xref: /external/skia/src/ports/SkFontHost_win.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 "SkString.h"
#include "SkEndian.h"
#include "SkFontHost.h"
#include "SkDescriptor.h"
#include "SkAdvancedTypefaceMetrics.h"
#include "SkStream.h"
#include "SkThread.h"
#include "SkTypeface_win.h"
#include "SkTypefaceCache.h"
#include "SkUtils.h"

#ifdef WIN32
#include "windows.h"
#include "tchar.h"
#include "Usp10.h"

// define this in your Makefile or .gyp to enforce AA requests
// which GDI ignores at small sizes. This flag guarantees AA
// for rotated text, regardless of GDI's notions.
//#define SK_ENFORCE_ROTATED_TEXT_AA_ON_WINDOWS

// client3d has to undefine this for now
#define CAN_USE_LOGFONT_NAME

static bool isLCD(const SkScalerContext::Rec& rec) {
    return SkMask::kLCD16_Format == rec.fMaskFormat ||
           SkMask::kLCD32_Format == rec.fMaskFormat;
}

static bool bothZero(SkScalar a, SkScalar b) {
    return 0 == a && 0 == b;
}

// returns false if there is any non-90-rotation or skew
static bool isAxisAligned(const SkScalerContext::Rec& rec) {
    return 0 == rec.fPreSkewX &&
           (bothZero(rec.fPost2x2[0][1], rec.fPost2x2[1][0]) ||
            bothZero(rec.fPost2x2[0][0], rec.fPost2x2[1][1]));
}

static bool needToRenderWithSkia(const SkScalerContext::Rec& rec) {
#ifdef SK_ENFORCE_ROTATED_TEXT_AA_ON_WINDOWS
    // What we really want to catch is when GDI will ignore the AA request and give
    // us BW instead. Smallish rotated text is one heuristic, so this code is just
    // an approximation. We shouldn't need to do this for larger sizes, but at those
    // sizes, the quality difference gets less and less between our general
    // scanconverter and GDI's.
    if (SkMask::kA8_Format == rec.fMaskFormat && !isAxisAligned(rec)) {
        return true;
    }
#endif
    // false means allow GDI to generate the bits
    return false;
}

using namespace skia_advanced_typeface_metrics_utils;

static const uint16_t BUFFERSIZE = (16384 - 32);
static uint8_t glyphbuf[BUFFERSIZE];

// Give 1MB font cache budget
#define FONT_CACHE_MEMORY_BUDGET    (1024 * 1024)

/**
 *  Since LOGFONT wants its textsize as an int, and we support fractional sizes,
 *  and since we have a cache of LOGFONTs for our tyepfaces, we always set the
 *  lfHeight to a canonical size, and then we use the 2x2 matrix to achieve the
 *  actual requested size.
 */
static const int gCanonicalTextSize = 64;

static void make_canonical(LOGFONT* lf) {
    lf->lfHeight = -gCanonicalTextSize;
    lf->lfQuality = CLEARTYPE_QUALITY;//PROOF_QUALITY;
    lf->lfCharSet = DEFAULT_CHARSET;
//    lf->lfClipPrecision = 64;
}

static SkTypeface::Style getStyle(const LOGFONT& lf) {
    unsigned style = 0;
    if (lf.lfWeight >= FW_BOLD) {
        style |= SkTypeface::kBold;
    }
    if (lf.lfItalic) {
        style |= SkTypeface::kItalic;
    }
    return (SkTypeface::Style)style;
}

static void setStyle(LOGFONT* lf, SkTypeface::Style style) {
    lf->lfWeight = (style & SkTypeface::kBold) != 0 ? FW_BOLD : FW_NORMAL ;
    lf->lfItalic = ((style & SkTypeface::kItalic) != 0);
}

static inline FIXED SkFixedToFIXED(SkFixed x) {
    return *(FIXED*)(&x);
}

static inline FIXED SkScalarToFIXED(SkScalar x) {
    return SkFixedToFIXED(SkScalarToFixed(x));
}

static unsigned calculateGlyphCount(HDC hdc) {
    // The 'maxp' table stores the number of glyphs at offset 4, in 2 bytes.
    const DWORD maxpTag =
        SkEndian_SwapBE32(SkSetFourByteTag('m', 'a', 'x', 'p'));
    uint16_t glyphs;
    if (GetFontData(hdc, maxpTag, 4, &glyphs, sizeof(glyphs)) != GDI_ERROR) {
        return SkEndian_SwapBE16(glyphs);
    }

    // Binary search for glyph count.
    static const MAT2 mat2 = {{0, 1}, {0, 0}, {0, 0}, {0, 1}};
    int32_t max = SK_MaxU16 + 1;
    int32_t min = 0;
    GLYPHMETRICS gm;
    while (min < max) {
        int32_t mid = min + ((max - min) / 2);
        if (GetGlyphOutlineW(hdc, mid, GGO_METRICS | GGO_GLYPH_INDEX, &gm, 0,
                             NULL, &mat2) == GDI_ERROR) {
            max = mid;
        } else {
            min = mid + 1;
        }
    }
    SkASSERT(min == max);
    return min;
}

static SkTypeface::Style GetFontStyle(const LOGFONT& lf) {
    int style = SkTypeface::kNormal;
    if (lf.lfWeight == FW_SEMIBOLD || lf.lfWeight == FW_DEMIBOLD || lf.lfWeight == FW_BOLD)
        style |= SkTypeface::kBold;
    if (lf.lfItalic)
        style |= SkTypeface::kItalic;

    return (SkTypeface::Style)style;
}

class LogFontTypeface : public SkTypeface {
public:
    LogFontTypeface(SkTypeface::Style style, SkFontID fontID, const LOGFONT& lf) :
      SkTypeface(style, fontID, false), fLogFont(lf) {}

    LOGFONT fLogFont;

    static LogFontTypeface* Create(const LOGFONT& lf) {
        SkTypeface::Style style = GetFontStyle(lf);
        SkFontID fontID = SkTypefaceCache::NewFontID();
        return new LogFontTypeface(style, fontID, lf);
    }
};

static const LOGFONT& get_default_font() {
    static LOGFONT gDefaultFont;
    return gDefaultFont;
}

static bool FindByLogFont(SkTypeface* face, SkTypeface::Style requestedStyle, void* ctx) {
    LogFontTypeface* lface = reinterpret_cast<LogFontTypeface*>(face);
    const LOGFONT* lf = reinterpret_cast<const LOGFONT*>(ctx);

    return getStyle(lface->fLogFont) == requestedStyle &&
           !memcmp(&lface->fLogFont, lf, sizeof(LOGFONT));
}

/**
 *  This guy is public. It first searches the cache, and if a match is not found,
 *  it creates a new face.
 */
SkTypeface* SkCreateTypefaceFromLOGFONT(const LOGFONT& origLF) {
    LOGFONT lf = origLF;
    make_canonical(&lf);
    SkTypeface* face = SkTypefaceCache::FindByProc(FindByLogFont, &lf);
    if (face) {
        face->ref();
    } else {
        face = LogFontTypeface::Create(lf);
        SkTypefaceCache::Add(face, getStyle(lf));
    }
    return face;
}

/**
 *  This guy is public
 */
void SkLOGFONTFromTypeface(const SkTypeface* face, LOGFONT* lf) {
    if (NULL == face) {
        *lf = get_default_font();
    } else {
        *lf = ((const LogFontTypeface*)face)->fLogFont;
    }
}

SkFontID SkFontHost::NextLogicalFont(SkFontID currFontID, SkFontID origFontID) {
  // Zero means that we don't have any fallback fonts for this fontID.
  // This function is implemented on Android, but doesn't have much
  // meaning here.
  return 0;
}

static void GetLogFontByID(SkFontID fontID, LOGFONT* lf) {
    LogFontTypeface* face = (LogFontTypeface*)SkTypefaceCache::FindByID(fontID);
    if (face) {
        *lf = face->fLogFont;
    } else {
        sk_bzero(lf, sizeof(LOGFONT));
    }
}

// Construct Glyph to Unicode table.
// Unicode code points that require conjugate pairs in utf16 are not
// supported.
// TODO(arthurhsu): Add support for conjugate pairs. It looks like that may
// require parsing the TTF cmap table (platform 4, encoding 12) directly instead
// of calling GetFontUnicodeRange().
static void populate_glyph_to_unicode(HDC fontHdc, const unsigned glyphCount,
                                      SkTDArray<SkUnichar>* glyphToUnicode) {
    DWORD glyphSetBufferSize = GetFontUnicodeRanges(fontHdc, NULL);
    if (!glyphSetBufferSize) {
        return;
    }

    SkAutoTDeleteArray<BYTE> glyphSetBuffer(new BYTE[glyphSetBufferSize]);
    GLYPHSET* glyphSet =
        reinterpret_cast<LPGLYPHSET>(glyphSetBuffer.get());
    if (GetFontUnicodeRanges(fontHdc, glyphSet) != glyphSetBufferSize) {
        return;
    }

    glyphToUnicode->setCount(glyphCount);
    memset(glyphToUnicode->begin(), 0, glyphCount * sizeof(SkUnichar));
    for (DWORD i = 0; i < glyphSet->cRanges; ++i) {
        // There is no guarantee that within a Unicode range, the corresponding
        // glyph id in a font file are continuous. So, even if we have ranges,
        // we can't just use the first and last entry of the range to compute
        // result. We need to enumerate them one by one.
        int count = glyphSet->ranges[i].cGlyphs;
        SkAutoTArray<WCHAR> chars(count + 1);
        chars[count] = 0;  // termintate string
        SkAutoTArray<WORD> glyph(count);
        for (USHORT j = 0; j < count; ++j) {
            chars[j] = glyphSet->ranges[i].wcLow + j;
        }
        GetGlyphIndicesW(fontHdc, chars.get(), count, glyph.get(),
                         GGI_MARK_NONEXISTING_GLYPHS);
        // If the glyph ID is valid, and the glyph is not mapped, then we will
        // fill in the char id into the vector. If the glyph is mapped already,
        // skip it.
        // TODO(arthurhsu): better improve this. e.g. Get all used char ids from
        // font cache, then generate this mapping table from there. It's
        // unlikely to have collisions since glyph reuse happens mostly for
        // different Unicode pages.
        for (USHORT j = 0; j < count; ++j) {
            if (glyph[j] != 0xffff && glyph[j] < glyphCount &&
                (*glyphToUnicode)[glyph[j]] == 0) {
                (*glyphToUnicode)[glyph[j]] = chars[j];
            }
        }
    }
}

//////////////////////////////////////////////////////////////////////////////////////

static int alignTo32(int n) {
    return (n + 31) & ~31;
}

struct MyBitmapInfo : public BITMAPINFO {
    RGBQUAD fMoreSpaceForColors[1];
};

class HDCOffscreen {
public:
    HDCOffscreen() {
        fFont = 0;
        fDC = 0;
        fBM = 0;
        fBits = NULL;
        fWidth = fHeight = 0;
        fIsBW = false;
        fColor = kInvalid_Color;
    }

    ~HDCOffscreen() {
        if (fDC) {
            DeleteDC(fDC);
        }
        if (fBM) {
            DeleteObject(fBM);
        }
    }

    void init(HFONT font, const XFORM& xform) {
        fFont = font;
        fXform = xform;
    }

    const void* draw(const SkGlyph&, bool isBW, bool whiteFG,
                     size_t* srcRBPtr);

private:
    HDC     fDC;
    HBITMAP fBM;
    HFONT   fFont;
    XFORM   fXform;
    void*   fBits;  // points into fBM
    COLORREF fColor;
    int     fWidth;
    int     fHeight;
    bool    fIsBW;

    enum {
        // will always trigger us to reset the color, since we
        // should only store 0 or 0xFFFFFF
        kInvalid_Color = 12345
    };
};

const void* HDCOffscreen::draw(const SkGlyph& glyph, bool isBW,
                               bool whiteFG, size_t* srcRBPtr) {
    if (0 == fDC) {
        fDC = CreateCompatibleDC(0);
        if (0 == fDC) {
            return NULL;
        }
        SetGraphicsMode(fDC, GM_ADVANCED);
        SetBkMode(fDC, TRANSPARENT);
        SetTextAlign(fDC, TA_LEFT | TA_BASELINE);
        SelectObject(fDC, fFont);
        fColor = kInvalid_Color;
    }

    if (fBM && (fIsBW != isBW || fWidth < glyph.fWidth || fHeight < glyph.fHeight)) {
        DeleteObject(fBM);
        fBM = 0;
    }
    fIsBW = isBW;

    COLORREF color = 0;
    if (fIsBW || whiteFG) {
        color = 0xFFFFFF;
    }
    if (fColor != color) {
        fColor = color;
        COLORREF prev = SetTextColor(fDC, color);
        SkASSERT(prev != CLR_INVALID);
    }

    fWidth = SkMax32(fWidth, glyph.fWidth);
    fHeight = SkMax32(fHeight, glyph.fHeight);

    int biWidth = isBW ? alignTo32(fWidth) : fWidth;

    if (0 == fBM) {
        MyBitmapInfo info;
        sk_bzero(&info, sizeof(info));
        if (isBW) {
            RGBQUAD blackQuad = { 0, 0, 0, 0 };
            RGBQUAD whiteQuad = { 0xFF, 0xFF, 0xFF, 0 };
            info.bmiColors[0] = blackQuad;
            info.bmiColors[1] = whiteQuad;
        }
        info.bmiHeader.biSize = sizeof(info.bmiHeader);
        info.bmiHeader.biWidth = biWidth;
        info.bmiHeader.biHeight = fHeight;
        info.bmiHeader.biPlanes = 1;
        info.bmiHeader.biBitCount = isBW ? 1 : 32;
        info.bmiHeader.biCompression = BI_RGB;
        if (isBW) {
            info.bmiHeader.biClrUsed = 2;
        }
        fBM = CreateDIBSection(fDC, &info, DIB_RGB_COLORS, &fBits, 0, 0);
        if (0 == fBM) {
            return NULL;
        }
        SelectObject(fDC, fBM);
    }

    // erase
    size_t srcRB = isBW ? (biWidth >> 3) : (fWidth << 2);
    size_t size = fHeight * srcRB;
    memset(fBits, ~color & 0xFF, size);

    XFORM xform = fXform;
    xform.eDx = (float)-glyph.fLeft;
    xform.eDy = (float)-glyph.fTop;
    SetWorldTransform(fDC, &xform);

    uint16_t glyphID = glyph.getGlyphID();
#if defined(UNICODE)
    ExtTextOut(fDC, 0, 0, ETO_GLYPH_INDEX, NULL, (LPCWSTR)&glyphID, 1, NULL);
#else
    ExtTextOut(fDC, 0, 0, ETO_GLYPH_INDEX, NULL, (LPCSTR)&glyphID, 1, NULL);
#endif
    GdiFlush();

    *srcRBPtr = srcRB;
    // offset to the start of the image
    return (const char*)fBits + (fHeight - glyph.fHeight) * srcRB;
}

//////////////////////////////////////////////////////////////////////////////////////

class SkScalerContext_Windows : public SkScalerContext {
public:
    SkScalerContext_Windows(const SkDescriptor* desc);
    virtual ~SkScalerContext_Windows();

protected:
    virtual unsigned generateGlyphCount();
    virtual uint16_t generateCharToGlyph(SkUnichar uni);
    virtual void generateAdvance(SkGlyph* glyph);
    virtual void generateMetrics(SkGlyph* glyph);
    virtual void generateImage(const SkGlyph& glyph);
    virtual void generatePath(const SkGlyph& glyph, SkPath* path);
    virtual void generateFontMetrics(SkPaint::FontMetrics* mX, SkPaint::FontMetrics* mY);

private:
    HDCOffscreen fOffscreen;
    SkScalar     fScale;  // to get from canonical size to real size
    MAT2         fMat22;
    XFORM        fXform;
    HDC          fDDC;
    HFONT        fSavefont;
    HFONT        fFont;
    SCRIPT_CACHE fSC;
    int          fGlyphCount;

    HFONT        fHiResFont;
    MAT2         fMat22Identity;
    SkMatrix     fHiResMatrix;
};

static float mul2float(SkScalar a, SkScalar b) {
    return SkScalarToFloat(SkScalarMul(a, b));
}

static FIXED float2FIXED(float x) {
    return SkFixedToFIXED(SkFloatToFixed(x));
}

static SkMutex gFTMutex;

#define HIRES_TEXTSIZE  2048
#define HIRES_SHIFT     11
static inline SkFixed HiResToFixed(int value) {
    return value << (16 - HIRES_SHIFT);
}

static bool needHiResMetrics(const SkScalar mat[2][2]) {
    return mat[1][0] || mat[0][1];
}

static BYTE compute_quality(const SkScalerContext::Rec& rec) {
    switch (rec.fMaskFormat) {
        case SkMask::kBW_Format:
            return NONANTIALIASED_QUALITY;
        case SkMask::kLCD16_Format:
        case SkMask::kLCD32_Format:
            return CLEARTYPE_QUALITY;
        default:
            return ANTIALIASED_QUALITY;
    }
}

SkScalerContext_Windows::SkScalerContext_Windows(const SkDescriptor* desc)
        : SkScalerContext(desc), fDDC(0), fFont(0), fSavefont(0), fSC(0)
        , fGlyphCount(-1) {
    SkAutoMutexAcquire  ac(gFTMutex);

    fScale = fRec.fTextSize / gCanonicalTextSize;

    fXform.eM11 = mul2float(fScale, fRec.fPost2x2[0][0]);
    fXform.eM12 = mul2float(fScale, fRec.fPost2x2[1][0]);
    fXform.eM21 = mul2float(fScale, fRec.fPost2x2[0][1]);
    fXform.eM22 = mul2float(fScale, fRec.fPost2x2[1][1]);
    fXform.eDx = 0;
    fXform.eDy = 0;

    fMat22.eM11 = float2FIXED(fXform.eM11);
    fMat22.eM12 = float2FIXED(fXform.eM12);
    fMat22.eM21 = float2FIXED(-fXform.eM21);
    fMat22.eM22 = float2FIXED(-fXform.eM22);

    fDDC = ::CreateCompatibleDC(NULL);
    SetGraphicsMode(fDDC, GM_ADVANCED);
    SetBkMode(fDDC, TRANSPARENT);

    // Scaling by the DPI is inconsistent with how Skia draws elsewhere
    //SkScalar height = -(fRec.fTextSize * GetDeviceCaps(ddc, LOGPIXELSY) / 72);
    LOGFONT lf;
    GetLogFontByID(fRec.fFontID, &lf);
    lf.lfHeight = -gCanonicalTextSize;
    lf.lfQuality = compute_quality(fRec);
    fFont = CreateFontIndirect(&lf);

    // if we're rotated, or want fractional widths, create a hires font
    fHiResFont = 0;
    if (needHiResMetrics(fRec.fPost2x2) || (fRec.fFlags & kSubpixelPositioning_Flag)) {
        lf.lfHeight = -HIRES_TEXTSIZE;
        fHiResFont = CreateFontIndirect(&lf);

        fMat22Identity.eM11 = fMat22Identity.eM22 = SkFixedToFIXED(SK_Fixed1);
        fMat22Identity.eM12 = fMat22Identity.eM21 = SkFixedToFIXED(0);

        // construct a matrix to go from HIRES logical units to our device units
        fRec.getSingleMatrix(&fHiResMatrix);
        SkScalar scale = SkScalarInvert(SkIntToScalar(HIRES_TEXTSIZE));
        fHiResMatrix.preScale(scale, scale);
    }
    fSavefont = (HFONT)SelectObject(fDDC, fFont);

    if (needToRenderWithSkia(fRec)) {
        this->forceGenerateImageFromPath();
    }

    fOffscreen.init(fFont, fXform);
}

SkScalerContext_Windows::~SkScalerContext_Windows() {
    if (fDDC) {
        ::SelectObject(fDDC, fSavefont);
        ::DeleteDC(fDDC);
    }
    if (fFont) {
        ::DeleteObject(fFont);
    }
    if (fHiResFont) {
        ::DeleteObject(fHiResFont);
    }
    if (fSC) {
        ::ScriptFreeCache(&fSC);
    }
}

unsigned SkScalerContext_Windows::generateGlyphCount() {
    if (fGlyphCount < 0) {
        fGlyphCount = calculateGlyphCount(fDDC);
    }
    return fGlyphCount;
}

uint16_t SkScalerContext_Windows::generateCharToGlyph(SkUnichar uni) {
    uint16_t index = 0;
    WCHAR c[2];
    // TODO(ctguil): Support characters that generate more than one glyph.
    if (SkUTF16_FromUnichar(uni, (uint16_t*)c) == 1) {
        // Type1 fonts fail with uniscribe API. Use GetGlyphIndices for plane 0.
        SkAssertResult(GetGlyphIndicesW(fDDC, c, 1, &index, 0));
    } else {
        // Use uniscribe to detemine glyph index for non-BMP characters.
        // Need to add extra item to SCRIPT_ITEM to work around a bug in older
        // windows versions. https://bugzilla.mozilla.org/show_bug.cgi?id=366643
        SCRIPT_ITEM si[2 + 1];
        int items;
        SkAssertResult(
            SUCCEEDED(ScriptItemize(c, 2, 2, NULL, NULL, si, &items)));

        WORD log[2];
        SCRIPT_VISATTR vsa;
        int glyphs;
        SkAssertResult(SUCCEEDED(ScriptShape(
            fDDC, &fSC, c, 2, 1, &si[0].a, &index, log, &vsa, &glyphs)));
    }
    return index;
}

void SkScalerContext_Windows::generateAdvance(SkGlyph* glyph) {
    this->generateMetrics(glyph);
}

void SkScalerContext_Windows::generateMetrics(SkGlyph* glyph) {

    SkASSERT(fDDC);

    GLYPHMETRICS gm;
    sk_bzero(&gm, sizeof(gm));

    glyph->fRsbDelta = 0;
    glyph->fLsbDelta = 0;

    // Note: need to use GGO_GRAY8_BITMAP instead of GGO_METRICS because GGO_METRICS returns a smaller
    // BlackBlox; we need the bigger one in case we need the image.  fAdvance is the same.
    uint32_t ret = GetGlyphOutlineW(fDDC, glyph->getGlyphID(0), GGO_GRAY8_BITMAP | GGO_GLYPH_INDEX, &gm, 0, NULL, &fMat22);

    if (GDI_ERROR != ret) {
        if (ret == 0) {
            // for white space, ret is zero and gmBlackBoxX, gmBlackBoxY are 1 incorrectly!
            gm.gmBlackBoxX = gm.gmBlackBoxY = 0;
        }
        glyph->fWidth   = gm.gmBlackBoxX;
        glyph->fHeight  = gm.gmBlackBoxY;
        glyph->fTop     = SkToS16(gm.gmptGlyphOrigin.y - gm.gmBlackBoxY);
        glyph->fLeft    = SkToS16(gm.gmptGlyphOrigin.x);
        glyph->fAdvanceX = SkIntToFixed(gm.gmCellIncX);
        glyph->fAdvanceY = -SkIntToFixed(gm.gmCellIncY);

        // we outset in all dimensions, since the image may bleed outside
        // of the computed bounds returned by GetGlyphOutline.
        // This was deduced by trial and error for small text (e.g. 8pt), so there
        // maybe a more precise way to make this adjustment...
        //
        // This test shows us clipping the tops of some of the CJK fonts unless we
        // increase the top of the box by 2, hence the height by 4. This seems to
        // correspond to an embedded bitmap font, but not sure.
        //     LayoutTests/fast/text/backslash-to-yen-sign-euc.html
        //
        if (glyph->fWidth) {    // don't outset an empty glyph
            glyph->fWidth += 4;
            glyph->fHeight += 4;
            glyph->fTop -= 2;
            glyph->fLeft -= 2;
        }

        if (fHiResFont) {
            SelectObject(fDDC, fHiResFont);
            sk_bzero(&gm, sizeof(gm));
            ret = GetGlyphOutlineW(fDDC, glyph->getGlyphID(0), GGO_METRICS | GGO_GLYPH_INDEX, &gm, 0, NULL, &fMat22Identity);
            if (GDI_ERROR != ret) {
                SkPoint advance;
                fHiResMatrix.mapXY(SkIntToScalar(gm.gmCellIncX), SkIntToScalar(gm.gmCellIncY), &advance);
                glyph->fAdvanceX = SkScalarToFixed(advance.fX);
                glyph->fAdvanceY = SkScalarToFixed(advance.fY);
            }
            SelectObject(fDDC, fFont);
        }
    } else {
        glyph->fWidth = 0;
    }
}

void SkScalerContext_Windows::generateFontMetrics(SkPaint::FontMetrics* mx, SkPaint::FontMetrics* my) {
// Note: This code was borrowed from generateLineHeight, which has a note
// stating that it may be incorrect.
    if (!(mx || my))
      return;

    SkASSERT(fDDC);

    OUTLINETEXTMETRIC otm;

    uint32_t ret = GetOutlineTextMetrics(fDDC, sizeof(otm), &otm);
    if (sizeof(otm) != ret) {
      return;
    }

    if (mx) {
        mx->fTop = -fScale * otm.otmTextMetrics.tmAscent;
        mx->fAscent = -fScale * otm.otmAscent;
        mx->fDescent = -fScale * otm.otmDescent;
        mx->fBottom = fScale * otm.otmTextMetrics.tmDescent;
        mx->fLeading = fScale * (otm.otmTextMetrics.tmInternalLeading
                                 + otm.otmTextMetrics.tmExternalLeading);
    }

    if (my) {
        my->fTop = -fScale * otm.otmTextMetrics.tmAscent;
        my->fAscent = -fScale * otm.otmAscent;
        my->fDescent = -fScale * otm.otmDescent;
        my->fBottom = fScale * otm.otmTextMetrics.tmDescent;
        my->fLeading = fScale * (otm.otmTextMetrics.tmInternalLeading
                                 + otm.otmTextMetrics.tmExternalLeading);
    }
}

#include "SkColorPriv.h"

// always packed xxRRGGBB
typedef uint32_t SkGdiRGB;

// gdi's bitmap is upside-down, so we reverse dst walking in Y
// whenever we copy it into skia's buffer

static inline uint8_t rgb_to_a8(SkGdiRGB rgb) {
    // can pick any component (low 3 bytes), since we're grayscale
    return rgb & 0xFF;
}

static inline uint16_t rgb_to_lcd16(SkGdiRGB rgb) {
    int r = (rgb >> 16) & 0xFF;
    int g = (rgb >>  8) & 0xFF;
    int b = (rgb >>  0) & 0xFF;
    return SkPackRGB16(SkR32ToR16(r), SkG32ToG16(g), SkB32ToB16(b));
}

static inline SkPMColor rgb_to_lcd32(SkGdiRGB rgb) {
    int r = (rgb >> 16) & 0xFF;
    int g = (rgb >>  8) & 0xFF;
    int b = (rgb >>  0) & 0xFF;
    int a = SkMax32(r, SkMax32(g, b));
    return SkPackARGB32(a, r, g, b);
}

// Is this GDI color neither black nor white? If so, we have to keep this
// image as is, rather than smashing it down to a BW mask.
//
// returns int instead of bool, since we don't want/have to pay to convert
// the zero/non-zero value into a bool
static int is_not_black_or_white(SkGdiRGB c) {
    // same as (but faster than)
    //      c &= 0x00FFFFFF;
    //      return 0 == c || 0x00FFFFFF == c;
    return (c + (c & 1)) & 0x00FFFFFF;
}

static bool is_rgb_really_bw(const SkGdiRGB* src, int width, int height, int srcRB) {
    for (int y = 0; y < height; ++y) {
        for (int x = 0; x < width; ++x) {
            if (is_not_black_or_white(src[x])) {
                return false;
            }
        }
        src = (const SkGdiRGB*)((const char*)src + srcRB);
    }
    return true;
}

static void rgb_to_bw(const SkGdiRGB* SK_RESTRICT src, size_t srcRB,
                      const SkGlyph& glyph, int32_t xorMask) {
    const int width = glyph.fWidth;
    const size_t dstRB = (width + 7) >> 3;
    uint8_t* SK_RESTRICT dst = (uint8_t*)((char*)glyph.fImage + (glyph.fHeight - 1) * dstRB);

    int byteCount = width >> 3;
    int bitCount = width & 7;

    // adjust srcRB to skip the values in our byteCount loop,
    // since we increment src locally there
    srcRB -= byteCount * 8 * sizeof(SkGdiRGB);

    for (int y = 0; y < glyph.fHeight; ++y) {
        if (byteCount > 0) {
            unsigned byte = 0;
            for (int i = 0; i < byteCount; ++i) {
                byte |= (src[0] ^ xorMask) & (1 << 7);
                byte |= (src[1] ^ xorMask) & (1 << 6);
                byte |= (src[2] ^ xorMask) & (1 << 5);
                byte |= (src[3] ^ xorMask) & (1 << 4);
                byte |= (src[4] ^ xorMask) & (1 << 3);
                byte |= (src[5] ^ xorMask) & (1 << 2);
                byte |= (src[6] ^ xorMask) & (1 << 1);
                byte |= (src[7] ^ xorMask) & (1 << 0);
                dst[i] = ~byte;
                src += 8;
            }
        }
        if (bitCount > 0) {
            unsigned byte = 0;
            unsigned mask = 0x80;
            for (int i = 0; i < bitCount; i++) {
                byte |= ~(src[i] ^ xorMask) & mask;
                mask >>= 1;
            }
            dst[byteCount] = byte;
        }
        src = (const SkGdiRGB*)((const char*)src + srcRB);
        dst -= dstRB;
    }
}

static void rgb_to_a8(const SkGdiRGB* SK_RESTRICT src, size_t srcRB,
                      const SkGlyph& glyph, int32_t xorMask) {
    const size_t dstRB = glyph.rowBytes();
    const int width = glyph.fWidth;
    uint8_t* SK_RESTRICT dst = (uint8_t*)((char*)glyph.fImage + (glyph.fHeight - 1) * dstRB);

    for (int y = 0; y < glyph.fHeight; y++) {
        for (int i = 0; i < width; i++) {
            dst[i] = rgb_to_a8(src[i] ^ xorMask);
        }
        src = (const SkGdiRGB*)((const char*)src + srcRB);
        dst -= dstRB;
    }
}

static void rgb_to_lcd16(const SkGdiRGB* SK_RESTRICT src, size_t srcRB,
                         const SkGlyph& glyph, int32_t xorMask) {
    const size_t dstRB = glyph.rowBytes();
    const int width = glyph.fWidth;
    uint16_t* SK_RESTRICT dst = (uint16_t*)((char*)glyph.fImage + (glyph.fHeight - 1) * dstRB);

    for (int y = 0; y < glyph.fHeight; y++) {
        for (int i = 0; i < width; i++) {
            dst[i] = rgb_to_lcd16(src[i] ^ xorMask);
        }
        src = (const SkGdiRGB*)((const char*)src + srcRB);
        dst = (uint16_t*)((char*)dst - dstRB);
    }
}

static void rgb_to_lcd32(const SkGdiRGB* SK_RESTRICT src, size_t srcRB,
                         const SkGlyph& glyph, int32_t xorMask) {
    const size_t dstRB = glyph.rowBytes();
    const int width = glyph.fWidth;
    SkPMColor* SK_RESTRICT dst = (SkPMColor*)((char*)glyph.fImage + (glyph.fHeight - 1) * dstRB);

    for (int y = 0; y < glyph.fHeight; y++) {
        for (int i = 0; i < width; i++) {
            dst[i] = rgb_to_lcd32(src[i] ^ xorMask);
        }
        src = (const SkGdiRGB*)((const char*)src + srcRB);
        dst = (SkPMColor*)((char*)dst - dstRB);
    }
}

void SkScalerContext_Windows::generateImage(const SkGlyph& glyph) {

    SkAutoMutexAcquire  ac(gFTMutex);

    SkASSERT(fDDC);

    const bool isBW = SkMask::kBW_Format == fRec.fMaskFormat;
    const bool isAA = !isLCD(fRec);
    const bool isWhite = SkToBool(fRec.fFlags & SkScalerContext::kGammaForWhite_Flag);
    const uint32_t rgbXOR = isWhite ? 0 : ~0;

    size_t srcRB;
    const void* bits = fOffscreen.draw(glyph, isBW, isWhite, &srcRB);
    if (!bits) {
        sk_bzero(glyph.fImage, glyph.computeImageSize());
        return;
    }

    int width = glyph.fWidth;
    size_t dstRB = glyph.rowBytes();
    if (isBW) {
        const uint8_t* src = (const uint8_t*)bits;
        uint8_t* dst = (uint8_t*)((char*)glyph.fImage + (glyph.fHeight - 1) * dstRB);
        for (int y = 0; y < glyph.fHeight; y++) {
            memcpy(dst, src, dstRB);
            src += srcRB;
            dst -= dstRB;
        }
    } else if (isAA) {
        const SkGdiRGB* src = (const SkGdiRGB*)bits;
#if 0 // can't do this (yet) since caller may really want gray8 for maskfilters
        if (is_rgb_really_bw(src, width, glyph.fHeight, srcRB)) {
            rgb_to_bw(src, srcRB, glyph);
            ((SkGlyph*)&glyph)->fMaskFormat = SkMask::kBW_Format;
        } else
#endif
        {
            rgb_to_a8(src, srcRB, glyph, rgbXOR);
        }
    } else {    // LCD16
        const SkGdiRGB* src = (const SkGdiRGB*)bits;
        if (is_rgb_really_bw(src, width, glyph.fHeight, srcRB)) {
            rgb_to_bw(src, srcRB, glyph, rgbXOR);
            ((SkGlyph*)&glyph)->fMaskFormat = SkMask::kBW_Format;
        } else {
            if (SkMask::kLCD16_Format == glyph.fMaskFormat) {
                rgb_to_lcd16(src, srcRB, glyph, rgbXOR);
            } else {
                SkASSERT(SkMask::kLCD32_Format == glyph.fMaskFormat);
                rgb_to_lcd32(src, srcRB, glyph, rgbXOR);
            }
        }
    }
}

void SkScalerContext_Windows::generatePath(const SkGlyph& glyph, SkPath* path) {

    SkAutoMutexAcquire  ac(gFTMutex);

    SkASSERT(&glyph && path);
    SkASSERT(fDDC);

    path->reset();

#if 0
    char buf[1024];
    sprintf(buf, "generatePath: id:%d, w=%d, h=%d, font:%s,fh:%d\n", glyph.fID, glyph.fWidth, glyph.fHeight, lf.lfFaceName, lf.lfHeight);
    OutputDebugString(buf);
#endif

    GLYPHMETRICS gm;
    uint32_t total_size = GetGlyphOutlineW(fDDC, glyph.fID, GGO_NATIVE | GGO_GLYPH_INDEX, &gm, BUFFERSIZE, glyphbuf, &fMat22);

    if (GDI_ERROR != total_size) {

        const uint8_t* cur_glyph = glyphbuf;
        const uint8_t* end_glyph = glyphbuf + total_size;

        while(cur_glyph < end_glyph) {
            const TTPOLYGONHEADER* th = (TTPOLYGONHEADER*)cur_glyph;

            const uint8_t* end_poly = cur_glyph + th->cb;
            const uint8_t* cur_poly = cur_glyph + sizeof(TTPOLYGONHEADER);

            path->moveTo(SkFixedToScalar(*(SkFixed*)(&th->pfxStart.x)), SkFixedToScalar(*(SkFixed*)(&th->pfxStart.y)));

            while(cur_poly < end_poly) {
                const TTPOLYCURVE* pc = (const TTPOLYCURVE*)cur_poly;

                if (pc->wType == TT_PRIM_LINE) {
                    for (uint16_t i = 0; i < pc->cpfx; i++) {
                        path->lineTo(SkFixedToScalar(*(SkFixed*)(&pc->apfx[i].x)), SkFixedToScalar(*(SkFixed*)(&pc->apfx[i].y)));
                    }
                }

                if (pc->wType == TT_PRIM_QSPLINE) {
                    for (uint16_t u = 0; u < pc->cpfx - 1; u++) { // Walk through points in spline
                        POINTFX pnt_b = pc->apfx[u];    // B is always the current point
                        POINTFX pnt_c = pc->apfx[u+1];

                        if (u < pc->cpfx - 2) {          // If not on last spline, compute C
                            pnt_c.x = SkFixedToFIXED(SkFixedAve(*(SkFixed*)(&pnt_b.x), *(SkFixed*)(&pnt_c.x)));
                            pnt_c.y = SkFixedToFIXED(SkFixedAve(*(SkFixed*)(&pnt_b.y), *(SkFixed*)(&pnt_c.y)));
                        }

                        path->quadTo(SkFixedToScalar(*(SkFixed*)(&pnt_b.x)), SkFixedToScalar(*(SkFixed*)(&pnt_b.y)), SkFixedToScalar(*(SkFixed*)(&pnt_c.x)), SkFixedToScalar(*(SkFixed*)(&pnt_c.y)));
                    }
                }
                cur_poly += sizeof(uint16_t) * 2 + sizeof(POINTFX) * pc->cpfx;
            }
            cur_glyph += th->cb;
            path->close();
        }
    }
    else {
        SkASSERT(false);
    }
    //char buf[1024];
    //sprintf(buf, "generatePath: count:%d\n", count);
    //OutputDebugString(buf);
}

void SkFontHost::Serialize(const SkTypeface* face, SkWStream* stream) {
    SkASSERT(!"SkFontHost::Serialize unimplemented");
}

SkTypeface* SkFontHost::Deserialize(SkStream* stream) {
    SkASSERT(!"SkFontHost::Deserialize unimplemented");
    return NULL;
}

static bool getWidthAdvance(HDC hdc, int gId, int16_t* advance) {
    // Initialize the MAT2 structure to the identify transformation matrix.
    static const MAT2 mat2 = {SkScalarToFIXED(1), SkScalarToFIXED(0),
                        SkScalarToFIXED(0), SkScalarToFIXED(1)};
    int flags = GGO_METRICS | GGO_GLYPH_INDEX;
    GLYPHMETRICS gm;
    if (GDI_ERROR == GetGlyphOutline(hdc, gId, flags, &gm, 0, NULL, &mat2)) {
        return false;
    }
    SkASSERT(advance);
    *advance = gm.gmCellIncX;
    return true;
}

// static
SkAdvancedTypefaceMetrics* SkFontHost::GetAdvancedTypefaceMetrics(
        uint32_t fontID,
        SkAdvancedTypefaceMetrics::PerGlyphInfo perGlyphInfo,
        const uint32_t* glyphIDs,
        uint32_t glyphIDsCount) {
    LOGFONT lf;
    GetLogFontByID(fontID, &lf);
    SkAdvancedTypefaceMetrics* info = NULL;

    HDC hdc = CreateCompatibleDC(NULL);
    HFONT font = CreateFontIndirect(&lf);
    HFONT savefont = (HFONT)SelectObject(hdc, font);
    HFONT designFont = NULL;

    // To request design units, create a logical font whose height is specified
    // as unitsPerEm.
    OUTLINETEXTMETRIC otm;
    if (!GetOutlineTextMetrics(hdc, sizeof(otm), &otm) ||
        !GetTextFace(hdc, LF_FACESIZE, lf.lfFaceName)) {
        goto Error;
    }
    lf.lfHeight = -SkToS32(otm.otmEMSquare);
    designFont = CreateFontIndirect(&lf);
    SelectObject(hdc, designFont);
    if (!GetOutlineTextMetrics(hdc, sizeof(otm), &otm)) {
        goto Error;
    }
    const unsigned glyphCount = calculateGlyphCount(hdc);

    info = new SkAdvancedTypefaceMetrics;
    info->fEmSize = otm.otmEMSquare;
    info->fMultiMaster = false;
    info->fLastGlyphID = SkToU16(glyphCount - 1);
    info->fStyle = 0;
#ifdef UNICODE
    // Get the buffer size needed first.
    size_t str_len = WideCharToMultiByte(CP_UTF8, 0, lf.lfFaceName, -1, NULL,
                                         0, NULL, NULL);
    // Allocate a buffer (str_len already has terminating null accounted for).
    char *familyName = new char[str_len];
    // Now actually convert the string.
    WideCharToMultiByte(CP_UTF8, 0, lf.lfFaceName, -1, familyName, str_len,
                          NULL, NULL);
    info->fFontName.set(familyName);
    delete [] familyName;
#else
    info->fFontName.set(lf.lfFaceName);
#endif

    if (perGlyphInfo & SkAdvancedTypefaceMetrics::kToUnicode_PerGlyphInfo) {
        populate_glyph_to_unicode(hdc, glyphCount, &(info->fGlyphToUnicode));
    }

    if (otm.otmTextMetrics.tmPitchAndFamily & TMPF_TRUETYPE) {
        info->fType = SkAdvancedTypefaceMetrics::kTrueType_Font;
    } else {
        info->fType = SkAdvancedTypefaceMetrics::kOther_Font;
        info->fItalicAngle = 0;
        info->fAscent = 0;
        info->fDescent = 0;
        info->fStemV = 0;
        info->fCapHeight = 0;
        info->fBBox = SkIRect::MakeEmpty();
        return info;
    }

    // If this bit is clear the font is a fixed pitch font.
    if (!(otm.otmTextMetrics.tmPitchAndFamily & TMPF_FIXED_PITCH)) {
        info->fStyle |= SkAdvancedTypefaceMetrics::kFixedPitch_Style;
    }
    if (otm.otmTextMetrics.tmItalic) {
        info->fStyle |= SkAdvancedTypefaceMetrics::kItalic_Style;
    }
    // Setting symbolic style by default for now.
    info->fStyle |= SkAdvancedTypefaceMetrics::kSymbolic_Style;
    if (otm.otmTextMetrics.tmPitchAndFamily & FF_ROMAN) {
        info->fStyle |= SkAdvancedTypefaceMetrics::kSerif_Style;
    } else if (otm.otmTextMetrics.tmPitchAndFamily & FF_SCRIPT) {
            info->fStyle |= SkAdvancedTypefaceMetrics::kScript_Style;
    }

    // The main italic angle of the font, in tenths of a degree counterclockwise
    // from vertical.
    info->fItalicAngle = otm.otmItalicAngle / 10;
    info->fAscent = SkToS16(otm.otmTextMetrics.tmAscent);
    info->fDescent = SkToS16(-otm.otmTextMetrics.tmDescent);
    // TODO(ctguil): Use alternate cap height calculation.
    // MSDN says otmsCapEmHeight is not support but it is returning a value on
    // my Win7 box.
    info->fCapHeight = otm.otmsCapEmHeight;
    info->fBBox =
        SkIRect::MakeLTRB(otm.otmrcFontBox.left, otm.otmrcFontBox.top,
                          otm.otmrcFontBox.right, otm.otmrcFontBox.bottom);

    // Figure out a good guess for StemV - Min width of i, I, !, 1.
    // This probably isn't very good with an italic font.
    int16_t min_width = SHRT_MAX;
    info->fStemV = 0;
    char stem_chars[] = {'i', 'I', '!', '1'};
    for (size_t i = 0; i < SK_ARRAY_COUNT(stem_chars); i++) {
        ABC abcWidths;
        if (GetCharABCWidths(hdc, stem_chars[i], stem_chars[i], &abcWidths)) {
            int16_t width = abcWidths.abcB;
            if (width > 0 && width < min_width) {
                min_width = width;
                info->fStemV = min_width;
            }
        }
    }

    // If bit 1 is set, the font may not be embedded in a document.
    // If bit 1 is clear, the font can be embedded.
    // If bit 2 is set, the embedding is read-only.
    if (otm.otmfsType & 0x1) {
        info->fType = SkAdvancedTypefaceMetrics::kNotEmbeddable_Font;
    } else if (perGlyphInfo &
               SkAdvancedTypefaceMetrics::kHAdvance_PerGlyphInfo) {
        if (info->fStyle & SkAdvancedTypefaceMetrics::kFixedPitch_Style) {
            appendRange(&info->fGlyphWidths, 0);
            info->fGlyphWidths->fAdvance.append(1, &min_width);
            finishRange(info->fGlyphWidths.get(), 0,
                        SkAdvancedTypefaceMetrics::WidthRange::kDefault);
        } else {
            info->fGlyphWidths.reset(
                getAdvanceData(hdc,
                               glyphCount,
                               glyphIDs,
                               glyphIDsCount,
                               &getWidthAdvance));
        }
    }

Error:
    SelectObject(hdc, savefont);
    DeleteObject(designFont);
    DeleteObject(font);
    DeleteDC(hdc);

    return info;
}

SkTypeface* SkFontHost::CreateTypefaceFromStream(SkStream* stream) {

    //Should not be used on Windows, keep linker happy
    SkASSERT(false);
    return SkCreateTypefaceFromLOGFONT(get_default_font());
}

SkStream* SkFontHost::OpenStream(SkFontID uniqueID) {
    const DWORD kTTCTag =
        SkEndian_SwapBE32(SkSetFourByteTag('t', 't', 'c', 'f'));
    LOGFONT lf;
    GetLogFontByID(uniqueID, &lf);

    HDC hdc = ::CreateCompatibleDC(NULL);
    HFONT font = CreateFontIndirect(&lf);
    HFONT savefont = (HFONT)SelectObject(hdc, font);

    SkMemoryStream* stream = NULL;
    DWORD tables[2] = {kTTCTag, 0};
    for (int i = 0; i < SK_ARRAY_COUNT(tables); i++) {
        size_t bufferSize = GetFontData(hdc, tables[i], 0, NULL, 0);
        if (bufferSize != GDI_ERROR) {
            stream = new SkMemoryStream(bufferSize);
            if (GetFontData(hdc, tables[i], 0, (void*)stream->getMemoryBase(),
                            bufferSize)) {
                break;
            } else {
                delete stream;
                stream = NULL;
            }
        }
    }

    SelectObject(hdc, savefont);
    DeleteObject(font);
    DeleteDC(hdc);

    return stream;
}

SkScalerContext* SkFontHost::CreateScalerContext(const SkDescriptor* desc) {
    return SkNEW_ARGS(SkScalerContext_Windows, (desc));
}

/** Return the closest matching typeface given either an existing family
 (specified by a typeface in that family) or by a familyName, and a
 requested style.
 1) If familyFace is null, use famillyName.
 2) If famillyName is null, use familyFace.
 3) If both are null, return the default font that best matches style
 This MUST not return NULL.
 */

SkTypeface* SkFontHost::CreateTypeface(const SkTypeface* familyFace,
                                       const char familyName[],
                                       const void* data, size_t bytelength,
                                       SkTypeface::Style style) {
    LOGFONT lf;
    if (NULL == familyFace && NULL == familyName) {
        lf = get_default_font();
    } else if (familyFace) {
        LogFontTypeface* face = (LogFontTypeface*)familyFace;
        lf = face->fLogFont;
    } else {
        memset(&lf, 0, sizeof(LOGFONT));
#ifdef UNICODE
        // Get the buffer size needed first.
        size_t str_len = ::MultiByteToWideChar(CP_UTF8, 0, familyName,
                                                -1, NULL, 0);
        // Allocate a buffer (str_len already has terminating null
        // accounted for).
        wchar_t *wideFamilyName = new wchar_t[str_len];
        // Now actually convert the string.
        ::MultiByteToWideChar(CP_UTF8, 0, familyName, -1,
                                wideFamilyName, str_len);
        ::wcsncpy(lf.lfFaceName, wideFamilyName, LF_FACESIZE);
        delete [] wideFamilyName;
#else
        ::strncpy(lf.lfFaceName, familyName, LF_FACESIZE);
#endif
        lf.lfFaceName[LF_FACESIZE-1] = '\0';
    }
    setStyle(&lf, style);
    return SkCreateTypefaceFromLOGFONT(lf);
}

size_t SkFontHost::ShouldPurgeFontCache(size_t sizeAllocatedSoFar) {
    if (sizeAllocatedSoFar > FONT_CACHE_MEMORY_BUDGET)
        return sizeAllocatedSoFar - FONT_CACHE_MEMORY_BUDGET;
    else
        return 0;   // nothing to do
}

SkTypeface* SkFontHost::CreateTypefaceFromFile(const char path[]) {
    printf("SkFontHost::CreateTypefaceFromFile unimplemented");
    return NULL;
}

void SkFontHost::FilterRec(SkScalerContext::Rec* rec) {
    unsigned flagsWeDontSupport = SkScalerContext::kDevKernText_Flag |
                                  SkScalerContext::kAutohinting_Flag |
                                  SkScalerContext::kEmbeddedBitmapText_Flag |
                                  SkScalerContext::kEmbolden_Flag |
                                  SkScalerContext::kLCD_BGROrder_Flag |
                                  SkScalerContext::kLCD_Vertical_Flag;
    rec->fFlags &= ~flagsWeDontSupport;

    SkPaint::Hinting h = rec->getHinting();

    // I think we can support no-hinting, if we get hires outlines and just
    // use skia to rasterize into a gray-scale mask...
#if 0
    switch (h) {
        case SkPaint::kNo_Hinting:
        case SkPaint::kSlight_Hinting:
            h = SkPaint::kNo_Hinting;
            break;
        case SkPaint::kNormal_Hinting:
        case SkPaint::kFull_Hinting:
            h = SkPaint::kNormal_Hinting;
            break;
        default:
            SkASSERT(!"unknown hinting");
    }
#else
    h = SkPaint::kNormal_Hinting;
#endif
    rec->setHinting(h);

// turn this off since GDI might turn A8 into BW! Need a bigger fix.
#if 0
    // Disable LCD when rotated, since GDI's output is ugly
    if (isLCD(*rec) && !isAxisAligned(*rec)) {
        rec->fMaskFormat = SkMask::kA8_Format;
    }
#endif

#if 0
    if (SkMask::kLCD16_Format == rec->fMaskFormat) {
        rec->fMaskFormat = SkMask::kLCD32_Format;
    }
#endif
    if (!isLCD(*rec)) {
        rec->fFlags &= ~(SkScalerContext::kGammaForBlack_Flag |
                         SkScalerContext::kGammaForWhite_Flag);
    }
}

//////////////////////////////////////////////////////////////////////////

void SkFontHost::GetGammaTables(const uint8_t* tables[2]) {
    tables[0] = NULL;
    tables[1] = NULL;
}

// If the luminance is <= this value, then apply the black gamma table
#define BLACK_GAMMA_THRESHOLD   0x40

// If the luminance is >= this value, then apply the white gamma table
#define WHITE_GAMMA_THRESHOLD   0xA0

int SkFontHost::ComputeGammaFlag(const SkPaint& paint) {
    if (paint.getShader() == NULL && paint.getColorFilter() == NULL) {
        SkColor c = paint.getColor();
        int r = SkColorGetR(c);
        int g = SkColorGetG(c);
        int b = SkColorGetB(c);
        int luminance = (r * 2 + g * 5 + b) >> 3;

#if 0   // we basically default to black, so don't need to return it
        if (luminance <= BLACK_GAMMA_THRESHOLD) {
            return SkScalerContext::kGammaForBlack_Flag;
        }
#endif
        if (luminance >= WHITE_GAMMA_THRESHOLD) {
            return SkScalerContext::kGammaForWhite_Flag;
        }
    }
    return 0;
}

#endif // WIN32