Fix the scale for complex script fonts and re-ajust y position.

Bug 5445861 : complex joining characters positioned in wrong place.

1. Set font size and scale for harfbuzz object based on Chrome's CL:http://trac.webkit.org/changeset/77504.
2. Truncate harfbuzz value to pixels for y position.
3. Ran through the page_cycler/intl2 tests with 5 iterations.

Change-Id: I38dcb07b2d23042e40781ea914c8c6e73f33c220

3 files changed, 45 insertions, 20 deletions

diff --git a/Source/WebCore/platform/graphics/android/FontAndroid.cpp b/Source/WebCore/platform/graphics/android/FontAndroid.cpp
index d435ad7..852413f 100644
--- a/Source/WebCore/platform/graphics/android/FontAndroid.cpp
+++ b/Source/WebCore/platform/graphics/android/FontAndroid.cpp
@@ -735,6 +735,16 @@ void TextRunWalker::setupFontForScriptRun()
     }
     m_item.face = complexPlatformData->harfbuzzFace();
     m_item.font->userData = const_cast<FontPlatformData*>(complexPlatformData);
+
+    int size = complexPlatformData->size();
+    m_item.font->x_ppem = size;
+    m_item.font->y_ppem = size;
+    // x_ and y_scale are the conversion factors from font design space (fEmSize) to 1/64th of device pixels in 16.16 format.
+    const int devicePixelFraction = 64;
+    const int multiplyFor16Dot16 = 1 << 16;
+    int scale = devicePixelFraction * size * multiplyFor16Dot16 / complexPlatformData->emSizeInFontUnits();
+    m_item.font->x_scale = scale;
+    m_item.font->y_scale = scale;
 }
 
 HB_FontRec* TextRunWalker::allocHarfbuzzFont()
@@ -743,13 +753,6 @@ HB_FontRec* TextRunWalker::allocHarfbuzzFont()
     memset(font, 0, sizeof(HB_FontRec));
     font->klass = &harfbuzzSkiaClass;
     font->userData = 0;
-    // The values which harfbuzzSkiaClass returns are already scaled to
-    // pixel units, so we just set all these to one to disable further
-    // scaling.
-    font->x_ppem = 1;
-    font->y_ppem = 1;
-    font->x_scale = 1;
-    font->y_scale = 1;
 
     return font;
 }
@@ -823,7 +826,9 @@ void TextRunWalker::setGlyphPositions(bool isRTL)
         int i = isRTL ? m_item.num_glyphs - iter - 1 : iter;
 
         m_glyphs16[i] = m_item.glyphs[i];
-        m_positions[i].set(SkIntToScalar(m_offsetX + position), m_startingY + SkIntToScalar(m_item.offsets[i].y));
+        int offsetX = truncateFixedPointToInteger(m_item.offsets[i].x);
+        int offsetY = truncateFixedPointToInteger(m_item.offsets[i].y);
+        m_positions[i].set(SkIntToScalar(m_offsetX + position) + offsetX, m_startingY + offsetY);
 
         int advance = truncateFixedPointToInteger(m_item.advances[i]);
         // The first half of the conjunction works around the case where
diff --git a/Source/WebCore/platform/graphics/android/FontPlatformData.h b/Source/WebCore/platform/graphics/android/FontPlatformData.h
index 5c3313e..1e46971 100644
--- a/Source/WebCore/platform/graphics/android/FontPlatformData.h
+++ b/Source/WebCore/platform/graphics/android/FontPlatformData.h
@@ -82,6 +82,7 @@ public:
 
     float size() const { return mTextSize; }
     unsigned hash() const;
+    int emSizeInFontUnits() const;
     bool isFixedPitch() const;
 
 #ifndef NDEBUG
@@ -113,6 +114,7 @@ private:
 
     SkTypeface* mTypeface;
     float       mTextSize;
+    mutable int mEmSizeInFontUnits;
     bool        mFakeBold;
     bool        mFakeItalic;
     FontOrientation mOrientation;
diff --git a/Source/WebCore/platform/graphics/android/FontPlatformDataAndroid.cpp b/Source/WebCore/platform/graphics/android/FontPlatformDataAndroid.cpp
index 3c90246..c09120f 100644
--- a/Source/WebCore/platform/graphics/android/FontPlatformDataAndroid.cpp
+++ b/Source/WebCore/platform/graphics/android/FontPlatformDataAndroid.cpp
@@ -33,6 +33,7 @@
 #ifdef SUPPORT_COMPLEX_SCRIPTS
 #include "HarfbuzzSkia.h"
 #endif
+#include "SkAdvancedTypefaceMetrics.h"
 #include "SkPaint.h"
 #include "SkTypeface.h"
 
@@ -74,7 +75,7 @@ FontPlatformData::RefCountedHarfbuzzFace::~RefCountedHarfbuzzFace()
 }
 
 FontPlatformData::FontPlatformData()
-    : mTypeface(NULL), mTextSize(0), mFakeBold(false), mFakeItalic(false),
+    : mTypeface(NULL), mTextSize(0), mEmSizeInFontUnits(0), mFakeBold(false), mFakeItalic(false),
       mOrientation(Horizontal), mTextOrientation(TextOrientationVerticalRight)
 {
     inc_count();
@@ -87,10 +88,10 @@ FontPlatformData::FontPlatformData(const FontPlatformData& src)
         SkSafeRef(src.mTypeface);
     }
 
-    mTypeface   = src.mTypeface;
-
-    mTextSize   = src.mTextSize;
-    mFakeBold   = src.mFakeBold;
+    mTypeface = src.mTypeface;
+    mTextSize = src.mTextSize;
+    mEmSizeInFontUnits = src.mEmSizeInFontUnits;
+    mFakeBold = src.mFakeBold;
     mFakeItalic = src.mFakeItalic;
     m_harfbuzzFace = src.m_harfbuzzFace;
     mOrientation = src.mOrientation;
@@ -102,7 +103,7 @@ FontPlatformData::FontPlatformData(const FontPlatformData& src)
 
 FontPlatformData::FontPlatformData(SkTypeface* tf, float textSize, bool fakeBold, bool fakeItalic,
     FontOrientation orientation, TextOrientation textOrientation)
-    : mTypeface(tf), mTextSize(textSize), mFakeBold(fakeBold), mFakeItalic(fakeItalic),
+    : mTypeface(tf), mTextSize(textSize), mEmSizeInFontUnits(0), mFakeBold(fakeBold), mFakeItalic(fakeItalic),
       mOrientation(orientation), mTextOrientation(textOrientation)
 {
     if (hashTableDeletedFontValue() != mTypeface) {
@@ -114,7 +115,7 @@ FontPlatformData::FontPlatformData(SkTypeface* tf, float textSize, bool fakeBold
 }
 
 FontPlatformData::FontPlatformData(const FontPlatformData& src, float textSize)
-    : mTypeface(src.mTypeface), mTextSize(textSize), mFakeBold(src.mFakeBold), mFakeItalic(src.mFakeItalic),
+    : mTypeface(src.mTypeface), mTextSize(textSize), mEmSizeInFontUnits(src.mEmSizeInFontUnits), mFakeBold(src.mFakeBold), mFakeItalic(src.mFakeItalic),
       m_harfbuzzFace(src.m_harfbuzzFace), mOrientation(src.mOrientation), mTextOrientation(src.mTextOrientation)
 {
     if (hashTableDeletedFontValue() != mTypeface) {
@@ -126,7 +127,7 @@ FontPlatformData::FontPlatformData(const FontPlatformData& src, float textSize)
 }
 
 FontPlatformData::FontPlatformData(float size, bool bold, bool oblique)
-    : mTypeface(NULL), mTextSize(size), mFakeBold(bold), mFakeItalic(oblique),
+    : mTypeface(NULL), mTextSize(size),  mEmSizeInFontUnits(0), mFakeBold(bold), mFakeItalic(oblique),
       mOrientation(Horizontal), mTextOrientation(TextOrientationVerticalRight)
 {
     inc_count();
@@ -134,7 +135,7 @@ FontPlatformData::FontPlatformData(float size, bool bold, bool oblique)
 }
 
 FontPlatformData::FontPlatformData(const FontPlatformData& src, SkTypeface* tf)
-    : mTypeface(tf), mTextSize(src.mTextSize), mFakeBold(src.mFakeBold),
+    : mTypeface(tf), mTextSize(src.mTextSize),  mEmSizeInFontUnits(0), mFakeBold(src.mFakeBold),
       mFakeItalic(src.mFakeItalic), mOrientation(src.mOrientation),
       mTextOrientation(src.mTextOrientation)
 {
@@ -158,6 +159,22 @@ FontPlatformData::~FontPlatformData()
     }
 }
 
+int FontPlatformData::emSizeInFontUnits() const
+{
+    if (mEmSizeInFontUnits)
+        return mEmSizeInFontUnits;
+
+    SkAdvancedTypefaceMetrics* metrics = 0;
+    if (mTypeface)
+        metrics = mTypeface->getAdvancedTypefaceMetrics(SkAdvancedTypefaceMetrics::kNo_PerGlyphInfo);
+    if (metrics) {
+        mEmSizeInFontUnits = metrics->fEmSize;
+        metrics->unref();
+    } else
+        mEmSizeInFontUnits = 1000;  // default value copied from Skia.
+    return mEmSizeInFontUnits;
+}
+
 FontPlatformData& FontPlatformData::operator=(const FontPlatformData& src)
 {
     if (hashTableDeletedFontValue() != src.mTypeface) {
@@ -167,9 +184,10 @@ FontPlatformData& FontPlatformData::operator=(const FontPlatformData& src)
         SkSafeUnref(mTypeface);
     }
 
-    mTypeface   = src.mTypeface;
-    mTextSize   = src.mTextSize;
-    mFakeBold   = src.mFakeBold;
+    mTypeface = src.mTypeface;
+    mEmSizeInFontUnits = src.mEmSizeInFontUnits;
+    mTextSize = src.mTextSize;
+    mFakeBold = src.mFakeBold;
     mFakeItalic = src.mFakeItalic;
     m_harfbuzzFace = src.m_harfbuzzFace;
     mOrientation = src.mOrientation;