[NOT PART OF THE DEFAULT BUILD] Compute the actual bounding metrics of the minus sign ('-') to get a more acurate math axis

layout/mathml/base/src/nsMathMLContainerFrame.cpp

@@ -158,22 +158,20 @@ nsMathMLContainerFrame::GetRuleThickness(nsIRenderingContext& aRenderingContext,
 {
   // get the bounding metrics of the overbar char, the rendering context
   // is assumed to have been set with the font of the current style context
-  nsBoundingMetrics bm;
+  nscoord xHeight;
+  aFontMetrics->GetXHeight(xHeight);
   PRUnichar overBar = 0x00AF;
+  nsBoundingMetrics bm;
   nsresult rv = aRenderingContext.GetBoundingMetrics(&overBar, PRUint32(1), bm);
   if (NS_SUCCEEDED(rv)) {
     aRuleThickness = bm.ascent + bm.descent;
   }
-  else {
-    printf("GetBoundingMetrics() failed in GetRuleThickness()\n");
+  if (NS_FAILED(rv) || aRuleThickness <= 0 || aRuleThickness >= xHeight) {
     // fall-back to the other version
     GetRuleThickness(aFontMetrics, aRuleThickness);
   }
  
 #if 0
-  nscoord xHeight;
-  aRuleThickness->GetXHeight(xHeight);
-
   nscoord oldRuleThickness;
   GetRuleThickness(aFontMetrics, oldRuleThickness);
 
@@ -186,6 +184,39 @@ nsMathMLContainerFrame::GetRuleThickness(nsIRenderingContext& aRenderingContext,
 #endif
 }
 
+void
+nsMathMLContainerFrame::GetAxisHeight(nsIRenderingContext& aRenderingContext, 
+                                     nsIFontMetrics*       aFontMetrics,
+                                     nscoord&              aAxisHeight)
+{
+  // get the bounding metrics of the minus sign, the rendering context
+  // is assumed to have been set with the font of the current style context
+  nscoord xHeight;
+  aFontMetrics->GetXHeight(xHeight);
+  PRUnichar minus = '-';
+  nsBoundingMetrics bm;
+  nsresult rv = aRenderingContext.GetBoundingMetrics(&minus, PRUint32(1), bm);
+  if (NS_SUCCEEDED(rv)) {
+    aAxisHeight = bm.ascent - (bm.ascent + bm.descent)/2;
+  }
+  if (NS_FAILED(rv) || aAxisHeight <= 0 || aAxisHeight >= xHeight) {
+    // fall-back to the other version
+    GetAxisHeight(aFontMetrics, aAxisHeight);
+  }
+ 
+#if 0
+  nscoord oldAxis;
+  GetAxisHeight(aFontMetrics, oldAxis);
+
+  PRUnichar plus = '+';
+  rv = aRenderingContext.GetBoundingMetrics(&plus, PRUint32(1), bm);
+  nscoord plusAxis = bm.ascent - (bm.ascent + bm.descent)/2;;
+  
+  printf("xheight:%4d Axis:%4d oldAxis:%4d  plusAxis:%4d\n",
+          xHeight, aAxisHeight, oldAxis, plusAxis);
+#endif
+}
+
 // ================
 // Utilities for parsing and retrieving numeric values
 // All returned values are in twips.

layout/mathml/base/src/nsMathMLContainerFrame.h

@@ -441,14 +441,19 @@ public:
       ruleThickness = NSToCoordRound (40.000f/430.556f * xHeight);
     }
 
-  // the rule thickness is not accurately obtained using the x-height.
-  // Here is a slow GetRuleThickness() which obtains the rule
-  // thickness by actually measuring the overbar char U+00AF
+  // Some parameters are not accurately obtained using the x-height.
+  // Here are some slower variants to obtain the desired metrics
+  // by actually measuring some characters
   static void
   GetRuleThickness(nsIRenderingContext& aRenderingContext, 
                    nsIFontMetrics*      aFontMetrics,
                    nscoord&             aRuleThickness);
 
+  static void
+  GetAxisHeight(nsIRenderingContext& aRenderingContext, 
+                nsIFontMetrics*      aFontMetrics,
+                nscoord&             aAxisHeight);
+
 protected:
 
   // information about the presentation policy of the frame

layout/mathml/base/src/nsMathMLmfencedFrame.cpp

@@ -330,9 +330,10 @@ nsMathMLmfencedFrame::Reflow(nsIPresContext*          aPresContext,
   nsStyleFont font;
   mStyleContext->GetStyle(eStyleStruct_Font, font);
   nsCOMPtr<nsIFontMetrics> fm;
-  aPresContext->GetMetricsFor(font.mFont, getter_AddRefs(fm));
+  aReflowState.rendContext->SetFont(font.mFont);
+  aReflowState.rendContext->GetFontMetrics(*getter_AddRefs(fm));
   nscoord axisHeight, em;
-  GetAxisHeight(fm, axisHeight);
+  GetAxisHeight(*aReflowState.rendContext, fm, axisHeight);
   em = NSToCoordRound(float(font.mFont.size));
  
   nscoord fontAscent, fontDescent;

layout/mathml/base/src/nsMathMLmfracFrame.cpp

@@ -355,7 +355,8 @@ nsMathMLmfracFrame::Place(nsIPresContext*      aPresContext,
   }
   else {
     // Rule 15d, App. G, TeXbook
-    GetAxisHeight (fm, axisHeight);
+//    GetAxisHeight (fm, axisHeight);
+    GetAxisHeight(aRenderingContext, fm, axisHeight);
 
     // min clearance between numerator or denominator and middle of bar
 

layout/mathml/base/src/nsMathMLmoFrame.cpp

@@ -131,9 +131,6 @@ nsMathMLmoFrame::Paint(nsIPresContext*      aPresContext,
       aRenderingContext.SetColor(NS_RGB(0,255,255));
       nscoord x = mReference.x + mBoundingMetrics.leftBearing;
       nscoord y = mReference.y - mBoundingMetrics.ascent;
-//nsRect rect;
-//mMathMLChar.GetRect(rect);
-//y = rect.y;
       nscoord w = mBoundingMetrics.rightBearing - mBoundingMetrics.leftBearing;
       nscoord h = mBoundingMetrics.ascent + mBoundingMetrics.descent;
       aRenderingContext.DrawRect(x,y,w,h);
@@ -558,9 +555,10 @@ nsMathMLmoFrame::Stretch(nsIPresContext*      aPresContext,
   nsStyleFont font;
   mStyleContext->GetStyle(eStyleStruct_Font, font);
   nsCOMPtr<nsIFontMetrics> fm;
-  aPresContext->GetMetricsFor(font.mFont, getter_AddRefs(fm));
+  aRenderingContext.SetFont(font.mFont);
+  aRenderingContext.GetFontMetrics(*getter_AddRefs(fm));
   nscoord fontAscent, fontDescent, axisHeight;
-  GetAxisHeight(fm, axisHeight);
+  GetAxisHeight(aRenderingContext, fm, axisHeight);
   fm->GetMaxAscent(fontAscent);
   fm->GetMaxDescent(fontDescent);
 

layout/mathml/base/src/nsMathMLmrootFrame.cpp

@@ -45,11 +45,14 @@
 // <msqrt> and <mroot> -- form a radical - implementation
 //
 
-//TODO:
-//  The code assumes that TeX fonts are picked! Another separate version of
-//  Reflow() is needed as a fall-back for cases where TeX fonts (CMSY/CMEX)
-//  are not installed on the system, e.g., the fall-back could explicitly
-//  draw the branches of the radical using th default rule thickness.
+//NOTE:
+//  The code assumes that TeX fonts are picked.
+//  There is not fall-back to draw the branches of the sqrt explicitly
+//  in the case where TeX fonts are not there. In general, there is not
+//  fall-back(s) in MathML when some (freely-downloadable) fonts are missing.
+//  Otherwise, this will add much work and unnecessary complexity to the core
+//  MathML  engine. Assuming that authors have the free fonts is part of the
+//  deal. We are not responsible for cases of misconfigurations out there.
 
 // additional style context to be used by our MathMLChar.
 #define NS_SQR_CHAR_STYLE_CONTEXT_INDEX   0
@@ -109,20 +112,26 @@ nsMathMLmrootFrame::Paint(nsIPresContext*      aPresContext,
 {
   nsresult rv = NS_OK;
 
-  
+  /////////////
+  // paint the content we are square-rooting
+  rv = nsMathMLContainerFrame::Paint(aPresContext, aRenderingContext, 
+                                     aDirtyRect, aWhichLayer);
   /////////////
   // paint the sqrt symbol
-  if ((NS_FRAME_PAINT_LAYER_FOREGROUND == aWhichLayer) &&
-      !NS_MATHML_HAS_ERROR(mPresentationData.flags))
+  if (!NS_MATHML_HAS_ERROR(mPresentationData.flags))
   {
     mSqrChar.Paint(aPresContext, aRenderingContext,
                    aDirtyRect, aWhichLayer, this);
-    // paint the overline bar
-    nsStyleColor color;
-    mStyleContext->GetStyle(eStyleStruct_Color, color);
-    aRenderingContext.SetColor(color.mColor);
-    aRenderingContext.FillRect(mBarRect.x, mBarRect.y, 
-                               mBarRect.width, mBarRect.height);
+
+    if (NS_FRAME_PAINT_LAYER_FOREGROUND == aWhichLayer)
+    {
+      // paint the overline bar
+      nsStyleColor color;
+      mStyleContext->GetStyle(eStyleStruct_Color, color);
+      aRenderingContext.SetColor(color.mColor);
+      aRenderingContext.FillRect(mBarRect.x, mBarRect.y, 
+                                 mBarRect.width, mBarRect.height);
+    }
 
 #if defined(NS_DEBUG) && defined(SHOW_BOUNDING_BOX)
     // for visual debug
@@ -144,10 +153,6 @@ nsMathMLmrootFrame::Paint(nsIPresContext*      aPresContext,
 #endif
   }
 
-  /////////////
-  // paint the content we are square-rooting
-  rv = nsMathMLContainerFrame::Paint(aPresContext, aRenderingContext, 
-                                     aDirtyRect, aWhichLayer);
   return rv;
 }
 

layout/mathml/base/src/nsMathMLmsqrtFrame.cpp

@@ -45,11 +45,14 @@
 // <msqrt> and <mroot> -- form a radical - implementation
 //
 
-//TODO:
-//  The code assumes that TeX fonts are picked! Another separate version of
-//  Reflow() is needed as a fall-back for cases where TeX fonts (CMSY/CMEX)
-//  are not installed on the system, e.g., the fall-back could explicitly
-//  draw the branches of the radical using th default rule thickness.
+//NOTE:
+//  The code assumes that TeX fonts are picked.
+//  There is not fall-back to draw the branches of the sqrt explicitly
+//  in the case where TeX fonts are not there. In general, there is not
+//  fall-back(s) in MathML when some (freely-downloadable) fonts are missing.
+//  Otherwise, this will add much work and unnecessary complexity to the core
+//  MathML  engine. Assuming that authors have the free fonts is part of the
+//  deal. We are not responsible for cases of misconfigurations out there.
 
 // additional style context to be used by our MathMLChar.
 #define NS_SQR_CHAR_STYLE_CONTEXT_INDEX   0
@@ -90,7 +93,7 @@ nsMathMLmsqrtFrame::Init(nsIPresContext*  aPresContext,
   rv = nsMathMLContainerFrame::Init(aPresContext, aContent, aParent,
                                     aContext, aPrevInFlow);
 
-  mEmbellishData.flags = NS_MATHML_STRETCH_ALL_CHILDREN_VERTICALLY;
+  mEmbellishData.flags |= NS_MATHML_STRETCH_ALL_CHILDREN_VERTICALLY;
 
   mSqrChar.SetEnum(aPresContext, eMathMLChar_Sqrt);
   ResolveMathMLCharStyle(aPresContext, mContent, mStyleContext, &mSqrChar);
@@ -109,20 +112,26 @@ nsMathMLmsqrtFrame::Paint(nsIPresContext*      aPresContext,
 {
   nsresult rv = NS_OK;
 
-  
+  /////////////
+  // paint the content we are square-rooting
+  rv = nsMathMLContainerFrame::Paint(aPresContext, aRenderingContext, 
+                                     aDirtyRect, aWhichLayer);
   /////////////
   // paint the sqrt symbol
-  if ((NS_FRAME_PAINT_LAYER_FOREGROUND == aWhichLayer) &&
-      !NS_MATHML_HAS_ERROR(mPresentationData.flags))
+  if (!NS_MATHML_HAS_ERROR(mPresentationData.flags))
   {
     mSqrChar.Paint(aPresContext, aRenderingContext,
                    aDirtyRect, aWhichLayer, this);
-    // paint the overline bar
-    nsStyleColor color;
-    mStyleContext->GetStyle(eStyleStruct_Color, color);
-    aRenderingContext.SetColor(color.mColor);
-    aRenderingContext.FillRect(mBarRect.x, mBarRect.y, 
-                               mBarRect.width, mBarRect.height);
+
+    if (NS_FRAME_PAINT_LAYER_FOREGROUND == aWhichLayer)
+    {
+      // paint the overline bar
+      nsStyleColor color;
+      mStyleContext->GetStyle(eStyleStruct_Color, color);
+      aRenderingContext.SetColor(color.mColor);
+      aRenderingContext.FillRect(mBarRect.x, mBarRect.y, 
+                                 mBarRect.width, mBarRect.height);
+    }
 
 #if defined(NS_DEBUG) && defined(SHOW_BOUNDING_BOX)
     // for visual debug
@@ -144,10 +153,6 @@ nsMathMLmsqrtFrame::Paint(nsIPresContext*      aPresContext,
 #endif
   }
 
-  /////////////
-  // paint the content we are square-rooting
-  rv = nsMathMLContainerFrame::Paint(aPresContext, aRenderingContext, 
-                                     aDirtyRect, aWhichLayer);
   return rv;
 }
 

layout/mathml/base/src/nsMathMLmtableFrame.cpp

@@ -111,10 +111,11 @@ nsMathMLmtableOuterFrame::Reflow(nsIPresContext*          aPresContext,
   nsStyleFont font;
   mStyleContext->GetStyle(eStyleStruct_Font, font);
   nsCOMPtr<nsIFontMetrics> fm;
-  aPresContext->GetMetricsFor(font.mFont, getter_AddRefs(fm));
+  aReflowState.rendContext->SetFont(font.mFont);
+  aReflowState.rendContext->GetFontMetrics(*getter_AddRefs(fm));
 
   nscoord axisHeight;
-  GetAxisHeight(fm, axisHeight);
+  GetAxisHeight(*aReflowState.rendContext, fm, axisHeight);
 
   // center about the axis
   aDesiredSize.ascent = aDesiredSize.height/2 + axisHeight;

layout/mathml/base/src/nsMathMLmtableFrame.h

@@ -159,6 +159,26 @@ public:
       axisHeight = NSToCoordRound (250.000f/430.556f * axisHeight);
     }
 
+
+  static void
+  GetAxisHeight(nsIRenderingContext& aRenderingContext, 
+                nsIFontMetrics*       aFontMetrics,
+                nscoord&              aAxisHeight)
+  {
+    // get the bounding metrics of the minus sign, the rendering context
+    // is assumed to have been set with the font of the current style context
+    nsBoundingMetrics bm;
+    PRUnichar minus = '-';
+    nsresult rv = aRenderingContext.GetBoundingMetrics(&minus, PRUint32(1), bm);
+    if (NS_SUCCEEDED(rv)) {
+      aAxisHeight = bm.ascent - (bm.ascent + bm.descent)/2;
+    }
+    if (NS_FAILED(rv) || aAxisHeight <= 0) {
+      // fall-back to the other version
+      GetAxisHeight(aFontMetrics, aAxisHeight);
+    }
+  }
+
 protected:
   nsMathMLmtableOuterFrame();
   virtual ~nsMathMLmtableOuterFrame();