Another use of clipping regions to eliminate flickering. Maybe I have to come

up with something better though, when the window titles are drawn as well...


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@15259 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/servers/app/WorkspacesLayer.cpp

@@ -205,19 +205,25 @@ WorkspacesLayer::_DarkenColor(RGBColor& color) const
 void
 WorkspacesLayer::Draw(const BRect& updateRect)
 {
-	// ToDo: either draw into an off-screen bitmap, or turn off flickering...
-
 	int32 columns, rows;
 	_GetGrid(columns, rows);
 
 	// draw grid
-	// horizontal lines
+
+	// make sure the grid around the active workspace is not drawn
+	// to reduce flicker
+	BRect activeRect = _WorkspaceAt(Window()->Desktop()->CurrentWorkspace());
+	BRegion gridRegion(VisibleRegion());
+	gridRegion.Exclude(activeRect);
+	GetDrawingEngine()->ConstrainClippingRegion(&gridRegion);
 
 	BRect frame = Frame();
 	BPoint pt(0,0);
 	ConvertToScreen(&pt);
 	frame.OffsetBy(pt);
 
+	// horizontal lines
+
 	GetDrawingEngine()->StrokeLine(BPoint(frame.left, frame.top),
 		BPoint(frame.right, frame.top), ViewColor());
 
@@ -238,6 +244,9 @@ WorkspacesLayer::Draw(const BRect& updateRect)
 			BPoint(rect.right, frame.bottom), ViewColor());
 	}
 
+	BRegion cRegion(VisibleRegion());
+	GetDrawingEngine()->ConstrainClippingRegion(&cRegion);
+
 	// draw workspaces
 
 	for (int32 i = rows * columns; i-- > 0;) {