Optimize egl cursor update events

Avoid invokeMethod on every cursor movement and use an event instead. This is more
lightweight and efficient. Also, there is no need to have a separate QObject just
for this.

Change-Id: I65ae202943eeb1e30cf22926576f84198f2487f8
Reviewed-by: Andy Nichols <andy.nichols@theqtcompany.com>

2 files changed, 34 insertions, 38 deletions

diff --git a/src/platformsupport/eglconvenience/qeglplatformcursor.cpp b/src/platformsupport/eglconvenience/qeglplatformcursor.cpp
index fc6e4bad8d..bf23d52465 100644
--- a/src/platformsupport/eglconvenience/qeglplatformcursor.cpp
+++ b/src/platformsupport/eglconvenience/qeglplatformcursor.cpp
@@ -62,7 +62,7 @@ QEGLPlatformCursor::QEGLPlatformCursor(QPlatformScreen *screen)
       m_textureCoordEntry(0),
       m_textureEntry(0),
       m_deviceListener(0),
-      m_updater(screen)
+      m_updateRequested(false)
 {
     QByteArray hideCursorVal = qgetenv("QT_QPA_EGLFS_HIDECURSOR");
     if (!hideCursorVal.isEmpty())
@@ -246,30 +246,43 @@ bool QEGLPlatformCursor::setCurrentCursor(QCursor *cursor)
 }
 #endif
 
-void QEGLPlatformCursorUpdater::update(const QPoint &pos, const QRegion &rgn)
+class CursorUpdateEvent : public QEvent
 {
-    m_active = false;
-    QWindowSystemInterface::handleExposeEvent(m_screen->topLevelAt(pos), rgn);
-    QWindowSystemInterface::flushWindowSystemEvents(QEventLoop::ExcludeUserInputEvents);
-}
-
-void QEGLPlatformCursorUpdater::scheduleUpdate(const QPoint &pos, const QRegion &rgn)
+public:
+    CursorUpdateEvent(const QPoint &pos, const QRegion &rgn)
+        : QEvent(QEvent::Type(QEvent::User + 1)),
+          m_pos(pos),
+          m_region(rgn)
+        { }
+    QPoint pos() const { return m_pos; }
+    QRegion region() const { return m_region; }
+
+private:
+    QPoint m_pos;
+    QRegion m_region;
+};
+
+bool QEGLPlatformCursor::event(QEvent *e)
 {
-    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));
+    if (e->type() == QEvent::User + 1) {
+        CursorUpdateEvent *ev = static_cast<CursorUpdateEvent *>(e);
+        m_updateRequested = false;
+        QWindowSystemInterface::handleExposeEvent(m_screen->topLevelAt(ev->pos()), ev->region());
+        QWindowSystemInterface::flushWindowSystemEvents(QEventLoop::ExcludeUserInputEvents);
+        return true;
+    }
+    return QPlatformCursor::event(e);
 }
 
 void QEGLPlatformCursor::update(const QRegion &rgn)
 {
-    m_updater.scheduleUpdate(m_cursor.pos, rgn);
+    if (!m_updateRequested) {
+        // 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.
+        m_updateRequested = true;
+        QCoreApplication::postEvent(this, new CursorUpdateEvent(m_cursor.pos, rgn));
+    }
 }
 
 QRect QEGLPlatformCursor::cursorRect() const
diff --git a/src/platformsupport/eglconvenience/qeglplatformcursor_p.h b/src/platformsupport/eglconvenience/qeglplatformcursor_p.h
index 1c05a06b63..481bb3c74c 100644
--- a/src/platformsupport/eglconvenience/qeglplatformcursor_p.h
+++ b/src/platformsupport/eglconvenience/qeglplatformcursor_p.h
@@ -70,24 +70,6 @@ private:
     QEGLPlatformCursor *m_cursor;
 };
 
-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, protected QOpenGLFunctions
 {
     Q_OBJECT
@@ -109,6 +91,7 @@ public:
     void updateMouseStatus();
 
 private:
+    bool event(QEvent *e) Q_DECL_OVERRIDE;
 #ifndef QT_NO_CURSOR
     bool setCurrentCursor(QCursor *cursor);
 #endif
@@ -150,7 +133,7 @@ private:
     int m_textureCoordEntry;
     int m_textureEntry;
     QEGLPlatformCursorDeviceListener *m_deviceListener;
-    QEGLPlatformCursorUpdater m_updater;
+    bool m_updateRequested;
 };
 
 QT_END_NAMESPACE