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

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

Index: third_party/WebKit/Source/core/layout/LayoutGrid.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutGrid.cpp b/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
index 26b4afd42c9f6a66f70e7a0e1a2aeccb0f5cc909..406a16c1a586f9bc8630e4e2c7069e46dab7746f 100644
--- a/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
@@ -2900,6 +2900,93 @@ void LayoutGrid::updateAutoMarginsInColumnAxisIfNeeded(LayoutBox& child) {
   }
 }
 
+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 =