Bug 881832 - Specify whether the height has changed when calling PresShell::ResizeReflow, since the PresContext size might have already been updated. r=dbaron

layout/base/MobileViewportManager.cpp

@@ -374,6 +374,8 @@ MobileViewportManager::RefreshViewportSize(bool aForceAdjustResolution)
     UpdateDisplayPortMargins();
   }
 
+  CSSSize oldSize = mMobileViewportSize;
+
   // Update internal state.
   mIsFirstPaint = false;
   mMobileViewportSize = viewport;
@@ -381,5 +383,7 @@ MobileViewportManager::RefreshViewportSize(bool aForceAdjustResolution)
   // Kick off a reflow.
   mPresShell->ResizeReflowIgnoreOverride(
     nsPresContext::CSSPixelsToAppUnits(viewport.width),
-    nsPresContext::CSSPixelsToAppUnits(viewport.height));
+    nsPresContext::CSSPixelsToAppUnits(viewport.height),
+    nsPresContext::CSSPixelsToAppUnits(oldSize.width),
+    nsPresContext::CSSPixelsToAppUnits(oldSize.height));
 }

layout/base/nsIPresShell.h

@@ -418,12 +418,12 @@ public:
    * Reflow the frame model into a new width and height.  The
    * coordinates for aWidth and aHeight must be in standard nscoord's.
    */
-  virtual nsresult ResizeReflow(nscoord aWidth, nscoord aHeight) = 0;
+  virtual nsresult ResizeReflow(nscoord aWidth, nscoord aHeight, nscoord aOldWidth = 0, nscoord aOldHeight = 0) = 0;
   /**
    * Do the same thing as ResizeReflow but even if ResizeReflowOverride was
    * called previously.
    */
-  virtual nsresult ResizeReflowIgnoreOverride(nscoord aWidth, nscoord aHeight) = 0;
+  virtual nsresult ResizeReflowIgnoreOverride(nscoord aWidth, nscoord aHeight, nscoord aOldWidth, nscoord aOldHeight) = 0;
 
   /**
    * Returns true if ResizeReflowOverride has been called.

layout/base/nsPresShell.cpp

@@ -1801,7 +1801,7 @@ PresShell::AsyncResizeEventCallback(nsITimer* aTimer, void* aPresShell)
 }
 
 nsresult
-PresShell::ResizeReflow(nscoord aWidth, nscoord aHeight)
+PresShell::ResizeReflow(nscoord aWidth, nscoord aHeight, nscoord aOldWidth, nscoord aOldHeight)
 {
   if (mZoomConstraintsClient) {
     // If we have a ZoomConstraintsClient and the available screen area
@@ -1817,11 +1817,11 @@ PresShell::ResizeReflow(nscoord aWidth, nscoord aHeight)
     return NS_OK;
   }
 
-  return ResizeReflowIgnoreOverride(aWidth, aHeight);
+  return ResizeReflowIgnoreOverride(aWidth, aHeight, aOldWidth, aOldHeight);
 }
 
 nsresult
-PresShell::ResizeReflowIgnoreOverride(nscoord aWidth, nscoord aHeight)
+PresShell::ResizeReflowIgnoreOverride(nscoord aWidth, nscoord aHeight, nscoord aOldWidth, nscoord aOldHeight)
 {
   NS_PRECONDITION(!mIsReflowing, "Shouldn't be in reflow here!");
 
@@ -1835,7 +1835,6 @@ PresShell::ResizeReflowIgnoreOverride(nscoord aWidth, nscoord aHeight)
     return NS_ERROR_NOT_AVAILABLE;
   }
 
-  nsSize oldVisibleSize = mPresContext->GetVisibleArea().Size();
   mPresContext->SetVisibleArea(nsRect(0, 0, aWidth, aHeight));
 
   // There isn't anything useful we can do if the initial reflow hasn't happened.
@@ -1848,8 +1847,8 @@ PresShell::ResizeReflowIgnoreOverride(nscoord aWidth, nscoord aHeight)
                   "shouldn't use unconstrained isize anymore");
 
   const bool isBSizeChanging = wm.IsVertical()
-                               ? oldVisibleSize.width != aWidth
-                               : oldVisibleSize.height != aHeight;
+                               ? aOldWidth != aWidth
+                               : aOldHeight != aHeight;
 
   RefPtr<nsViewManager> viewManagerDeathGrip = mViewManager;
   // Take this ref after viewManager so it'll make sure to go away first.

layout/base/nsPresShell.h

@@ -118,8 +118,8 @@ public:
   virtual void BeginObservingDocument() override;
   virtual void EndObservingDocument() override;
   virtual nsresult Initialize(nscoord aWidth, nscoord aHeight) override;
-  virtual nsresult ResizeReflow(nscoord aWidth, nscoord aHeight) override;
-  virtual nsresult ResizeReflowIgnoreOverride(nscoord aWidth, nscoord aHeight) override;
+  virtual nsresult ResizeReflow(nscoord aWidth, nscoord aHeight, nscoord aOldWidth = 0, nscoord aOldHeight = 0) override;
+  virtual nsresult ResizeReflowIgnoreOverride(nscoord aWidth, nscoord aHeight, nscoord aOldWidth, nscoord aOldHeight) override;
   virtual nsIPageSequenceFrame* GetPageSequenceFrame() const override;
   virtual nsCanvasFrame* GetCanvasFrame() const override;
 

view/nsViewManager.cpp

@@ -189,7 +189,7 @@ void nsViewManager::DoSetWindowDimensions(nscoord aWidth, nscoord aHeight)
     // Don't resize the widget. It is already being set elsewhere.
     mRootView->SetDimensions(newDim, true, false);
     if (mPresShell)
-      mPresShell->ResizeReflow(aWidth, aHeight);
+      mPresShell->ResizeReflow(aWidth, aHeight, oldDim.width, oldDim.height);
   }
 }