Changeset 112919 in webkit

Timestamp:

Apr 2, 2012, 12:37:59 PM (14 years ago)

Author:

commit-queue@webkit.org

Message:

Scroll position is lost after hide/show element
​https://bugs.webkit.org/show_bug.cgi?id=72852

Source/WebCore:

Maintain the scroll position of an overflowing element in the ElementRareData when the scrollable
RenderLayer is destroyed, which can be used to restore the scroll position if the same element gets
back a RenderLayer.

WebKit behaviour will be the same as Firefox and IE. It differs from Opera as it does not reset the
scroll position when an element is moved to another location in the same document. However Opera resets
the scroll position for elements moved to another document, which matches other browsers.

Patch by Rakesh KN <​rakesh.kn@motorola.com> on 2012-04-02
Reviewed by Julien Chaffraix.

Test: fast/overflow/scroll-div-hide-show.html

• dom/Element.cpp:

(WebCore::Element::removedFromDocument):
Reset the saved scroll offset if the node is moved to another location in the same document or another one.

(WebCore::Element::savedLayerScrollOffset):
(WebCore::Element::setSavedLayerScrollOffset):

• dom/Element.h:

Add helper functions to access the layer scroll offset from the element's rare data.

• dom/ElementRareData.h:

(ElementRareData):
Add the scroll offset book-keeping.

• rendering/RenderLayer.cpp:

(WebCore::RenderLayer::RenderLayer):
Restore the scroll offset.
(WebCore::RenderLayer::~RenderLayer):
Store the scroll offset if document is not being destroyed.

LayoutTests:

Patch by Rakesh KN <​rakesh.kn@motorola.com> on 2012-04-02
Reviewed by Julien Chaffraix.

• fast/overflow/scroll-div-hide-show-expected.txt: Added.
• fast/overflow/scroll-div-hide-show.html: Added.

Location:

trunk

Files:

• LayoutTests/ChangeLog (modified) (1 diff)
• LayoutTests/fast/overflow/scroll-div-hide-show-expected.txt (added)
• LayoutTests/fast/overflow/scroll-div-hide-show.html (added)
• Source/WebCore/ChangeLog (modified) (1 diff)
• Source/WebCore/dom/Element.cpp (modified) (2 diffs)
• Source/WebCore/dom/Element.h (modified) (1 diff)
• Source/WebCore/dom/ElementRareData.h (modified) (1 diff)
• Source/WebCore/rendering/RenderLayer.cpp (modified) (2 diffs)

trunk/LayoutTests/ChangeLog

@@ +1 @@
+2012-04-02  Rakesh KN  <rakesh.kn@motorola.com>
+
+        Scroll position is lost after hide/show element
+        https://bugs.webkit.org/show_bug.cgi?id=72852
+
+        Reviewed by Julien Chaffraix.
+
+        * fast/overflow/scroll-div-hide-show-expected.txt: Added.
+        * fast/overflow/scroll-div-hide-show.html: Added.
+
 2012-04-02  Stephen Chenney  <schenney@chromium.org>
 

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2012-04-02  Rakesh KN  <rakesh.kn@motorola.com>
+
+        Scroll position is lost after hide/show element
+        https://bugs.webkit.org/show_bug.cgi?id=72852
+
+        Maintain the scroll position of an overflowing element in the ElementRareData when the scrollable 
+        RenderLayer is destroyed, which can be used to restore the scroll position if the same element gets
+        back a RenderLayer.
+
+        WebKit behaviour will be the same as Firefox and IE. It differs from Opera as it does not reset the
+        scroll position when an element is moved to another location in the same document. However Opera resets
+        the scroll position for elements moved to another document, which matches other browsers.
+
+        Reviewed by Julien Chaffraix.
+
+        Test: fast/overflow/scroll-div-hide-show.html
+
+        * dom/Element.cpp:
+        (WebCore::Element::removedFromDocument):
+        Reset the saved scroll offset if the node is moved to another location in the same document or another one.
+
+        (WebCore::Element::savedLayerScrollOffset):
+        (WebCore::Element::setSavedLayerScrollOffset):
+        * dom/Element.h:
+        Add helper functions to access the layer scroll offset from the element's rare data.
+
+        * dom/ElementRareData.h:
+        (ElementRareData):
+        Add the scroll offset book-keeping.
+
+        * rendering/RenderLayer.cpp:
+        (WebCore::RenderLayer::RenderLayer):
+        Restore the scroll offset.
+        (WebCore::RenderLayer::~RenderLayer):
+        Store the scroll offset if document is not being destroyed.
+
 2012-04-02  Alexis Menard  <alexis.menard@openbossa.org>
 

trunk/Source/WebCore/dom/Element.cpp

@@ -904 +904 @@
 void Element::removedFromDocument()
 {
+    setSavedLayerScrollOffset(IntSize());
+
     if (m_attributeData) {
         if (hasID()) {
@@ -2067 +2069 @@
 }
 
+IntSize Element::savedLayerScrollOffset() const
+{
+    return hasRareData() ? rareData()->m_savedLayerScrollOffset : IntSize();
+}
+
+void Element::setSavedLayerScrollOffset(const IntSize& size)
+{
+    if (size.isZero() && !hasRareData())
+        return;
+    ensureRareData()->m_savedLayerScrollOffset = size;
+}
+
 } // namespace WebCore

trunk/Source/WebCore/dom/Element.h

@@ -403 +403 @@
     bool hasClass() const;
 
+    IntSize savedLayerScrollOffset() const;
+    void setSavedLayerScrollOffset(const IntSize&);
+
 protected:
     Element(const QualifiedName& tagName, Document* document, ConstructionType type)

trunk/Source/WebCore/dom/ElementRareData.h

@@ -75 +75 @@
     bool m_styleAffectedByEmpty;
 
+    IntSize m_savedLayerScrollOffset;
+
 #if ENABLE(FULLSCREEN_API)
     bool m_containsFullScreenElement;

trunk/Source/WebCore/rendering/RenderLayer.cpp

@@ -195 +195 @@
         m_hasVisibleContent = renderer->style()->visibility() == VISIBLE;
     }
+
+    Node* node = renderer->node();
+    if (node && node->isElementNode()) {
+        // We save and restore only the scrollOffset as the other scroll values are recalculated.
+        Element* element = toElement(node);
+        m_scrollOffset = element->savedLayerScrollOffset();
+        element->setSavedLayerScrollOffset(IntSize());
+    }
 }
 
@@ -207 +215 @@
         if (FrameView* frameView = frame->view())
             frameView->removeScrollableArea(this);
+    }
+
+    if (!m_renderer->documentBeingDestroyed()) {
+        Node* node = m_renderer->node();
+        if (node && node->isElementNode())
+            toElement(node)->setSavedLayerScrollOffset(m_scrollOffset);
     }