Include column rules for LayoutMultiColumnSet paint invalidation rects.

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

Index: third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.cpp b/third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.cpp
index c2ffb57d6b0f1d4e116b43903d8f17fd1b3ab2ff..dfdde1ccae781ff8e5d9551a99ff35e0506189d4 100644
--- a/third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.cpp
@@ -476,4 +476,66 @@ LayoutRect LayoutMultiColumnSet::flowThreadPortionRect() const
     return portionRect;
 }
 
+bool LayoutMultiColumnSet::computeColumnRuleBounds(const LayoutPoint& paintOffset, Vector<LayoutRect>& columnRuleBounds) const
+{
+    if (flowThread()->isLayoutPagedFlowThread())
+        return false;
+
+    const ComputedStyle& blockStyle = multiColumnBlockFlow()->styleRef();

[wkorman, 2016/07/01 19:32:24]

Maybe helpful to naive eng to link to spec in a comment here or in header:

https://www.w3.org/TR/css3-multicol/#column-gaps-and-rules

[chrishtr, 2016/07/01 22:31:32]

Done.

+    bool ruleTransparent = blockStyle.columnRuleIsTransparent();
+    EBorderStyle ruleStyle = blockStyle.columnRuleStyle();
+    LayoutUnit ruleThickness(blockStyle.columnRuleWidth());
+    LayoutUnit colGap = columnGap();
+    bool renderRule = ruleStyle > BorderStyleHidden && !ruleTransparent;
+    if (!renderRule)
+        return false;
+
+    unsigned colCount = actualColumnCount();
+    if (colCount <= 1)
+        return false;
+
+    bool leftToRight = style()->isLeftToRightDirection();
+    LayoutUnit currLogicalLeftOffset = leftToRight ? LayoutUnit() : contentLogicalWidth();
+    LayoutUnit ruleAdd = borderAndPaddingLogicalLeft();
+    LayoutUnit ruleLogicalLeft = leftToRight ? LayoutUnit() : contentLogicalWidth();
+    LayoutUnit inlineDirectionSize = pageLogicalWidth();
+
+    for (unsigned i = 0; i < colCount; i++) {
+        // Move to the next position.
+        if (leftToRight) {
+            ruleLogicalLeft += inlineDirectionSize + colGap / 2;
+            currLogicalLeftOffset += inlineDirectionSize + colGap;
+        } else {
+            ruleLogicalLeft -= (inlineDirectionSize + colGap / 2);
+            currLogicalLeftOffset -= (inlineDirectionSize + colGap);
+        }
+
+        // Now paint the column rule.

[wkorman, 2016/07/01 19:32:24]

Update comment, just accumulating bounds vs painting.

[chrishtr, 2016/07/01 22:31:32]

Done.

+        if (i < colCount - 1) {
+            LayoutUnit ruleLeft = isHorizontalWritingMode() ? paintOffset.x() + ruleLogicalLeft - ruleThickness / 2 + ruleAdd : paintOffset.x() + borderLeft() + paddingLeft();

[wkorman, 2016/07/01 19:32:24]

nit: hard to read, maybe split into if/else block or helper method that takes
three refs. Fine as is too.

[chrishtr, 2016/07/01 22:31:32]

Good idea, done.

+            LayoutUnit ruleRight = isHorizontalWritingMode() ? ruleLeft + ruleThickness : ruleLeft + contentWidth();
+            LayoutUnit ruleTop = isHorizontalWritingMode() ? paintOffset.y() + borderTop() + paddingTop() : paintOffset.y() + ruleLogicalLeft - ruleThickness / 2 + ruleAdd;
+            LayoutUnit ruleBottom = isHorizontalWritingMode() ? ruleTop + contentHeight() : ruleTop + ruleThickness;
+
+            columnRuleBounds.append(LayoutRect(ruleLeft, ruleTop, ruleRight - ruleLeft, ruleBottom - ruleTop));
+        }
+
+        ruleLogicalLeft = currLogicalLeftOffset;
+    }
+    return true;
+}
+
+LayoutRect LayoutMultiColumnSet::localOverflowRectForPaintInvalidation() const
+{
+    LayoutRect blockFlowBounds = LayoutBlockFlow::localOverflowRectForPaintInvalidation();
+
+    // Now add in column rule bounds, if present.
+    Vector<LayoutRect> columnRuleBounds;
+    if (computeColumnRuleBounds(LayoutPoint(), columnRuleBounds)) {
+        for (auto& bound : columnRuleBounds)
+            blockFlowBounds.unite(bound);
+    }
+    return blockFlowBounds;
+}
+
 } // namespace blink