Cocoa: add scroll optimization when scrolling both hor and ver

4 files changed, 70 insertions, 0 deletions

diff --git a/src/gui/kernel/qcocoaview_mac.mm b/src/gui/kernel/qcocoaview_mac.mm
index 18a2be1..1b81699 100644
--- a/src/gui/kernel/qcocoaview_mac.mm
+++ b/src/gui/kernel/qcocoaview_mac.mm
@@ -579,6 +579,10 @@ static int qCocoaViewCount = 0;
     }
 
 #ifndef QT_NO_WHEELEVENT
+    // ### Qt 5: Send one QWheelEvent with dx, dy and dz
+
+    QMacScrollOptimization::initNewScroll();
+
     if (deltaX != 0) {
         QWheelEvent qwe(qlocal, qglobal, deltaX, buttons, keyMods, Qt::Horizontal);
         qt_sendSpontaneousEvent(widgetToGetMouse, &qwe);
@@ -595,6 +599,8 @@ static int qCocoaViewCount = 0;
         QWheelEvent qwe(qlocal, qglobal, deltaZ, buttons, keyMods, (Qt::Orientation)3);
         qt_sendSpontaneousEvent(widgetToGetMouse, &qwe);
     }
+
+    QMacScrollOptimization::performDelayedScroll();
 #endif //QT_NO_WHEELEVENT
 }
 
diff --git a/src/gui/kernel/qt_cocoa_helpers_mac.mm b/src/gui/kernel/qt_cocoa_helpers_mac.mm
index 35b9d52..ddbf53f 100644
--- a/src/gui/kernel/qt_cocoa_helpers_mac.mm
+++ b/src/gui/kernel/qt_cocoa_helpers_mac.mm
@@ -1724,6 +1724,12 @@ void qt_mac_post_retranslateAppMenu()
 #endif
 }
 
+QWidgetPrivate *QMacScrollOptimization::_target = 0;
+bool QMacScrollOptimization::_inWheelEvent = false;
+int QMacScrollOptimization::_dx = 0;
+int QMacScrollOptimization::_dy = 0;
+QRect QMacScrollOptimization::_scrollRect = QRect(0, 0, -1, -1);
+
 #ifdef QT_MAC_USE_COCOA
 // This method implements the magic for the drawRectSpecial method.
 // We draw a line at the upper edge of the content view in order to
diff --git a/src/gui/kernel/qt_cocoa_helpers_mac_p.h b/src/gui/kernel/qt_cocoa_helpers_mac_p.h
index c30fdc0..eab8a86 100644
--- a/src/gui/kernel/qt_cocoa_helpers_mac_p.h
+++ b/src/gui/kernel/qt_cocoa_helpers_mac_p.h
@@ -103,6 +103,7 @@
 #include <qtimer.h>
 #include <qtooltip.h>
 #include <private/qeffects_p.h>
+#include <private/qwidget_p.h>
 #include <qtextdocument.h>
 #include <qdebug.h>
 #include <qpoint.h>
@@ -245,6 +246,59 @@ void qt_cocoaPostMessageAfterEventLoopExit(id target, SEL selector, int argCount
 
 #endif
 
+class QMacScrollOptimization {
+    // This class is made optimize for the case when the user
+    // scrolls both horizontally and vertically at the same
+    // time. This will result in two QWheelEvents (one for each
+    // direction), which will typically result in two calls to
+    // QWidget::_scroll_sys. Rather than copying pixels twize on
+    // screen because of this, we add this helper class to try to
+    // get away with only one blit.
+    static QWidgetPrivate *_target;
+    static bool _inWheelEvent;
+    static int _dx;
+    static int _dy;
+    static QRect _scrollRect;
+
+public:
+    static void initNewScroll()
+    {
+        _inWheelEvent = true;
+    }
+
+    static bool delayScroll(QWidgetPrivate *target, int dx, int dy, const QRect &scrollRect)
+    {
+        if (!_inWheelEvent)
+            return false;
+        if (_target && _target != target)
+            return false;
+        if (_scrollRect.width() != -1 && _scrollRect != scrollRect)
+            return false;
+
+        _target = target;
+        _dx += dx;
+        _dy += dy;
+        _scrollRect = scrollRect;
+        return true;
+    }
+
+    static void performDelayedScroll()
+    {
+        if (!_inWheelEvent)
+            return;
+        if (!_target)
+            return;
+
+        _inWheelEvent = false;
+        _target->scroll_sys(_dx, _dy, _scrollRect);
+
+        _target = 0;
+        _dx = 0;
+        _dy = 0;
+        _scrollRect = QRect(0, 0, -1, -1);
+    }
+};
+
 void qt_mac_post_retranslateAppMenu();
 
 void qt_mac_display(QWidget *widget);
diff --git a/src/gui/kernel/qwidget_mac.mm b/src/gui/kernel/qwidget_mac.mm
index 03f496e..f3fbaa7 100644
--- a/src/gui/kernel/qwidget_mac.mm
+++ b/src/gui/kernel/qwidget_mac.mm
@@ -4654,6 +4654,10 @@ void QWidgetPrivate::scroll_sys(int dx, int dy)
 void QWidgetPrivate::scroll_sys(int dx, int dy, const QRect &qscrollRect)
 {
     Q_Q(QWidget);
+
+    if (QMacScrollOptimization::delayScroll(this, dx, dy, qscrollRect))
+        return;
+
     if (QApplicationPrivate::graphicsSystem() && !paintOnScreen()) {
         // INVARIANT: Alien paint engine
         scrollRect(qscrollRect, dx, dy);