Changeset 284677 in webkit

Timestamp:

Oct 22, 2021, 6:24:11 AM (5 years ago)

Author:

Alan Bujtas

Message:

FontCascade::widthForSimpleText fails to produce matching measured width for monospace font
​https://bugs.webkit.org/show_bug.cgi?id=232104
<rdar://83991027>

Reviewed by Antti Koivisto.

Source/WebCore:

Adjust widthForSimpleText to match WidthIterator's logic as the comment says:

"This is needed only to match the result of the slow path

Same glyph widths but different floating point arithmetic can produce different run width."

(see r213008)

• platform/graphics/FontCascade.cpp:

(WebCore::FontCascade::widthForSimpleText const):

LayoutTests:

• platform/ios-wk2/TestExpectations:

Location:

trunk

Files:

• LayoutTests/ChangeLog (modified) (1 diff)
• LayoutTests/platform/ios-wk2/TestExpectations (modified) (1 diff)
• Source/WebCore/ChangeLog (modified) (1 diff)
• Source/WebCore/platform/graphics/FontCascade.cpp (modified) (2 diffs)

trunk/LayoutTests/ChangeLog

@@ +1 @@
+2021-10-22  Alan Bujtas  <zalan@apple.com>
+
+        FontCascade::widthForSimpleText fails to produce matching measured width for monospace font
+        https://bugs.webkit.org/show_bug.cgi?id=232104
+        <rdar://83991027>
+
+        Reviewed by Antti Koivisto.
+
+        * platform/ios-wk2/TestExpectations:
+
 2021-10-21  Cathie Chen  <cathiechen@igalia.com>
 

trunk/LayoutTests/platform/ios-wk2/TestExpectations

@@ -1205 +1205 @@
 
 webkit.org/b/163362 platform/ios/ios/plugin/youtube-flash-plugin-iframe.html [ Pass Failure ]
-
-webkit.org/b/231378 platform/ios/fast/text/system-monospaced-numbers.html [ Failure ]
 
 webkit.org/b/164960 http/tests/security/module-correct-mime-types.html [ Slow ]

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2021-10-22  Alan Bujtas  <zalan@apple.com>
+
+        FontCascade::widthForSimpleText fails to produce matching measured width for monospace font
+        https://bugs.webkit.org/show_bug.cgi?id=232104
+        <rdar://83991027>
+
+        Reviewed by Antti Koivisto.
+
+        Adjust widthForSimpleText to match WidthIterator's logic as the comment says:
+
+          "This is needed only to match the result of the slow path
+           Same glyph widths but different floating point arithmetic can produce different run width."
+        (see r213008)
+
+        * platform/graphics/FontCascade.cpp:
+        (WebCore::FontCascade::widthForSimpleText const):
+
 2021-10-22  Carlos Garcia Campos  <cgarcia@igalia.com>
 

trunk/Source/WebCore/platform/graphics/FontCascade.cpp

@@ -312 +312 @@
 
     GlyphBuffer glyphBuffer;
-    float runWidth = 0;
+    float beforeWidth = 0;
     auto& font = primaryFont();
     for (unsigned i = 0; i < text.length(); ++i) {
         auto glyph = glyphDataForCharacter(text[i], false).glyph;
         auto glyphWidth = font.widthForGlyph(glyph);
-        runWidth += glyphWidth;
+        beforeWidth += glyphWidth;
         glyphBuffer.add(glyph, font, glyphWidth, i);
     }
@@ -324 +324 @@
     // This is needed only to match the result of the slow path.
     // Same glyph widths but different floating point arithmetic can produce different run width.
-    float runWidthDifferenceWithTransformApplied = -runWidth;
+    float afterWidth = 0;
     for (size_t i = 0; i < glyphBuffer.size(); ++i)
-        runWidthDifferenceWithTransformApplied += WebCore::width(glyphBuffer.advanceAt(i));
-    runWidth += runWidthDifferenceWithTransformApplied;
-
-    runWidth += WebCore::width(initialAdvance);
+        afterWidth += WebCore::width(glyphBuffer.advanceAt(i));
+    auto additionalAdvance = afterWidth - beforeWidth;
+
+    auto finalWidth = beforeWidth + additionalAdvance;
+    finalWidth += WebCore::width(initialAdvance);
 
     if (cacheEntry)
-        *cacheEntry = runWidth;
-    return runWidth;
+        *cacheEntry = finalWidth;
+    return finalWidth;
 }