Schedule cursor update on URL cursor image loaded

third_party/WebKit/Source/core/layout/LayoutObject.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 1875 matching lines @@
         toImageContentData(m_style->contentData())->image() : nullptr;
     StyleImage* oldContentImage = oldStyle && oldStyle->contentData() && oldStyle->contentData()->isImage() ?
         toImageContentData(oldStyle->contentData())->image() : nullptr;
     updateImage(oldContentImage, newContentImage);
 
     StyleImage* newBoxReflectMaskImage = m_style->boxReflect() ? m_style->boxReflect()->mask().image() : nullptr;
     StyleImage* oldBoxReflectMaskImage = oldStyle && oldStyle->boxReflect() ? oldStyle->boxReflect()->mask().image() : nullptr;
     updateImage(oldBoxReflectMaskImage, newBoxReflectMaskImage);
 
     updateShapeImage(oldStyle ? oldStyle->shapeOutside() : 0, m_style->shapeOutside());
+    updateCursorImages(oldStyle ? oldStyle->cursors() : nullptr, m_style->cursors());
 
     bool doesNotNeedLayoutOrPaintInvalidation = !m_parent;
 
     styleDidChange(diff, oldStyle.get());
 
     // FIXME: |this| might be destroyed here. This can currently happen for a LayoutTextFragment when
     // its first-letter block gets an update in LayoutTextFragment::styleDidChange. For LayoutTextFragment(s),
     // we will safely bail out with the doesNotNeedLayoutOrPaintInvalidation flag. We might want to broaden
     // this condition in the future as we move layoutObject changes out of layout and into style changes.
     if (doesNotNeedLayoutOrPaintInvalidation)
@@ skipping 204 matching lines @@
         if (currNew->image())
             currNew->image()->addClient(this);
     }
 
     for (const FillLayer* currOld = oldLayers; currOld; currOld = currOld->next()) {
         if (currOld->image())
             currOld->image()->removeClient(this);
     }
 }
 
+void LayoutObject::updateCursorImages(const CursorList* oldCursors, const CursorList* newCursors)
+{
+    if (oldCursors && newCursors && *oldCursors == *newCursors)
+        return;
+
+    if (newCursors) {
+        for (const CursorData& cursorNew : *newCursors) {
+            if (cursorNew.image())
+                cursorNew.image()->addClient(this);
+        }
+    }
+    removeCursorImageClient(oldCursors);
+}
+
 void LayoutObject::updateImage(StyleImage* oldImage, StyleImage* newImage)
 {
     if (oldImage != newImage) {
         if (oldImage)
             oldImage->removeClient(this);
         if (newImage)
             newImage->addClient(this);
     }
 }
 
@@ skipping 509 matching lines @@
         if (StyleImage* maskBoxImage = m_style->maskBoxImage().image())
             maskBoxImage->removeClient(this);
 
         if (m_style->contentData() && m_style->contentData()->isImage())
             toImageContentData(m_style->contentData())->image()->removeClient(this);
 
         if (m_style->boxReflect() && m_style->boxReflect()->mask().image())
             m_style->boxReflect()->mask().image()->removeClient(this);
 
         removeShapeImageClient(m_style->shapeOutside());
+        removeCursorImageClient(m_style->cursors());
     }
 
     if (frameView())
         setIsBackgroundAttachmentFixedObject(false);
 }
 
 void LayoutObject::insertedIntoTree()
 {
     // FIXME: We should ASSERT(isRooted()) here but generated content makes some out-of-order insertion.
 
@@ skipping 165 matching lines @@
 }
 
 void LayoutObject::removeShapeImageClient(ShapeValue* shapeValue)
 {
     if (!shapeValue)
         return;
     if (StyleImage* shapeImage = shapeValue->image())
         shapeImage->removeClient(this);
 }
 
+void LayoutObject::removeCursorImageClient(const CursorList* cursorList)
+{
+    if (!cursorList)
+        return;
+    for (const CursorData& cursor : *cursorList) {
+        if (cursor.image())
+            cursor.image()->removeClient(this);
+    }
+}
+
 PositionWithAffinity LayoutObject::positionForPoint(const LayoutPoint&)
 {
     return createPositionWithAffinity(caretMinOffset());
 }
 
 void LayoutObject::updateDragState(bool dragOn)
 {
     bool valueChanged = (dragOn != isDragging());
     setIsDragging(dragOn);
     if (valueChanged && node()) {
@@ skipping 325 matching lines @@
 
 void LayoutObject::imageChanged(ImageResource* image, const IntRect* rect)
 {
     ASSERT(m_node);
 
     // Image change notifications should not be received during paint because
     // the resulting invalidations will be cleared following paint. This can also
     // lead to modifying the tree out from under paint(), see: crbug.com/616700.
     DCHECK(document().lifecycle().state() != DocumentLifecycle::LifecycleState::InPaint);
 
+    if (const CursorList* cursors = style()->cursors()) {

[eae, 2016/07/12 16:16:00]

I'm not entirely sure how we handle cursor images today but this feels like the
wrong place for this logic. Complicating the imageChanged method for the
LayoutObject base class for a _very_ rare edge case strikes me as undesirable.

How about adding this logic to CursorData instead?

[chongz, 2016/07/12 20:08:12]

I've moved the logic to |LayoutFrame|, will it be a better place?
I'm not sure if I understood your suggestion, do you mean:
1. Only move |imageChanged| logic to |CursorData|, but leaves the listeners
here?
e.g. Create a method |CursorData::imageChanged(frame, image)| and call from
here.

Or, 

2. Move everything inside |CursorData|?
e.g. Register resource listeners in |CursorData::setImage()|.

+        for (const CursorData& cursor : *cursors) {
+            if (cursor.image() && cursor.image()->cachedImage() == image) {
+                if (LocalFrame* frame = this->frame()) {
+                    // Cursor update scheduling is done by the local root, which is the main frame if there
+                    // are no RemoteFrame ancestors in the frame tree. Use of localFrameRoot() is
+                    // discouraged but will change when cursor update scheduling is moved from EventHandler
+                    // to PageEventHandler.
+                    frame->localFrameRoot()->eventHandler().scheduleCursorUpdate();
+                }
+            }
+        }
+    }
+
     imageChanged(static_cast<WrappedImagePtr>(image), rect);
 }
 
 Element* LayoutObject::offsetParent(const Element* unclosedBase) const
 {
     if (isDocumentElement() || isBody())
         return nullptr;
 
     if (isFixedPositioned())
         return nullptr;
@@ skipping 457 matching lines @@
         const blink::LayoutObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showLayoutTreeAndMark(object1, "*", object2, "-", 0);
     } else {
         WTFLogAlways("%s", "Cannot showLayoutTree. Root is (nil)");
     }
 }
 
 #endif