Changeset 98373 in webkit

Timestamp:

Oct 25, 2011 12:26:04 PM (12 years ago)

Author:

tony@chromium.org

Message:

avoid unnecessary layouts of flex items during the flex pass
​https://bugs.webkit.org/show_bug.cgi?id=70557

Reviewed by Ojan Vafai.

If the preferred size of a flex item is provided, we don't need to
layout the flex item when computing the preferred size. This allows
us to only call layout on each flex item once in the common case.

No new tests, covered by existing tests.

• rendering/RenderFlexibleBox.cpp:

(WebCore::RenderFlexibleBox::flowAwareLogicalWidthLengthForChild):
(WebCore::RenderFlexibleBox::preferredLogicalContentWidthForFlexItem):
(WebCore::RenderFlexibleBox::computePreferredLogicalWidth):
(WebCore::RenderFlexibleBox::layoutAndPlaceChildrenInlineDirection):

• rendering/RenderFlexibleBox.h:

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• rendering/RenderFlexibleBox.cpp (modified) (4 diffs)
• rendering/RenderFlexibleBox.h (modified) (1 diff)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2011-10-25  Tony Chang  <tony@chromium.org>
+
+        avoid unnecessary layouts of flex items during the flex pass
+        https://bugs.webkit.org/show_bug.cgi?id=70557
+
+        Reviewed by Ojan Vafai.
+
+        If the preferred size of a flex item is provided, we don't need to
+        layout the flex item when computing the preferred size.  This allows
+        us to only call layout on each flex item once in the common case.
+
+        No new tests, covered by existing tests.
+
+        * rendering/RenderFlexibleBox.cpp:
+        (WebCore::RenderFlexibleBox::flowAwareLogicalWidthLengthForChild):
+        (WebCore::RenderFlexibleBox::preferredLogicalContentWidthForFlexItem):
+        (WebCore::RenderFlexibleBox::computePreferredLogicalWidth):
+        (WebCore::RenderFlexibleBox::layoutAndPlaceChildrenInlineDirection):
+        * rendering/RenderFlexibleBox.h:
+
 2011-10-25  Fady Samuel  <fsamuel@chromium.org>
 

trunk/Source/WebCore/rendering/RenderFlexibleBox.cpp

@@ -229 +229 @@
 }
 
+Length RenderFlexibleBox::flowAwareLogicalWidthLengthForChild(RenderBox* child) const
+{
+    return isHorizontalFlow() ? child->style()->width() : child->style()->height();
+}
+
 bool RenderFlexibleBox::isFlowAwareLogicalHeightAuto() const
 {
@@ -494 +499 @@
 LayoutUnit RenderFlexibleBox::preferredLogicalContentWidthForFlexItem(RenderBox* child) const
 {
-    Length width = isHorizontalFlow() ? child->style()->width() : child->style()->height();
-    if (width.isAuto()) {
+    Length logicalWidthLength = flowAwareLogicalWidthLengthForChild(child);
+    if (logicalWidthLength.isAuto()) {
         LayoutUnit logicalWidth = hasOrthogonalFlow(child) ? child->logicalHeight() : child->maxPreferredLogicalWidth();
         return logicalWidth - logicalBorderAndPaddingWidthForChild(child) - logicalScrollbarHeightForChild(child);
     }
-    return isHorizontalFlow() ? child->contentWidth() : child->contentHeight();
+    return logicalWidthLength.calcMinValue(flowAwareContentLogicalWidth());
 }
 
@@ -555 +560 @@
     LayoutUnit flexboxAvailableLogicalWidth = flowAwareContentLogicalWidth();
     for (RenderBox* child = iterator.first(); child; child = iterator.next()) {
-        // We always have to lay out flexible objects again, since the flex distribution
-        // may have changed, and we need to reallocate space.
-        child->clearOverrideSize();
-        if (!relayoutChildren)
-            child->setChildNeedsLayout(true);
-        child->layoutIfNeeded();
-
-        // We can't just use marginStartForChild, et. al. because "auto" needs to be treated as 0.
+        if (flowAwareLogicalWidthLengthForChild(child).isAuto()) {
+            child->clearOverrideSize();
+            if (!relayoutChildren)
+                child->setChildNeedsLayout(true);
+            child->layoutIfNeeded();
+        }
+
+        // We set the margins because we want to make sure 'auto' has a margin
+        // of 0 and because if we're not auto sizing, we don't do a layout that
+        // computes the start/end margins.
         if (isHorizontalFlow()) {
-            preferredLogicalWidth += child->style()->marginLeft().calcMinValue(flexboxAvailableLogicalWidth);
-            preferredLogicalWidth += child->style()->marginRight().calcMinValue(flexboxAvailableLogicalWidth);
+            child->setMarginLeft(child->style()->marginLeft().calcMinValue(flexboxAvailableLogicalWidth));
+            child->setMarginRight(child->style()->marginRight().calcMinValue(flexboxAvailableLogicalWidth));
+            preferredLogicalWidth += child->marginLeft() + child->marginRight();
         } else {
-            preferredLogicalWidth += child->style()->marginTop().calcMinValue(flexboxAvailableLogicalWidth);
-            preferredLogicalWidth += child->style()->marginBottom().calcMinValue(flexboxAvailableLogicalWidth);
+            child->setMarginTop(child->style()->marginTop().calcMinValue(flexboxAvailableLogicalWidth));
+            child->setMarginBottom(child->style()->marginBottom().calcMinValue(flexboxAvailableLogicalWidth));
+            preferredLogicalWidth += child->marginTop() + child->marginBottom();
         }
 
@@ -671 +680 @@
         } else if (isFlowAwareLogicalHeightAuto())
             setFlowAwareLogicalHeight(std::max(flowAwareLogicalHeight(), flowAwareBorderAndPaddingLogicalHeight() + flowAwareMarginLogicalHeightForChild(child) + flowAwareLogicalHeightForChild(child) + scrollbarLogicalHeight()));
-
-        if (marginStartStyleForChild(child).isAuto())
-            setFlowAwareMarginStartForChild(child, 0);
-        if (marginEndStyleForChild(child).isAuto())
-            setFlowAwareMarginEndForChild(child, 0);
 
         startEdge += flowAwareMarginStartForChild(child);

trunk/Source/WebCore/rendering/RenderFlexibleBox.h

@@ -59 +59 @@
     bool isLeftToRightFlow() const;
     bool isFlowAwareLogicalHeightAuto() const;
+    Length flowAwareLogicalWidthLengthForChild(RenderBox* child) const;
     void setFlowAwareLogicalHeight(LayoutUnit);
     LayoutUnit flowAwareLogicalHeightForChild(RenderBox* child);