Invisible Operators should not add space.

https://bugs.webkit.org/show_bug.cgi?id=115786 Reviewed by Chris Fleizach. Source/WebCore: This change adds special handling for invisible operator to ensure they really behave as empty box. We now ignore their glyph widths and do not paint them. Test: mathml/presentation/mo-invisible.html * rendering/mathml/RenderMathMLOperator.cpp: (WebCore::RenderMathMLOperator::computePreferredLogicalWidths): (WebCore::RenderMathMLOperator::paint): * rendering/mathml/RenderMathMLOperator.h: LayoutTests: Add a reftest based on the examples of the MathML specification to verify that invisible operators do not add space. * mathml/presentation/mo-invisible-expected.html: Added. * mathml/presentation/mo-invisible.html: Added. Canonical link: https://commits.webkit.org/148076@main git-svn-id: https://svn.webkit.org/repository/webkit/trunk@165464 268f45cc-cd09-0410-ab3c-d52691b4dbfc
WebKit · Mar 12, 2014 · 5038cfb3b23eb6e5895fa6e8b8b3396e2ebe36ad · 5038cfb
1 parent 767ec3e
commit 5038cfb3b23eb6e5895fa6e8b8b3396e2ebe36ad
Showing 7 changed files with 154 additions and 3 deletions.
diff --git a/LayoutTests/ChangeLog b/LayoutTests/ChangeLog
@@ -1,3 +1,15 @@
+2014-03-12  Frédéric Wang  <fred.wang@free.fr>
+
+        Invisible Operators should not add space.
+        https://bugs.webkit.org/show_bug.cgi?id=115786
+
+        Reviewed by Chris Fleizach.
+
+        Add a reftest based on the examples of the MathML specification to verify that invisible operators do not add space.
+
+        * mathml/presentation/mo-invisible-expected.html: Added.
+        * mathml/presentation/mo-invisible.html: Added.
+
 2014-03-11  Frédéric Wang  <fred.wang@free.fr>
 
         Implement MathML spacing around operators .

diff --git a/LayoutTests/mathml/presentation/mo-invisible-expected.html b/LayoutTests/mathml/presentation/mo-invisible-expected.html
@@ -0,0 +1,56 @@
+<!doctype html>
+<html>
+  <head>
+    <title>invisible operators</title>
+    <meta charset="utf-8"/>
+  </head>
+  <body>
+
+   <math>
+     <mrow>
+       <mi>f</mi>
+       <mo lspace="0em" rspace="0em"></mo>
+       <mrow>
+         <mo>(</mo>
+         <mi>x</mi>
+         <mo>)</mo>
+       </mrow>
+     </mrow>
+   </math>
+   <math>
+     <mrow>
+       <mi>sin</mi>
+       <mo lspace="0em" rspace="0em"></mo>
+       <mi>x</mi>
+     </mrow>
+   </math>
+   <math>
+     <mrow>
+       <mi>x</mi>
+       <mo lspace="0em" rspace="0em"></mo>
+       <mi>y</mi>
+     </mrow>
+   </math>
+   <math>
+     <msub>
+       <mi>m</mi>
+       <mrow>
+         <mn>1</mn>
+         <mo lspace="0em" rspace="0em"></mo>
+         <mn>2</mn>
+       </mrow>
+     </msub>
+   </math>
+   <math>
+     <mrow>
+       <mn>2</mn>
+       <mo lspace="0em" rspace="0em"></mo>
+       <mfrac>
+         <mn>3</mn>
+         <mn>4</mn>
+       </mfrac>
+     </mrow>
+   </math>
+
+  </body>
+</html>
diff --git a/LayoutTests/mathml/presentation/mo-invisible.html b/LayoutTests/mathml/presentation/mo-invisible.html
@@ -0,0 +1,58 @@
+<!doctype html>
+<html>
+ <head>
+   <title>invisible operators</title>
+   <meta charset="utf-8"/>
+ </head>
+ <body>
+
+   <!-- These examples are taken from http://www.w3.org/TR/MathML/chapter3.html#presm.invisibleops.
+        The invisible operator glyphs should render as empty box and, per the operator dictionary, should not have space around them. -->
+   <math>
+     <mrow>
+       <mi>f</mi>
+       <mo>&#x2061;<!--FUNCTION APPLICATION--></mo>
+       <mrow>
+         <mo>(</mo>
+         <mi>x</mi>
+         <mo>)</mo>
+       </mrow>
+     </mrow>
+   </math>
+   <math>
+     <mrow>
+       <mi>sin</mi>
+       <mo>&#x2061;<!--FUNCTION APPLICATION--></mo>
+       <mi>x</mi>
+     </mrow>
+   </math>
+   <math>
+     <mrow>
+       <mi>x</mi>
+       <mo>&#x2062;<!--INVISIBLE TIMES--></mo>
+       <mi>y</mi>
+     </mrow>
+   </math>
+   <math>
+     <msub>
+       <mi>m</mi>
+       <mrow>
+         <mn>1</mn>
+         <mo>&#x2063;<!--INVISIBLE SEPARATOR--></mo>
+         <mn>2</mn>
+       </mrow>
+     </msub>
+   </math>
+   <math>
+     <mrow>
+       <mn>2</mn>
+       <mo>&#x2064;<!-- INVISIBLE PLUS --></mo>
+       <mfrac>
+         <mn>3</mn>
+         <mn>4</mn>
+       </mfrac>
+     </mrow>
+   </math>
+
+ </body>
+</html>
diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
@@ -1,3 +1,19 @@
+2014-03-12  Frédéric Wang  <fred.wang@free.fr>
+
+        Invisible Operators should not add space.
+        https://bugs.webkit.org/show_bug.cgi?id=115786
+
+        Reviewed by Chris Fleizach.
+
+        This change adds special handling for invisible operator to ensure they really behave as empty box. We now ignore their glyph widths and do not paint them.
+
+        Test: mathml/presentation/mo-invisible.html
+
+        * rendering/mathml/RenderMathMLOperator.cpp:
+        (WebCore::RenderMathMLOperator::computePreferredLogicalWidths):
+        (WebCore::RenderMathMLOperator::paint):
+        * rendering/mathml/RenderMathMLOperator.h:
+
 2014-03-11  Frédéric Wang  <fred.wang@free.fr>
 
         Implement MathML spacing around operators .

diff --git a/Source/WebCore/rendering/mathml/RenderMathMLOperator.cpp b/Source/WebCore/rendering/mathml/RenderMathMLOperator.cpp
@@ -1302,6 +1302,13 @@ void RenderMathMLOperator::computePreferredLogicalWidths()
     bool allowStretching = shouldAllowStretching(stretchedCharacter);
     if (!allowStretching) {
         RenderMathMLToken::computePreferredLogicalWidths();
+        if (isInvisibleOperator()) {
+            // In some fonts, glyphs for invisible operators have nonzero width. Consequently, we subtract that width here to avoid wide gaps.
+            float glyphWidth = advanceForCharacter(m_operator);
+            ASSERT(glyphWidth <= m_minPreferredLogicalWidth);
+            m_minPreferredLogicalWidth -= glyphWidth;
+            m_maxPreferredLogicalWidth -= glyphWidth;
+        }
         return;
     }
 
@@ -1529,7 +1536,8 @@ void RenderMathMLOperator::fillWithExtensionGlyph(PaintInfo& info, const LayoutP
 
 void RenderMathMLOperator::paint(PaintInfo& info, const LayoutPoint& paintOffset)
 {
-    if (info.context->paintingDisabled() || info.phase != PaintPhaseForeground || style().visibility() != VISIBLE)
+    // We skip painting for invisible operators too to avoid some "missing character" glyph to appear if appropriate math fonts are not available.
+    if (info.context->paintingDisabled() || info.phase != PaintPhaseForeground || style().visibility() != VISIBLE || isInvisibleOperator())
         return;
 
     if (!m_isStretched && !m_stretchyCharacter) {

diff --git a/Source/WebCore/rendering/mathml/RenderMathMLOperator.h b/Source/WebCore/rendering/mathml/RenderMathMLOperator.h
@@ -87,6 +87,8 @@ class RenderMathMLOperator final : public RenderMathMLToken {
     virtual void paintChildren(PaintInfo& forSelf, const LayoutPoint&, PaintInfo& forChild, bool usePrintRect) override;
     virtual bool isRenderMathMLOperator() const override { return true; }
     bool isFencedOperator() { return isAnonymous(); }
+    // The following operators are invisible: U+2061 FUNCTION APPLICATION, U+2062 INVISIBLE TIMES, U+2063 INVISIBLE SEPARATOR, U+2064 INVISIBLE PLUS.
+    bool isInvisibleOperator() const { return 0x2061 <= m_operator && m_operator <= 0x2064; }
     virtual bool isChildAllowed(const RenderObject&, const RenderStyle&) const override;
     virtual void computePreferredLogicalWidths() override;
     virtual void computeLogicalHeight(LayoutUnit logicalHeight, LayoutUnit logicalTop, LogicalExtentComputedValues&) const override;

diff --git a/Source/WebCore/rendering/mathml/RenderMathMLRow.cpp b/Source/WebCore/rendering/mathml/RenderMathMLRow.cpp
@@ -59,8 +59,7 @@ void RenderMathMLRow::updateOperatorProperties()
 {
     for (RenderObject* child = firstChild(); child; child = child->nextSibling()) {
         if (child->isRenderMathMLBlock()) {
-            auto renderOperator = toRenderMathMLBlock(child)->unembellishedOperator();
-            if (renderOperator)
+            if (auto renderOperator = toRenderMathMLBlock(child)->unembellishedOperator())
                 renderOperator->updateOperatorProperties();
         }
     }