QTabWidget documentMode not working correctly on Mac

This feature was implemented in Carbon and was never ported to Cocoa.
The major problem is the fact that Cocoa draws a line under the titlebar,
regardless of what we say. The only way to avoid drawing that line is
by adding a native toolbar and ask it not to draw its baseline. If there
is not toolbar, as it happens in this case, there is no way to prevent
that line from being drawn. So instead we paint over that line and hope
for the best.

Task-number: QTBUG-8159
Reviewed-by: Richard Moe Gustavsen

1 files changed, 117 insertions, 3 deletions

diff --git a/src/gui/kernel/qt_cocoa_helpers_mac.mm b/src/gui/kernel/qt_cocoa_helpers_mac.mm
index a05c7d5..024c1fc 100644
--- a/src/gui/kernel/qt_cocoa_helpers_mac.mm
+++ b/src/gui/kernel/qt_cocoa_helpers_mac.mm
@@ -1163,15 +1163,81 @@ void qt_mac_updateContentBorderMetricts(void * /*OSWindowRef */window, const ::H
 #endif
 }
 
+#if QT_MAC_USE_COCOA
+void qt_mac_replaceDrawRect(void * /*OSWindowRef */window, QWidgetPrivate *widget)
+{
+    QMacCocoaAutoReleasePool pool;
+    OSWindowRef theWindow = static_cast<OSWindowRef>(window);
+    if(!theWindow)
+        return;
+    id theClass = [[[theWindow contentView] superview] class];
+    // What we do here is basically to add a new selector to NSThemeFrame called
+    // "drawRectOriginal:" which will contain the original implementation of
+    // "drawRect:". After that we get the new implementation from QCocoaWindow
+    // and exchange them. The new implementation is called drawRectSpecial.
+    // We cannot just add the method because it might have been added before and since
+    // we cannot remove a method once it has been added we need to ask QCocoaWindow if
+    // we did the swap or not.
+    if(!widget->drawRectOriginalAdded) {
+        Method m2 = class_getInstanceMethod(theClass, @selector(drawRect:));
+        if(!m2) {
+            // This case is pretty extreme, no drawRect means no drawing!
+            return;
+        }
+        class_addMethod(theClass, @selector(drawRectOriginal:), method_getImplementation(m2), method_getTypeEncoding(m2));
+        widget->drawRectOriginalAdded = true;
+    }
+    if(widget->originalDrawMethod) {
+        Method m0 = class_getInstanceMethod([theWindow class], @selector(drawRectSpecial:));
+        if(!m0) {
+            // Ok, this means the methods were never swapped. Just ignore
+            return;
+        }
+        Method m1 = class_getInstanceMethod(theClass, @selector(drawRect:));
+        if(!m1) {
+            // Ok, this means the methods were never swapped. Just ignore
+            return;
+        }
+        // We have the original method here. Proceed and swap the methods.
+        method_exchangeImplementations(m1, m0);
+        widget->originalDrawMethod = false;
+        [window display];
+    }
+}
+
+void qt_mac_replaceDrawRectOriginal(void * /*OSWindowRef */window, QWidgetPrivate *widget)
+{
+    QMacCocoaAutoReleasePool pool;
+    OSWindowRef theWindow = static_cast<OSWindowRef>(window);
+    id theClass = [[[theWindow contentView] superview] class];
+    // Now we need to revert the methods to their original state.
+    // We cannot remove the method, so we just keep track of it in QCocoaWindow.
+    Method m0 = class_getInstanceMethod([theWindow class], @selector(drawRectSpecial:));
+    if(!m0) {
+        // Ok, this means the methods were never swapped. Just ignore
+        return;
+    }
+    Method m1 = class_getInstanceMethod(theClass, @selector(drawRect:));
+    if(!m1) {
+        // Ok, this means the methods were never swapped. Just ignore
+        return;
+    }
+    method_exchangeImplementations(m1, m0);
+    widget->originalDrawMethod = true;
+    [window display];
+}
+#endif // QT_MAC_USE_COCOA
+
 void qt_mac_showBaseLineSeparator(void * /*OSWindowRef */window, bool show)
 {
+    if(!window)
+        return;
 #if QT_MAC_USE_COCOA
     QMacCocoaAutoReleasePool pool;
     OSWindowRef theWindow = static_cast<OSWindowRef>(window);
     NSToolbar *macToolbar = [theWindow toolbar];
-    if (macToolbar)
-        [macToolbar setShowsBaselineSeparator: show];
-#endif
+    [macToolbar setShowsBaselineSeparator:show];
+#endif // QT_MAC_USE_COCOA
 }
 
 QStringList qt_mac_NSArrayToQStringList(void *nsarray)
@@ -1403,4 +1469,52 @@ void qt_mac_post_retranslateAppMenu()
 #endif
 }
 
+#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
+// override the title baseline.
+void macDrawRectOnTop(void * /*OSWindowRef */window)
+{
+    OSWindowRef theWindow = static_cast<OSWindowRef>(window);
+    NSView *contentView = [theWindow contentView];
+    if(!contentView)
+        return;
+    // Get coordinates of the content view
+    NSRect contentRect = [contentView frame];
+    // Draw a line on top of the already drawn line.
+    // We need to check if we are active or not to use the proper color.
+    if([window isKeyWindow] || [window isMainWindow]) {
+        [[NSColor colorWithCalibratedRed:1.0 green:1.0 blue:1.0 alpha:1.0] set];
+    } else {
+        [[NSColor colorWithCalibratedRed:1.0 green:1.0 blue:1.0 alpha:1.0] set];
+    }
+    NSPoint origin = NSMakePoint(0, contentRect.size.height);
+    NSPoint end = NSMakePoint(contentRect.size.width, contentRect.size.height);
+    [NSBezierPath strokeLineFromPoint:origin toPoint:end];
+}
+
+// This method will (or at least should) get called only once.
+// Its mission is to find out if we are active or not. If we are active
+// we assume that we were launched via finder, otherwise we assume
+// we were called from the command line. The distinction is important,
+// since in the first case we don't need to trigger a paintEvent, while
+// in the second case we do.
+void macSyncDrawingOnFirstInvocation(void * /*OSWindowRef */window)
+{
+    OSWindowRef theWindow = static_cast<OSWindowRef>(window);
+    NSApplication *application = [NSApplication sharedApplication];
+    NSToolbar *toolbar = [window toolbar];
+    if([application isActive]) {
+        // Launched from finder
+        [toolbar setShowsBaselineSeparator:NO];
+    } else {
+        // Launched from commandline
+        [toolbar setVisible:false];
+        [toolbar setShowsBaselineSeparator:NO];
+        [toolbar setVisible:true];
+        [theWindow display];
+    }
+}
+#endif // QT_MAC_USE_COCOA
+
 QT_END_NAMESPACE