Bug 949404 - Applications are half repainted once the keyboard is closed. r=Cwiiis

gfx/layers/FrameMetrics.h

@@ -113,6 +113,30 @@ public:
     return mCumulativeResolution / mResolution;
   }
 
+  // Ensure the scrollableRect is at least as big as the compositionBounds
+  // because the scrollableRect can be smaller if the content is not large
+  // and the scrollableRect hasn't been updated yet.
+  // We move the scrollableRect up because we don't know if we can move it
+  // down. i.e. we know that scrollableRect can go back as far as zero.
+  // but we don't know how much further ahead it can go.
+  CSSRect GetExpandedScrollableRect() const
+  {
+    CSSRect scrollableRect = mScrollableRect;
+    if (scrollableRect.width < mCompositionBounds.width) {
+      scrollableRect.x = std::max(0.f,
+                                  scrollableRect.x - (mCompositionBounds.width - scrollableRect.width));
+      scrollableRect.width = mCompositionBounds.width;
+    }
+
+    if (scrollableRect.height < mCompositionBounds.height) {
+      scrollableRect.y = std::max(0.f,
+                                  scrollableRect.y - (mCompositionBounds.height - scrollableRect.height));
+      scrollableRect.height = mCompositionBounds.height;
+    }
+
+    return scrollableRect;
+  }
+
   /**
    * Return the scale factor needed to fit the viewport
    * into its composition bounds.

gfx/layers/ipc/AsyncPanZoomController.cpp

@@ -1165,25 +1165,8 @@ const CSSRect AsyncPanZoomController::CalculatePendingDisplayPort(
     aEstimatedPaintDuration > EPSILON ? aEstimatedPaintDuration : 1.0;
 
   CSSIntRect compositionBounds = gfx::RoundedIn(aFrameMetrics.mCompositionBounds / aFrameMetrics.mZoom);
-  CSSRect scrollableRect = aFrameMetrics.mScrollableRect;
-
-  // Ensure the scrollableRect is at least as big as the compositionBounds
-  // because the scrollableRect can be smaller if the content is not large
-  // and the scrollableRect hasn't been updated yet.
-  // We move the scrollableRect up because we don't know if we can move it
-  // down. i.e. we know that scrollableRect can go back as far as zero.
-  // but we don't know how much further ahead it can go.
-  if (scrollableRect.width < compositionBounds.width) {
-      scrollableRect.x = std::max(0.f,
-                                  scrollableRect.x - (compositionBounds.width - scrollableRect.width));
-      scrollableRect.width = compositionBounds.width;
-  }
-  if (scrollableRect.height < compositionBounds.height) {
-      scrollableRect.y = std::max(0.f,
-                                  scrollableRect.y - (compositionBounds.height - scrollableRect.height));
-      scrollableRect.height = compositionBounds.height;
-  }
 
+  CSSRect scrollableRect = aFrameMetrics.GetExpandedScrollableRect();
   CSSPoint scrollOffset = aFrameMetrics.mScrollOffset;
 
   CSSRect displayPort = CSSRect(compositionBounds);

widget/xpwidgets/APZCCallbackHelper.cpp

@@ -78,8 +78,8 @@ MaybeAlignAndClampDisplayPort(mozilla::layers::FrameMetrics& aFrameMetrics,
       - aActualScrollOffset;
   }
 
-  // Finally, clamp the display port to the scrollable rect.
-  CSSRect scrollableRect = aFrameMetrics.mScrollableRect;
+  // Finally, clamp the display port to the expanded scrollable rect.
+  CSSRect scrollableRect = aFrameMetrics.GetExpandedScrollableRect();
   displayPort = scrollableRect.Intersect(displayPort + aActualScrollOffset)
     - aActualScrollOffset;
 }