[css-grid] Initial support for implicit grid before explicit grid

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 42b03d34f4a3ed31c22d368ce506ae4f4457199a..17330535460b3c56b90238f8c956a22cec1bccdd 100644
--- a/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
@@ -656,7 +656,9 @@ GridTrackSize LayoutGrid::gridTrackSize(GridTrackSizingDirection direction, size
 {
     bool isForColumns = direction == ForColumns;
     const Vector<GridTrackSize>& trackStyles = isForColumns ? style()->gridTemplateColumns() : style()->gridTemplateRows();
-    const GridTrackSize& trackSize = (i >= trackStyles.size()) ? (isForColumns ? style()->gridAutoColumns() : style()->gridAutoRows()) : trackStyles[i];
+    const GridTrackSize& autoTrackSize = isForColumns ? style()->gridAutoColumns() : style()->gridAutoRows();
+    int translatedIndex = i + (isForColumns ? m_smallestColumnStart : m_smallestRowStart);
+    const GridTrackSize& trackSize = (translatedIndex < 0 || translatedIndex >= static_cast<int>(trackStyles.size())) ? autoTrackSize : trackStyles[translatedIndex];
 
     GridLength minTrackBreadth = trackSize.minTrackBreadth();
     GridLength maxTrackBreadth = trackSize.maxTrackBreadth();
@@ -1132,9 +1134,15 @@ void LayoutGrid::placeItemsOnGrid()
             continue;
 
         GridCoordinate coordinate = cachedGridCoordinate(*child);
-        if (!coordinate.rows.isDefinite() || !coordinate.columns.isDefinite()) {
+        if (!coordinate.rows.isIndefinite())
+            coordinate.rows.translate(abs(m_smallestRowStart));
+        if (!coordinate.columns.isIndefinite())
+            coordinate.columns.translate(abs(m_smallestColumnStart));
+        m_gridItemCoordinate.set(child, coordinate);
+
+        if (coordinate.rows.isIndefinite() || coordinate.columns.isIndefinite()) {
             GridSpan majorAxisPositions = (autoPlacementMajorAxisDirection() == ForColumns) ? coordinate.columns : coordinate.rows;
-            if (!majorAxisPositions.isDefinite())
+            if (majorAxisPositions.isIndefinite())

[svillar, 2015/12/18 13:08:30]

See my comments in GridPosition.h about why !isDefinite() != isIndefinite()

                 autoMajorAxisAutoGridItems.append(child);
             else
                 specifiedMajorAxisAutoGridItems.append(child);
@@ -1166,6 +1174,9 @@ void LayoutGrid::populateExplicitGridAndOrderIterator()
 {
     OrderIteratorPopulator populator(m_orderIterator);
 
+    m_smallestRowStart = 0;
+    m_smallestColumnStart = 0;

[svillar, 2015/12/18 13:08:30]

Using a single line is allowed in this case.

[Manuel Rego, 2015/12/18 22:42:30]

Acknowledged.

+
     size_t maximumRowIndex = std::max<size_t>(1, GridResolvedPosition::explicitGridRowCount(*style()));
     size_t maximumColumnIndex = std::max<size_t>(1, GridResolvedPosition::explicitGridColumnCount(*style()));
 
@@ -1184,26 +1195,28 @@ void LayoutGrid::populateExplicitGridAndOrderIterator()
         m_gridItemCoordinate.set(child, GridCoordinate(rowPositions, columnPositions));
 
         // |positions| is 0 if we need to run the auto-placement algorithm.
-        if (rowPositions.isDefinite()) {
-            maximumRowIndex = std::max<size_t>(maximumRowIndex, rowPositions.resolvedFinalPosition());
+        if (!rowPositions.isIndefinite()) {
+            m_smallestRowStart = std::min(m_smallestRowStart, rowPositions.untranslatedResolvedInitialPosition());
+            maximumRowIndex = std::max<int>(maximumRowIndex, rowPositions.untranslatedResolvedFinalPosition());
         } else {
             // Grow the grid for items with a definite row span, getting the largest such span.
             size_t spanSize = GridResolvedPosition::spanSizeForAutoPlacedItem(*style(), *child, ForRows);
-            maximumRowIndex = std::max<size_t>(maximumRowIndex, spanSize);
+            maximumRowIndex = std::max(maximumRowIndex, spanSize);
         }
 
-        if (columnPositions.isDefinite()) {
-            maximumColumnIndex = std::max<size_t>(maximumColumnIndex, columnPositions.resolvedFinalPosition());
+        if (!columnPositions.isIndefinite()) {
+            m_smallestColumnStart = std::min(m_smallestColumnStart, columnPositions.untranslatedResolvedInitialPosition());

[svillar, 2015/12/18 13:08:30]

Same comments about !isDefinite and isIndefinite

+            maximumColumnIndex = std::max<int>(maximumColumnIndex, columnPositions.untranslatedResolvedFinalPosition());
         } else {
             // Grow the grid for items with a definite column span, getting the largest such span.
             size_t spanSize = GridResolvedPosition::spanSizeForAutoPlacedItem(*style(), *child, ForColumns);
-            maximumColumnIndex = std::max<size_t>(maximumColumnIndex, spanSize);
+            maximumColumnIndex = std::max(maximumColumnIndex, spanSize);
         }
     }
 
-    m_grid.grow(maximumRowIndex);
+    m_grid.grow(maximumRowIndex + abs(m_smallestRowStart));
     for (auto& column : m_grid)
-        column.grow(maximumColumnIndex);
+        column.grow(maximumColumnIndex + abs(m_smallestColumnStart));
 }
 
 PassOwnPtr<GridCoordinate> LayoutGrid::createEmptyGridAreaAtSpecifiedPositionsOutsideGrid(const LayoutBox& gridItem, GridTrackSizingDirection specifiedDirection, const GridSpan& specifiedPositions) const
@@ -1476,11 +1489,12 @@ void LayoutGrid::offsetAndBreadthForPositionedChild(const LayoutBox& child, Grid
     ASSERT(child.isHorizontalWritingMode() == isHorizontalWritingMode());
 
     GridSpan positions = GridResolvedPosition::resolveGridPositionsFromStyle(*style(), child, direction);
-    if (!positions.isDefinite()) {
+    if (positions.isIndefinite()) {
         offset = LayoutUnit();
         breadth = (direction == ForColumns) ? clientLogicalWidth() : clientLogicalHeight();
         return;
     }
+    positions.translate(direction == ForColumns ? m_smallestColumnStart : m_smallestRowStart);

[svillar, 2015/12/18 13:08:30]

Not sure why we need this here...

[Manuel Rego, 2015/12/18 22:42:30]

Basically positioned objects are skipped in
populateExplicitGridAndOrderIterator() and placeItemsOnGrid().

We need to resolve the positions here and translate them as usual.

 
     GridPosition startPosition = (direction == ForColumns) ? child.style()->gridColumnStart() : child.style()->gridRowStart();
     GridPosition endPosition = (direction == ForColumns) ? child.style()->gridColumnEnd() : child.style()->gridRowEnd();