Implement <video controls> dodging for text track layout

Source/core/layout/LayoutMedia.cpp

 /*
  * Copyright (C) 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 10 matching lines @@
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 
 #include "core/layout/LayoutMedia.h"
 
 #include "core/html/HTMLMediaElement.h"
+#include "core/html/shadow/MediaControls.h"
+#include "core/layout/LayoutTextTrackContainer.h"
 #include "core/layout/LayoutView.h"
 
 namespace blink {
 
 LayoutMedia::LayoutMedia(HTMLMediaElement* video)
     : LayoutImage(video)
 {
     setImageResource(LayoutImageResource::create());
 }
 
 LayoutMedia::~LayoutMedia()
 {
 }
 
 HTMLMediaElement* LayoutMedia::mediaElement() const
 {
     return toHTMLMediaElement(node());
 }
 
 void LayoutMedia::layout()
 {
     LayoutSize oldSize = contentBoxRect().size();
 
     LayoutImage::layout();
 
     LayoutSize newSize = contentBoxRect().size();
 
+    bool sizeChanged = newSize != oldSize;
+
     LayoutState state(*this, locationOffset());
 
-    for (LayoutObject* child = m_children.firstChild(); child; child = child->nextSibling()) {
-        ASSERT(child->node()->isMediaControls() || child->node()->isTextTrackContainer());
+    // Iterate the children in reverse order so that the media controls are laid
+    // out before the text track container.
+    IntRect controlsRect;
+#if ENABLE(ASSERT)
+    bool didLayoutTextTrackContainer = false;
+#endif
+    for (LayoutObject* child = m_children.lastChild(); child; child = child->previousSibling()) {

[fs, 2015/03/17 10:27:56]

I think you could also just drop the for-loop entirely and do something like:

RELEASE_ASSERT(onlyTwoChildren(m_children));
LayoutObject* controls = m_children.lastChild();
LayoutObject* textTrackContainer = nullptr;
if (m_children.lastChild() != m_children.firstChild())
    textTrackContainer = m_children.firstChild();

// Layout one and then the other.
...

Or some variant thereof.

+        bool isMediaControls = child->node()->isMediaControls();
+        bool isTextTrackContainer = child->node()->isTextTrackContainer();
+        ASSERT(isMediaControls || isTextTrackContainer);
 
-        if (newSize == oldSize && !child->needsLayout())
-            continue;
+        if (isTextTrackContainer) {
+#if ENABLE(ASSERT)
+            didLayoutTextTrackContainer = true;
+#endif
+            static_cast<LayoutTextTrackContainer*>(child)->setControlsRect(controlsRect);
+        }
 
-        LayoutBox* layoutBox = toLayoutBox(child);
-        layoutBox->setLocation(LayoutPoint(borderLeft(), borderTop()) + LayoutSize(paddingLeft(), paddingTop()));
-        layoutBox->style()->setHeight(Length(newSize.height(), Fixed));
-        layoutBox->style()->setWidth(Length(newSize.width(), Fixed));
-        layoutBox->forceLayout();
+        if (sizeChanged || child->needsLayout()) {
+            LayoutBox* layoutBox = toLayoutBox(child);
+            layoutBox->setLocation(LayoutPoint(borderLeft(), borderTop()) + LayoutSize(paddingLeft(), paddingTop()));
+            layoutBox->style()->setHeight(Length(newSize.height(), Fixed));
+            layoutBox->style()->setWidth(Length(newSize.width(), Fixed));
+            layoutBox->forceLayout();
+        }
+
+        if (isMediaControls) {
+            ASSERT(!didLayoutTextTrackContainer);
+            controlsRect = toMediaControls(child->node())->absoluteRectForTextTracks();
+        }
     }
 
     clearNeedsLayout();
 }
 
 bool LayoutMedia::isChildAllowed(LayoutObject* child, const LayoutStyle&) const
 {
     // Two types of child layout objects are allowed: media controls
     // and the text track container. Filter children by node type.
     ASSERT(child->node());
@@ skipping 11 matching lines @@
         return true;
 
     return false;
 }
 
 void LayoutMedia::paintReplaced(const PaintInfo&, const LayoutPoint&)
 {
 }
 
 } // namespace blink