trying optimal scrolling solution perf-wise

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@45756 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/scrlwing.cpp

@@ -483,11 +483,7 @@ void wxScrollHelper::HandleOnScroll(wxScrollWinEvent& event)
     }
 
     bool needsRefresh = false;
-#ifdef __WXMAC__
-    // OS X blocks on immediate redraws, so make this a refresh
-    if (!wxScrolledWindowHasChildren(m_targetWindow))
-      needsRefresh = true;
-#endif
+
     int dx = 0,
         dy = 0;
     int orient = event.GetOrientation();
@@ -519,7 +515,12 @@ void wxScrollHelper::HandleOnScroll(wxScrollWinEvent& event)
         // flush all pending repaints before we change m_{x,y}ScrollPosition, as
         // otherwise invalidated area could be updated incorrectly later when
         // ScrollWindow() makes sure they're repainted before scrolling them
+#ifdef __WXMAC__
+        // wxWindowMac is taking care of making sure the update area is correctly
+        // set up, while not forcing an immediate redraw
+#else
         m_targetWindow->Update();
+#endif
     }
 
     if (orient == wxHORIZONTAL)

src/mac/carbon/window.cpp

@@ -2634,7 +2634,8 @@ void wxWindowMac::ScrollWindow(int dx, int dy, const wxRect *rect)
 
         if ( m_peer->GetNeedsDisplay() )
         {
-            // because HIViewScrollRect does not scroll the already invalidated area we have two options:
+            // because HIViewScrollRect does not scroll the already invalidated area we have two options
+            // in case there is already a pending redraw on that area
             // either immediate redraw or full invalidate
 #if 1
             // is the better overall solution, as it does not slow down scrolling
@@ -2655,14 +2656,8 @@ void wxWindowMac::ScrollWindow(int dx, int dy, const wxRect *rect)
         scrollrect.Offset( -MacGetLeftBorderSize() , -MacGetTopBorderSize() ) ;
         m_peer->ScrollRect( &scrollrect , dx , dy ) ;
 
-        // becuase HIViewScrollRect does not scroll the already invalidated area we have two options
-        // either immediate redraw or full invalidate
 #if 0
-        // is the better overall solution, as it does not slow down scrolling
-        m_peer->SetNeedsDisplay() ;
-#else
         // this would be the preferred version for fast drawing controls
-
         HIViewRender(m_peer->GetControlRef()) ;
 #endif
     }