[CSS Grid Layout] Do not stretch always grid items with auto width

Source/core/layout/LayoutGrid.cpp

 /*
  * Copyright (C) 2011 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 1257 matching lines @@
         SubtreeLayoutScope layoutScope(*child);
         if (oldOverrideContainingBlockContentLogicalWidth != overrideContainingBlockContentLogicalWidth || (oldOverrideContainingBlockContentLogicalHeight != overrideContainingBlockContentLogicalHeight && child->hasRelativeLogicalHeight()))
             layoutScope.setNeedsLayout(child, LayoutInvalidationReason::GridChanged);
 
         child->setOverrideContainingBlockContentLogicalWidth(overrideContainingBlockContentLogicalWidth);
         child->setOverrideContainingBlockContentLogicalHeight(overrideContainingBlockContentLogicalHeight);
 
         // Stretching logic might force a child layout, so we need to run it before the layoutIfNeeded
         // call to avoid unnecessary relayouts. This might imply that child margins, needed to correctly
         // determine the available space before stretching, are not set yet.
-        applyStretchAlignmentToChildIfNeeded(*child, overrideContainingBlockContentLogicalHeight);
+        applyStretchAlignmentToChildIfNeeded(*child);
 
         child->layoutIfNeeded();
 
 #if ENABLE(ASSERT)
         const GridCoordinate& coordinate = cachedGridCoordinate(*child);
         ASSERT(coordinate.columns.resolvedInitialPosition.toInt() < sizingData.columnTracks.size());
         ASSERT(coordinate.rows.resolvedInitialPosition.toInt() < sizingData.rowTracks.size());
 #endif
         child->setLogicalLocation(findChildLogicalPosition(*child, sizingData));
 
@@ skipping 157 matching lines @@
     ASSERT_NOT_REACHED();
     return 0;
 }
 
 static inline LayoutUnit constrainedChildIntrinsicContentLogicalHeight(const LayoutBox& child)
 {
     LayoutUnit childIntrinsicContentLogicalHeight = child.intrinsicContentLogicalHeight();
     return child.constrainLogicalHeightByMinMax(childIntrinsicContentLogicalHeight + child.borderAndPaddingLogicalHeight(), childIntrinsicContentLogicalHeight);
 }
 
-bool LayoutGrid::allowedToStretchLogicalHeightForChild(const LayoutBox& child) const
+bool LayoutGrid::hasAutoSizeInColumnAxisForChild(const LayoutBox& child) const
 {
-    return child.style()->logicalHeight().isAuto() && !child.style()->marginBeforeUsing(style()).isAuto() && !child.style()->marginAfterUsing(style()).isAuto();
+    return isHorizontalWritingMode() ? child.style()->height().isAuto() : child.style()->width().isAuto();
+}
+
+bool LayoutGrid::hasAutoSizeInRowAxisForChild(const LayoutBox& child) const
+{
+    return isHorizontalWritingMode() ? child.style()->width().isAuto() : child.style()->height().isAuto();
+}
+
+bool LayoutGrid::allowedToStretchChildAlongColumnAxis(const LayoutBox& child) const
+{
+    return hasAutoSizeInColumnAxisForChild(child) && !child.style()->marginBeforeUsing(style()).isAuto() && !child.style()->marginAfterUsing(style()).isAuto();
+}
+
+bool LayoutGrid::allowedToStretchChildAlongRowAxis(const LayoutBox& child) const
+{
+    return hasAutoSizeInRowAxisForChild(child) && !child.style()->marginStartUsing(style()).isAuto() && !child.style()->marginEndUsing(style()).isAuto();
 }
 
 // FIXME: This logic is shared by LayoutFlexibleBox, so it should be moved to LayoutBox.
 bool LayoutGrid::needToStretchChildLogicalHeight(const LayoutBox& child) const
 {
     if (ComputedStyle::resolveAlignment(styleRef(), child.styleRef(), ItemPositionStretch) != ItemPositionStretch)
         return false;
 
     return isHorizontalWritingMode() && child.style()->height().isAuto();
 }
@@ skipping 47 matching lines @@
     // Because we want to avoid multiple layouts, stretching logic might be performed before
     // children are laid out, so we can't use the child cached values. Hence, we need to
     // compute margins in order to determine the available height before stretching.
     if (childMarginLogicalHeight == 0)
         childMarginLogicalHeight = computeMarginLogicalHeightForChild(child);
 
     return gridAreaBreadthForChild - childMarginLogicalHeight;
 }
 
 // FIXME: This logic is shared by LayoutFlexibleBox, so it should be moved to LayoutBox.
-void LayoutGrid::applyStretchAlignmentToChildIfNeeded(LayoutBox& child, LayoutUnit gridAreaBreadthForChild)
+void LayoutGrid::applyStretchAlignmentToChildIfNeeded(LayoutBox& child)
 {
-    if (!allowedToStretchLogicalHeightForChild(child) || ComputedStyle::resolveAlignment(styleRef(), child.styleRef(), ItemPositionStretch) != ItemPositionStretch) {
-        child.clearOverrideLogicalContentHeight();
+    child.clearOverrideSize();
+
+    if (!allowedToStretchChildAlongRowAxis(child) || ComputedStyle::resolveJustification(styleRef(), child.styleRef(), ItemPositionStretch) != ItemPositionStretch) {
+        if (hasAutoSizeInRowAxisForChild(child)) {
+            LayoutUnit childPreferredWidth = std::min(child.maxPreferredLogicalWidth(), child.overrideContainingBlockContentLogicalWidth()  - child.marginLogicalWidth());

[Manuel Rego, 2015/07/13 12:40:07]

This is what's breaking "min-width: auto;".

From one side you'd need something like
LayoutBox::constrainLogicalWidthByMinMax().

On the other hand, you're using the maxPreferredLogicalWidth()
and in the case of "min-width: auto;" we need to use the
minPreferredLogicalWdith().

[jfernandez, 2015/07/14 13:36:08]

That's correct, thanks for pointing it out.
I'm not sure about this; we want item's width to fit its content, so we want max
preferred width if there is enough space available.

Which is true is that if there is no space available, grid cell width less than
min preferred width of item's content, then we should let the min width logic
decide.  I've added a new function for this purpose, called
canShrinkToFitInRowAxisForChild, which I hope solves all these cases.

+            child.setOverrideLogicalContentWidth(childPreferredWidth - child.borderAndPaddingLogicalWidth());
+            if (childPreferredWidth != child.logicalWidth())
+                child.setNeedsLayout(LayoutInvalidationReason::GridChanged);
+        }
+    }
+
+    if (!allowedToStretchChildAlongColumnAxis(child) || ComputedStyle::resolveAlignment(styleRef(), child.styleRef(), ItemPositionStretch) != ItemPositionStretch)
         return;
-    }
 
     bool hasOrthogonalWritingMode = child.isHorizontalWritingMode() != isHorizontalWritingMode();
     // FIXME: If the child has orthogonal flow, then it already has an override height set, so use it.
     // FIXME: grid track sizing and positioning do not support orthogonal modes yet.
     if (!hasOrthogonalWritingMode) {
-        LayoutUnit stretchedLogicalHeight = availableAlignmentSpaceForChildBeforeStretching(gridAreaBreadthForChild, child);
+        LayoutUnit stretchedLogicalHeight = availableAlignmentSpaceForChildBeforeStretching(child.overrideContainingBlockContentLogicalHeight(), child);
         LayoutUnit desiredLogicalHeight = child.constrainLogicalHeightByMinMax(stretchedLogicalHeight, -1);
 
         // FIXME: Can avoid laying out here in some cases. See https://webkit.org/b/87905.
         bool childNeedsRelayout = desiredLogicalHeight != child.logicalHeight();
         if (childNeedsRelayout || !child.hasOverrideLogicalContentHeight())
             child.setOverrideLogicalContentHeight(desiredLogicalHeight - child.borderAndPaddingLogicalHeight());
         if (childNeedsRelayout) {
             child.setLogicalHeight(0);
             child.setNeedsLayout(LayoutInvalidationReason::GridChanged);
         }
@@ skipping 307 matching lines @@
 
     return LayoutPoint(columnPosition, rowPositionForChild(child));
 }
 
 void LayoutGrid::paintChildren(const PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     GridPainter(*this).paintChildren(paintInfo, paintOffset);
 }
 
 } // namespace blink