Optimize QCocoaView::registerDragTypes and mode switching in QtCreator.

We were registering the types each time drag and drop was enabled, which
caused slowdowns when for example switching between the Edit and Debug
modes in QtCreator.

Instead, register the types on first enable and also when the custom types
change. Add check to draggingEntered() that disables the drag if
WA_DropSiteRegistered is false.

Reviewed-by: nrc

3 files changed, 17 insertions, 8 deletions

diff --git a/src/gui/kernel/qcocoaview_mac.mm b/src/gui/kernel/qcocoaview_mac.mm
index ff36ca1fc4..4ceae3ff47 100644
--- a/src/gui/kernel/qcocoaview_mac.mm
+++ b/src/gui/kernel/qcocoaview_mac.mm
@@ -198,6 +198,7 @@ extern "C" {
     }
     composing = false;
     sendKeyEvents = true;
+    currentCustomTypes = 0;
     [self setHidden:YES];
     return self;
 }
@@ -212,10 +213,16 @@ extern "C" {
                                                object:self];
 }
 
--(void)registerDragTypes:(bool)accept
+-(void)registerDragTypes
 {
     QMacCocoaAutoReleasePool pool;
-    if (accept) {
+    // Calling registerForDraggedTypes is slow, so only do it once for each widget
+    // or when the custom types change.
+    const QStringList& customTypes = qEnabledDraggedTypes();
+    if (currentCustomTypes == 0 || *currentCustomTypes != customTypes) {
+        if (currentCustomTypes == 0)
+            currentCustomTypes = new QStringList();
+        *currentCustomTypes = customTypes;
         const NSString* mimeTypeGeneric = @"com.trolltech.qt.MimeTypeName";
 	NSMutableArray *supportedTypes = [NSMutableArray arrayWithObjects:NSColorPboardType, 
                                    NSFilenamesPboardType, NSStringPboardType, 
@@ -227,13 +234,10 @@ extern "C" {
                                    NSFilesPromisePboardType, NSInkTextPboardType, 
                                    NSMultipleTextSelectionPboardType, mimeTypeGeneric, nil];
         // Add custom types supported by the application.
-        const QStringList& customTypes = qEnabledDraggedTypes();
         for (int i = 0; i < customTypes.size(); i++) {
            [supportedTypes addObject:reinterpret_cast<const NSString *>(QCFString::toCFStringRef(customTypes[i]))];
         }
         [self registerForDraggedTypes:supportedTypes];
-    } else {
-        [self unregisterDraggedTypes];
     }
 }
 
@@ -282,6 +286,8 @@ extern "C" {
 
 - (NSDragOperation)draggingEntered:(id <NSDraggingInfo>)sender 
 { 
+    if (qwidget->testAttribute(Qt::WA_DropSiteRegistered) == false)
+        return NSDragOperationNone;
     [self addDropData:sender];
     QMimeData *mimeData = dropData;
     if (QDragManager::self()->source())
@@ -414,6 +420,8 @@ extern "C" {
 - (void)dealloc
 {
     [[NSNotificationCenter defaultCenter] removeObserver:self];
+    delete currentCustomTypes;
+    [self unregisterDraggedTypes];
     [super dealloc];
 }
 
diff --git a/src/gui/kernel/qcocoaview_mac_p.h b/src/gui/kernel/qcocoaview_mac_p.h
index 9de94d5fc7..983c762c86 100644
--- a/src/gui/kernel/qcocoaview_mac_p.h
+++ b/src/gui/kernel/qcocoaview_mac_p.h
@@ -83,6 +83,7 @@ Q_GUI_EXPORT
     bool composing;
     int composingLength;
     bool sendKeyEvents;
+    QStringList *currentCustomTypes;
 }
 - (id)initWithQWidget:(QWidget *)widget widgetPrivate:(QWidgetPrivate *)widgetprivate;
 - (void) finishInitWithQWidget:(QWidget *)widget widgetPrivate:(QWidgetPrivate *)widgetprivate;
@@ -91,7 +92,7 @@ Q_GUI_EXPORT
 - (NSDragOperation)draggingUpdated:(id < NSDraggingInfo >)sender;
 - (void)draggingExited:(id < NSDraggingInfo >)sender;
 - (BOOL)performDragOperation:(id <NSDraggingInfo>)sender;
-- (void)registerDragTypes:(bool)accept;
+- (void)registerDragTypes;
 - (void)removeDropData;
 - (void)addDropData:(id <NSDraggingInfo>)sender;
 - (void)setSupportedActions:(NSDragOperation)actions;
diff --git a/src/gui/kernel/qwidget_mac.mm b/src/gui/kernel/qwidget_mac.mm
index 3f89ff397d..b315eaf9c6 100644
--- a/src/gui/kernel/qwidget_mac.mm
+++ b/src/gui/kernel/qwidget_mac.mm
@@ -4497,8 +4497,8 @@ void QWidgetPrivate::registerDropSite(bool on)
     SetControlDragTrackingEnabled(qt_mac_nativeview_for(q), on);
 #else
     NSView *view = qt_mac_nativeview_for(q);
-    if ([view isKindOfClass:[QT_MANGLE_NAMESPACE(QCocoaView) class]]) {
-        [static_cast<QT_MANGLE_NAMESPACE(QCocoaView) *>(view) registerDragTypes:on];
+    if (on && [view isKindOfClass:[QT_MANGLE_NAMESPACE(QCocoaView) class]]) {
+        [static_cast<QT_MANGLE_NAMESPACE(QCocoaView) *>(view) registerDragTypes];
     }
 #endif
 }