Bug 726817 - Add nsIFrameLoaderOwner.clampScrollPosition. r=roc

Add an attribute to nsIFrameLoaderOwner that allows the clamping of set scroll
positions to be toggled.

content/base/public/nsIFrameLoader.idl

@@ -67,7 +67,7 @@ typedef unsigned long long nsContentViewId;
  * These APIs are designed to be used with nsIDOMWindowUtils
  * setDisplayPort() and setResolution().
  */
-[scriptable, uuid(fbd25468-d2cf-487b-bc58-a0e105398b47)]
+[scriptable, uuid(c04c5c40-fa2a-4e9c-94f5-b362a10a86cb)]
 interface nsIContentView : nsISupports
 {
   /**
@@ -265,6 +265,13 @@ interface nsIFrameLoader : nsISupports
    * Defaults to true.
    */
   attribute boolean clipSubdocument;
+
+  /**
+   * If false, then the subdocument's scroll coordinates will not be clamped
+   * to their scroll boundaries.
+   * Defaults to true.
+   */
+  attribute boolean clampScrollPosition;
 };
 
 native alreadyAddRefed_nsFrameLoader(already_AddRefed<nsFrameLoader>);

content/base/src/nsFrameLoader.cpp

@@ -76,6 +76,7 @@
 #include "nsFrameLoader.h"
 #include "nsIDOMEventTarget.h"
 #include "nsIFrame.h"
+#include "nsIScrollableFrame.h"
 #include "nsSubDocumentFrame.h"
 #include "nsDOMError.h"
 #include "nsGUIEvent.h"
@@ -330,6 +331,7 @@ nsFrameLoader::nsFrameLoader(Element* aOwner, bool aNetworkCreated)
   , mRemoteBrowserShown(false)
   , mRemoteFrame(false)
   , mClipSubdocument(true)
+  , mClampScrollPosition(true)
   , mCurrentRemoteFrame(nsnull)
   , mRemoteBrowser(nsnull)
   , mRenderMode(RENDER_MODE_DEFAULT)
@@ -1755,6 +1757,38 @@ nsFrameLoader::SetClipSubdocument(bool aClip)
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsFrameLoader::GetClampScrollPosition(bool* aResult)
+{
+  *aResult = mClampScrollPosition;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsFrameLoader::SetClampScrollPosition(bool aClamp)
+{
+  mClampScrollPosition = aClamp;
+
+  // When turning clamping on, make sure the current position is clamped.
+  if (aClamp) {
+    nsIFrame* frame = GetPrimaryFrameOfOwningContent();
+    if (frame) {
+      nsSubDocumentFrame* subdocFrame = do_QueryFrame(frame);
+      if (subdocFrame) {
+        nsIFrame* subdocRootFrame = subdocFrame->GetSubdocumentRootFrame();
+        if (subdocRootFrame) {
+          nsIScrollableFrame* subdocRootScrollFrame = subdocRootFrame->PresContext()->PresShell()->
+            GetRootScrollFrameAsScrollable();
+          if (subdocRootScrollFrame) {
+            subdocRootScrollFrame->ScrollTo(subdocRootScrollFrame->GetScrollPosition(), nsIScrollableFrame::INSTANT);
+          }
+        }
+      }
+    }
+  }
+  return NS_OK;
+}
+
 nsIntSize
 nsFrameLoader::GetSubDocumentSize(const nsIFrame *aIFrame)
 {

content/base/src/nsFrameLoader.h

@@ -289,6 +289,8 @@ public:
 
   bool ShouldClipSubdocument() { return mClipSubdocument; }
 
+  bool ShouldClampScrollPosition() { return mClampScrollPosition; }
+
 private:
 
   bool ShouldUseRemoteProcess();
@@ -342,6 +344,7 @@ private:
   bool mRemoteBrowserShown : 1;
   bool mRemoteFrame : 1;
   bool mClipSubdocument : 1;
+  bool mClampScrollPosition : 1;
 
   // XXX leaking
   nsCOMPtr<nsIObserver> mChildHost;

layout/generic/nsGfxScrollFrame.cpp

@@ -1550,7 +1550,11 @@ void
 nsGfxScrollFrameInner::ScrollTo(nsPoint aScrollPosition,
                                 nsIScrollableFrame::ScrollMode aMode)
 {
-  mDestination = ClampScrollPosition(aScrollPosition);
+  if (ShouldClampScrollPosition()) {
+    mDestination = ClampScrollPosition(aScrollPosition);
+  } else {
+    mDestination = aScrollPosition;
+  }
 
   if (aMode == nsIScrollableFrame::INSTANT) {
     // Asynchronous scrolling is not allowed, so we'll kill any existing
@@ -1713,6 +1717,15 @@ bool nsGfxScrollFrameInner::IsIgnoringViewportClipping() const
   return subdocFrame && !subdocFrame->ShouldClipSubdocument();
 }
 
+bool nsGfxScrollFrameInner::ShouldClampScrollPosition() const
+{
+  if (!mIsRoot)
+    return true;
+  nsSubDocumentFrame* subdocFrame = static_cast<nsSubDocumentFrame*>
+    (nsLayoutUtils::GetCrossDocParentFrame(mOuter->PresContext()->PresShell()->GetRootFrame()));
+  return !subdocFrame || subdocFrame->ShouldClampScrollPosition();
+}
+
 bool nsGfxScrollFrameInner::IsAlwaysActive() const
 {
   // The root scrollframe for a non-chrome document which is the direct
@@ -1812,17 +1825,23 @@ ClampInt(nscoord aLower, nscoord aVal, nscoord aUpper, nscoord aAppUnitsPerPixel
 }
 
 nsPoint
-nsGfxScrollFrameInner::ClampAndRestrictToDevPixels(const nsPoint& aPt,
-                                                   nsIntPoint* aPtDevPx) const
+nsGfxScrollFrameInner::RestrictToDevPixels(const nsPoint& aPt,
+                                           nsIntPoint* aPtDevPx,
+                                           bool aShouldClamp) const
 {
   nsPresContext* presContext = mOuter->PresContext();
   nscoord appUnitsPerDevPixel = presContext->AppUnitsPerDevPixel();
   // Convert to device pixels so we scroll to an integer offset of device
   // pixels. But we also need to make sure that our position remains
   // inside the allowed region.
-  nsRect scrollRange = GetScrollRange();
-  *aPtDevPx = nsIntPoint(ClampInt(scrollRange.x, aPt.x, scrollRange.XMost(), appUnitsPerDevPixel),
-                         ClampInt(scrollRange.y, aPt.y, scrollRange.YMost(), appUnitsPerDevPixel));
+  if (aShouldClamp) {
+    nsRect scrollRange = GetScrollRange();
+    *aPtDevPx = nsIntPoint(ClampInt(scrollRange.x, aPt.x, scrollRange.XMost(), appUnitsPerDevPixel),
+                           ClampInt(scrollRange.y, aPt.y, scrollRange.YMost(), appUnitsPerDevPixel));
+  } else {
+    *aPtDevPx = nsIntPoint(NSAppUnitsToIntPixels(aPt.x, appUnitsPerDevPixel),
+                           NSAppUnitsToIntPixels(aPt.y, appUnitsPerDevPixel));
+  }
   return nsPoint(NSIntPixelsToAppUnits(aPtDevPx->x, appUnitsPerDevPixel),
                  NSIntPixelsToAppUnits(aPtDevPx->y, appUnitsPerDevPixel));
 }
@@ -1858,7 +1877,8 @@ nsGfxScrollFrameInner::ScrollToImpl(nsPoint aPt)
   nsPresContext* presContext = mOuter->PresContext();
   nscoord appUnitsPerDevPixel = presContext->AppUnitsPerDevPixel();
   nsIntPoint ptDevPx;
-  nsPoint pt = ClampAndRestrictToDevPixels(aPt, &ptDevPx);
+
+  nsPoint pt = RestrictToDevPixels(aPt, &ptDevPx, ShouldClampScrollPosition());
 
   nsPoint curPos = GetScrollPosition();
   if (pt == curPos) {

layout/generic/nsGfxScrollFrame.h

@@ -177,7 +177,7 @@ public:
   }
   nsRect GetScrollRange() const;
 
-  nsPoint ClampAndRestrictToDevPixels(const nsPoint& aPt, nsIntPoint* aPtDevPx) const;
+  nsPoint RestrictToDevPixels(const nsPoint& aPt, nsIntPoint* aPtDevPx, bool aShouldClamp) const;
   nsPoint ClampScrollPosition(const nsPoint& aPt) const;
   static void AsyncScrollCallback(nsITimer *aTimer, void* anInstance);
   void ScrollTo(nsPoint aScrollPosition, nsIScrollableFrame::ScrollMode aMode);
@@ -261,6 +261,8 @@ public:
 
   bool IsIgnoringViewportClipping() const;
 
+  bool ShouldClampScrollPosition() const;
+
   bool IsAlwaysActive() const;
   void MarkActive();
   void MarkInactive();

layout/generic/nsSubDocumentFrame.h

@@ -130,6 +130,12 @@ public:
     return !frameLoader || frameLoader->ShouldClipSubdocument();
   }
 
+  bool ShouldClampScrollPosition()
+  {
+    nsFrameLoader* frameLoader = FrameLoader();
+    return !frameLoader || frameLoader->ShouldClampScrollPosition();
+  }
+
 protected:
   friend class AsyncFrameInit;