Changeset 186911 in webkit

Timestamp:

Jul 16, 2015 2:54:06 PM (9 years ago)

Author:

Simon Fraser

Message:

Fix disappearing position:fixed elements in fixed layout mode
​https://bugs.webkit.org/show_bug.cgi?id=147019

Reviewed by Tim Horton.
Source/WebCore:

Test: compositing/fixed-with-fixed-layout.html

When in fixed layout mode, and being scaled down, viewportConstrainedVisibleContentRect() is
the wrong thing to use to determine if position:fixed elements are clipped out. In this case,
use the simpler document bounds (before scaling).

In the long term, there needs to be an equivalent of viewportConstrainedVisibleContentRect()
that gives an appropriate rect that can be used here.

• rendering/RenderLayerCompositor.cpp:

(WebCore::RenderLayerCompositor::requiresCompositingForPosition):

LayoutTests:

Test with four fixed elements in fixed layout mode.

• compositing/fixed-with-fixed-layout-expected.txt: Added.
• compositing/fixed-with-fixed-layout.html: Added.

Location:

trunk

Files:

• LayoutTests/ChangeLog (modified) (1 diff)
• LayoutTests/compositing/fixed-with-fixed-layout-expected.txt (added)
• LayoutTests/compositing/fixed-with-fixed-layout.html (added)
• Source/WebCore/ChangeLog (modified) (1 diff)
• Source/WebCore/rendering/RenderLayerCompositor.cpp (modified) (1 diff)

trunk/LayoutTests/ChangeLog

@@ +1 @@
+2015-07-16  Simon Fraser  <simon.fraser@apple.com>
+
+        Fix disappearing position:fixed elements in fixed layout mode
+        https://bugs.webkit.org/show_bug.cgi?id=147019
+
+        Reviewed by Tim Horton.
+        
+        Test with four fixed elements in fixed layout mode.
+
+        * compositing/fixed-with-fixed-layout-expected.txt: Added.
+        * compositing/fixed-with-fixed-layout.html: Added.
+
 2015-07-16  Filip Pizlo  <fpizlo@apple.com>
 

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2015-07-16  Simon Fraser  <simon.fraser@apple.com>
+
+        Fix disappearing position:fixed elements in fixed layout mode
+        https://bugs.webkit.org/show_bug.cgi?id=147019
+
+        Reviewed by Tim Horton.
+
+        Test: compositing/fixed-with-fixed-layout.html
+        
+        When in fixed layout mode, and being scaled down, viewportConstrainedVisibleContentRect() is
+        the wrong thing to use to determine if position:fixed elements are clipped out. In this case,
+        use the simpler document bounds (before scaling).
+        
+        In the long term,  there needs to be an equivalent of viewportConstrainedVisibleContentRect()
+        that gives an appropriate rect that can be used here.
+
+        * rendering/RenderLayerCompositor.cpp:
+        (WebCore::RenderLayerCompositor::requiresCompositingForPosition):
+
 2015-07-16  Benjamin Poulain  <bpoulain@apple.com>
 

trunk/Source/WebCore/rendering/RenderLayerCompositor.cpp

@@ -2740 +2740 @@
 
     // Fixed position elements that are invisible in the current view don't get their own layer.
-    LayoutRect viewBounds = m_renderView.frameView().viewportConstrainedVisibleContentRect();
+    // FIXME: We shouldn't have to check useFixedLayout() here; one of the viewport rects needs to give the correct answer.
+    LayoutRect viewBounds;
+    if (m_renderView.frameView().useFixedLayout())
+        viewBounds = m_renderView.unscaledDocumentRect();
+    else
+        viewBounds = m_renderView.frameView().viewportConstrainedVisibleContentRect();
     LayoutRect layerBounds = layer.calculateLayerBounds(&layer, LayoutSize(), RenderLayer::UseLocalClipRectIfPossible | RenderLayer::IncludeLayerFilterOutsets | RenderLayer::UseFragmentBoxesExcludingCompositing
         | RenderLayer::ExcludeHiddenDescendants | RenderLayer::DontConstrainForMask | RenderLayer::IncludeCompositedDescendants);