Changeset 154753 in webkit for trunk/Source/WebCore/rendering/RenderGrid.cpp

Timestamp:

Aug 28, 2013, 9:48:53 AM (12 years ago)

Author:

[email protected]

Message:

[CSS Grid Layout] Handle 'span' positions during layout
​https://bugs.webkit.org/show_bug.cgi?id=119756

Reviewed by Andreas Kling.

From Blink r149133 by <​[email protected]>

Source/WebCore:

Properly handle the 'span' keyword during layout. We only had
parsing support so far but with this change we are able to
recognize these positions and act accordingly.

• rendering/RenderGrid.cpp:

(WebCore::RenderGrid::resolveGridPositionsFromStyle):
(WebCore::RenderGrid::resolveGridPositionAgainstOppositePosition):

• rendering/RenderGrid.h:
• rendering/style/GridPosition.h:

(WebCore::GridPosition::shouldBeResolvedAgainstOppositePosition):

LayoutTests:

Added some new test cases to verify that we properly resolve
'span' positions.

• fast/css-grid-layout/grid-item-negative-position-resolution-expected.txt:
• fast/css-grid-layout/grid-item-negative-position-resolution.html:
• fast/css-grid-layout/grid-item-spanning-resolution-expected.txt:
• fast/css-grid-layout/grid-item-spanning-resolution.html:

File:

• trunk/Source/WebCore/rendering/RenderGrid.cpp (modified) (3 diffs)

trunk/Source/WebCore/rendering/RenderGrid.cpp

@@ -721 +721 @@
     const GridPositionSide finalPositionSide = (direction == ForColumns) ? ColumnEndSide : RowEndSide;
 
+    // We should NEVER see both spans as they should have been handled during style resolve.
+    ASSERT(!initialPosition.isSpan() || !finalPosition.isSpan());
+
     if (initialPosition.isAuto() && finalPosition.isAuto()) {
         if (style()->gridAutoFlow() == AutoFlowNone)
@@ -729 +732 @@
     }
 
-    if (initialPosition.isAuto()) {
-        // Infer the position from the final position ('auto / 1' case).
+    if (initialPosition.shouldBeResolvedAgainstOppositePosition()) {
+        // Infer the position from the final position ('auto / 1' or 'span 2 / 3' case).
         const size_t finalResolvedPosition = resolveGridPositionFromStyle(finalPosition, finalPositionSide);
-        return adoptPtr(new GridSpan(finalResolvedPosition, finalResolvedPosition));
-    }
-
-    if (finalPosition.isAuto()) {
-        // Infer our position from the initial position ('1 / auto' case).
+        return resolveGridPositionAgainstOppositePosition(finalResolvedPosition, initialPosition, initialPositionSide);
+    }
+
+    if (finalPosition.shouldBeResolvedAgainstOppositePosition()) {
+        // Infer our position from the initial position ('1 / auto' or '3 / span 2' case).
         const size_t initialResolvedPosition = resolveGridPositionFromStyle(initialPosition, initialPositionSide);
-        return adoptPtr(new GridSpan(initialResolvedPosition, initialResolvedPosition));
+        return resolveGridPositionAgainstOppositePosition(initialResolvedPosition, finalPosition, finalPositionSide);
     }
 
@@ -789 +792 @@
     ASSERT_NOT_REACHED();
     return 0;
+}
+
+PassOwnPtr<RenderGrid::GridSpan> RenderGrid::resolveGridPositionAgainstOppositePosition(size_t resolvedOppositePosition, const GridPosition& position, GridPositionSide side) const
+{
+    if (position.isAuto())
+        return GridSpan::create(resolvedOppositePosition, resolvedOppositePosition);
+
+    ASSERT(position.isSpan());
+    ASSERT(position.spanPosition() > 0);
+
+    // 'span 1' is contained inside a single grid track regardless of the direction.
+    // That's why the CSS span value is one more than the offset we apply.
+    size_t positionOffset = position.spanPosition() - 1;
+    if (side == ColumnStartSide || side == RowStartSide) {
+        size_t initialResolvedPosition = std::max<int>(0, resolvedOppositePosition - positionOffset);
+        return GridSpan::create(initialResolvedPosition, resolvedOppositePosition);
+    }
+
+    return GridSpan::create(resolvedOppositePosition, resolvedOppositePosition + positionOffset);
 }