[css-grid] Positioned items can be placed on the implicit grid

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 1692 matching lines @@
         return;
     }
 
     // For positioned items we cannot use GridSpan::translate(). Because we could end up with negative values, as the positioned items do not create implicit tracks per spec.
     int smallestStart = abs(isForColumns ? m_smallestColumnStart : m_smallestRowStart);
     int startLine = positions.untranslatedStartLine() + smallestStart;
     int endLine = positions.untranslatedEndLine() + smallestStart;
 
     GridPosition startPosition = isForColumns ? child.style()->gridColumnStart() : child.style()->gridRowStart();
     GridPosition endPosition = isForColumns ? child.style()->gridColumnEnd() : child.style()->gridRowEnd();
-    int firstExplicitLine = smallestStart;
-    size_t autoRepeatCount = autoRepeatCountForDirection(direction);
-    int lastExplicitLine = (isForColumns ? GridPositionsResolver::explicitGridColumnCount(styleRef(), autoRepeatCount) : GridPositionsResolver::explicitGridRowCount(styleRef(), autoRepeatCount)) + smallestStart;
+    int lastLine = isForColumns ? gridColumnCount() : gridRowCount();
 
     bool startIsAuto = startPosition.isAuto()
         || (startPosition.isNamedGridArea() && !NamedLineCollection::isValidNamedLineOrArea(startPosition.namedGridLine(), styleRef(), GridPositionsResolver::initialPositionSide(direction)))
-        || (startLine < firstExplicitLine)
-        || (startLine > lastExplicitLine);
+        || (startLine < 0)
+        || (startLine > lastLine);
     bool endIsAuto = endPosition.isAuto()
         || (endPosition.isNamedGridArea() && !NamedLineCollection::isValidNamedLineOrArea(endPosition.namedGridLine(), styleRef(), GridPositionsResolver::finalPositionSide(direction)))
-        || (endLine < firstExplicitLine)
-        || (endLine > lastExplicitLine);
+        || (endLine < 0)
+        || (endLine > lastLine);
 
     LayoutUnit start;
     if (!startIsAuto) {
         if (isForColumns) {
             if (styleRef().isLeftToRightDirection())
                 start = m_columnPositions[startLine] - borderLogicalLeft();
             else
                 start = logicalWidth() - translateRTLCoordinate(m_columnPositions[startLine]) - borderLogicalRight();
         } else {
             start = m_rowPositions[startLine] - borderBefore();
         }
     }
 
     LayoutUnit end = isForColumns ? clientLogicalWidth() : clientLogicalHeight();
     if (!endIsAuto) {
         if (isForColumns) {
             if (styleRef().isLeftToRightDirection())
                 end = m_columnPositions[endLine] - borderLogicalLeft();
             else
                 end = logicalWidth() - translateRTLCoordinate(m_columnPositions[endLine]) - borderLogicalRight();
         } else {
             end = m_rowPositions[endLine] - borderBefore();
         }
 
         // These vectors store line positions including gaps, but we shouldn't consider them for the edges of the grid.
-        if (endLine > firstExplicitLine && endLine < lastExplicitLine) {
+        if (endLine > 0 && endLine < lastLine) {
             end -= guttersSize(direction, 2);
             end -= isForColumns ? m_offsetBetweenColumns : m_offsetBetweenRows;
         }
     }
 
     breadth = end - start;
     offset = start;
 
     if (isForColumns && !styleRef().isLeftToRightDirection() && !child.styleRef().hasStaticInlinePosition(child.isHorizontalWritingMode())) {
         // If the child doesn't have a static inline position (i.e. "left" and/or "right" aren't "auto",
         // we need to calculate the offset from the left (even if we're in RTL).
         if (endIsAuto) {
             offset = LayoutUnit();
         } else {
             offset = translateRTLCoordinate(m_columnPositions[endLine]) - borderLogicalLeft();
 
-            if (endLine > firstExplicitLine && endLine < lastExplicitLine) {
+            if (endLine > 0 && endLine < lastLine) {
                 offset += guttersSize(direction, 2);
                 offset += isForColumns ? m_offsetBetweenColumns : m_offsetBetweenRows;
             }
         }
     }
 
 }
 
 GridArea LayoutGrid::cachedGridArea(const LayoutBox& gridItem) const
 {
@@ skipping 479 matching lines @@
     return LayoutPoint(rowAxisOffset, columnAxisOffsetForChild(child, sizingData));
 }
 
 void LayoutGrid::paintChildren(const PaintInfo& paintInfo, const LayoutPoint& paintOffset) const
 {
     if (!m_gridItemArea.isEmpty())
         GridPainter(*this).paintChildren(paintInfo, paintOffset);
 }
 
 } // namespace blink