Fix vertical text scaling on Mac.

src/ports/SkFontHost_mac.cpp

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include <vector>
 #ifdef SK_BUILD_FOR_MAC
@@ skipping 106 matching lines @@
 public:
     const T* fData;
 };
 
 // inline versions of these rect helpers
 
 static bool CGRectIsEmpty_inline(const CGRect& rect) {
     return rect.size.width <= 0 || rect.size.height <= 0;
 }
 
-static void CGRectInset_inline(CGRect* rect, CGFloat dx, CGFloat dy) {
-    rect->origin.x += dx;
-    rect->origin.y += dy;
-    rect->size.width -= dx * 2;
-    rect->size.height -= dy * 2;
-}
-
 static CGFloat CGRectGetMinX_inline(const CGRect& rect) {
     return rect.origin.x;
 }
 
 static CGFloat CGRectGetMaxX_inline(const CGRect& rect) {
     return rect.origin.x + rect.size.width;
 }
 
 static CGFloat CGRectGetMinY_inline(const CGRect& rect) {
     return rect.origin.y;
@@ skipping 100 matching lines @@
         SkDebugf("could not parse uname release %s\n", info.release);
     }
     return version;
 }
 
 static int darwinVersion() {
     static int darwin_version = readVersion();
     return darwin_version;
 }
 
-static bool isLeopard() {
-    return darwinVersion() == 9;
-}
-
 static bool isSnowLeopard() {
     return darwinVersion() == 10;
 }
 
 static bool isLion() {
     return darwinVersion() == 11;
 }
 
 static bool isMountainLion() {
     return darwinVersion() == 12;
@@ skipping 25 matching lines @@
                                                    SkScalar sx = SK_Scalar1,
                                                    SkScalar sy = SK_Scalar1) {
     return CGAffineTransformMake( ScalarToCG(matrix[SkMatrix::kMScaleX] * sx),
                                  -ScalarToCG(matrix[SkMatrix::kMSkewY]  * sy),
                                  -ScalarToCG(matrix[SkMatrix::kMSkewX]  * sx),
                                   ScalarToCG(matrix[SkMatrix::kMScaleY] * sy),
                                   ScalarToCG(matrix[SkMatrix::kMTransX] * sx),
                                   ScalarToCG(matrix[SkMatrix::kMTransY] * sy));
 }
 
-static SkScalar getFontScale(CGFontRef cgFont) {
-    int unitsPerEm = CGFontGetUnitsPerEm(cgFont);
-    return SkScalarInvert(SkIntToScalar(unitsPerEm));
-}
-
 ///////////////////////////////////////////////////////////////////////////////
 
 #define BITMAP_INFO_RGB (kCGImageAlphaNoneSkipFirst | kCGBitmapByteOrder32Host)
 #define BITMAP_INFO_GRAY (kCGImageAlphaNone)
 
 /**
  * There does not appear to be a publicly accessable API for determining if lcd
  * font smoothing will be applied if we request it. The main issue is that if
  * smoothing is applied a gamma of 2.0 will be used, if not a gamma of 1.0.
  */
@@ skipping 205 matching lines @@
     if (cfFontName != NULL && cfFontTraits != NULL && cfAttributes != NULL && cfTraits != NULL) {
         CFDictionaryAddValue(cfTraits, kCTFontSymbolicTrait, cfFontTraits);
 
         CFDictionaryAddValue(cfAttributes, kCTFontFamilyNameAttribute, cfFontName);
         CFDictionaryAddValue(cfAttributes, kCTFontTraitsAttribute, cfTraits);
 
         AutoCFRelease<CTFontDescriptorRef> ctFontDesc(
                 CTFontDescriptorCreateWithAttributes(cfAttributes));
 
         if (ctFontDesc != NULL) {
-            if (isLeopard()) {
-                // CTFontCreateWithFontDescriptor on Leopard ignores the name
-                AutoCFRelease<CTFontRef> ctNamed(CTFontCreateWithName(cfFontName, 1, NULL));
-                ctFont = CTFontCreateCopyWithAttributes(ctNamed, 1, NULL, ctFontDesc);
-            } else {
-                ctFont = CTFontCreateWithFontDescriptor(ctFontDesc, 0, NULL);
-            }
+            ctFont = CTFontCreateWithFontDescriptor(ctFontDesc, 0, NULL);
         }
     }
 
     return ctFont ? NewFromFontRef(ctFont, familyName) : NULL;
 }
 
 static SkTypeface* GetDefaultFace() {
     SK_DECLARE_STATIC_MUTEX(gMutex);
     SkAutoMutexAcquire ma(gMutex);
 
@@ skipping 91 matching lines @@
         if (face) {
             SkTypefaceCache::Add(face, style);
         } else {
             face = GetDefaultFace();
             face->ref();
         }
     }
     return face;
 }
 
-static void flip(SkMatrix* matrix) {
-    matrix->setSkewX(-matrix->getSkewX());
-    matrix->setSkewY(-matrix->getSkewY());
-}
-
 ///////////////////////////////////////////////////////////////////////////////
 
+/** GlyphRect is in FUnits (em space, y up). */
 struct GlyphRect {
     int16_t fMinX;
     int16_t fMinY;
     int16_t fMaxX;
     int16_t fMaxY;
 };
 
 class SkScalerContext_Mac : public SkScalerContext {
 public:
     SkScalerContext_Mac(SkTypeface_Mac*, const SkDescriptor*);
-    virtual ~SkScalerContext_Mac();
-
+    virtual ~SkScalerContext_Mac() { };

[caryclark, 2013/05/14 20:08:09]

can we remove the destructor altogether at this point?

[bungeman-skia, 2013/05/14 22:30:21]

Done.

 
 protected:
     unsigned generateGlyphCount(void) SK_OVERRIDE;
     uint16_t generateCharToGlyph(SkUnichar uni) SK_OVERRIDE;
     void generateAdvance(SkGlyph* glyph) SK_OVERRIDE;
     void generateMetrics(SkGlyph* glyph) SK_OVERRIDE;
     void generateImage(const SkGlyph& glyph) SK_OVERRIDE;
     void generatePath(const SkGlyph& glyph, SkPath* path) SK_OVERRIDE;
     void generateFontMetrics(SkPaint::FontMetrics* mX, SkPaint::FontMetrics* mY) SK_OVERRIDE;
 
 private:
     static void CTPathElement(void *info, const CGPathElement *element);
+    
+    /** Returns the offset from the horizontal origin to the vertical origin in SkGlyph units. */
+    void getVerticalOffset(CGGlyph glyphID, SkPoint* offset) const;
+    
+    /** Initializes and returns the value of fFBoundingBoxesGlyphOffset.
+     *
+     *  For use with (and must be called before) generateBBoxes.
+     */
     uint16_t getFBoundingBoxesGlyphOffset();
-    void getVerticalOffset(CGGlyph glyphID, SkIPoint* offset) const;
+    
+    /** Initializes fFBoundingBoxes and returns true on success.
+     *
+     *  On Lion and Mountain Lion, CTFontGetBoundingRectsForGlyphs has a bug which causes it to
+     *  return a bad value in bounds.origin.x for SFNT fonts whose hhea::numberOfHMetrics is
+     *  less than its maxp::numGlyphs. When this is the case we try to read the bounds from the
+     *  font directly.
+     *
+     *  This routine initializes fFBoundingBoxes to an array of
+     *  fGlyphCount - fFBoundingBoxesGlyphOffset GlyphRects which contain the bounds in FUnits
+     *  (em space, y up) of glyphs with ids in the range [fFBoundingBoxesGlyphOffset, fGlyphCount).
+     *
+     *  Returns true if fFBoundingBoxes is properly initialized. The table can only be properly
+     *  initialized for a TrueType font with 'head', 'loca', and 'glyf' tables.
+     *
+     *  TODO: A future optimization will compute fFBoundingBoxes once per fCTFont.
+     */
     bool generateBBoxes();
 
-    CGAffineTransform fTransform;
-    SkMatrix fUnitMatrix; // without font size
-    SkMatrix fVerticalMatrix; // unit rotated
-    SkMatrix fMatrix; // with font size
-    SkMatrix fFBoundingBoxesMatrix; // lion-specific fix
+    /** Converts from FUnits (em space, y up) to SkGlyph units (pixels, y down).
+     *
+     *  Used on Snow Leopard to correct CTFontGetVerticalTranslationsForGlyphs.
+     *  Used on Lion to correct CTFontGetBoundingRectsForGlyphs.
+     */
+    SkMatrix fFUnitMatrix;
+    
     Offscreen fOffscreen;
     AutoCFRelease<CTFontRef> fCTFont;
-    AutoCFRelease<CTFontRef> fCTVerticalFont; // for vertical advance
+    
+    /** Vertical variant of fCTFont.
+     *
+     *  CT vertical metrics are pre-rotated (in em space, before transform) 90deg clock-wise.
+     *  This makes kCTFontDefaultOrientation dangerous, because the metrics from
+     *  kCTFontHorizontalOrientation are in a different space from kCTFontVerticalOrientation.
+     *  Use fCTVerticalFont with kCTFontVerticalOrientation to get metrics in the same space.
+     */
+    AutoCFRelease<CTFontRef> fCTVerticalFont;
+    
     AutoCFRelease<CGFontRef> fCGFont;
-    GlyphRect* fFBoundingBoxes;
+    SkAutoTMalloc<GlyphRect> fFBoundingBoxes;
     uint16_t fFBoundingBoxesGlyphOffset;
     uint16_t fGlyphCount;
     bool fGeneratedFBoundingBoxes;
-    bool fDoSubPosition;
-    bool fVertical;
+    const bool fDoSubPosition;
+    const bool fVertical;
 
     friend class Offscreen;
 
     typedef SkScalerContext INHERITED;
 };
 
 SkScalerContext_Mac::SkScalerContext_Mac(SkTypeface_Mac* typeface,
                                          const SkDescriptor* desc)
         : INHERITED(typeface, desc)
-        , fFBoundingBoxes(NULL)
+        , fFBoundingBoxes()
         , fFBoundingBoxesGlyphOffset(0)
         , fGeneratedFBoundingBoxes(false)
+        , fDoSubPosition(SkToBool(fRec.fFlags & kSubpixelPositioning_Flag))
+        , fVertical(SkToBool(fRec.fFlags & kVertical_Flag))
+
 {
     CTFontRef ctFont = typeface->fFontRef.get();
     CFIndex numGlyphs = CTFontGetGlyphCount(ctFont);
-
-    // Get the state we need
-    fRec.getSingleMatrix(&fMatrix);
-    fUnitMatrix = fMatrix;
-
-    // extract the font size out of the matrix, but leave the skewing for italic
-    SkScalar reciprocal = SkScalarInvert(fRec.fTextSize);
-    fUnitMatrix.preScale(reciprocal, reciprocal);
-
     SkASSERT(numGlyphs >= 1 && numGlyphs <= 0xFFFF);
-
-    fTransform = MatrixToCGAffineTransform(fMatrix);
-
-    CGAffineTransform transform;
-    CGFloat unitFontSize;
-    if (isLeopard()) {
-        // passing 1 for pointSize to Leopard sets the font size to 1 pt.
-        // pass the CoreText size explicitly
-        transform = MatrixToCGAffineTransform(fUnitMatrix);
-        unitFontSize = SkScalarToFloat(fRec.fTextSize);
-    } else {
-        // since our matrix includes everything, we pass 1 for pointSize
-        transform = fTransform;
-        unitFontSize = 1;
-    }
-    flip(&fUnitMatrix); // flip to fix up bounds later
-    fVertical = SkToBool(fRec.fFlags & kVertical_Flag);
+    fGlyphCount = SkToU16(numGlyphs);
+    
+    fRec.getSingleMatrix(&fFUnitMatrix);
+    CGAffineTransform transform = MatrixToCGAffineTransform(fFUnitMatrix);
+    
     AutoCFRelease<CTFontDescriptorRef> ctFontDesc;
     if (fVertical) {
         AutoCFRelease<CFMutableDictionaryRef> cfAttributes(CFDictionaryCreateMutable(
                 kCFAllocatorDefault, 0,
                 &kCFTypeDictionaryKeyCallBacks,
                 &kCFTypeDictionaryValueCallBacks));
         if (cfAttributes) {
             CTFontOrientation ctOrientation = kCTFontVerticalOrientation;
             AutoCFRelease<CFNumberRef> cfVertical(CFNumberCreate(
                     kCFAllocatorDefault, kCFNumberSInt32Type, &ctOrientation));
             CFDictionaryAddValue(cfAttributes, kCTFontOrientationAttribute, cfVertical);
             ctFontDesc = CTFontDescriptorCreateWithAttributes(cfAttributes);
         }
     }
-    fCTFont = CTFontCreateCopyWithAttributes(ctFont, unitFontSize, &transform, ctFontDesc);
+    // Since our matrix includes everything, we pass 1 for size.
+    fCTFont = CTFontCreateCopyWithAttributes(ctFont, 1.f, &transform, ctFontDesc);

[caryclark, 2013/05/14 20:08:09]

It looks like the rest of Skia mostly uses 1.f instead of 1 only in places where
it is forcing a float result, e.g., 1.f / 255 -- so I think it would be just as
clear and consistent to pass '1' here.

[bungeman-skia, 2013/05/14 22:30:21]

Done.

     fCGFont = CTFontCopyGraphicsFont(fCTFont, NULL);
     if (fVertical) {
         CGAffineTransform rotateLeft = CGAffineTransformMake(0, -1, 1, 0, 0, 0);
         transform = CGAffineTransformConcat(rotateLeft, transform);
-        fCTVerticalFont = CTFontCreateCopyWithAttributes(ctFont, unitFontSize, &transform, NULL);
-        fVerticalMatrix = fUnitMatrix;
-        if (isSnowLeopard()) {
-            SkScalar scale = SkScalarMul(fRec.fTextSize, getFontScale(fCGFont));
-            fVerticalMatrix.preScale(scale, scale);
-        } else {
-            fVerticalMatrix.preRotate(SkIntToScalar(90));
-        }
-        fVerticalMatrix.postScale(SK_Scalar1, -SK_Scalar1);
+        fCTVerticalFont = CTFontCreateCopyWithAttributes(ctFont, 1.f, &transform, NULL);

[caryclark, 2013/05/14 20:08:09]

and here

[bungeman-skia, 2013/05/14 22:30:21]

Done.

     }
-    fGlyphCount = SkToU16(numGlyphs);
-    fDoSubPosition = SkToBool(fRec.fFlags & kSubpixelPositioning_Flag);
-}
-
-SkScalerContext_Mac::~SkScalerContext_Mac() {
-    delete[] fFBoundingBoxes;
+    SkScalar emPerFUnit = SkScalarInvert(SkIntToScalar(CGFontGetUnitsPerEm(fCGFont)));
+    fFUnitMatrix.preScale(emPerFUnit, -emPerFUnit);
 }
 
 CGRGBPixel* Offscreen::getCG(const SkScalerContext_Mac& context, const SkGlyph& glyph,
                              CGGlyph glyphID, size_t* rowBytesPtr,
                              bool generateA8FromLCD) {
     if (!fRGBSpace) {
         //It doesn't appear to matter what color space is specified.
         //Regular blends and antialiased text are always (s*a + d*(1-a))
         //and smoothed text is always g=2.0.
         fRGBSpace = CGColorSpaceCreateDeviceRGB();
@@ skipping 28 matching lines @@
         fCG = CGBitmapContextCreate(image, fSize.fWidth, fSize.fHeight, 8,
                                     rowBytes, fRGBSpace, BITMAP_INFO_RGB);
 
         // skia handles quantization itself, so we disable this for cg to get
         // full fractional data from them.
         CGContextSetAllowsFontSubpixelQuantization(fCG, false);
         CGContextSetShouldSubpixelQuantizeFonts(fCG, false);
 
         CGContextSetTextDrawingMode(fCG, kCGTextFill);
         CGContextSetFont(fCG, context.fCGFont);
-        CGContextSetFontSize(fCG, 1);
-        CGContextSetTextMatrix(fCG, context.fTransform);
+        CGContextSetFontSize(fCG, 1.0f /*CTFontGetSize(context.fCTFont)*/);
+        CGContextSetTextMatrix(fCG, CTFontGetMatrix(context.fCTFont));
 
-        CGContextSetAllowsFontSubpixelPositioning(fCG, context.fDoSubPosition);
-        CGContextSetShouldSubpixelPositionFonts(fCG, context.fDoSubPosition);
+        // Because CG always draws from the horizontal baseline,
+        // if there is a non-integral translation from the horizontal origin to the vertical origin,
+        // then CG cannot draw the glyph in the correct location without subpixel positioning.
+        CGContextSetAllowsFontSubpixelPositioning(fCG, context.fDoSubPosition || context.fVertical);
+        CGContextSetShouldSubpixelPositionFonts(fCG, context.fDoSubPosition || context.fVertical);
 
         // Draw white on black to create mask.
         // TODO: Draw black on white and invert, CG has a special case codepath.
         CGContextSetGrayFillColor(fCG, 1.0f, 1.0f);
 
         // force our checks below to happen
         fDoAA = !doAA;
         fDoLCD = !doLCD;
     }
 
@@ skipping 12 matching lines @@
 
     // erase to black
     sk_memset_rect32(image, 0, glyph.fWidth, glyph.fHeight, rowBytes);
 
     float subX = 0;
     float subY = 0;
     if (context.fDoSubPosition) {
         subX = SkFixedToFloat(glyph.getSubXFixed());
         subY = SkFixedToFloat(glyph.getSubYFixed());
     }
+    
+    // CGContextShowGlyphsAtPoint always draws using the horizontal baseline origin.
     if (context.fVertical) {
-        SkIPoint offset;
+        SkPoint offset;
         context.getVerticalOffset(glyphID, &offset);
         subX += offset.fX;
         subY += offset.fY;
     }
+    
     CGContextShowGlyphsAtPoint(fCG, -glyph.fLeft + subX,
                                glyph.fTop + glyph.fHeight - subY,
                                &glyphID, 1);
 
     SkASSERT(rowBytesPtr);
     *rowBytesPtr = rowBytes;
     return image;
 }
 
-void SkScalerContext_Mac::getVerticalOffset(CGGlyph glyphID, SkIPoint* offset) const {
-    CGSize vertOffset;
-    CTFontGetVerticalTranslationsForGlyphs(fCTVerticalFont, &glyphID, &vertOffset, 1);
-    const SkPoint trans = {CGToScalar(vertOffset.width),
-                           CGToScalar(vertOffset.height)};
-    SkPoint floatOffset;
-    fVerticalMatrix.mapPoints(&floatOffset, &trans, 1);
-    if (!isSnowLeopard()) {
-    // SnowLeopard fails to apply the font's matrix to the vertical metrics,
-    // but Lion and Leopard do. The unit matrix describes the font's matrix at
-    // point size 1. There may be some way to avoid mapping here by setting up
-    // fVerticalMatrix differently, but this works for now.
-        fUnitMatrix.mapPoints(&floatOffset, 1);
+void SkScalerContext_Mac::getVerticalOffset(CGGlyph glyphID, SkPoint* offset) const {
+    // Snow Leopard returns cgVertOffset in completely un-transformed FUnits (em space, y up).
+    // Lion and Leopard return cgVertOffset in CG units (pixels, y up).
+    CGSize cgVertOffset;
+    CTFontGetVerticalTranslationsForGlyphs(fCTFont, &glyphID, &cgVertOffset, 1);
+
+    SkPoint skVertOffset = { CGToScalar(cgVertOffset.width), CGToScalar(cgVertOffset.height) };
+    if (isSnowLeopard()) {
+        // From FUnits (em space, y up) to SkGlyph units (pixels, y down).
+        fFUnitMatrix.mapPoints(&skVertOffset, 1);
+    } else {
+        // From CG units (pixels, y up) to SkGlyph units (pixels, y down).
+        skVertOffset.fY = -skVertOffset.fY;
     }
-    offset->fX = SkScalarRound(floatOffset.fX);
-    offset->fY = SkScalarRound(floatOffset.fY);
+    
+    *offset = skVertOffset;
 }
 
 uint16_t SkScalerContext_Mac::getFBoundingBoxesGlyphOffset() {
     if (fFBoundingBoxesGlyphOffset) {
         return fFBoundingBoxesGlyphOffset;
     }
     fFBoundingBoxesGlyphOffset = fGlyphCount; // fallback for all fonts
     AutoCGTable<SkOTTableHorizontalHeader> hheaTable(fCGFont);
     if (hheaTable.fData) {
         fFBoundingBoxesGlyphOffset = SkEndian_SwapBE16(hheaTable->numberOfHMetrics);
     }
     return fFBoundingBoxesGlyphOffset;
 }
 
-/*
- * Lion has a bug in CTFontGetBoundingRectsForGlyphs which returns a bad value
- * in theBounds.origin.x for fonts whose numOfLogHorMetrics is less than its
- * glyph count. This workaround reads the glyph bounds from the font directly.
- *
- * The table is computed only if the font is a TrueType font, if the glyph
- * value is >= fFBoundingBoxesGlyphOffset. (called only if fFBoundingBoxesGlyphOffset < fGlyphCount).
- *
- * TODO: A future optimization will compute fFBoundingBoxes once per CGFont, and
- * compute fFBoundingBoxesMatrix once per font context.
- */
 bool SkScalerContext_Mac::generateBBoxes() {
     if (fGeneratedFBoundingBoxes) {
-        return NULL != fFBoundingBoxes;
+        return NULL != fFBoundingBoxes.get();
     }
     fGeneratedFBoundingBoxes = true;
 
     AutoCGTable<SkOTTableHead> headTable(fCGFont);
     if (!headTable.fData) {
         return false;
     }
 
     AutoCGTable<SkOTTableIndexToLocation> locaTable(fCGFont);
     if (!locaTable.fData) {
         return false;
     }
 
     AutoCGTable<SkOTTableGlyph> glyfTable(fCGFont);
     if (!glyfTable.fData) {
         return false;
     }
 
     uint16_t entries = fGlyphCount - fFBoundingBoxesGlyphOffset;
-    fFBoundingBoxes = new GlyphRect[entries];
+    fFBoundingBoxes.reset(entries);
 
     SkOTTableHead::IndexToLocFormat locaFormat = headTable->indexToLocFormat;
     SkOTTableGlyph::Iterator glyphDataIter(*glyfTable.fData, *locaTable.fData, locaFormat);
     glyphDataIter.advance(fFBoundingBoxesGlyphOffset);
     for (uint16_t boundingBoxesIndex = 0; boundingBoxesIndex < entries; ++boundingBoxesIndex) {
         const SkOTTableGlyphData* glyphData = glyphDataIter.next();
         GlyphRect& rect = fFBoundingBoxes[boundingBoxesIndex];
         rect.fMinX = SkEndian_SwapBE16(glyphData->xMin);
         rect.fMinY = SkEndian_SwapBE16(glyphData->yMin);
         rect.fMaxX = SkEndian_SwapBE16(glyphData->xMax);
         rect.fMaxY = SkEndian_SwapBE16(glyphData->yMax);
     }
-    fFBoundingBoxesMatrix = fMatrix;
-    flip(&fFBoundingBoxesMatrix);
-    SkScalar fontScale = getFontScale(fCGFont);
-    fFBoundingBoxesMatrix.preScale(fontScale, fontScale);
     return true;
 }
 
 unsigned SkScalerContext_Mac::generateGlyphCount(void) {
     return fGlyphCount;
 }
 
 uint16_t SkScalerContext_Mac::generateCharToGlyph(SkUnichar uni) {
     CGGlyph     cgGlyph;
     UniChar     theChar;
@@ skipping 10 matching lines @@
     }
 
     return cgGlyph;
 }
 
 void SkScalerContext_Mac::generateAdvance(SkGlyph* glyph) {
     this->generateMetrics(glyph);
 }
 
 void SkScalerContext_Mac::generateMetrics(SkGlyph* glyph) {
-    CGSize advance;
-    CGRect bounds;
-    CGGlyph cgGlyph;
+    const CGGlyph cgGlyph = (CGGlyph) glyph->getGlyphID(fBaseGlyphCount);
+    glyph->zeroMetrics();
+    
+    // The following block produces cgAdvance in CG units (pixels, y up).
+    CGSize cgAdvance;
+    if (fVertical) {
+        CTFontGetAdvancesForGlyphs(fCTVerticalFont, kCTFontVerticalOrientation,
+                                   &cgGlyph, &cgAdvance, 1);
+    } else {
+        CTFontGetAdvancesForGlyphs(fCTFont, kCTFontHorizontalOrientation,
+                                   &cgGlyph, &cgAdvance, 1);
+    }
+    glyph->fAdvanceX =  SkFloatToFixed_Check(cgAdvance.width);
+    glyph->fAdvanceY = -SkFloatToFixed_Check(cgAdvance.height);
 
-    // Get the state we need
-    cgGlyph = (CGGlyph) glyph->getGlyphID(fBaseGlyphCount);
+    // The following produces skBounds in SkGlyph units (pixels, y down),
+    // or returns early if skBounds would be empty.
+    SkRect skBounds;
+    
+    // On Mountain Lion, CTFontGetBoundingRectsForGlyphs with kCTFontVerticalOrientation and
+    // CTFontGetVerticalTranslationsForGlyphs do not agree when using OTF CFF fonts.
+    // For TTF fonts these two do agree and we can use CTFontGetBoundingRectsForGlyphs to get
+    // the bounding box and CTFontGetVerticalTranslationsForGlyphs to then draw the glyph
+    // inside that bounding box. However, with OTF CFF fonts this does not work. It appears that
+    // CTFontGetBoundingRectsForGlyphs with kCTFontVerticalOrientation on OTF CFF fonts tries
+    // to center the glyph along the vertical baseline and also perform some mysterious shift
+    // along the baseline. CTFontGetVerticalTranslationsForGlyphs does not appear to perform
+    // these steps.
+    //
+    // It is not known which is correct (or if either is correct). However, we must always draw
+    // from the horizontal origin and must use CTFontGetVerticalTranslationsForGlyphs to draw.
+    // As a result, we do not call CTFontGetBoundingRectsForGlyphs for vertical glyphs.
+    
+    // On Snow Leopard, CTFontGetBoundingRectsForGlyphs ignores kCTFontVerticalOrientation and
+    // returns horizontal bounds.
+    
+    // On Lion and Mountain Lion, CTFontGetBoundingRectsForGlyphs has a bug which causes it to
+    // return a bad value in cgBounds.origin.x for SFNT fonts whose hhea::numberOfHMetrics is
+    // less than its maxp::numGlyphs. When this is the case we try to read the bounds from the
+    // font directly.
+    if ((isLion() || isMountainLion()) &&
+        (cgGlyph < fGlyphCount && cgGlyph >= getFBoundingBoxesGlyphOffset() && generateBBoxes()))
+    {
+        const GlyphRect& gRect = fFBoundingBoxes[cgGlyph - fFBoundingBoxesGlyphOffset];
+        if (gRect.fMinX >= gRect.fMaxX || gRect.fMinY >= gRect.fMaxY) {
+            return;
+        }
+        skBounds = SkRect::MakeLTRB(gRect.fMinX, gRect.fMinY, gRect.fMaxX, gRect.fMaxY);
+        // From FUnits (em space, y up) to SkGlyph units (pixels, y down).
+        fFUnitMatrix.mapRect(&skBounds);
+
+    } else {
+        // CTFontGetBoundingRectsForGlyphs produces cgBounds in CG units (pixels, y up).
+        CGRect cgBounds;
+        CTFontGetBoundingRectsForGlyphs(fCTFont, kCTFontHorizontalOrientation,
+                                        &cgGlyph, &cgBounds, 1);
+    
+        // BUG?
+        // 0x200B (zero-advance space) seems to return a huge (garbage) bounds, when
+        // it should be empty. So, if we see a zero-advance, we check if it has an
+        // empty path or not, and if so, we jam the bounds to 0. Hopefully a zero-advance
+        // is rare, so we won't incur a big performance cost for this extra check.
+        if (0 == cgAdvance.width && 0 == cgAdvance.height) {
+            AutoCFRelease<CGPathRef> path(CTFontCreatePathForGlyph(fCTFont, cgGlyph, NULL));
+            if (NULL == path || CGPathIsEmpty(path)) {
+                return;
+            }
+        }
+
+        if (CGRectIsEmpty_inline(cgBounds)) {
+            return;
+        }
+
+        // Convert cgBounds to SkGlyph units (pixels, y down).
+        skBounds = SkRect::MakeXYWH(cgBounds.origin.x, -cgBounds.origin.y - cgBounds.size.height,
+                                    cgBounds.size.width, cgBounds.size.height);
+    }
 
     if (fVertical) {
-        if (!isSnowLeopard()) {
-            // Lion and Leopard respect the vertical font metrics.
-            CTFontGetBoundingRectsForGlyphs(fCTVerticalFont, kCTFontVerticalOrientation,
-                                            &cgGlyph, &bounds, 1);
-        } else {
-            // Snow Leopard and earlier respect the vertical font metrics for
-            // advances, but not bounds, so use the default box and adjust it below.
-            CTFontGetBoundingRectsForGlyphs(fCTFont, kCTFontDefaultOrientation,
-                                            &cgGlyph, &bounds, 1);
-        }
-        CTFontGetAdvancesForGlyphs(fCTVerticalFont, kCTFontVerticalOrientation,
-                                   &cgGlyph, &advance, 1);
-    } else {
-        CTFontGetBoundingRectsForGlyphs(fCTFont, kCTFontDefaultOrientation,
-                                        &cgGlyph, &bounds, 1);
-        CTFontGetAdvancesForGlyphs(fCTFont, kCTFontDefaultOrientation,
-                                   &cgGlyph, &advance, 1);
+        // Due to all of the vertical bounds bugs, skBounds is always the horizontal bounds.
+        // Convert these horizontal bounds into vertical bounds.
+        SkPoint offset;
+        getVerticalOffset(cgGlyph, &offset);
+        skBounds.offset(offset);
     }
-
-    // BUG?
-    // 0x200B (zero-advance space) seems to return a huge (garbage) bounds, when
-    // it should be empty. So, if we see a zero-advance, we check if it has an
-    // empty path or not, and if so, we jam the bounds to 0. Hopefully a zero-advance
-    // is rare, so we won't incur a big performance cost for this extra check.
-    if (0 == advance.width && 0 == advance.height) {
-        AutoCFRelease<CGPathRef> path(CTFontCreatePathForGlyph(fCTFont, cgGlyph, NULL));
-        if (NULL == path || CGPathIsEmpty(path)) {
-            bounds = CGRectMake(0, 0, 0, 0);
-        }
+    
+    // Currently the bounds are based on being rendered at (0,0).
+    // The top left must not move, since that is the base from which subpixel positioning is offset.
+    if (fDoSubPosition) {
+        skBounds.fRight += SkFixedToFloat(glyph->getSubXFixed());
+        skBounds.fBottom += SkFixedToFloat(glyph->getSubYFixed());
     }
-
-    glyph->zeroMetrics();
-    glyph->fAdvanceX =  SkFloatToFixed_Check(advance.width);
-    glyph->fAdvanceY = -SkFloatToFixed_Check(advance.height);
-
-    if (CGRectIsEmpty_inline(bounds)) {
-        return;
-    }
-
-    if (isLeopard() && !fVertical) {
-        // Leopard does not consider the matrix skew in its bounds.
-        // Run the bounding rectangle through the skew matrix to determine
-        // the true bounds. However, this doesn't work if the font is vertical.
-        // FIXME (Leopard): If the font has synthetic italic (e.g., matrix skew)
-        // and the font is vertical, the bounds need to be recomputed.
-        SkRect glyphBounds = SkRect::MakeXYWH(
-                bounds.origin.x, bounds.origin.y,
-                bounds.size.width, bounds.size.height);
-        fUnitMatrix.mapRect(&glyphBounds);
-        bounds.origin.x = glyphBounds.fLeft;
-        bounds.origin.y = glyphBounds.fTop;
-        bounds.size.width = glyphBounds.width();
-        bounds.size.height = glyphBounds.height();
-    }
-    // Adjust the bounds
-    //
-    // CTFontGetBoundingRectsForGlyphs ignores the font transform, so we need
-    // to transform the bounding box ourselves.
-    //
-    // The bounds are also expanded by 1 pixel, to give CG room for anti-aliasing.
-    CGRectInset_inline(&bounds, -1, -1);
-
-    // Get the metrics
-    bool lionAdjustedMetrics = false;
-    if (isLion() || isMountainLion()) {
-        if (cgGlyph < fGlyphCount && cgGlyph >= getFBoundingBoxesGlyphOffset() && generateBBoxes()){
-            lionAdjustedMetrics = true;
-            SkRect adjust;
-            const GlyphRect& gRect = fFBoundingBoxes[cgGlyph - fFBoundingBoxesGlyphOffset];
-            adjust.set(gRect.fMinX, gRect.fMinY, gRect.fMaxX, gRect.fMaxY);
-            fFBoundingBoxesMatrix.mapRect(&adjust);
-            bounds.origin.x = SkScalarToFloat(adjust.fLeft) - 1;
-            bounds.origin.y = SkScalarToFloat(adjust.fTop) - 1;
-        }
-        // Lion returns fractions in the bounds
-        glyph->fWidth = SkToU16(sk_float_ceil2int(bounds.size.width));
-        glyph->fHeight = SkToU16(sk_float_ceil2int(bounds.size.height));
-    } else {
-        glyph->fWidth = SkToU16(sk_float_round2int(bounds.size.width));
-        glyph->fHeight = SkToU16(sk_float_round2int(bounds.size.height));
-    }
-    glyph->fTop = SkToS16(-sk_float_round2int(CGRectGetMaxY_inline(bounds)));
-    glyph->fLeft = SkToS16(sk_float_round2int(CGRectGetMinX_inline(bounds)));
-    SkIPoint offset;
-    if (fVertical && (isSnowLeopard() || lionAdjustedMetrics)) {
-        // SnowLeopard doesn't respect vertical metrics, so compute them manually.
-        // Also compute them for Lion when the metrics were computed by hand.
-        getVerticalOffset(cgGlyph, &offset);
-        glyph->fLeft += offset.fX;
-        glyph->fTop += offset.fY;
-    }
+    
+    SkIRect skIBounds;
+    skBounds.roundOut(&skIBounds);
+    // Expand the bounds by 1 pixel, to give CG room for anti-aliasing.
+    // Note that this outset is to allow room for LCD smoothed glyphs. However, the correct outset
+    // is not currently known, as CG dilates the outlines by some percentage.
+    // Note that if this context is A8 and not back-forming from LCD, there is no need to outset.
+    skIBounds.outset(1, 1);
+    glyph->fLeft = SkToS16(skIBounds.fLeft);
+    glyph->fTop = SkToS16(skIBounds.fTop);
+    glyph->fWidth = SkToU16(skIBounds.width());
+    glyph->fHeight = SkToU16(skIBounds.height());
+    
 #ifdef HACK_COLORGLYPHS
     glyph->fMaskFormat = SkMask::kARGB32_Format;
 #endif
 }
 
 #include "SkColorPriv.h"
 
 static void build_power_table(uint8_t table[], float ee) {
     for (int i = 0; i < 256; i++) {
         float x = i / 255.f;
@@ skipping 267 matching lines @@
     }
 
     CGGlyph cgGlyph = (CGGlyph)glyph.getGlyphID(fBaseGlyphCount);
     AutoCFRelease<CGPathRef> cgPath(CTFontCreatePathForGlyph(font, cgGlyph, NULL));
 
     path->reset();
     if (cgPath != NULL) {
         CGPathApply(cgPath, path, SkScalerContext_Mac::CTPathElement);
     }
 
-    if (fRec.fFlags & SkScalerContext::kSubpixelPositioning_Flag) {
+    if (fDoSubPosition) {
         SkMatrix m;
         m.setScale(SkScalarInvert(scaleX), SkScalarInvert(scaleY));
         path->transform(m);
         // balance the call to CTFontCreateCopyWithAttributes
         CFSafeRelease(font);
     }
-    if (fRec.fFlags & SkScalerContext::kVertical_Flag) {
-        SkIPoint offset;
+    if (fVertical) {
+        SkPoint offset;
         getVerticalOffset(cgGlyph, &offset);
-        path->offset(SkIntToScalar(offset.fX), SkIntToScalar(offset.fY));
+        path->offset(offset.fX, offset.fY);
     }
 }
 
 void SkScalerContext_Mac::generateFontMetrics(SkPaint::FontMetrics* mx,
                                               SkPaint::FontMetrics* my) {
     CGRect theBounds = CTFontGetBoundingBox(fCTFont);
 
     SkPaint::FontMetrics theMetrics;
     theMetrics.fTop          = CGToScalar(-CGRectGetMaxY_inline(theBounds));
     theMetrics.fAscent       = CGToScalar(-CTFontGetAscent(fCTFont));
@@ skipping 826 matching lines @@
             return NULL;
         }
         return create_from_dataProvider(pr);
     }
 };
 
 SkFontMgr* SkFontMgr::Factory() {
     return SkNEW(SkFontMgr_Mac);
 }
 #endif