Scroll the dirty parts of the scroll area in scrollby for Cocoa.

Ah! One less ###!
The scroll functions in Carbon and Cocoa don't scroll the regions that
have been marked dirty. In the past, we killed performance by updating
the whole view. We got a workaround for Carbon in the form of an SPI,
but I wasn't aware of a corresponding item in the NSView API, but it is
there publically and available in 10.5. Fast scrolling in Cocoa now for
people who like to use the keyboard.

Reviewed by: Morten Sørvig

1 files changed, 3 insertions, 14 deletions

diff --git a/src/gui/kernel/qwidget_mac.mm b/src/gui/kernel/qwidget_mac.mm
index ad80f15..a75c2a3 100644
--- a/src/gui/kernel/qwidget_mac.mm
+++ b/src/gui/kernel/qwidget_mac.mm
@@ -4347,20 +4347,9 @@ void QWidgetPrivate::scroll_sys(int dx, int dy, const QRect &r)
         }
     }
 
-    // ### Scroll the dirty regions as well, the following is not correct.
-    QRegion displayRegion = r.isNull() ? dirtyOnWidget : (dirtyOnWidget & r);
-    const QVector<QRect> &rects = dirtyOnWidget.rects();
-    const QVector<QRect>::const_iterator end = rects.end();
-    QVector<QRect>::const_iterator it = rects.begin();
-    while (it != end) {
-         const QRect rect = *it;
-         const NSRect dirtyRect = NSMakeRect(rect.x() + dx, rect.y() + dy,
-                                             rect.width(), rect.height());
-         [view setNeedsDisplayInRect:dirtyRect];
-         ++it;
-    }
-    [view scrollRect:scrollRect by:NSMakeSize(dx, dy)];
-    // Yes, we potentially send a duplicate area, but I think Cocoa can handle it.
+    NSSize deltaSize = NSMakeSize(dx, dy);
+    [view translateRectsNeedingDisplayInRect:scrollRect by:deltaSize];
+    [view scrollRect:scrollRect by:deltaSize];
     [view setNeedsDisplayInRect:deltaXRect];
     [view setNeedsDisplayInRect:deltaYRect];
 #endif // QT_MAC_USE_COCOA