[CSS Grid Layout] Support for justify-items property.

Source/core/rendering/RenderGrid.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 1100 matching lines @@
 LayoutUnit RenderGrid::centeredColumnPositionForChild(const RenderBox* child) const
 {
     const GridCoordinate& coordinate = cachedGridCoordinate(child);
     LayoutUnit startOfColumn = m_columnPositions[coordinate.columns.resolvedInitialPosition.toInt()];
     LayoutUnit endOfColumn = m_columnPositions[coordinate.columns.resolvedFinalPosition.next().toInt()];
     LayoutUnit columnPosition = startOfColumn + marginStartForChild(child);
     // FIXME: This should account for the grid item's <overflow-position>.
     return columnPosition + std::max<LayoutUnit>(0, endOfColumn - startOfColumn - child->logicalWidth()) / 2;
 }
 
+static ItemPosition resolveJustification(const RenderStyle* parentStyle, const RenderStyle* childStyle)
+{
+    ItemPosition justify = childStyle->justifySelf();
+    if (justify == ItemPositionAuto)
+        justify = (parentStyle->justifyItems() == ItemPositionAuto) ? ItemPositionStretch : parentStyle->justifyItems();
+
+    return justify;
+}
+
 LayoutUnit RenderGrid::columnPositionForChild(const RenderBox* child) const
 {
-    ItemPosition childJustifySelf = child->style()->justifySelf();
-    switch (childJustifySelf) {
+    bool hasOrthogonalWritingMode = child->isHorizontalWritingMode() != isHorizontalWritingMode();
+    ItemPosition justifySelf = resolveJustification(style(), child->style());
+
+    switch (justifySelf) {

[Julien - ping for review, 2014/08/22 21:22:14]

Unneeded variable:

switch(resolveJustification(style(), child->style()) {

[jfernandez, 2014/08/26 11:23:13]

Done.

     case ItemPositionSelfStart:
+        // If orthogonal writing-modes, this computes to 'Start'.

[Julien - ping for review, 2014/08/22 21:22:14]

'start' (lowercase s) to match the specification.

Nit: This reads better for me but you may disagree -> For orthogonal
writing-modes, this computes to 'start'

[jfernandez, 2014/08/26 11:23:13]

Done.

+        // FIXME: grid track sizing and positioning does not support orthogonal modes yet.

[Julien - ping for review, 2014/08/22 21:22:14]

grid track sizing and position *do* not support (it's plural :))

[jfernandez, 2014/08/26 11:23:13]

Done.

+        if (hasOrthogonalWritingMode)
+            return columnPositionAlignedWithGridContainerStart(child);
+
         // self-start is based on the child's direction. That's why we need to check against the grid container's direction.
         if (child->style()->direction() != style()->direction())
             return columnPositionAlignedWithGridContainerEnd(child);
 
         return columnPositionAlignedWithGridContainerStart(child);
     case ItemPositionSelfEnd:
+        // If orthogonal writing-modes, this computes to 'Start'.
+        // FIXME: grid track sizing and positioning does not support orthogonal modes yet.

[Julien - ping for review, 2014/08/22 21:22:14]

Same comments.

[jfernandez, 2014/08/26 11:23:13]

Done.

+        if (hasOrthogonalWritingMode)
+            return columnPositionAlignedWithGridContainerEnd(child);
+
         // self-end is based on the child's direction. That's why we need to check against the grid container's direction.
         if (child->style()->direction() != style()->direction())
             return columnPositionAlignedWithGridContainerStart(child);
 
         return columnPositionAlignedWithGridContainerEnd(child);
 
-    case ItemPositionFlexStart:
-    case ItemPositionFlexEnd:
-        // Only used in flex layout, for other layout, it's equivalent to 'start'.
-        return columnPositionAlignedWithGridContainerStart(child);

[Julien - ping for review, 2014/08/22 21:22:14]

Unneeded change. We can agree / disagree over which format is more readable but
this touches the history for no good reason.

[jfernandez, 2014/08/26 11:23:13]

Acknowledged.

-
     case ItemPositionLeft:
         // If the property's axis is not parallel with the inline axis, this is equivalent to ‘start’.
         if (!isHorizontalWritingMode())
             return columnPositionAlignedWithGridContainerStart(child);
 
         if (style()->isLeftToRightDirection())
             return columnPositionAlignedWithGridContainerStart(child);
 
         return columnPositionAlignedWithGridContainerEnd(child);
     case ItemPositionRight:
         // If the property's axis is not parallel with the inline axis, this is equivalent to ‘start’.
         if (!isHorizontalWritingMode())
             return columnPositionAlignedWithGridContainerStart(child);
 
         if (style()->isLeftToRightDirection())
             return columnPositionAlignedWithGridContainerEnd(child);
 
         return columnPositionAlignedWithGridContainerStart(child);
 
     case ItemPositionCenter:
         return centeredColumnPositionForChild(child);
+        // Only used in flex layout, for other layout, it's equivalent to 'start'.
+    case ItemPositionFlexStart:
     case ItemPositionStart:
         return columnPositionAlignedWithGridContainerStart(child);
+        // Only used in flex layout, for other layout, it's equivalent to 'start'.
+    case ItemPositionFlexEnd:
     case ItemPositionEnd:
         return columnPositionAlignedWithGridContainerEnd(child);
 
     case ItemPositionAuto:
+        break;

[Julien - ping for review, 2014/08/22 21:22:14]

ASSERT_NOT_REACHED();

[jfernandez, 2014/08/26 11:23:13]

There is such ASSERT at the end of the function, which is also used by the
"default" case. 

     case ItemPositionStretch:
     case ItemPositionBaseline:
     case ItemPositionLastBaseline:
         // FIXME: Implement the previous values. For now, we always start align the child.
         return startOfColumnForChild(child);
     }
 
     ASSERT_NOT_REACHED();
     return 0;
 }
@@ skipping 198 matching lines @@
     if (isOutOfFlowPositioned())
         return "RenderGrid (positioned)";
     if (isAnonymous())
         return "RenderGrid (generated)";
     if (isRelPositioned())
         return "RenderGrid (relative positioned)";
     return "RenderGrid";
 }
 
 } // namespace blink