Invalidate first line display item clients when first line style changes

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

Index: third_party/WebKit/Source/core/layout/LayoutObject.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutObject.cpp b/third_party/WebKit/Source/core/layout/LayoutObject.cpp
index 21e6e9cd7f463c54dd4d7ea778c4bf3770bf49ad..6eff4c82fd77ef5a0083738c0bd244bc39a5877c 100644
--- a/third_party/WebKit/Source/core/layout/LayoutObject.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutObject.cpp
@@ -725,11 +725,6 @@ bool LayoutObject::skipInvalidationWhenLaidOutChildren() const
     return !hasBoxEffect();
 }
 
-LayoutBlock* LayoutObject::firstLineBlock() const
-{
-    return nullptr;
-}
-
 static inline bool objectIsRelayoutBoundary(const LayoutObject* object)
 {
     // FIXME: In future it may be possible to broaden these conditions in order to improve performance.
@@ -1837,12 +1832,25 @@ void LayoutObject::setPseudoStyle(PassRefPtr<ComputedStyle> pseudoStyle)
 void LayoutObject::firstLineStyleDidChange(const ComputedStyle& oldStyle, const ComputedStyle& newStyle)
 {
     StyleDifference diff = oldStyle.visualInvalidationDiff(newStyle);
-    if (diff.hasDifference()) {
-        // TODO(rune@opera.com): We should use the diff to determine whether a repaint vs. layout
-        // is needed, but for now just assume a layout will be required. The diff code
-        // in LayoutObject::setStyle would need to be factored out so that it could be reused.
-        setNeedsLayoutAndPrefWidthsRecalcAndFullPaintInvalidation(LayoutInvalidationReason::StyleChange);
+
+    if (diff.needsPaintInvalidation() || diff.textDecorationOrColorChanged()) {
+        LayoutBlockFlow* firstLineContainer = nullptr;
+        if (canHaveFirstLineOrFirstLetterStyle()) {

[chrishtr, 2015/12/03 18:41:56]

It seems it would be cleaner to make firstLineStyleDidChange() virtual and
implement this stuff in LayoutBlockFlow, LayoutButton and LayoutInline.

[Xianzhu, 2015/12/03 19:10:40]

That would need to duplicate more than half of this method into three copies.
How about making 'LayoutBlockFlow* firstLineContainerBlock()' virtual, so that
line 1838-1846 can be one line:
   if (LayoutBlockFlow* firstLineContainerBlock =
this->firstLineContainerBlock())
?

[Xianzhu, 2015/12/03 19:45:13]

I think it might be be better to separate FIRST_LINE (for LayoutBlock) and
FIRST_LINE_INHERITED (for LayoutInline) for firstLineStyleDidChange() from
Element::pseudoStyleCacheIsValid(). Trying this.

[mstensho (USE GERRIT), 2015/12/03 19:58:02]

FWIW, I think what we already have here is good.

+            firstLineContainer = toLayoutBlock(this)->nearestInnerBlockWithFirstLine();
+        } else if (isLayoutInline()) {
+            if (InlineBox* firstLineBox = toLayoutInline(this)->firstLineBoxIncludingCulling()) {
+                if (firstLineBox->isFirstLineStyle())
+                    firstLineContainer = toLayoutBlockFlow(containingBlock());
+            }
+        }
+        if (firstLineContainer) {
+            firstLineContainer->invalidateDisplayItemClientsOfFirstLine();
+            if (!RuntimeEnabledFeatures::slimmingPaintV2Enabled())
+                firstLineContainer->setShouldDoFullPaintInvalidation();
+        }
     }
+    if (diff.needsLayout())
+        setNeedsLayoutAndPrefWidthsRecalc(LayoutInvalidationReason::StyleChange);
 }
 
 void LayoutObject::markContainingBlocksForOverflowRecalc()
@@ -2802,8 +2810,8 @@ static PassRefPtr<ComputedStyle> firstLineStyleForCachedUncachedType(StyleCacheS
     if (layoutObject->isBeforeOrAfterContent())
         layoutObjectForFirstLineStyle = layoutObject->parent();
 
-    if (layoutObjectForFirstLineStyle->isLayoutBlockFlow() || layoutObjectForFirstLineStyle->isLayoutButton()) {
-        if (LayoutBlock* firstLineBlock = layoutObjectForFirstLineStyle->firstLineBlock()) {
+    if (layoutObjectForFirstLineStyle->canHaveFirstLineOrFirstLetterStyle()) {
+        if (LayoutBlock* firstLineBlock = toLayoutBlock(layoutObjectForFirstLineStyle)->enclosingFirstLineStyleBlock()) {
             if (type == Cached)
                 return firstLineBlock->getCachedPseudoStyle(FIRST_LINE, style);
             return firstLineBlock->getUncachedPseudoStyle(PseudoStyleRequest(FIRST_LINE), style, firstLineBlock == layoutObject ? style : 0);