Bug 605618 Part 8: Content process map from view IDs to content elements r=cjones sr=roc

content/base/public/nsINode.h

@@ -580,16 +580,6 @@ public:
                             nsIAtom *aPropertyName,
                             nsresult *aStatus = nsnull) const;
 
-  /**
-   * Useful template for use with SetProperty.
-   */
-  template <class T>
-  static void DestroyProperty(void* aObject, nsIAtom* aPropertyName,
-                              void* aPropertyValue, void* aData)
-  {
-    delete static_cast<T*>(aPropertyValue);
-  }
-
   /**
    * Set a property to be associated with this node. This will overwrite an
    * existing value if one exists. The existing value is destroyed using the

dom/base/nsDOMWindowUtils.cpp

@@ -992,6 +992,21 @@ nsDOMWindowUtils::GetFocusedInputType(char** aType)
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsDOMWindowUtils::FindElementWithViewId(nsViewID aID,
+                                        nsIDOMElement** aResult)
+{
+  if (aID == FrameMetrics::ROOT_SCROLL_ID) {
+    nsPresContext* presContext = GetPresContext();
+    nsIDocument* document = presContext->Document();
+    CallQueryInterface(document->GetRootElement(), aResult);
+    return NS_OK;
+  }
+
+  nsRefPtr<nsIContent> content = nsLayoutUtils::FindContentFor(aID);
+  return CallQueryInterface(content, aResult);
+}
+
 NS_IMETHODIMP
 nsDOMWindowUtils::GetScreenPixelsPerCSSPixel(float* aScreenPixels)
 {

dom/interfaces/base/nsIDOMWindowUtils.idl

@@ -822,10 +822,19 @@ interface nsIDOMWindowUtils : nsISupports {
                                   in AString value2);
 };
 
+typedef unsigned long long nsViewID;
+
 [scriptable, uuid(3a0334aa-b9cc-4b32-9b6c-599cd4e40d5b)]
 interface nsIDOMWindowUtils_MOZILLA_2_0_BRANCH : nsISupports {
   /**
    * Get the type of the currently focused html input, if any.
    */
   readonly attribute string focusedInputType;
+
+  /**
+   * Given a view ID from the compositor process, retrieve the element
+   * associated with a view. For scrollpanes for documents, the root
+   * element of the document is returned.
+   */
+  nsIDOMElement findElementWithViewId(in nsViewID aId);
 };

layout/base/nsDisplayList.cpp

@@ -69,8 +69,6 @@ using namespace mozilla;
 using namespace mozilla::layers;
 typedef FrameMetrics::ViewID ViewID;
 
-static ViewID sScrollIdCounter = FrameMetrics::START_SCROLL_ID;
-
 nsDisplayListBuilder::nsDisplayListBuilder(nsIFrame* aReferenceFrame,
     Mode aMode, PRBool aBuildCaret)
     : mReferenceFrame(aReferenceFrame),
@@ -1637,19 +1635,8 @@ nsDisplayScrollLayer::BuildLayer(nsDisplayListBuilder* aBuilder,
 
   // Get the already set unique ID for scrolling this content remotely.
   // Or, if not set, generate a new ID.
-  ViewID scrollId;
-  {
   nsIContent* content = mFrame->GetContent();
-    void* scrollIdProperty = content->GetProperty(nsGkAtoms::RemoteId);
-    if (scrollIdProperty) {
-      scrollId = *static_cast<ViewID*>(scrollIdProperty);
-    } else {
-      scrollId = sScrollIdCounter++;
-      content->SetProperty(nsGkAtoms::RemoteId, new ViewID(scrollId),
-                           nsINode::DestroyProperty<ViewID>);
-    }
-  }
-
+  ViewID scrollId = nsLayoutUtils::FindIDFor(content);
 
   nsRect viewport = mViewportFrame->GetRect() -
                     mViewportFrame->GetPosition() +

layout/base/nsLayoutUtils.cpp

@@ -97,6 +97,7 @@
 #include "nsCanvasFrame.h"
 #include "gfxDrawable.h"
 #include "gfxUtils.h"
+#include "nsDataHashtable.h"
 
 #ifdef MOZ_SVG
 #include "nsSVGUtils.h"
@@ -121,6 +122,61 @@ bool nsLayoutUtils::gPreventAssertInCompareTreePosition = false;
 typedef gfxPattern::GraphicsFilter GraphicsFilter;
 typedef FrameMetrics::ViewID ViewID;
 
+static ViewID sScrollIdCounter = FrameMetrics::START_SCROLL_ID;
+
+typedef nsDataHashtable<nsUint64HashKey, nsIContent*> ContentMap;
+static ContentMap* sContentMap = NULL;
+static ContentMap& GetContentMap() {
+  if (!sContentMap) {
+    sContentMap = new ContentMap();
+    nsresult rv = sContentMap->Init();
+    NS_ABORT_IF_FALSE(NS_SUCCEEDED(rv), "Could not initialize map.");
+  }
+  return *sContentMap;
+}
+
+static void DestroyViewID(void* aObject, nsIAtom* aPropertyName,
+                          void* aPropertyValue, void* aData)
+{
+  ViewID* id = static_cast<ViewID*>(aPropertyValue);
+  GetContentMap().Remove(*id);
+  delete id;
+}
+
+ViewID
+nsLayoutUtils::FindIDFor(nsIContent* aContent)
+{
+  ViewID scrollId;
+
+  void* scrollIdProperty = aContent->GetProperty(nsGkAtoms::RemoteId);
+  if (scrollIdProperty) {
+    scrollId = *static_cast<ViewID*>(scrollIdProperty);
+  } else {
+    scrollId = sScrollIdCounter++;
+    aContent->SetProperty(nsGkAtoms::RemoteId, new ViewID(scrollId),
+                          DestroyViewID);
+    GetContentMap().Put(scrollId, aContent);
+  }
+
+  return scrollId;
+}
+
+nsIContent*
+nsLayoutUtils::FindContentFor(ViewID aId)
+{
+  NS_ABORT_IF_FALSE(aId != FrameMetrics::NULL_SCROLL_ID &&
+                    aId != FrameMetrics::ROOT_SCROLL_ID,
+                    "Cannot find a content element in map for null or root IDs.");
+  nsIContent* content;
+  bool exists = GetContentMap().Get(aId, &content);
+
+  if (exists) {
+    return content;
+  } else {
+    return nsnull;
+  }
+}
+
 /**
  * A namespace class for static layout utilities.
  */
@@ -3907,6 +3963,16 @@ nsLayoutUtils::AssertTreeOnlyEmptyNextInFlows(nsIFrame *aSubtreeRoot)
 }
 #endif
 
+/* static */
+void
+nsLayoutUtils::Shutdown()
+{
+  if (sContentMap) {
+    delete sContentMap;
+    sContentMap = NULL;
+  }
+}
+
 nsSetAttrRunnable::nsSetAttrRunnable(nsIContent* aContent, nsIAtom* aAttrName,
                                      const nsAString& aValue)
   : mContent(aContent),

layout/base/nsLayoutUtils.h

@@ -83,6 +83,17 @@ class nsLayoutUtils
 public:
   typedef mozilla::layers::FrameMetrics::ViewID ViewID;
 
+  /**
+   * Finds previously assigned or generates a unique ViewID for the given
+   * content element.
+   */
+  static ViewID FindIDFor(nsIContent* aContent);
+
+  /**
+   * Find content for given ID.
+   */
+  static nsIContent* FindContentFor(ViewID aId);
+
   /**
    * Use heuristics to figure out the name of the child list that
    * aChildFrame is currently in.
@@ -1290,6 +1301,8 @@ public:
        aPresContext->Type() == nsPresContext::eContext_PageLayout);
   }
 
+  static void Shutdown();
+
 #ifdef DEBUG
   /**
    * Assert that there are no duplicate continuations of the same frame

layout/build/nsLayoutStatics.cpp

@@ -380,4 +380,6 @@ nsLayoutStatics::Shutdown()
   nsFrameList::Shutdown();
 
   nsHTMLInputElement::DestroyUploadLastDir();
+
+  nsLayoutUtils::Shutdown();
 }