[css-grid] Implementing the grid's first line baseline.

third_party/WebKit/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 2882 matching lines @@
   if (marginBefore.isAuto() && marginAfter.isAuto()) {
     child.setMarginBefore(availableAlignmentSpace / 2, style());
     child.setMarginAfter(availableAlignmentSpace / 2, style());
   } else if (marginBefore.isAuto()) {
     child.setMarginBefore(availableAlignmentSpace, style());
   } else if (marginAfter.isAuto()) {
     child.setMarginAfter(availableAlignmentSpace, style());
   }
 }
 
+static int synthesizedBaselineFromContentBox(const LayoutBox& box,
+                                             LineDirectionMode direction) {
+  if (direction == HorizontalLine) {
+    return (box.size().height() - box.borderBottom() - box.paddingBottom() -
+            box.verticalScrollbarWidth())

[svillar, 2016/10/21 12:53:06]

Why aren't you directly using contentHeight() ?

[jfernandez, 2016/10/26 14:22:31]

Well, we don't want contentHeight, but the distance from the box's top position
to its border-box bottom edge. 

+        .toInt();
+  }
+  return (box.size().width() - box.borderLeft() - box.paddingLeft() -
+          box.horizontalScrollbarHeight())

[svillar, 2016/10/21 12:53:06]

Why aren't you directly using contentWidth() ?

[jfernandez, 2016/10/26 14:22:31]

Ditto.

+      .toInt();
+}
+
+int LayoutGrid::baselinePosition(FontBaseline,
+                                 bool,
+                                 LineDirectionMode direction,
+                                 LinePositionMode mode) const {

[Manuel Rego, 2016/10/25 19:42:09]

This is the same code than flexbox, probably it'd be nice to add
a comment about a future refactoring.

[jfernandez, 2016/10/26 14:22:31]

Acknowledged.

+  DCHECK_EQ(mode, PositionOnContainingLine);
+  int baseline = firstLineBoxBaseline();
+  // We take content-box's bottom if no valid baseline.
+  if (baseline == -1)
+    baseline = synthesizedBaselineFromContentBox(*this, direction);
+
+  return baseline + beforeMarginInLineDirection(direction);
+}
+
+int LayoutGrid::firstLineBoxBaseline() const {
+  if (isWritingModeRoot())
+    return -1;
+  const LayoutBox* baselineChild = nullptr;
+  for (const LayoutBox* child = m_orderIterator.first(); child;

[svillar, 2016/10/21 12:53:06]

This is order-modified document order not grid-modified document order.

[Manuel Rego, 2016/10/25 19:42:09]

Yeah you should check the things in the first row using
m_grid[0] and the items in the first busy cell
as we do in GridPainter.

[jfernandez, 2016/10/26 14:22:31]

Done.

+       child = m_orderIterator.next()) {
+    if (child->isOutOfFlowPositioned())
+      continue;
+    const GridSpan& rowsSpan = cachedGridSpan(*child, ForRows);
+    // TODO (lajava): propertly identifying grid items whose areas
+    // intersect the grid container's first row.
+    if (rowsSpan.startLine() > 0)
+      continue;
+    ItemPosition align = alignSelfForChild(*child).position();
+    // Orthogonal children don't participate in baseline alignment.
+    if (align == ItemPositionBaseline && !isOrthogonalChild(*child) &&
+        !hasAutoMarginsInColumnAxis(*child)) {
+      // TODO (lajava): self-baseline and content-baseline alignment
+      // still not implemented.
+      baselineChild = child;
+      break;
+    }
+    if (!baselineChild)
+      baselineChild = child;
+  }
+
+  if (!baselineChild)
+    return -1;
+
+  if (isOrthogonalChild(*baselineChild)) {
+    return ((isHorizontalWritingMode() ? baselineChild->size().height()
+                                       : baselineChild->size().width()) +
+            baselineChild->logicalTop())
+        .toInt();
+  }
+
+  int baseline = baselineChild->firstLineBoxBaseline();
+  if (baseline == -1) {
+    // TODO (lajava): We should pass |direction| into
+    // firstLineBoxBaseline and stop bailing out if we're a writing
+    // mode root.  This would also fix some cases where the grid is
+    // orthogonal to its container.
+    LineDirectionMode direction =
+        isHorizontalWritingMode() ? HorizontalLine : VerticalLine;
+    return (synthesizedBaselineFromContentBox(*baselineChild, direction) +
+            baselineChild->logicalTop())
+        .toInt();
+  }
+
+  return (baseline + baselineChild->logicalTop()).toInt();
+}
+
+int LayoutGrid::inlineBlockBaseline(LineDirectionMode direction) const {

[Manuel Rego, 2016/10/25 19:42:09]

Again same code than flexbox, please add a comment.

[jfernandez, 2016/10/26 14:22:31]

Acknowledged.

+  int baseline = firstLineBoxBaseline();
+  if (baseline != -1)
+    return baseline;
+
+  int marginHeight =
+      (direction == HorizontalLine ? marginTop() : marginRight()).toInt();
+  return synthesizedBaselineFromContentBox(*this, direction) + marginHeight;
+}
+
 GridAxisPosition LayoutGrid::columnAxisPositionForChild(
     const LayoutBox& child) const {
   bool hasSameWritingMode =
       child.styleRef().getWritingMode() == styleRef().getWritingMode();
   bool childIsLTR = child.styleRef().isLeftToRightDirection();
 
   switch (alignSelfForChild(child).position()) {
     case ItemPositionSelfStart:
       // TODO (lajava): Should we implement this logic in a generic utility
       // function?
@@ skipping 410 matching lines @@
   if (!m_gridItemArea.isEmpty())
     GridPainter(*this).paintChildren(paintInfo, paintOffset);
 }
 
 bool LayoutGrid::cachedHasDefiniteLogicalHeight() const {
   SECURITY_DCHECK(m_hasDefiniteLogicalHeight);
   return m_hasDefiniteLogicalHeight.value();
 }
 
 }  // namespace blink