Changeset 251848 in webkit

Timestamp:

Oct 31, 2019 8:40:10 AM (4 years ago)

Author:

Alan Bujtas

Message:

[LFC][IFC] Do not merge completely collapsed run with the previous run
​https://bugs.webkit.org/show_bug.cgi?id=203658
<rdar://problem/56769334>

Reviewed by Antti Koivisto.

When a whitespace run is completely collapsed (and visually empty), we should not try to merge it with previous text runs.
E.g. [before \nafter] -> [before][ ][\n][after] -> [before ][][after] -> [before ][after]

^content inline items ^{line runs} display runs

• layout/inlineformatting/InlineLine.cpp:

(WebCore::Layout::Line::close):

• layout/inlineformatting/InlineLine.h:

(WebCore::Layout::Line::Run::hasTrailingCollapsedContent const):
(WebCore::Layout::Line::Run::canBeExtended const): Deleted.

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• layout/inlineformatting/InlineLine.cpp (modified) (1 diff)
• layout/inlineformatting/InlineLine.h (modified) (2 diffs)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2019-10-31  Zalan Bujtas  <zalan@apple.com>
+
+        [LFC][IFC] Do not merge completely collapsed run with the previous run
+        https://bugs.webkit.org/show_bug.cgi?id=203658
+        <rdar://problem/56769334>
+
+        Reviewed by Antti Koivisto.
+
+        When a whitespace run is completely collapsed (and visually empty), we should not try to merge it with previous text runs.
+        E.g. [before  \nafter] -> [before][  ][\n][after] -> [before ][][after] -> [before ][after]
+                ^content               ^inline items             ^line runs          ^display runs
+
+        * layout/inlineformatting/InlineLine.cpp:
+        (WebCore::Layout::Line::close):
+        * layout/inlineformatting/InlineLine.h:
+        (WebCore::Layout::Line::Run::hasTrailingCollapsedContent const):
+        (WebCore::Layout::Line::Run::canBeExtended const): Deleted.
+
 2019-10-31  Zalan Bujtas  <zalan@apple.com>
 

trunk/Source/WebCore/layout/inlineformatting/InlineLine.cpp

@@ -116 +116 @@
     unsigned index = 1;
     while (index < m_runList.size()) {
+        auto canMergeRuns = [](const auto& previousRun, const auto& currentRun) {
+            // Do not merge runs across inline boxes (<span>foo</span><span>bar</span>)
+            if (&previousRun->layoutBox() !=  &currentRun->layoutBox())
+                return false;
+            // Only text content can be merged.
+            if (!previousRun->isText() || !currentRun->isText())
+                return false;
+            // Merged content needs to be continuous.
+            if (previousRun->hasTrailingCollapsedContent())
+                return false;
+            // Visually empty runs are ignored.
+            if (currentRun->isCollapsedToZeroAdvanceWidth())
+                return false;
+            return true;
+        };
         auto& previousRun = m_runList[index - 1];
-        if (!previousRun->canBeExtended()) {
-            ++index;
+        auto& currentRun = m_runList[index];
+        if (canMergeRuns(previousRun, currentRun)) {
+            previousRun->expand(*currentRun);
+            m_runList.remove(index);
             continue;
         }
-        auto& currentRun = m_runList[index];
-        // Do not merge runs from different boxes (<span>foo</span><span>bar</span>)
-        // or within the same layout box but with preserved \n
-        // (<span>text\n<span <- both the "text" and "\" belong to the same layout box)
-        auto canAppendToPreviousRun = currentRun->isText() && &currentRun->layoutBox() ==  &previousRun->layoutBox();
-        if (!canAppendToPreviousRun) {
-            ++index;
-            continue;
-        }
-        // Only text content can be extended atm.
-        ASSERT(previousRun->isText());
-        ASSERT(currentRun->isText());
-        previousRun->expand(*currentRun);
-        m_runList.remove(index);
+        ++index;
     }
 

trunk/Source/WebCore/layout/inlineformatting/InlineLine.h

@@ -95 +95 @@
 
         bool isCollapsible() const { return m_inlineItem.isText() && downcast<InlineTextItem>(m_inlineItem).isCollapsible(); }
+        bool hasTrailingCollapsedContent() const { return m_hasTrailingCollapsedContent; }
         bool isWhitespace() const;
-        bool canBeExtended() const;
 
         const InlineItem& m_inlineItem;
@@ -178 +178 @@
 }
 
-inline bool Line::Run::canBeExtended() const
-{
-    return isText() && !m_hasTrailingCollapsedContent;
-}
-
 inline bool Line::Run::isCollapsedToZeroAdvanceWidth() const
 {