Changeset 285826 in webkit

Timestamp:

Nov 15, 2021, 12:47:49 PM (5 years ago)

Author:

Alan Bujtas

Message:

[LFC][IFC] Fix fast/text/letter-spacing-negative-opacity.html
​https://bugs.webkit.org/show_bug.cgi?id=233132

Reviewed by Antti Koivisto.

Special case the negative letter spacing content when computing the content logical width.

• layout/formattingContexts/inline/InlineLine.cpp:

(WebCore::Layout::Line::appendTextContent):

1. Negative letter space value could produce negative content width
2. Subsequent text content (e.g. "this text has whitepspace content") may go from positive to negative content width as parts of the content may produce positive width even with negative letter spacing.

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• layout/formattingContexts/inline/InlineLine.cpp (modified) (1 diff)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2021-11-15  Alan Bujtas  <zalan@apple.com>
+
+        [LFC][IFC] Fix fast/text/letter-spacing-negative-opacity.html
+        https://bugs.webkit.org/show_bug.cgi?id=233132
+
+        Reviewed by Antti Koivisto.
+
+        Special case the negative letter spacing content when computing the content logical width.
+
+        * layout/formattingContexts/inline/InlineLine.cpp:
+        (WebCore::Layout::Line::appendTextContent):
+        1. Negative letter space value could produce negative content width
+        2. Subsequent text content (e.g. "this text has whitepspace content") may go from positive to negative content width as parts of the content may produce positive width even with negative letter spacing.
+
 2021-11-15  Chris Dumez  <cdumez@apple.com>
 

trunk/Source/WebCore/layout/formattingContexts/inline/InlineLine.cpp

@@ -343 +343 @@
         auto contentLogicalRight = runLogicalLeft + logicalWidth + m_clonedEndDecorationWidthForInlineBoxRuns;
         m_contentLogicalWidth = std::max(oldContentLogicalWidth, contentLogicalRight);
+    } else if (style.letterSpacing() >= 0) {
+        m_runs.last().expand(inlineTextItem, logicalWidth);
+        m_contentLogicalWidth += logicalWidth;
     } else {
-        m_runs.last().expand(inlineTextItem, logicalWidth);
-        // Do not let negative letter spacing make the content shorter than it already is.
-        m_contentLogicalWidth += std::max(0.0f, logicalWidth);
+        auto& lastRun = m_runs.last();
+        ASSERT(lastRun.isText());
+        // Negative letter spacing should only shorten the content to the boundary of the previous run.
+        // FIXME: We may need to traverse all the way to the previous non-text run (or even across inline boxes).
+        auto lastRunLogicalWidth = lastRun.logicalWidth();
+        auto contentWidthWithoutLastTextRun = m_contentLogicalWidth - std::max(0.f, lastRunLogicalWidth);
+        lastRun.expand(inlineTextItem, logicalWidth);
+        m_contentLogicalWidth = std::max(contentWidthWithoutLastTextRun, lastRunLogicalWidth + logicalWidth);
     }