Bug 1094072 - Update selection carets after reflow. r=roc

Let SelectionCarets inherits from nsIReflowObserver so it could refresh
its position after reflow. This fixes the incorrect position of
selection carets after we rotate the device to change the screen from
portrait mode to landscape mode and vice versa.

layout/base/SelectionCarets.cpp

@@ -71,6 +71,7 @@ static const int32_t kScrollEndTimerDelay = 300;
 static bool kSupportNonEditableFields = false;
 
 NS_IMPL_ISUPPORTS(SelectionCarets,
+                  nsIReflowObserver,
                   nsISelectionListener,
                   nsIScrollObserver,
                   nsISupportsWeakReference)
@@ -107,6 +108,20 @@ SelectionCarets::SelectionCarets(nsIPresShell* aPresShell)
   }
 }
 
+void
+SelectionCarets::Init()
+{
+  nsPresContext* presContext = mPresShell->GetPresContext();
+  MOZ_ASSERT(presContext, "PresContext should be given in PresShell::Init()");
+
+  nsIDocShell* docShell = presContext->GetDocShell();
+  if (!docShell) {
+    return;
+  }
+
+  docShell->AddWeakReflowObserver(this);
+}
+
 SelectionCarets::~SelectionCarets()
 {
   SELECTIONCARETS_LOG("Destructor");
@@ -125,6 +140,20 @@ SelectionCarets::~SelectionCarets()
   mPresShell = nullptr;
 }
 
+void
+SelectionCarets::Terminate()
+{
+  nsPresContext* presContext = mPresShell->GetPresContext();
+  MOZ_ASSERT(presContext, "PresContext should be given in PresShell::Init()");
+
+  nsIDocShell* docShell = presContext->GetDocShell();
+  if (docShell) {
+    docShell->RemoveWeakReflowObserver(this);
+  }
+
+  mPresShell = nullptr;
+}
+
 nsEventStatus
 SelectionCarets::HandleEvent(WidgetEvent* aEvent)
 {
@@ -1090,3 +1119,20 @@ SelectionCarets::FireScrollEnd(nsITimer* aTimer, void* aSelectionCarets)
   self->SetVisibility(true);
   self->UpdateSelectionCarets();
 }
+
+NS_IMETHODIMP
+SelectionCarets::Reflow(DOMHighResTimeStamp aStart, DOMHighResTimeStamp aEnd)
+{
+  if (mVisible) {
+    SELECTIONCARETS_LOG("Update selection carets after reflow!");
+    UpdateSelectionCarets();
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+SelectionCarets::ReflowInterruptible(DOMHighResTimeStamp aStart,
+                                     DOMHighResTimeStamp aEnd)
+{
+  return Reflow(aStart, aEnd);
+}

layout/base/SelectionCarets.h

@@ -7,6 +7,7 @@
 #ifndef SelectionCarets_h__
 #define SelectionCarets_h__
 
+#include "nsIReflowObserver.h"
 #include "nsIScrollObserver.h"
 #include "nsISelectionListener.h"
 #include "nsWeakPtr.h"
@@ -48,7 +49,8 @@ class Selection;
  *          UX spec, when selection contains only one characters, the image of
  *          caret becomes tilt.
  */
-class SelectionCarets MOZ_FINAL : public nsISelectionListener,
+class SelectionCarets MOZ_FINAL : public nsIReflowObserver,
+                                  public nsISelectionListener,
                                   public nsIScrollObserver,
                                   public nsSupportsWeakReference
 {
@@ -65,6 +67,7 @@ public:
   explicit SelectionCarets(nsIPresShell *aPresShell);
 
   NS_DECL_ISUPPORTS
+  NS_DECL_NSIREFLOWOBSERVER
   NS_DECL_NSISELECTIONLISTENER
 
   // nsIScrollObserver
@@ -74,10 +77,8 @@ public:
   virtual void AsyncPanZoomStarted(const mozilla::CSSIntPoint aScrollPos) MOZ_OVERRIDE;
   virtual void AsyncPanZoomStopped(const mozilla::CSSIntPoint aScrollPos) MOZ_OVERRIDE;
 
-  void Terminate()
-  {
-    mPresShell = nullptr;
-  }
+  void Init();
+  void Terminate();
 
   nsEventStatus HandleEvent(WidgetEvent* aEvent);
 

layout/base/nsPresShell.cpp

@@ -903,6 +903,7 @@ PresShell::Init(nsIDocument* aDocument,
   if (SelectionCaretPrefEnabled()) {
     // Create selection caret handle
     mSelectionCarets = new SelectionCarets(this);
+    mSelectionCarets->Init();
   }