bf3da30a34185bd
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Jørgen Lind <jorgen.lind@digia.com>

2 files changed, 43 insertions, 3 deletions

diff --git a/src/platformsupport/eglconvenience/qeglplatformcursor.cpp b/src/platformsupport/eglconvenience/qeglplatformcursor.cpp
index 70e7c4e4db..e99581183e 100644
--- a/src/platformsupport/eglconvenience/qeglplatformcursor.cpp
+++ b/src/platformsupport/eglconvenience/qeglplatformcursor.cpp
@@ -69,7 +69,8 @@ QEGLPlatformCursor::QEGLPlatformCursor(QPlatformScreen *screen)
       m_vertexCoordEntry(0),
       m_textureCoordEntry(0),
       m_textureEntry(0),
-      m_deviceListener(0)
+      m_deviceListener(0),
+      m_updater(screen)
 {
     QByteArray hideCursorVal = qgetenv("QT_QPA_EGLFS_HIDECURSOR");
     if (!hideCursorVal.isEmpty())
@@ -270,12 +271,32 @@ bool QEGLPlatformCursor::setCurrentCursor(QCursor *cursor)
 }
 #endif
 
-void QEGLPlatformCursor::update(const QRegion &rgn)
+void QEGLPlatformCursorUpdater::update(const QPoint &pos, const QRegion &rgn)
 {
-    QWindowSystemInterface::handleExposeEvent(m_screen->topLevelAt(m_cursor.pos), rgn);
+    m_active = false;
+    QWindowSystemInterface::handleExposeEvent(m_screen->topLevelAt(pos), rgn);
     QWindowSystemInterface::flushWindowSystemEvents();
 }
 
+void QEGLPlatformCursorUpdater::scheduleUpdate(const QPoint &pos, const QRegion &rgn)
+{
+    if (m_active)
+        return;
+
+    m_active = true;
+
+    // Must not flush the window system events directly from here since we are likely to
+    // be a called directly from QGuiApplication's processMouseEvents. Flushing events
+    // could cause reentering by dispatching more queued mouse events.
+    QMetaObject::invokeMethod(this, "update", Qt::QueuedConnection,
+                              Q_ARG(QPoint, pos), Q_ARG(QRegion, rgn));
+}
+
+void QEGLPlatformCursor::update(const QRegion &rgn)
+{
+    m_updater.scheduleUpdate(m_cursor.pos, rgn);
+}
+
 QRect QEGLPlatformCursor::cursorRect() const
 {
     return QRect(m_cursor.pos - m_cursor.hotSpot, m_cursor.size);
diff --git a/src/platformsupport/eglconvenience/qeglplatformcursor_p.h b/src/platformsupport/eglconvenience/qeglplatformcursor_p.h
index c9ff9a1198..6f4216874a 100644
--- a/src/platformsupport/eglconvenience/qeglplatformcursor_p.h
+++ b/src/platformsupport/eglconvenience/qeglplatformcursor_p.h
@@ -68,6 +68,24 @@ private:
     int m_mouseCount;
 };
 
+class QEGLPlatformCursorUpdater : public QObject
+{
+    Q_OBJECT
+
+public:
+    QEGLPlatformCursorUpdater(QPlatformScreen *screen)
+        : m_screen(screen), m_active(false) { }
+
+    void scheduleUpdate(const QPoint &pos, const QRegion &rgn);
+
+private slots:
+    void update(const QPoint &pos, const QRegion &rgn);
+
+private:
+    QPlatformScreen *m_screen;
+    bool m_active;
+};
+
 class QEGLPlatformCursor : public QPlatformCursor
 {
 public:
@@ -130,6 +148,7 @@ private:
     int m_textureCoordEntry;
     int m_textureEntry;
     QEGLPlatformCursorDeviceListener *m_deviceListener;
+    QEGLPlatformCursorUpdater m_updater;
 };
 
 QT_END_NAMESPACE