Fix vertical text scaling on Mac.

src/ports/SkFontHost_mac.cpp

Index: src/ports/SkFontHost_mac.cpp
===================================================================
--- src/ports/SkFontHost_mac.cpp	(revision 9039)
+++ src/ports/SkFontHost_mac.cpp	(working copy)
@@ -124,13 +124,6 @@
     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;
 }
@@ -251,10 +244,6 @@
     return darwin_version;
 }
 
-static bool isLeopard() {
-    return darwinVersion() == 9;
-}
-
 static bool isSnowLeopard() {
     return darwinVersion() == 10;
 }
@@ -300,11 +289,6 @@
                                   ScalarToCG(matrix[SkMatrix::kMTransY] * sy));
 }
 
-static SkScalar getFontScale(CGFontRef cgFont) {
-    int unitsPerEm = CGFontGetUnitsPerEm(cgFont);
-    return SkScalarInvert(SkIntToScalar(unitsPerEm));
-}
-
 ///////////////////////////////////////////////////////////////////////////////
 
 #define BITMAP_INFO_RGB (kCGImageAlphaNoneSkipFirst | kCGBitmapByteOrder32Host)
@@ -530,13 +514,7 @@
                 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);
         }
     }
 
@@ -648,13 +626,9 @@
     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;
@@ -665,9 +639,8 @@
 class SkScalerContext_Mac : public SkScalerContext {
 public:
     SkScalerContext_Mac(SkTypeface_Mac*, const SkDescriptor*);
-    virtual ~SkScalerContext_Mac();
+    virtual ~SkScalerContext_Mac() { };
 
-
 protected:
     unsigned generateGlyphCount(void) SK_OVERRIDE;
     uint16_t generateCharToGlyph(SkUnichar uni) SK_OVERRIDE;
@@ -680,24 +653,32 @@
 private:
     static void CTPathElement(void *info, const CGPathElement *element);
     uint16_t getFBoundingBoxesGlyphOffset();
-    void getVerticalOffset(CGGlyph glyphID, SkIPoint* offset) const;
+    /** Returns the offset from the horizontal origin to the vertical origin in SkGlyph units. */
+    void getVerticalOffset(CGGlyph glyphID, SkPoint* offset) const;
     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
+    /** 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;
 
@@ -707,39 +688,22 @@
 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))
+
 {
+    //this->forceGenerateImageFromPath();
     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(
@@ -754,29 +718,18 @@
             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);
     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);
     }
-    fGlyphCount = SkToU16(numGlyphs);
-    fDoSubPosition = SkToBool(fRec.fFlags & kSubpixelPositioning_Flag);
+    SkScalar emPerFUnit = SkScalarInvert(SkIntToScalar(CGFontGetUnitsPerEm(fCGFont)));
+    fFUnitMatrix.preScale(emPerFUnit, -emPerFUnit);
 }
 
-SkScalerContext_Mac::~SkScalerContext_Mac() {
-    delete[] fFBoundingBoxes;
-}
-
 CGRGBPixel* Offscreen::getCG(const SkScalerContext_Mac& context, const SkGlyph& glyph,
                              CGGlyph glyphID, size_t* rowBytesPtr,
                              bool generateA8FromLCD) {
@@ -823,11 +776,14 @@
 
         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.
@@ -860,12 +816,15 @@
         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);
@@ -875,22 +834,21 @@
     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 {
+    // SnowLeopard 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 {
+        skVertOffset.fY = -skVertOffset.fY;
     }
-    offset->fX = SkScalarRound(floatOffset.fX);
-    offset->fY = SkScalarRound(floatOffset.fY);
+    
+    *offset = skVertOffset;
 }
 
 uint16_t SkScalerContext_Mac::getFBoundingBoxesGlyphOffset() {
@@ -938,7 +896,7 @@
     }
 
     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);
@@ -951,10 +909,6 @@
         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;
 }
 
@@ -985,105 +939,87 @@
 }
 
 void SkScalerContext_Mac::generateMetrics(SkGlyph* glyph) {
-    CGSize advance;
-    CGRect bounds;
-    CGGlyph cgGlyph;
-
-    // Get the state we need
-    cgGlyph = (CGGlyph) glyph->getGlyphID(fBaseGlyphCount);
-
+    const CGGlyph cgGlyph = (CGGlyph) glyph->getGlyphID(fBaseGlyphCount);
+    glyph->zeroMetrics();
+    
+    bool wantedVerticalBoundsButGotHorizontalBounds = false;
+    
+    // The following block produces gcAdvance and cgBounds in CG units (pixels, y up).
+    CGSize cgAdvance;
+    CGRect cgBounds;
     if (fVertical) {
         if (!isSnowLeopard()) {
-            // Lion and Leopard respect the vertical font metrics.
+            // Lion and Mountain Lion respect requests for vertical bounds.
             CTFontGetBoundingRectsForGlyphs(fCTVerticalFont, kCTFontVerticalOrientation,
-                                            &cgGlyph, &bounds, 1);
+                                            &cgGlyph, &cgBounds, 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);
+            // Snow Leopard does not respect requests for vertical bounds.
+            // Request the horizontal bounds and adjust it below.
+            CTFontGetBoundingRectsForGlyphs(fCTFont, kCTFontHorizontalOrientation,
+                                            &cgGlyph, &cgBounds, 1);
+            wantedVerticalBoundsButGotHorizontalBounds = true;
         }
+        // All versions respect requests for vertical advances.
         CTFontGetAdvancesForGlyphs(fCTVerticalFont, kCTFontVerticalOrientation,
-                                   &cgGlyph, &advance, 1);
+                                   &cgGlyph, &cgAdvance, 1);
     } else {
-        CTFontGetBoundingRectsForGlyphs(fCTFont, kCTFontDefaultOrientation,
-                                        &cgGlyph, &bounds, 1);
-        CTFontGetAdvancesForGlyphs(fCTFont, kCTFontDefaultOrientation,
-                                   &cgGlyph, &advance, 1);
+        CTFontGetBoundingRectsForGlyphs(fCTFont, kCTFontHorizontalOrientation,
+                                        &cgGlyph, &cgBounds, 1);
+        CTFontGetAdvancesForGlyphs(fCTFont, kCTFontHorizontalOrientation,
+                                   &cgGlyph, &cgAdvance, 1);
     }
+    glyph->fAdvanceX =  SkFloatToFixed_Check(cgAdvance.width);
+    glyph->fAdvanceY = -SkFloatToFixed_Check(cgAdvance.height);
+    
+    // Now work around all the bounds bugs.
 
     // 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) {
+    if (0 == cgAdvance.width && 0 == cgAdvance.height) {
         AutoCFRelease<CGPathRef> path(CTFontCreatePathForGlyph(fCTFont, cgGlyph, NULL));
         if (NULL == path || CGPathIsEmpty(path)) {
-            bounds = CGRectMake(0, 0, 0, 0);
+            return;
         }
     }
 
-    glyph->zeroMetrics();
-    glyph->fAdvanceX =  SkFloatToFixed_Check(advance.width);
-    glyph->fAdvanceY = -SkFloatToFixed_Check(advance.height);
-
-    if (CGRectIsEmpty_inline(bounds)) {
+    if (CGRectIsEmpty_inline(cgBounds)) {
         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;
+    // Convert bounds to SkGlyph units (pixels, y down).
+    SkRect skBounds = SkRect::MakeXYWH(cgBounds.origin.x, -cgBounds.origin.y - cgBounds.size.height,
+                                       cgBounds.size.width, cgBounds.size.height);
     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;
+            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);
+            wantedVerticalBoundsButGotHorizontalBounds = fVertical;
         }
-        // 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.
+    if (wantedVerticalBoundsButGotHorizontalBounds) {
+        // Snow Leopard does not respect requests for vertical bounds.
+        // Our own fFBoundingBoxes are for horizontal bounds.
+        // Convert these horizontal bounds into vertical bounds.
+        SkPoint offset;
         getVerticalOffset(cgGlyph, &offset);
-        glyph->fLeft += offset.fX;
-        glyph->fTop += offset.fY;
+        skBounds.offset(offset);
     }
+    SkIRect skIBounds;
+    skBounds.roundOut(&skIBounds);
+    // Expand the bounds by 1 pixel, to give CG room for anti-aliasing.
+    // Note that we currently don't know how much room to give subpixel smoothed glyphs
+    // as CG dilates the outlines by some amount.
+    skIBounds.outset(1, 1);
+    glyph->fTop = SkToS16(skIBounds.fTop);
+    glyph->fLeft = SkToS16(skIBounds.fLeft);
+    glyph->fWidth = SkToU16(skIBounds.width());
+    glyph->fHeight = SkToU16(skIBounds.height());
+    
 #ifdef HACK_COLORGLYPHS
     glyph->fMaskFormat = SkMask::kARGB32_Format;
 #endif
@@ -1371,17 +1307,17 @@
         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);
     }
 }