[css-flexbox] Use correct aspect ratio for min-size: auto

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

Index: third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp b/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp
index f735ab00a391df20b08aabec6cc348f1ae456e59..fd997c69763684f74286088cd0c98f9a7f8d2a43 100644
--- a/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp
@@ -42,6 +42,11 @@
 
 namespace blink {
 
+static bool hasAspectRatio(const LayoutBox& child)
+{
+    return child.isImage() || child.isCanvas() || child.isVideo();
+}
+
 struct LayoutFlexibleBox::LineContext {
     LineContext(LayoutUnit crossAxisOffset, LayoutUnit crossAxisExtent, size_t numberOfChildren, LayoutUnit maxAscent)
         : crossAxisOffset(crossAxisOffset)
@@ -452,7 +457,7 @@ LayoutUnit LayoutFlexibleBox::computeMainAxisExtentForChild(const LayoutBox& chi
     // computeLogicalWidth always re-computes the intrinsic widths. However, when our logical width is auto,
     // we can just use our cached value. So let's do that here. (Compare code in LayoutBlock::computePreferredLogicalWidths)
     LayoutUnit borderAndPadding = child.borderAndPaddingLogicalWidth();
-    if (child.styleRef().logicalWidth().isAuto()) {
+    if (child.styleRef().logicalWidth().isAuto() && !hasAspectRatio(child)) {
         if (size.type() == MinContent)
             return child.minPreferredLogicalWidth() - borderAndPadding;
         if (size.type() == MaxContent)
@@ -625,6 +630,43 @@ LayoutPoint LayoutFlexibleBox::flowAwareLocationForChild(const LayoutBox& child)
     return isHorizontalFlow() ? child.location() : child.location().transposedPoint();
 }
 
+bool LayoutFlexibleBox::useChildAspectRatio(const LayoutBox& child) const
+{
+    if (!hasAspectRatio(child))
+        return false;
+    if (child.intrinsicSize().height() == 0) {
+        // We can't compute a ratio in this case.
+        return false;
+    }
+    Length crossSize;
+    if (isHorizontalFlow())
+        crossSize = child.styleRef().height();
+    else
+        crossSize = child.styleRef().width();
+    return crossAxisLengthIsDefinite(child, crossSize);
+}
+
+LayoutUnit LayoutFlexibleBox::computeMainSizeFromAspectRatio(const LayoutBox& child, Length crossSizeLength) const
+{
+    ASSERT(useChildAspectRatio(child));
+
+    LayoutUnit crossSize;
+    if (crossSizeLength.isFixed()) {
+        crossSize = crossSizeLength.value();
+    } else {
+        ASSERT(crossSizeLength.hasPercent());
+        crossSize = hasOrthogonalFlow(child) ?
+            adjustBorderBoxLogicalWidthForBoxSizing(valueForLength(crossSizeLength, contentWidth())) :
+            child.computePercentageLogicalHeight(crossSizeLength);
+    }
+
+    const LayoutSize& childIntrinsicSize = child.intrinsicSize();
+    double ratio = childIntrinsicSize.width().toFloat() / childIntrinsicSize.height().toFloat();
+    if (isHorizontalFlow())
+        return crossSize * ratio;
+    return crossSize / ratio;
+}
+
 void LayoutFlexibleBox::setFlowAwareLocationForChild(LayoutBox& child, const LayoutPoint& location)
 {
     if (isHorizontalFlow())
@@ -650,6 +692,19 @@ bool LayoutFlexibleBox::mainAxisLengthIsDefinite(const LayoutBox& child, const L
     return true;
 }
 
+bool LayoutFlexibleBox::crossAxisLengthIsDefinite(const LayoutBox& child, const Length& length) const
+{
+    if (length.isAuto())
+        return false;
+    if (length.hasPercent()) {
+        return hasOrthogonalFlow(child) ?
+            hasDefiniteLogicalWidth() :
+            child.computePercentageLogicalHeight(length) != -1;
+

[leviw_travelin_and_unemployed, 2016/01/27 23:18:45]

This seems like a weird empty line </whitespace-jerk>

[cbiesinger, 2016/01/27 23:25:25]

Oh oops. Removed.

+    }
+    return true;
+}
+
 bool LayoutFlexibleBox::childFlexBaseSizeRequiresLayout(const LayoutBox& child) const
 {
     return !mainAxisLengthIsDefinite(child, flexBasisForChild(child)) && (
@@ -926,13 +981,17 @@ LayoutUnit LayoutFlexibleBox::adjustChildSizeForMinAndMax(const LayoutBox& child
         if (mainAxisLengthIsDefinite(child, mainSize)) {
             LayoutUnit resolvedMainSize = computeMainAxisExtentForChild(child, MainOrPreferredSize, mainSize);
             ASSERT(resolvedMainSize >= 0);
+            // TODO(cbiesinger): For items with an aspect ratio, clamp this size through the converted cross-size min/max size. crbug.com/249112
             LayoutUnit specifiedSize = maxExtent != -1 ? std::min(resolvedMainSize, maxExtent) : resolvedMainSize;
 
             minExtent = std::min(specifiedSize, contentSize);
+        } else if (useChildAspectRatio(child)) {
+            Length crossSizeLength = isHorizontalFlow() ? child.styleRef().height() : child.styleRef().width();
+            LayoutUnit transferredSize = computeMainSizeFromAspectRatio(child, crossSizeLength);
+            minExtent = std::min(transferredSize, contentSize);
         } else {
             minExtent = contentSize;
         }
-        // TODO(cbiesinger): Implement aspect ratio handling (here, transferred size) - crbug.com/249112
     }
     ASSERT(minExtent >= 0);
     return std::max(childSize, minExtent);
@@ -1177,6 +1236,7 @@ bool LayoutFlexibleBox::needToStretchChildLogicalHeight(const LayoutBox& child)
     if (isHorizontalFlow() != child.styleRef().isHorizontalWritingMode())
         return false;
 
+    // TODO(cbiesinger): what about indefinite percentage heights?
     return isHorizontalFlow() ? child.styleRef().height().isAuto() : child.styleRef().width().isAuto();
 }
 
@@ -1206,6 +1266,7 @@ EOverflow LayoutFlexibleBox::crossAxisOverflowForChild(const LayoutBox& child) c
         return child.styleRef().overflowY();
     return child.styleRef().overflowX();
 }
+
 void LayoutFlexibleBox::layoutAndPlaceChildren(LayoutUnit& crossAxisOffset, const OrderedFlexItemList& children, const Vector<LayoutUnit, 16>& childSizes, LayoutUnit availableFreeSpace, bool relayoutChildren, SubtreeLayoutScope& layoutScope, Vector<LineContext>& lineContexts)
 {
     ASSERT(childSizes.size() == children.size());