Cocoa: Make touch events work again.

Bring back the ref-counted enable on enter/leave
workaround we had in Qt 4: If any widget in a
window sets WA_AcceptTouchEvents then that window
will start processing touch events.

Enabling touch events has implications for delivery
of other events, for example by causing scrolling
event lag.

Change-Id: I307488937f417612eff624bf9892b82a7f69c1b7
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>

4 files changed, 31 insertions, 0 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoanativeinterface.h b/src/plugins/platforms/cocoa/qcocoanativeinterface.h
index b1b8dccca5..ca84312059 100644
--- a/src/plugins/platforms/cocoa/qcocoanativeinterface.h
+++ b/src/plugins/platforms/cocoa/qcocoanativeinterface.h
@@ -112,6 +112,15 @@ private:
 
     // Embedding NSViews as child QWindows
     static void setWindowContentView(QPlatformWindow *window, void *nsViewContentView);
+
+    // Register if a window should deliver touch events. Enabling
+    // touch events has implications for delivery of other events,
+    // for example by causing scrolling event lag.
+    //
+    // The registration is ref-counted: multiple widgets can enable
+    // touch events, which then will be delivered until the widget
+    // deregisters.
+    static void registerTouchWindow(QWindow *window,  bool enable);
 };
 
 #endif // QCOCOANATIVEINTERFACE_H
diff --git a/src/plugins/platforms/cocoa/qcocoanativeinterface.mm b/src/plugins/platforms/cocoa/qcocoanativeinterface.mm
index a7f4d3b823..ededb63487 100644
--- a/src/plugins/platforms/cocoa/qcocoanativeinterface.mm
+++ b/src/plugins/platforms/cocoa/qcocoanativeinterface.mm
@@ -119,6 +119,8 @@ QPlatformNativeInterface::NativeResourceForIntegrationFunction QCocoaNativeInter
         return NativeResourceForIntegrationFunction(QCocoaNativeInterface::cgImageToQImage);
     if (resource.toLower() == "setwindowcontentview")
         return NativeResourceForIntegrationFunction(QCocoaNativeInterface::setWindowContentView);
+    if (resource.toLower() == "registertouchwindow")
+        return NativeResourceForIntegrationFunction(QCocoaNativeInterface::registerTouchWindow);
 
     return 0;
 }
@@ -227,4 +229,11 @@ void QCocoaNativeInterface::setWindowContentView(QPlatformWindow *window, void *
     cocoaPlatformWindow->setContentView(reinterpret_cast<NSView *>(contentView));
 }
 
+void QCocoaNativeInterface::registerTouchWindow(QWindow *window,  bool enable)
+{
+    QCocoaWindow *cocoaWindow = static_cast<QCocoaWindow *>(window->handle());
+    if (cocoaWindow)
+        cocoaWindow->registerTouch(enable);
+}
+
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/cocoa/qcocoawindow.h b/src/plugins/platforms/cocoa/qcocoawindow.h
index 5029321247..e1de5f0add 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.h
+++ b/src/plugins/platforms/cocoa/qcocoawindow.h
@@ -147,6 +147,8 @@ public:
     void setMenubar(QCocoaMenuBar *mb);
     QCocoaMenuBar *menubar() const;
 
+    void registerTouch(bool enable);
+
     qreal devicePixelRatio() const;
     void exposeWindow();
     void obscureWindow();
@@ -187,6 +189,7 @@ public: // for QNSView
     bool m_hasModalSession;
     bool m_frameStrutEventsEnabled;
     bool m_isExposed;
+    int m_registerTouchCount;
 };
 
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/cocoa/qcocoawindow.mm b/src/plugins/platforms/cocoa/qcocoawindow.mm
index 9988cea597..e74f9dcfe0 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.mm
+++ b/src/plugins/platforms/cocoa/qcocoawindow.mm
@@ -201,6 +201,7 @@ QCocoaWindow::QCocoaWindow(QWindow *tlw)
     , m_hasModalSession(false)
     , m_frameStrutEventsEnabled(false)
     , m_isExposed(false)
+    , m_registerTouchCount(0)
 {
 #ifdef QT_COCOA_ENABLE_WINDOW_DEBUG
     qDebug() << "QCocoaWindow::QCocoaWindow" << this;
@@ -899,6 +900,15 @@ QCocoaMenuBar *QCocoaWindow::menubar() const
     return m_menubar;
 }
 
+void QCocoaWindow::registerTouch(bool enable)
+{
+    m_registerTouchCount += enable ? 1 : -1;
+    if (m_registerTouchCount == 1)
+        [m_contentView setAcceptsTouchEvents:YES];
+    else if (m_registerTouchCount == 0)
+        [m_contentView setAcceptsTouchEvents:NO];
+}
+
 qreal QCocoaWindow::devicePixelRatio() const
 {
 #if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_7