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 "SkAdvancedTypefaceMetrics.h"
#include "SkBase64.h"
#include "SkColorPriv.h"
#include "SkData.h"
#include "SkDescriptor.h"
#include "SkFontDescriptor.h"
#include "SkFontHost.h"
#include "SkGlyph.h"
#include "SkMaskGamma.h"
#include "SkOTTable_maxp.h"
#include "SkOTTable_name.h"
#include "SkOTUtils.h"
#include "SkPath.h"
#include "SkSFNTHeader.h"
#include "SkStream.h"
#include "SkString.h"
#include "SkTemplates.h"
#include "SkThread.h"
#include "SkTypeface_win.h"
#include "SkTypefaceCache.h"
#include "SkUtils.h"

#include "SkTypes.h"
#include <tchar.h>
#include <usp10.h>
#include <objbase.h>

static void (*gEnsureLOGFONTAccessibleProc)(const LOGFONT&);

void SkTypeface_SetEnsureLOGFONTAccessibleProc(void (*proc)(const LOGFONT&)) {
    gEnsureLOGFONTAccessibleProc = proc;
}

static void call_ensure_accessible(const LOGFONT& lf) {
    if (gEnsureLOGFONTAccessibleProc) {
        gEnsureLOGFONTAccessibleProc(lf);
    }
}

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

// always packed xxRRGGBB
typedef uint32_t SkGdiRGB;

// 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

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
    return rec.getHinting() == SkPaint::kNo_Hinting || rec.getHinting() == SkPaint::kSlight_Hinting;
}

using namespace skia_advanced_typeface_metrics_utils;

static void tchar_to_skstring(const TCHAR t[], SkString* s) {
#ifdef UNICODE
    size_t sSize = WideCharToMultiByte(CP_UTF8, 0, t, -1, NULL, 0, NULL, NULL);
    s->resize(sSize);
    WideCharToMultiByte(CP_UTF8, 0, t, -1, s->writable_str(), sSize, NULL, NULL);
#else
    s->set(t);
#endif
}

static void dcfontname_to_skstring(HDC deviceContext, const LOGFONT& lf, SkString* familyName) {
    int fontNameLen; //length of fontName in TCHARS.
    if (0 == (fontNameLen = GetTextFace(deviceContext, 0, NULL))) {
        call_ensure_accessible(lf);
        if (0 == (fontNameLen = GetTextFace(deviceContext, 0, NULL))) {
            fontNameLen = 0;
        }
    }

    SkAutoSTArray<LF_FULLFACESIZE, TCHAR> fontName(fontNameLen+1);
    if (0 == GetTextFace(deviceContext, fontNameLen, fontName.get())) {
        call_ensure_accessible(lf);
        if (0 == GetTextFace(deviceContext, fontNameLen, fontName.get())) {
            fontName[0] = 0;
        }
    }

    tchar_to_skstring(fontName.get(), familyName);
}

static void make_canonical(LOGFONT* lf) {
    lf->lfHeight = -2048;
    lf->lfQuality = CLEARTYPE_QUALITY;//PROOF_QUALITY;
    lf->lfCharSet = DEFAULT_CHARSET;
//    lf->lfClipPrecision = 64;
}

static SkTypeface::Style get_style(const LOGFONT& lf) {
    unsigned style = 0;
    if (lf.lfWeight >= FW_BOLD) {
        style |= SkTypeface::kBold;
    }
    if (lf.lfItalic) {
        style |= SkTypeface::kItalic;
    }
    return static_cast<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 SkFixed SkFIXEDToFixed(FIXED x) {
    return *(SkFixed*)(&x);
}

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

static unsigned calculateGlyphCount(HDC hdc, const LOGFONT& lf) {
    TEXTMETRIC textMetric;
    if (0 == GetTextMetrics(hdc, &textMetric)) {
        textMetric.tmPitchAndFamily = TMPF_VECTOR;
        call_ensure_accessible(lf);
        GetTextMetrics(hdc, &textMetric);
    }

    if (!(textMetric.tmPitchAndFamily & TMPF_VECTOR)) {
        return textMetric.tmLastChar;
    }

    // The 'maxp' table stores the number of glyphs at offset 4, in 2 bytes.
    uint16_t glyphs;
    if (GDI_ERROR != GetFontData(hdc, SkOTTableMaximumProfile::TAG, 4, &glyphs, sizeof(glyphs))) {
        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 unsigned calculateUPEM(HDC hdc, const LOGFONT& lf) {
    TEXTMETRIC textMetric;
    if (0 == GetTextMetrics(hdc, &textMetric)) {
        textMetric.tmPitchAndFamily = TMPF_VECTOR;
        call_ensure_accessible(lf);
        GetTextMetrics(hdc, &textMetric);
    }

    if (!(textMetric.tmPitchAndFamily & TMPF_VECTOR)) {
        return textMetric.tmMaxCharWidth;
    }

    OUTLINETEXTMETRIC otm;
    unsigned int otmRet = GetOutlineTextMetrics(hdc, sizeof(otm), &otm);
    if (0 == otmRet) {
        call_ensure_accessible(lf);
        otmRet = GetOutlineTextMetrics(hdc, sizeof(otm), &otm);
    }

    return (0 == otmRet) ? 0 : otm.otmEMSquare;
}

class LogFontTypeface : public SkTypeface {
public:
    LogFontTypeface(SkTypeface::Style style, SkFontID fontID, const LOGFONT& lf, bool serializeAsStream = false) :
        SkTypeface(style, fontID, false), fLogFont(lf), fSerializeAsStream(serializeAsStream) {

        // If the font has cubic outlines, it will not be rendered with ClearType.
        HFONT font = CreateFontIndirect(&lf);

        HDC deviceContext = ::CreateCompatibleDC(NULL);
        HFONT savefont = (HFONT)SelectObject(deviceContext, font);

        TEXTMETRIC textMetric;
        if (0 == GetTextMetrics(deviceContext, &textMetric)) {
            call_ensure_accessible(lf);
            if (0 == GetTextMetrics(deviceContext, &textMetric)) {
                textMetric.tmPitchAndFamily = TMPF_TRUETYPE;
            }
        }
        if (deviceContext) {
            ::SelectObject(deviceContext, savefont);
            ::DeleteDC(deviceContext);
        }
        if (font) {
            ::DeleteObject(font);
        }

        // The fixed pitch bit is set if the font is *not* fixed pitch.
        this->setIsFixedPitch((textMetric.tmPitchAndFamily & TMPF_FIXED_PITCH) == 0);

        // Used a logfont on a memory context, should never get a device font.
        // Therefore all TMPF_DEVICE will be PostScript (cubic) fonts.
        fCanBeLCD = !((textMetric.tmPitchAndFamily & TMPF_VECTOR) &&
                      (textMetric.tmPitchAndFamily & TMPF_DEVICE));
    }

    LOGFONT fLogFont;
    bool fSerializeAsStream;
    bool fCanBeLCD;

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

    static void EnsureAccessible(const SkTypeface* face) {
        call_ensure_accessible(static_cast<const LogFontTypeface*>(face)->fLogFont);
    }

protected:
    virtual SkStream* onOpenStream(int* ttcIndex) const SK_OVERRIDE;
    virtual SkScalerContext* onCreateScalerContext(const SkDescriptor*) const SK_OVERRIDE;
    virtual void onFilterRec(SkScalerContextRec*) const SK_OVERRIDE;
    virtual SkAdvancedTypefaceMetrics* onGetAdvancedTypefaceMetrics(
                                SkAdvancedTypefaceMetrics::PerGlyphInfo,
                                const uint32_t*, uint32_t) const SK_OVERRIDE;
    virtual void onGetFontDescriptor(SkFontDescriptor*, bool*) const SK_OVERRIDE;
    virtual int onCountGlyphs() const SK_OVERRIDE;
    virtual int onGetUPEM() const SK_OVERRIDE;
    virtual SkTypeface::LocalizedStrings* onCreateFamilyNameIterator() const SK_OVERRIDE;
    virtual int onGetTableTags(SkFontTableTag tags[]) const SK_OVERRIDE;
    virtual size_t onGetTableData(SkFontTableTag, size_t offset,
                                  size_t length, void* data) const SK_OVERRIDE;
    virtual SkTypeface* onRefMatchingStyle(Style) const SK_OVERRIDE;
};

class FontMemResourceTypeface : public LogFontTypeface {
public:
    /**
     *  Takes ownership of fontMemResource.
     */
    FontMemResourceTypeface(SkTypeface::Style style, SkFontID fontID, const LOGFONT& lf, HANDLE fontMemResource) :
        LogFontTypeface(style, fontID, lf, true), fFontMemResource(fontMemResource) {
    }

    HANDLE fFontMemResource;

    /**
     *  The created FontMemResourceTypeface takes ownership of fontMemResource.
     */
    static FontMemResourceTypeface* Create(const LOGFONT& lf, HANDLE fontMemResource) {
        SkTypeface::Style style = get_style(lf);
        SkFontID fontID = SkTypefaceCache::NewFontID();
        return new FontMemResourceTypeface(style, fontID, lf, fontMemResource);
    }

protected:
    virtual void weak_dispose() const SK_OVERRIDE {
        RemoveFontMemResourceEx(fFontMemResource);
        //SkTypefaceCache::Remove(this);
        INHERITED::weak_dispose();
    }

private:
    typedef LogFontTypeface INHERITED;
};

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

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

    return lface &&
           get_style(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::FindByProcAndRef(FindByLogFont, &lf);
    if (NULL == face) {
        face = LogFontTypeface::Create(lf);
        SkTypefaceCache::Add(face, get_style(lf));
    }
    return face;
}

/**
 *  The created SkTypeface takes ownership of fontMemResource.
 */
SkTypeface* SkCreateFontMemResourceTypefaceFromLOGFONT(const LOGFONT& origLF, HANDLE fontMemResource) {
    LOGFONT lf = origLF;
    make_canonical(&lf);
    FontMemResourceTypeface* face = FontMemResourceTypeface::Create(lf, fontMemResource);
    SkTypefaceCache::Add(face, get_style(lf), false);
    return face;
}

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

// 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;
    }

    ~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, size_t* srcRBPtr);

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

const void* HDCOffscreen::draw(const SkGlyph& glyph, bool isBW,
                               size_t* srcRBPtr) {
    // Can we share the scalercontext's fDDC, so we don't need to create
    // a separate fDC here?
    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);

        COLORREF color = 0x00FFFFFF;
        SkDEBUGCODE(COLORREF prev =) SetTextColor(fDC, color);
        SkASSERT(prev != CLR_INVALID);
    }

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

    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, 0, size);

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

    uint16_t glyphID = glyph.getGlyphID();
    BOOL ret = ExtTextOutW(fDC, 0, 0, ETO_GLYPH_INDEX, NULL, reinterpret_cast<LPCWSTR>(&glyphID), 1, NULL);
    GdiFlush();
    if (0 == ret) {
        return NULL;
    }
    *srcRBPtr = srcRB;
    // offset to the start of the image
    return (const char*)fBits + (fHeight - glyph.fHeight) * srcRB;
}

//////////////////////////////////////////////////////////////////////////////
#define BUFFERSIZE (1 << 13)

class SkScalerContext_GDI : public SkScalerContext {
public:
    SkScalerContext_GDI(SkTypeface*, const SkDescriptor* desc);
    virtual ~SkScalerContext_GDI();

    // Returns true if the constructor was able to complete all of its
    // initializations (which may include calling GDI).
    bool isValid() const;

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

private:
    DWORD getGDIGlyphPath(const SkGlyph& glyph, UINT flags,
                          SkAutoSTMalloc<BUFFERSIZE, uint8_t>* glyphbuf);

    HDCOffscreen fOffscreen;
    /** fGsA is the non-rotational part of total matrix without the text height scale.
     *  Used to find the magnitude of advances.
     */
    MAT2         fGsA;
    /** The total matrix without the textSize. */
    MAT2         fMat22;
    /** Scales font to EM size. */
    MAT2         fHighResMat22;
    HDC          fDDC;
    HFONT        fSavefont;
    HFONT        fFont;
    SCRIPT_CACHE fSC;
    int          fGlyphCount;

    /** The total matrix which also removes EM scale. */
    SkMatrix     fHiResMatrix;
    /** fG_inv is the inverse of the rotational part of the total matrix.
     *  Used to set the direction of advances.
     */
    SkMatrix     fG_inv;
    enum Type {
        kTrueType_Type, kBitmap_Type,
    } fType;
    TEXTMETRIC fTM;
};

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

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:
            if (rec.fFlags & SkScalerContext::kGenA8FromLCD_Flag) {
                return CLEARTYPE_QUALITY;
            } else {
                return ANTIALIASED_QUALITY;
            }
    }
}

SkScalerContext_GDI::SkScalerContext_GDI(SkTypeface* rawTypeface,
                                                 const SkDescriptor* desc)
        : SkScalerContext(rawTypeface, desc)
        , fDDC(0)
        , fSavefont(0)
        , fFont(0)
        , fSC(0)
        , fGlyphCount(-1)
{
    LogFontTypeface* typeface = reinterpret_cast<LogFontTypeface*>(rawTypeface);

    fDDC = ::CreateCompatibleDC(NULL);
    if (!fDDC) {
        return;
    }
    SetGraphicsMode(fDDC, GM_ADVANCED);
    SetBkMode(fDDC, TRANSPARENT);

    SkPoint h = SkPoint::Make(SK_Scalar1, 0);
    // A is the total matrix.
    SkMatrix A;
    fRec.getSingleMatrix(&A);
    A.mapPoints(&h, 1);

    // Find the Given's matrix [[c, -s],[s, c]] which rotates the baseline vector h
    // (where the baseline is mapped to) to the positive horizontal axis.
    const SkScalar& a = h.fX;
    const SkScalar& b = h.fY;
    SkScalar c, s;
    if (0 == b) {
        c = SkDoubleToScalar(_copysign(SK_Scalar1, a));
        s = 0;
    } else if (0 == a) {
        c = 0;
        s = SkDoubleToScalar(-_copysign(SK_Scalar1, b));
    } else if (SkScalarAbs(b) > SkScalarAbs(a)) {
        SkScalar t = a / b;
        SkScalar u = SkDoubleToScalar(_copysign(SkScalarSqrt(SK_Scalar1 + t*t), b));
        s = -1 / u;
        c = -s * t;
    } else {
        SkScalar t = b / a;
        SkScalar u = SkDoubleToScalar(_copysign(SkScalarSqrt(SK_Scalar1 + t*t), a));
        c = 1 / u;
        s = -c * t;
    }

    // G is the Given's Matrix for A (rotational matrix such that GA[0][1] == 0).
    SkMatrix G;
    G.setAll(c, -s, 0,
             s,  c, 0,
             0,  0, SkScalarToPersp(SK_Scalar1));

    // GA is the matrix A with rotation removed.
    SkMatrix GA(G);
    GA.preConcat(A);

    // textSize is the actual device size we want (as opposed to the size the user requested).
    // If the scale is negative, this means the matrix will do the flip anyway.
    SkScalar textSize = SkScalarAbs(SkScalarRoundToScalar(GA.get(SkMatrix::kMScaleY)));
    if (textSize == 0) {
        textSize = SK_Scalar1;
    }

    // sA is the total matrix A without the textSize (so GDI knows the text size separately).
    // When this matrix is used with GetGlyphOutline, no further processing is needed.
    SkMatrix sA(A);
    SkScalar scale = SkScalarInvert(textSize);
    sA.preScale(scale, scale); //remove text size

    // GsA is the non-rotational part of A without the text height scale.
    // This is what is used to find the magnitude of advances.
    SkMatrix GsA(GA);
    GsA.preScale(scale, scale); //remove text size, G is rotational so reorders with the scale.

    fGsA.eM11 = SkScalarToFIXED(GsA.get(SkMatrix::kMScaleX));
    fGsA.eM12 = SkScalarToFIXED(-GsA.get(SkMatrix::kMSkewY)); // This should be ~0.
    fGsA.eM21 = SkScalarToFIXED(-GsA.get(SkMatrix::kMSkewX));
    fGsA.eM22 = SkScalarToFIXED(GsA.get(SkMatrix::kMScaleY));

    // fG_inv is G inverse, which is fairly simple since G is 2x2 rotational.
    fG_inv.setAll(G.get(SkMatrix::kMScaleX), -G.get(SkMatrix::kMSkewX), G.get(SkMatrix::kMTransX),
                  -G.get(SkMatrix::kMSkewY), G.get(SkMatrix::kMScaleY), G.get(SkMatrix::kMTransY),
                  G.get(SkMatrix::kMPersp0), G.get(SkMatrix::kMPersp1), G.get(SkMatrix::kMPersp2));

    LOGFONT lf = typeface->fLogFont;
    lf.lfHeight = -SkScalarTruncToInt(textSize);
    lf.lfQuality = compute_quality(fRec);
    fFont = CreateFontIndirect(&lf);
    if (!fFont) {
        return;
    }

    fSavefont = (HFONT)SelectObject(fDDC, fFont);

    if (0 == GetTextMetrics(fDDC, &fTM)) {
        call_ensure_accessible(lf);
        if (0 == GetTextMetrics(fDDC, &fTM)) {
            fTM.tmPitchAndFamily = TMPF_TRUETYPE;
        }
    }
    // Used a logfont on a memory context, should never get a device font.
    // Therefore all TMPF_DEVICE will be PostScript fonts.

    // If TMPF_VECTOR is set, one of TMPF_TRUETYPE or TMPF_DEVICE must be set,
    // otherwise we have a vector FON, which we don't support.
    // This was determined by testing with Type1 PFM/PFB and OpenTypeCFF OTF,
    // as well as looking at Wine bugs and sources.
    SkASSERT(!(fTM.tmPitchAndFamily & TMPF_VECTOR) ||
              (fTM.tmPitchAndFamily & (TMPF_TRUETYPE | TMPF_DEVICE)));

    XFORM xform;
    if (fTM.tmPitchAndFamily & TMPF_VECTOR) {
        // Truetype or PostScript.
        // Stroked FON also gets here (TMPF_VECTOR), but we don't handle it.
        fType = SkScalerContext_GDI::kTrueType_Type;

        // fPost2x2 is column-major, left handed (y down).
        // XFORM 2x2 is row-major, left handed (y down).
        xform.eM11 = SkScalarToFloat(sA.get(SkMatrix::kMScaleX));
        xform.eM12 = SkScalarToFloat(sA.get(SkMatrix::kMSkewY));
        xform.eM21 = SkScalarToFloat(sA.get(SkMatrix::kMSkewX));
        xform.eM22 = SkScalarToFloat(sA.get(SkMatrix::kMScaleY));
        xform.eDx = 0;
        xform.eDy = 0;

        // MAT2 is row major, right handed (y up).
        fMat22.eM11 = float2FIXED(xform.eM11);
        fMat22.eM12 = float2FIXED(-xform.eM12);
        fMat22.eM21 = float2FIXED(-xform.eM21);
        fMat22.eM22 = float2FIXED(xform.eM22);

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

        // Create a hires font if we need linear metrics.
        if (this->isSubpixel()) {
            OUTLINETEXTMETRIC otm;
            UINT success = GetOutlineTextMetrics(fDDC, sizeof(otm), &otm);
            if (0 == success) {
                call_ensure_accessible(lf);
                success = GetOutlineTextMetrics(fDDC, sizeof(otm), &otm);
            }
            if (0 != success) {
                SkScalar scale = SkIntToScalar(otm.otmEMSquare);

                SkScalar textScale = scale / textSize;
                fHighResMat22.eM11 = float2FIXED(textScale);
                fHighResMat22.eM12 = float2FIXED(0);
                fHighResMat22.eM21 = float2FIXED(0);
                fHighResMat22.eM22 = float2FIXED(textScale);

                SkScalar invScale = SkScalarInvert(scale);
                fHiResMatrix = A;
                fHiResMatrix.preScale(invScale, invScale);
            }
        }

    } else {
        // Assume bitmap
        fType = SkScalerContext_GDI::kBitmap_Type;

        xform.eM11 = 1.0f;
        xform.eM12 = 0.0f;
        xform.eM21 = 0.0f;
        xform.eM22 = 1.0f;
        xform.eDx = 0.0f;
        xform.eDy = 0.0f;

        // fPost2x2 is column-major, left handed (y down).
        // MAT2 is row major, right handed (y up).
        fMat22.eM11 = SkScalarToFIXED(fRec.fPost2x2[0][0]);
        fMat22.eM12 = SkScalarToFIXED(-fRec.fPost2x2[1][0]);
        fMat22.eM21 = SkScalarToFIXED(-fRec.fPost2x2[0][1]);
        fMat22.eM22 = SkScalarToFIXED(fRec.fPost2x2[1][1]);
    }

    fOffscreen.init(fFont, xform);
}

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

bool SkScalerContext_GDI::isValid() const {
    return fDDC && fFont;
}

unsigned SkScalerContext_GDI::generateGlyphCount() {
    if (fGlyphCount < 0) {
        fGlyphCount = calculateGlyphCount(
                          fDDC, static_cast<const LogFontTypeface*>(this->getTypeface())->fLogFont);
    }
    return fGlyphCount;
}

uint16_t SkScalerContext_GDI::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_GDI::generateAdvance(SkGlyph* glyph) {
    this->generateMetrics(glyph);
}

void SkScalerContext_GDI::generateMetrics(SkGlyph* glyph) {
    SkASSERT(fDDC);

    if (fType == SkScalerContext_GDI::kBitmap_Type) {
        SIZE size;
        WORD glyphs = glyph->getGlyphID(0);
        if (0 == GetTextExtentPointI(fDDC, &glyphs, 1, &size)) {
            glyph->fWidth = SkToS16(fTM.tmMaxCharWidth);
        } else {
            glyph->fWidth = SkToS16(size.cx);
        }
        glyph->fHeight = SkToS16(size.cy);

        glyph->fTop = SkToS16(-fTM.tmAscent);
        glyph->fLeft = SkToS16(0);
        glyph->fAdvanceX = SkIntToFixed(glyph->fWidth);
        glyph->fAdvanceY = 0;

        // Apply matrix to advance.
        glyph->fAdvanceY = SkFixedMul(SkFIXEDToFixed(fMat22.eM21), glyph->fAdvanceX);
        glyph->fAdvanceX = SkFixedMul(SkFIXEDToFixed(fMat22.eM11), glyph->fAdvanceX);

        return;
    }

    UINT glyphId = glyph->getGlyphID(0);

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

    DWORD status = GetGlyphOutlineW(fDDC, glyphId, GGO_METRICS | GGO_GLYPH_INDEX, &gm, 0, NULL, &fMat22);
    if (GDI_ERROR == status) {
        LogFontTypeface::EnsureAccessible(this->getTypeface());
        status = GetGlyphOutlineW(fDDC, glyphId, GGO_METRICS | GGO_GLYPH_INDEX, &gm, 0, NULL, &fMat22);
        if (GDI_ERROR == status) {
            glyph->zeroMetrics();
            return;
        }
    }

    bool empty = false;
    // The black box is either the embedded bitmap size or the outline extent.
    // It is 1x1 if nothing is to be drawn, but will also be 1x1 if something very small
    // is to be drawn, like a '.'. We need to outset '.' but do not wish to outset ' '.
    if (1 == gm.gmBlackBoxX && 1 == gm.gmBlackBoxY) {
        // If GetGlyphOutline with GGO_NATIVE returns 0, we know there was no outline.
        DWORD bufferSize = GetGlyphOutlineW(fDDC, glyphId, GGO_NATIVE | GGO_GLYPH_INDEX, &gm, 0, NULL, &fMat22);
        empty = (0 == bufferSize);
    }

    glyph->fTop = SkToS16(-gm.gmptGlyphOrigin.y);
    glyph->fLeft = SkToS16(gm.gmptGlyphOrigin.x);
    if (empty) {
        glyph->fWidth = 0;
        glyph->fHeight = 0;
    } else {
        // Outset, since the image may bleed out of the black box.
        // For embedded bitmaps the black box should be exact.
        // For outlines we need to outset by 1 in all directions for bleed.
        // For ClearType we need to outset by 2 for bleed.
        glyph->fWidth = gm.gmBlackBoxX + 4;
        glyph->fHeight = gm.gmBlackBoxY + 4;
        glyph->fTop -= 2;
        glyph->fLeft -= 2;
    }
    glyph->fAdvanceX = SkIntToFixed(gm.gmCellIncX);
    glyph->fAdvanceY = SkIntToFixed(gm.gmCellIncY);
    glyph->fRsbDelta = 0;
    glyph->fLsbDelta = 0;

    if (this->isSubpixel()) {
        sk_bzero(&gm, sizeof(gm));
        status = GetGlyphOutlineW(fDDC, glyphId, GGO_METRICS | GGO_GLYPH_INDEX, &gm, 0, NULL, &fHighResMat22);
        if (GDI_ERROR != status) {
            SkPoint advance;
            fHiResMatrix.mapXY(SkIntToScalar(gm.gmCellIncX), SkIntToScalar(gm.gmCellIncY), &advance);
            glyph->fAdvanceX = SkScalarToFixed(advance.fX);
            glyph->fAdvanceY = SkScalarToFixed(advance.fY);
        }
    } else if (!isAxisAligned(this->fRec)) {
        status = GetGlyphOutlineW(fDDC, glyphId, GGO_METRICS | GGO_GLYPH_INDEX, &gm, 0, NULL, &fGsA);
        if (GDI_ERROR != status) {
            SkPoint advance;
            fG_inv.mapXY(SkIntToScalar(gm.gmCellIncX), SkIntToScalar(gm.gmCellIncY), &advance);
            glyph->fAdvanceX = SkScalarToFixed(advance.fX);
            glyph->fAdvanceY = SkScalarToFixed(advance.fY);
        }
    }
}

static const MAT2 gMat2Identity = {{0, 1}, {0, 0}, {0, 0}, {0, 1}};
void SkScalerContext_GDI::generateFontMetrics(SkPaint::FontMetrics* mx, SkPaint::FontMetrics* my) {
    if (!(mx || my)) {
      return;
    }

    if (mx) {
        sk_bzero(mx, sizeof(*mx));
    }
    if (my) {
        sk_bzero(my, sizeof(*my));
    }

    SkASSERT(fDDC);

#ifndef SK_GDI_ALWAYS_USE_TEXTMETRICS_FOR_FONT_METRICS
    if (fType == SkScalerContext_GDI::kBitmap_Type) {
#endif
        if (mx) {
            mx->fTop = SkIntToScalar(-fTM.tmAscent);
            mx->fAscent = SkIntToScalar(-fTM.tmAscent);
            mx->fDescent = SkIntToScalar(fTM.tmDescent);
            mx->fBottom = SkIntToScalar(fTM.tmDescent);
            mx->fLeading = SkIntToScalar(fTM.tmExternalLeading);
        }

        if (my) {
            my->fTop = SkIntToScalar(-fTM.tmAscent);
            my->fAscent = SkIntToScalar(-fTM.tmAscent);
            my->fDescent = SkIntToScalar(fTM.tmDescent);
            my->fBottom = SkIntToScalar(fTM.tmDescent);
            my->fLeading = SkIntToScalar(fTM.tmExternalLeading);
            my->fAvgCharWidth = SkIntToScalar(fTM.tmAveCharWidth);
            my->fMaxCharWidth = SkIntToScalar(fTM.tmMaxCharWidth);
            my->fXMin = 0;
            my->fXMax = my->fMaxCharWidth;
            //my->fXHeight = 0;
        }
#ifndef SK_GDI_ALWAYS_USE_TEXTMETRICS_FOR_FONT_METRICS
        return;
    }
#endif

    OUTLINETEXTMETRIC otm;

    uint32_t ret = GetOutlineTextMetrics(fDDC, sizeof(otm), &otm);
    if (0 == ret) {
        LogFontTypeface::EnsureAccessible(this->getTypeface());
        ret = GetOutlineTextMetrics(fDDC, sizeof(otm), &otm);
    }
    if (0 == ret) {
        return;
    }

    if (mx) {
        mx->fTop = SkIntToScalar(-otm.otmrcFontBox.left);
        mx->fAscent = SkIntToScalar(-otm.otmAscent);
        mx->fDescent = SkIntToScalar(-otm.otmDescent);
        mx->fBottom = SkIntToScalar(otm.otmrcFontBox.right);
        mx->fLeading = SkIntToScalar(otm.otmLineGap);
    }

    if (my) {
#ifndef SK_GDI_ALWAYS_USE_TEXTMETRICS_FOR_FONT_METRICS
        my->fTop = SkIntToScalar(-otm.otmrcFontBox.top);
        my->fAscent = SkIntToScalar(-otm.otmAscent);
        my->fDescent = SkIntToScalar(-otm.otmDescent);
        my->fBottom = SkIntToScalar(-otm.otmrcFontBox.bottom);
        my->fLeading = SkIntToScalar(otm.otmLineGap);
        my->fAvgCharWidth = SkIntToScalar(otm.otmTextMetrics.tmAveCharWidth);
        my->fMaxCharWidth = SkIntToScalar(otm.otmTextMetrics.tmMaxCharWidth);
        my->fXMin = SkIntToScalar(otm.otmrcFontBox.left);
        my->fXMax = SkIntToScalar(otm.otmrcFontBox.right);
#endif
        my->fXHeight = SkIntToScalar(otm.otmsXHeight);

        GLYPHMETRICS gm;
        sk_bzero(&gm, sizeof(gm));
        DWORD len = GetGlyphOutlineW(fDDC, 'x', GGO_METRICS, &gm, 0, 0, &gMat2Identity);
        if (len != GDI_ERROR && gm.gmBlackBoxY > 0) {
            my->fXHeight = SkIntToScalar(gm.gmBlackBoxY);
        }
    }
}

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

#define SK_SHOW_TEXT_BLIT_COVERAGE 0

static void build_power_table(uint8_t table[], float ee) {
    for (int i = 0; i < 256; i++) {
        float x = i / 255.f;
        x = sk_float_pow(x, ee);
        int xx = SkScalarRound(SkFloatToScalar(x * 255));
        table[i] = SkToU8(xx);
    }
}

/**
 *  This will invert the gamma applied by GDI (gray-scale antialiased), so we
 *  can get linear values.
 *
 *  GDI grayscale appears to use a hard-coded gamma of 2.3.
 *
 *  GDI grayscale appears to draw using the black and white rasterizer at four
 *  times the size and then downsamples to compute the coverage mask. As a
 *  result there are only seventeen total grays. This lack of fidelity means
 *  that shifting into other color spaces is imprecise.
 */
static const uint8_t* getInverseGammaTableGDI() {
    // Since build_power_table is idempotent, many threads can build gTableGdi
    // simultaneously.

    // Microsoft Specific:
    // Making gInited volatile provides read-aquire and write-release in vc++.
    // In VS2012, see compiler option /volatile:(ms|iso).
    // Replace with C++11 atomics when possible.
    static volatile bool gInited;
    static uint8_t gTableGdi[256];
    if (gInited) {
        // Need a L/L (read) barrier (full acquire not needed). If gInited is observed
        // true then gTableGdi is observable, but it must be requested.
    } else {
        build_power_table(gTableGdi, 2.3f);
        // Need a S/S (write) barrier (full release not needed) here so that this
        // write to gInited becomes observable after gTableGdi.
        gInited = true;
    }
    return gTableGdi;
}

/**
 *  This will invert the gamma applied by GDI ClearType, so we can get linear
 *  values.
 *
 *  GDI ClearType uses SPI_GETFONTSMOOTHINGCONTRAST / 1000 as the gamma value.
 *  If this value is not specified, the default is a gamma of 1.4.
 */
static const uint8_t* getInverseGammaTableClearType() {
    // We don't expect SPI_GETFONTSMOOTHINGCONTRAST to ever change, so building
    // gTableClearType with build_power_table is effectively idempotent.

    // Microsoft Specific:
    // Making gInited volatile provides read-aquire and write-release in vc++.
    // In VS2012, see compiler option /volatile:(ms|iso).
    // Replace with C++11 atomics when possible.
    static volatile bool gInited;
    static uint8_t gTableClearType[256];
    if (gInited) {
        // Need a L/L (read) barrier (acquire not needed). If gInited is observed
        // true then gTableClearType is observable, but it must be requested.
    } else {
        UINT level = 0;
        if (!SystemParametersInfo(SPI_GETFONTSMOOTHINGCONTRAST, 0, &level, 0) || !level) {
            // can't get the data, so use a default
            level = 1400;
        }
        build_power_table(gTableClearType, level / 1000.0f);
        // Need a S/S (write) barrier (release not needed) here so that this
        // write to gInited becomes observable after gTableClearType.
        gInited = true;
    }
    return gTableClearType;
}

#include "SkColorPriv.h"

//Cannot assume that the input rgb is gray due to possible setting of kGenA8FromLCD_Flag.
template<bool APPLY_PREBLEND>
static inline uint8_t rgb_to_a8(SkGdiRGB rgb, const uint8_t* table8) {
    U8CPU r = (rgb >> 16) & 0xFF;
    U8CPU g = (rgb >>  8) & 0xFF;
    U8CPU b = (rgb >>  0) & 0xFF;
    return sk_apply_lut_if<APPLY_PREBLEND>(SkComputeLuminance(r, g, b), table8);
}

template<bool APPLY_PREBLEND>
static inline uint16_t rgb_to_lcd16(SkGdiRGB rgb, const uint8_t* tableR,
                                                  const uint8_t* tableG,
                                                  const uint8_t* tableB) {
    U8CPU r = sk_apply_lut_if<APPLY_PREBLEND>((rgb >> 16) & 0xFF, tableR);
    U8CPU g = sk_apply_lut_if<APPLY_PREBLEND>((rgb >>  8) & 0xFF, tableG);
    U8CPU b = sk_apply_lut_if<APPLY_PREBLEND>((rgb >>  0) & 0xFF, tableB);
#if SK_SHOW_TEXT_BLIT_COVERAGE
    r = SkMax32(r, 10); g = SkMax32(g, 10); b = SkMax32(b, 10);
#endif
    return SkPack888ToRGB16(r, g, b);
}

template<bool APPLY_PREBLEND>
static inline SkPMColor rgb_to_lcd32(SkGdiRGB rgb, const uint8_t* tableR,
                                                   const uint8_t* tableG,
                                                   const uint8_t* tableB) {
    U8CPU r = sk_apply_lut_if<APPLY_PREBLEND>((rgb >> 16) & 0xFF, tableR);
    U8CPU g = sk_apply_lut_if<APPLY_PREBLEND>((rgb >>  8) & 0xFF, tableG);
    U8CPU b = sk_apply_lut_if<APPLY_PREBLEND>((rgb >>  0) & 0xFF, tableB);
#if SK_SHOW_TEXT_BLIT_COVERAGE
    r = SkMax32(r, 10); g = SkMax32(g, 10); b = SkMax32(b, 10);
#endif
    return SkPackARGB32(0xFF, 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, size_t 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 = SkTAddOffset<const SkGdiRGB>(src, srcRB);
    }
    return true;
}

// gdi's bitmap is upside-down, so we reverse dst walking in Y
// whenever we copy it into skia's buffer
static void rgb_to_bw(const SkGdiRGB* SK_RESTRICT src, size_t srcRB,
                      const SkGlyph& glyph) {
    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) {
            for (int i = 0; i < byteCount; ++i) {
                unsigned byte = 0;
                byte |= src[0] & (1 << 7);
                byte |= src[1] & (1 << 6);
                byte |= src[2] & (1 << 5);
                byte |= src[3] & (1 << 4);
                byte |= src[4] & (1 << 3);
                byte |= src[5] & (1 << 2);
                byte |= src[6] & (1 << 1);
                byte |= src[7] & (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] & mask;
                mask >>= 1;
            }
            dst[byteCount] = byte;
        }
        src = SkTAddOffset<const SkGdiRGB>(src, srcRB);
        dst -= dstRB;
    }
#if SK_SHOW_TEXT_BLIT_COVERAGE
    if (glyph.fWidth > 0 && glyph.fHeight > 0) {
        uint8_t* first = (uint8_t*)glyph.fImage;
        uint8_t* last = (uint8_t*)((char*)glyph.fImage + glyph.fHeight * dstRB - 1);
        *first |= 1 << 7;
        *last |= bitCount == 0 ? 1 : 1 << (8 - bitCount);
    }
#endif
}

template<bool APPLY_PREBLEND>
static void rgb_to_a8(const SkGdiRGB* SK_RESTRICT src, size_t srcRB,
                      const SkGlyph& glyph, const uint8_t* table8) {
    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<APPLY_PREBLEND>(src[i], table8);
#if SK_SHOW_TEXT_BLIT_COVERAGE
            dst[i] = SkMax32(dst[i], 10);
#endif
        }
        src = SkTAddOffset<const SkGdiRGB>(src, srcRB);
        dst -= dstRB;
    }
}

template<bool APPLY_PREBLEND>
static void rgb_to_lcd16(const SkGdiRGB* SK_RESTRICT src, size_t srcRB, const SkGlyph& glyph,
                         const uint8_t* tableR, const uint8_t* tableG, const uint8_t* tableB) {
    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<APPLY_PREBLEND>(src[i], tableR, tableG, tableB);
        }
        src = SkTAddOffset<const SkGdiRGB>(src, srcRB);
        dst = (uint16_t*)((char*)dst - dstRB);
    }
}

template<bool APPLY_PREBLEND>
static void rgb_to_lcd32(const SkGdiRGB* SK_RESTRICT src, size_t srcRB, const SkGlyph& glyph,
                         const uint8_t* tableR, const uint8_t* tableG, const uint8_t* tableB) {
    const size_t dstRB = glyph.rowBytes();
    const int width = glyph.fWidth;
    uint32_t* SK_RESTRICT dst = (uint32_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_lcd32<APPLY_PREBLEND>(src[i], tableR, tableG, tableB);
        }
        src = SkTAddOffset<const SkGdiRGB>(src, srcRB);
        dst = (uint32_t*)((char*)dst - dstRB);
    }
}

static inline unsigned clamp255(unsigned x) {
    SkASSERT(x <= 256);
    return x - (x >> 8);
}

void SkScalerContext_GDI::generateImage(const SkGlyph& glyph) {
    SkASSERT(fDDC);

    const bool isBW = SkMask::kBW_Format == fRec.fMaskFormat;
    const bool isAA = !isLCD(fRec);

    size_t srcRB;
    const void* bits = fOffscreen.draw(glyph, isBW, &srcRB);
    if (NULL == bits) {
        LogFontTypeface::EnsureAccessible(this->getTypeface());
        bits = fOffscreen.draw(glyph, isBW, &srcRB);
        if (NULL == bits) {
            sk_bzero(glyph.fImage, glyph.computeImageSize());
            return;
        }
    }

    if (!isBW) {
        const uint8_t* table;
        //The offscreen contains a GDI blit if isAA and kGenA8FromLCD_Flag is not set.
        //Otherwise the offscreen contains a ClearType blit.
        if (isAA && !(fRec.fFlags & SkScalerContext::kGenA8FromLCD_Flag)) {
            table = getInverseGammaTableGDI();
        } else {
            table = getInverseGammaTableClearType();
        }
        //Note that the following cannot really be integrated into the
        //pre-blend, since we may not be applying the pre-blend; when we aren't
        //applying the pre-blend it means that a filter wants linear anyway.
        //Other code may also be applying the pre-blend, so we'd need another
        //one with this and one without.
        SkGdiRGB* addr = (SkGdiRGB*)bits;
        for (int y = 0; y < glyph.fHeight; ++y) {
            for (int x = 0; x < glyph.fWidth; ++x) {
                int r = (addr[x] >> 16) & 0xFF;
                int g = (addr[x] >>  8) & 0xFF;
                int b = (addr[x] >>  0) & 0xFF;
                addr[x] = (table[r] << 16) | (table[g] << 8) | table[b];
            }
            addr = SkTAddOffset<SkGdiRGB>(addr, srcRB);
        }
    }

    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;
        }
#if SK_SHOW_TEXT_BLIT_COVERAGE
            if (glyph.fWidth > 0 && glyph.fHeight > 0) {
                int bitCount = width & 7;
                uint8_t* first = (uint8_t*)glyph.fImage;
                uint8_t* last = (uint8_t*)((char*)glyph.fImage + glyph.fHeight * dstRB - 1);
                *first |= 1 << 7;
                *last |= bitCount == 0 ? 1 : 1 << (8 - bitCount);
            }
#endif
    } else if (isAA) {
        // since the caller may require A8 for maskfilters, we can't check for BW
        // ... until we have the caller tell us that explicitly
        const SkGdiRGB* src = (const SkGdiRGB*)bits;
        if (fPreBlend.isApplicable()) {
            rgb_to_a8<true>(src, srcRB, glyph, fPreBlend.fG);
        } else {
            rgb_to_a8<false>(src, srcRB, glyph, fPreBlend.fG);
        }
    } else {    // LCD16
        const SkGdiRGB* src = (const SkGdiRGB*)bits;
        if (is_rgb_really_bw(src, width, glyph.fHeight, srcRB)) {
            rgb_to_bw(src, srcRB, glyph);
            ((SkGlyph*)&glyph)->fMaskFormat = SkMask::kBW_Format;
        } else {
            if (SkMask::kLCD16_Format == glyph.fMaskFormat) {
                if (fPreBlend.isApplicable()) {
                    rgb_to_lcd16<true>(src, srcRB, glyph,
                                       fPreBlend.fR, fPreBlend.fG, fPreBlend.fB);
                } else {
                    rgb_to_lcd16<false>(src, srcRB, glyph,
                                        fPreBlend.fR, fPreBlend.fG, fPreBlend.fB);
                }
            } else {
                SkASSERT(SkMask::kLCD32_Format == glyph.fMaskFormat);
                if (fPreBlend.isApplicable()) {
                    rgb_to_lcd32<true>(src, srcRB, glyph,
                                       fPreBlend.fR, fPreBlend.fG, fPreBlend.fB);
                } else {
                    rgb_to_lcd32<false>(src, srcRB, glyph,
                                        fPreBlend.fR, fPreBlend.fG, fPreBlend.fB);
                }
            }
        }
    }
}

class GDIGlyphbufferPointIter {
public:
    GDIGlyphbufferPointIter(const uint8_t* glyphbuf, DWORD total_size)
        : fHeaderIter(glyphbuf, total_size), fCurveIter(), fPointIter()
    { }

    POINTFX next() {
nextHeader:
        if (!fCurveIter.isSet()) {
            const TTPOLYGONHEADER* header = fHeaderIter.next();
            SkASSERT(header);
            fCurveIter.set(header);
            const TTPOLYCURVE* curve = fCurveIter.next();
            SkASSERT(curve);
            fPointIter.set(curve);
            return header->pfxStart;
        }

        const POINTFX* nextPoint = fPointIter.next();
        if (NULL == nextPoint) {
            const TTPOLYCURVE* curve = fCurveIter.next();
            if (NULL == curve) {
                fCurveIter.set();
                goto nextHeader;
            } else {
                fPointIter.set(curve);
            }
            nextPoint = fPointIter.next();
            SkASSERT(nextPoint);
        }
        return *nextPoint;
    }

    WORD currentCurveType() {
        return fPointIter.fCurveType;
    }

private:
    /** Iterates over all of the polygon headers in a glyphbuf. */
    class GDIPolygonHeaderIter {
    public:
        GDIPolygonHeaderIter(const uint8_t* glyphbuf, DWORD total_size)
            : fCurPolygon(reinterpret_cast<const TTPOLYGONHEADER*>(glyphbuf))
            , fEndPolygon(SkTAddOffset<const TTPOLYGONHEADER>(glyphbuf, total_size))
        { }

        const TTPOLYGONHEADER* next() {
            if (fCurPolygon >= fEndPolygon) {
                return NULL;
            }
            const TTPOLYGONHEADER* thisPolygon = fCurPolygon;
            fCurPolygon = SkTAddOffset<const TTPOLYGONHEADER>(fCurPolygon, fCurPolygon->cb);
            return thisPolygon;
        }
    private:
        const TTPOLYGONHEADER* fCurPolygon;
        const TTPOLYGONHEADER* fEndPolygon;
    };

    /** Iterates over all of the polygon curves in a polygon header. */
    class GDIPolygonCurveIter {
    public:
        GDIPolygonCurveIter() : fCurCurve(NULL), fEndCurve(NULL) { }

        GDIPolygonCurveIter(const TTPOLYGONHEADER* curPolygon)
            : fCurCurve(SkTAddOffset<const TTPOLYCURVE>(curPolygon, sizeof(TTPOLYGONHEADER)))
            , fEndCurve(SkTAddOffset<const TTPOLYCURVE>(curPolygon, curPolygon->cb))
        { }

        bool isSet() { return fCurCurve != NULL; }

        void set(const TTPOLYGONHEADER* curPolygon) {
            fCurCurve = SkTAddOffset<const TTPOLYCURVE>(curPolygon, sizeof(TTPOLYGONHEADER));
            fEndCurve = SkTAddOffset<const TTPOLYCURVE>(curPolygon, curPolygon->cb);
        }
        void set() {
            fCurCurve = NULL;
            fEndCurve = NULL;
        }

        const TTPOLYCURVE* next() {
            if (fCurCurve >= fEndCurve) {
                return NULL;
            }
            const TTPOLYCURVE* thisCurve = fCurCurve;
            fCurCurve = SkTAddOffset<const TTPOLYCURVE>(fCurCurve, size_of_TTPOLYCURVE(*fCurCurve));
            return thisCurve;
        }
    private:
        size_t size_of_TTPOLYCURVE(const TTPOLYCURVE& curve) {
            return 2*sizeof(WORD) + curve.cpfx*sizeof(POINTFX);
        }
        const TTPOLYCURVE* fCurCurve;
        const TTPOLYCURVE* fEndCurve;
    };

    /** Iterates over all of the polygon points in a polygon curve. */
    class GDIPolygonCurvePointIter {
    public:
        GDIPolygonCurvePointIter() : fCurveType(0), fCurPoint(NULL), fEndPoint(NULL) { }

        GDIPolygonCurvePointIter(const TTPOLYCURVE* curPolygon)
            : fCurveType(curPolygon->wType)
            , fCurPoint(&curPolygon->apfx[0])
            , fEndPoint(&curPolygon->apfx[curPolygon->cpfx])
        { }

        bool isSet() { return fCurPoint != NULL; }

        void set(const TTPOLYCURVE* curPolygon) {
            fCurveType = curPolygon->wType;
            fCurPoint = &curPolygon->apfx[0];
            fEndPoint = &curPolygon->apfx[curPolygon->cpfx];
        }
        void set() {
            fCurPoint = NULL;
            fEndPoint = NULL;
        }

        const POINTFX* next() {
            if (fCurPoint >= fEndPoint) {
                return NULL;
            }
            const POINTFX* thisPoint = fCurPoint;
            ++fCurPoint;
            return thisPoint;
        }

        WORD fCurveType;
    private:
        const POINTFX* fCurPoint;
        const POINTFX* fEndPoint;
    };

    GDIPolygonHeaderIter fHeaderIter;
    GDIPolygonCurveIter fCurveIter;
    GDIPolygonCurvePointIter fPointIter;
};

static void sk_path_from_gdi_path(SkPath* path, const uint8_t* glyphbuf, DWORD 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( SkFIXEDToFixed(th->pfxStart.x)),
                     SkFixedToScalar(-SkFIXEDToFixed(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( SkFIXEDToFixed(pc->apfx[i].x)),
                                 SkFixedToScalar(-SkFIXEDToFixed(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(SkFIXEDToFixed(pnt_b.x),
                                                            SkFIXEDToFixed(pnt_c.x)));
                        pnt_c.y = SkFixedToFIXED(SkFixedAve(SkFIXEDToFixed(pnt_b.y),
                                                            SkFIXEDToFixed(pnt_c.y)));
                    }

                    path->quadTo(SkFixedToScalar( SkFIXEDToFixed(pnt_b.x)),
                                 SkFixedToScalar(-SkFIXEDToFixed(pnt_b.y)),
                                 SkFixedToScalar( SkFIXEDToFixed(pnt_c.x)),
                                 SkFixedToScalar(-SkFIXEDToFixed(pnt_c.y)));
                }
            }
            // Advance past this TTPOLYCURVE.
            cur_poly += sizeof(WORD) * 2 + sizeof(POINTFX) * pc->cpfx;
        }
        cur_glyph += th->cb;
        path->close();
    }
}

static void sk_path_from_gdi_paths(SkPath* path, const uint8_t* glyphbuf, DWORD total_size,
                                   GDIGlyphbufferPointIter hintedYs) {
    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( SkFIXEDToFixed(th->pfxStart.x)),
                     SkFixedToScalar(-SkFIXEDToFixed(hintedYs.next().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( SkFIXEDToFixed(pc->apfx[i].x)),
                                 SkFixedToScalar(-SkFIXEDToFixed(hintedYs.next().y)));
                }
            }

            if (pc->wType == TT_PRIM_QSPLINE) {
                POINTFX currentPoint = pc->apfx[0];
                POINTFX hintedY = hintedYs.next();
                // only take the hinted y if it wasn't flipped
                if (hintedYs.currentCurveType() == TT_PRIM_QSPLINE) {
                    currentPoint.y = hintedY.y;
                }
                for (uint16_t u = 0; u < pc->cpfx - 1; u++) { // Walk through points in spline
                    POINTFX pnt_b = currentPoint;//pc->apfx[u]; // B is always the current point
                    POINTFX pnt_c = pc->apfx[u+1];
                    POINTFX hintedY = hintedYs.next();
                    // only take the hinted y if it wasn't flipped
                    if (hintedYs.currentCurveType() == TT_PRIM_QSPLINE) {
                        pnt_c.y = hintedY.y;
                    }
                    currentPoint.x = pnt_c.x;
                    currentPoint.y = pnt_c.y;

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

                    path->quadTo(SkFixedToScalar( SkFIXEDToFixed(pnt_b.x)),
                                 SkFixedToScalar(-SkFIXEDToFixed(pnt_b.y)),
                                 SkFixedToScalar( SkFIXEDToFixed(pnt_c.x)),
                                 SkFixedToScalar(-SkFIXEDToFixed(pnt_c.y)));
                }
            }
            // Advance past this TTPOLYCURVE.
            cur_poly += sizeof(WORD) * 2 + sizeof(POINTFX) * pc->cpfx;
        }
        cur_glyph += th->cb;
        path->close();
    }
}

DWORD SkScalerContext_GDI::getGDIGlyphPath(const SkGlyph& glyph, UINT flags,
                                               SkAutoSTMalloc<BUFFERSIZE, uint8_t>* glyphbuf)
{
    GLYPHMETRICS gm;

    DWORD total_size = GetGlyphOutlineW(fDDC, glyph.fID, flags, &gm, BUFFERSIZE, glyphbuf->get(), &fMat22);
    // Sometimes GetGlyphOutlineW returns a number larger than BUFFERSIZE even if BUFFERSIZE > 0.
    // It has been verified that this does not involve a buffer overrun.
    if (GDI_ERROR == total_size || total_size > BUFFERSIZE) {
        // GDI_ERROR because the BUFFERSIZE was too small, or because the data was not accessible.
        // When the data is not accessable GetGlyphOutlineW fails rather quickly,
        // so just try to get the size. If that fails then ensure the data is accessible.
        total_size = GetGlyphOutlineW(fDDC, glyph.fID, flags, &gm, 0, NULL, &fMat22);
        if (GDI_ERROR == total_size) {
            LogFontTypeface::EnsureAccessible(this->getTypeface());
            total_size = GetGlyphOutlineW(fDDC, glyph.fID, flags, &gm, 0, NULL, &fMat22);
            if (GDI_ERROR == total_size) {
                SkASSERT(false);
                return 0;
            }
        }

        glyphbuf->reset(total_size);

        DWORD ret = GetGlyphOutlineW(fDDC, glyph.fID, flags, &gm, total_size, glyphbuf->get(), &fMat22);
        if (GDI_ERROR == ret) {
            LogFontTypeface::EnsureAccessible(this->getTypeface());
            ret = GetGlyphOutlineW(fDDC, glyph.fID, flags, &gm, total_size, glyphbuf->get(), &fMat22);
            if (GDI_ERROR == ret) {
                SkASSERT(false);
                return 0;
            }
        }
    }
    return total_size;
}

void SkScalerContext_GDI::generatePath(const SkGlyph& glyph, SkPath* path) {
    SkASSERT(&glyph && path);
    SkASSERT(fDDC);

    path->reset();

    // Out of all the fonts on a typical Windows box,
    // 25% of glyphs require more than 2KB.
    // 1% of glyphs require more than 4KB.
    // 0.01% of glyphs require more than 8KB.
    // 8KB is less than 1% of the normal 1MB stack on Windows.
    // Note that some web fonts glyphs require more than 20KB.
    //static const DWORD BUFFERSIZE = (1 << 13);

    //GDI only uses hinted outlines when axis aligned.
    UINT format = GGO_NATIVE | GGO_GLYPH_INDEX;
    if (fRec.getHinting() == SkPaint::kNo_Hinting || fRec.getHinting() == SkPaint::kSlight_Hinting){
        format |= GGO_UNHINTED;
    }
    SkAutoSTMalloc<BUFFERSIZE, uint8_t> glyphbuf(BUFFERSIZE);
    DWORD total_size = getGDIGlyphPath(glyph, format, &glyphbuf);
    if (0 == total_size) {
        return;
    }

    if (fRec.getHinting() != SkPaint::kSlight_Hinting) {
        sk_path_from_gdi_path(path, glyphbuf, total_size);
    } else {
        //GDI only uses hinted outlines when axis aligned.
        UINT format = GGO_NATIVE | GGO_GLYPH_INDEX;

        SkAutoSTMalloc<BUFFERSIZE, uint8_t> hintedGlyphbuf(BUFFERSIZE);
        DWORD hinted_total_size = getGDIGlyphPath(glyph, format, &hintedGlyphbuf);
        if (0 == hinted_total_size) {
            return;
        }

        sk_path_from_gdi_paths(path, glyphbuf, total_size,
                               GDIGlyphbufferPointIter(hintedGlyphbuf, hinted_total_size));
    }
}

static void logfont_for_name(const char* familyName, LOGFONT* lf) {
    sk_bzero(lf, 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 - 1);
    delete [] wideFamilyName;
    lf->lfFaceName[LF_FACESIZE-1] = L'\0';
#else
    ::strncpy(lf->lfFaceName, familyName, LF_FACESIZE - 1);
    lf->lfFaceName[LF_FACESIZE - 1] = '\0';
#endif
}

void LogFontTypeface::onGetFontDescriptor(SkFontDescriptor* desc,
                                          bool* isLocalStream) const {
    // Get the actual name of the typeface. The logfont may not know this.
    HFONT font = CreateFontIndirect(&fLogFont);

    HDC deviceContext = ::CreateCompatibleDC(NULL);
    HFONT savefont = (HFONT)SelectObject(deviceContext, font);

    SkString familyName;
    dcfontname_to_skstring(deviceContext, fLogFont, &familyName);

    if (deviceContext) {
        ::SelectObject(deviceContext, savefont);
        ::DeleteDC(deviceContext);
    }
    if (font) {
        ::DeleteObject(font);
    }

    desc->setFamilyName(familyName.c_str());
    *isLocalStream = this->fSerializeAsStream;
}

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;
}

SkAdvancedTypefaceMetrics* LogFontTypeface::onGetAdvancedTypefaceMetrics(
        SkAdvancedTypefaceMetrics::PerGlyphInfo perGlyphInfo,
        const uint32_t* glyphIDs,
        uint32_t glyphIDsCount) const {
    LOGFONT lf = fLogFont;
    SkAdvancedTypefaceMetrics* info = NULL;

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

    const char stem_chars[] = {'i', 'I', '!', '1'};
    int16_t min_width;
    unsigned glyphCount;

    // To request design units, create a logical font whose height is specified
    // as unitsPerEm.
    OUTLINETEXTMETRIC otm;
    unsigned int otmRet = GetOutlineTextMetrics(hdc, sizeof(otm), &otm);
    if (0 == otmRet) {
        call_ensure_accessible(lf);
        otmRet = GetOutlineTextMetrics(hdc, sizeof(otm), &otm);
    }
    if (!otmRet || !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;
    }
    glyphCount = calculateGlyphCount(hdc, fLogFont);

    info = new SkAdvancedTypefaceMetrics;
    info->fEmSize = otm.otmEMSquare;
    info->fMultiMaster = false;
    info->fLastGlyphID = SkToU16(glyphCount - 1);
    info->fStyle = 0;
    tchar_to_skstring(lf.lfFaceName, &info->fFontName);

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

    if (glyphCount > 0 &&
        (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();
        goto ReturnInfo;
    }

    // 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;
    }
    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.
    min_width = SHRT_MAX;
    info->fStemV = 0;
    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:
ReturnInfo:
    SelectObject(hdc, savefont);
    DeleteObject(designFont);
    DeleteObject(font);
    DeleteDC(hdc);

    return info;
}

//Dummy representation of a Base64 encoded GUID from create_unique_font_name.
#define BASE64_GUID_ID "XXXXXXXXXXXXXXXXXXXXXXXX"
//Length of GUID representation from create_id, including NULL terminator.
#define BASE64_GUID_ID_LEN SK_ARRAY_COUNT(BASE64_GUID_ID)

SK_COMPILE_ASSERT(BASE64_GUID_ID_LEN < LF_FACESIZE, GUID_longer_than_facesize);

/**
   NameID 6 Postscript names cannot have the character '/'.
   It would be easier to hex encode the GUID, but that is 32 bytes,
   and many systems have issues with names longer than 28 bytes.
   The following need not be any standard base64 encoding.
   The encoded value is never decoded.
*/
static const char postscript_safe_base64_encode[] =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "abcdefghijklmnopqrstuvwxyz"
    "0123456789-_=";

/**
   Formats a GUID into Base64 and places it into buffer.
   buffer should have space for at least BASE64_GUID_ID_LEN characters.
   The string will always be null terminated.
   XXXXXXXXXXXXXXXXXXXXXXXX0
 */
static void format_guid_b64(const GUID& guid, char* buffer, size_t bufferSize) {
    SkASSERT(bufferSize >= BASE64_GUID_ID_LEN);
    size_t written = SkBase64::Encode(&guid, sizeof(guid), buffer, postscript_safe_base64_encode);
    SkASSERT(written < LF_FACESIZE);
    buffer[written] = '\0';
}

/**
   Creates a Base64 encoded GUID and places it into buffer.
   buffer should have space for at least BASE64_GUID_ID_LEN characters.
   The string will always be null terminated.
   XXXXXXXXXXXXXXXXXXXXXXXX0
 */
static HRESULT create_unique_font_name(char* buffer, size_t bufferSize) {
    GUID guid = {};
    if (FAILED(CoCreateGuid(&guid))) {
        return E_UNEXPECTED;
    }
    format_guid_b64(guid, buffer, bufferSize);

    return S_OK;
}

/**
   Introduces a font to GDI. On failure will return NULL. The returned handle
   should eventually be passed to RemoveFontMemResourceEx.
*/
static HANDLE activate_font(SkData* fontData) {
    DWORD numFonts = 0;
    //AddFontMemResourceEx just copies the data, but does not specify const.
    HANDLE fontHandle = AddFontMemResourceEx(const_cast<void*>(fontData->data()),
                                             static_cast<DWORD>(fontData->size()),
                                             0,
                                             &numFonts);

    if (fontHandle != NULL && numFonts < 1) {
        RemoveFontMemResourceEx(fontHandle);
        return NULL;
    }

    return fontHandle;
}

static SkTypeface* create_from_stream(SkStream* stream) {
    // Create a unique and unpredictable font name.
    // Avoids collisions and access from CSS.
    char familyName[BASE64_GUID_ID_LEN];
    const int familyNameSize = SK_ARRAY_COUNT(familyName);
    if (FAILED(create_unique_font_name(familyName, familyNameSize))) {
        return NULL;
    }

    // Change the name of the font.
    SkAutoTUnref<SkData> rewrittenFontData(SkOTUtils::RenameFont(stream, familyName, familyNameSize-1));
    if (NULL == rewrittenFontData.get()) {
        return NULL;
    }

    // Register the font with GDI.
    HANDLE fontReference = activate_font(rewrittenFontData.get());
    if (NULL == fontReference) {
        return NULL;
    }

    // Create the typeface.
    LOGFONT lf;
    logfont_for_name(familyName, &lf);

    return SkCreateFontMemResourceTypefaceFromLOGFONT(lf, fontReference);
}

SkStream* LogFontTypeface::onOpenStream(int* ttcIndex) const {
    *ttcIndex = 0;

    const DWORD kTTCTag =
        SkEndian_SwapBE32(SkSetFourByteTag('t', 't', 'c', 'f'));
    LOGFONT lf = fLogFont;

    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++) {
        DWORD bufferSize = GetFontData(hdc, tables[i], 0, NULL, 0);
        if (bufferSize == GDI_ERROR) {
            call_ensure_accessible(lf);
            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;
}

int LogFontTypeface::onCountGlyphs() const {
    HDC hdc = ::CreateCompatibleDC(NULL);
    HFONT font = CreateFontIndirect(&fLogFont);
    HFONT savefont = (HFONT)SelectObject(hdc, font);

    unsigned int glyphCount = calculateGlyphCount(hdc, fLogFont);

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

    return glyphCount;
}

int LogFontTypeface::onGetUPEM() const {
    HDC hdc = ::CreateCompatibleDC(NULL);
    HFONT font = CreateFontIndirect(&fLogFont);
    HFONT savefont = (HFONT)SelectObject(hdc, font);

    unsigned int upem = calculateUPEM(hdc, fLogFont);

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

    return upem;
}

SkTypeface::LocalizedStrings* LogFontTypeface::onCreateFamilyNameIterator() const {
    SkTypeface::LocalizedStrings* nameIter =
        SkOTUtils::LocalizedStrings_NameTable::CreateForFamilyNames(*this);
    if (NULL == nameIter) {
        SkString familyName;
        this->getFamilyName(&familyName);
        SkString language("und"); //undetermined
        nameIter = new SkOTUtils::LocalizedStrings_SingleName(familyName, language);
    }
    return nameIter;
}

int LogFontTypeface::onGetTableTags(SkFontTableTag tags[]) const {
    SkSFNTHeader header;
    if (sizeof(header) != this->onGetTableData(0, 0, sizeof(header), &header)) {
        return 0;
    }

    int numTables = SkEndian_SwapBE16(header.numTables);

    if (tags) {
        size_t size = numTables * sizeof(SkSFNTHeader::TableDirectoryEntry);
        SkAutoSTMalloc<0x20, SkSFNTHeader::TableDirectoryEntry> dir(numTables);
        if (size != this->onGetTableData(0, sizeof(header), size, dir.get())) {
            return 0;
        }

        for (int i = 0; i < numTables; ++i) {
            tags[i] = SkEndian_SwapBE32(dir[i].tag);
        }
    }
    return numTables;
}

size_t LogFontTypeface::onGetTableData(SkFontTableTag tag, size_t offset,
                                       size_t length, void* data) const
{
    LOGFONT lf = fLogFont;

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

    tag = SkEndian_SwapBE32(tag);
    if (NULL == data) {
        length = 0;
    }
    DWORD bufferSize = GetFontData(hdc, tag, offset, data, length);
    if (bufferSize == GDI_ERROR) {
        call_ensure_accessible(lf);
        bufferSize = GetFontData(hdc, tag, offset, data, length);
    }

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

    return bufferSize == GDI_ERROR ? 0 : bufferSize;
}

SkScalerContext* LogFontTypeface::onCreateScalerContext(const SkDescriptor* desc) const {
    SkScalerContext_GDI* ctx = SkNEW_ARGS(SkScalerContext_GDI,
                                                (const_cast<LogFontTypeface*>(this), desc));
    if (!ctx->isValid()) {
        SkDELETE(ctx);
        ctx = NULL;
    }
    return ctx;
}

void LogFontTypeface::onFilterRec(SkScalerContextRec* rec) const {
    if (rec->fFlags & SkScalerContext::kLCD_BGROrder_Flag ||
        rec->fFlags & SkScalerContext::kLCD_Vertical_Flag)
    {
        rec->fMaskFormat = SkMask::kA8_Format;
        rec->fFlags |= SkScalerContext::kGenA8FromLCD_Flag;
    }

    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();
    switch (h) {
        case SkPaint::kNo_Hinting:
            break;
        case SkPaint::kSlight_Hinting:
            // Only do slight hinting when axis aligned.
            // TODO: re-enable slight hinting when FontHostTest can pass.
            //if (!isAxisAligned(*rec)) {
                h = SkPaint::kNo_Hinting;
            //}
            break;
        case SkPaint::kNormal_Hinting:
        case SkPaint::kFull_Hinting:
            // TODO: need to be able to distinguish subpixel positioned glyphs
            // and linear metrics.
            //rec->fFlags &= ~SkScalerContext::kSubpixelPositioning_Flag;
            h = SkPaint::kNormal_Hinting;
            break;
        default:
            SkDEBUGFAIL("unknown hinting");
    }
    //TODO: if this is a bitmap font, squash hinting and subpixel.
    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 (!fCanBeLCD && isLCD(*rec)) {
        rec->fMaskFormat = SkMask::kA8_Format;
        rec->fFlags &= ~SkScalerContext::kGenA8FromLCD_Flag;
    }
}

static SkTypeface* create_typeface(const SkTypeface* familyFace,
                                   const char familyName[],
                                   unsigned styleBits) {
    LOGFONT lf;
    if (NULL == familyFace && NULL == familyName) {
        lf = get_default_font();
    } else if (familyFace) {
        LogFontTypeface* face = (LogFontTypeface*)familyFace;
        lf = face->fLogFont;
    } else {
        logfont_for_name(familyName, &lf);
    }
    setStyle(&lf, (SkTypeface::Style)styleBits);
    return SkCreateTypefaceFromLOGFONT(lf);
}

SkTypeface* LogFontTypeface::onRefMatchingStyle(Style style) const {
    return create_typeface(this, NULL, style);
}

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

#include "SkFontMgr.h"
#include "SkDataTable.h"

static bool valid_logfont_for_enum(const LOGFONT& lf) {
    // TODO: Vector FON is unsupported and should not be listed.
    return
        // Ignore implicit vertical variants.
        lf.lfFaceName[0] && lf.lfFaceName[0] != '@'

        // DEFAULT_CHARSET is used to get all fonts, but also implies all
        // character sets. Filter assuming all fonts support ANSI_CHARSET.
        && ANSI_CHARSET == lf.lfCharSet
    ;
}

/** An EnumFontFamExProc implementation which interprets builderParam as
 *  an SkTDArray<ENUMLOGFONTEX>* and appends logfonts which
 *  pass the valid_logfont_for_enum predicate.
 */
static int CALLBACK enum_family_proc(const LOGFONT* lf, const TEXTMETRIC*,
                                     DWORD fontType, LPARAM builderParam) {
    if (valid_logfont_for_enum(*lf)) {
        SkTDArray<ENUMLOGFONTEX>* array = (SkTDArray<ENUMLOGFONTEX>*)builderParam;
        *array->append() = *(ENUMLOGFONTEX*)lf;
    }
    return 1; // non-zero means continue
}

static SkFontStyle compute_fontstyle(const LOGFONT& lf) {
    return SkFontStyle(lf.lfWeight, SkFontStyle::kNormal_Width,
                       lf.lfItalic ? SkFontStyle::kItalic_Slant
                                   : SkFontStyle::kUpright_Slant);
}

class SkFontStyleSetGDI : public SkFontStyleSet {
public:
    SkFontStyleSetGDI(const TCHAR familyName[]) {
        LOGFONT lf;
        sk_bzero(&lf, sizeof(lf));
        lf.lfCharSet = DEFAULT_CHARSET;
        _tcscpy_s(lf.lfFaceName, familyName);

        HDC hdc = ::CreateCompatibleDC(NULL);
        ::EnumFontFamiliesEx(hdc, &lf, enum_family_proc, (LPARAM)&fArray, 0);
        ::DeleteDC(hdc);
    }

    virtual int count() SK_OVERRIDE {
        return fArray.count();
    }

    virtual void getStyle(int index, SkFontStyle* fs, SkString* styleName) SK_OVERRIDE {
        if (fs) {
            *fs = compute_fontstyle(fArray[index].elfLogFont);
        }
        if (styleName) {
            const ENUMLOGFONTEX& ref = fArray[index];
            // For some reason, ENUMLOGFONTEX and LOGFONT disagree on their type in the
            // non-unicode version.
            //      ENUMLOGFONTEX uses BYTE
            //      LOGFONT uses CHAR
            // Here we assert they that the style name is logically the same (size) as
            // a TCHAR, so we can use the same converter function.
            SkASSERT(sizeof(TCHAR) == sizeof(ref.elfStyle[0]));
            tchar_to_skstring((const TCHAR*)ref.elfStyle, styleName);
        }
    }

    virtual SkTypeface* createTypeface(int index) SK_OVERRIDE {
        return SkCreateTypefaceFromLOGFONT(fArray[index].elfLogFont);
    }

    virtual SkTypeface* matchStyle(const SkFontStyle& pattern) SK_OVERRIDE {
        // todo:
        return SkCreateTypefaceFromLOGFONT(fArray[0].elfLogFont);
    }

private:
    SkTDArray<ENUMLOGFONTEX> fArray;
};

class SkFontMgrGDI : public SkFontMgr {
public:
    SkFontMgrGDI() {
        LOGFONT lf;
        sk_bzero(&lf, sizeof(lf));
        lf.lfCharSet = DEFAULT_CHARSET;

        HDC hdc = ::CreateCompatibleDC(NULL);
        ::EnumFontFamiliesEx(hdc, &lf, enum_family_proc, (LPARAM)&fLogFontArray, 0);
        ::DeleteDC(hdc);
    }

protected:
    virtual int onCountFamilies() SK_OVERRIDE {
        return fLogFontArray.count();
    }

    virtual void onGetFamilyName(int index, SkString* familyName) SK_OVERRIDE {
        SkASSERT((unsigned)index < (unsigned)fLogFontArray.count());
        tchar_to_skstring(fLogFontArray[index].elfLogFont.lfFaceName, familyName);
    }

    virtual SkFontStyleSet* onCreateStyleSet(int index) SK_OVERRIDE {
        SkASSERT((unsigned)index < (unsigned)fLogFontArray.count());
        return SkNEW_ARGS(SkFontStyleSetGDI, (fLogFontArray[index].elfLogFont.lfFaceName));
    }

    virtual SkFontStyleSet* onMatchFamily(const char familyName[]) SK_OVERRIDE {
        if (NULL == familyName) {
            familyName = "";    // do we need this check???
        }
        LOGFONT lf;
        logfont_for_name(familyName, &lf);
        return SkNEW_ARGS(SkFontStyleSetGDI, (lf.lfFaceName));
    }

    virtual SkTypeface* onMatchFamilyStyle(const char familyName[],
                                           const SkFontStyle& fontstyle) SK_OVERRIDE {
        // could be in base impl
        SkAutoTUnref<SkFontStyleSet> sset(this->matchFamily(familyName));
        return sset->matchStyle(fontstyle);
    }

    virtual SkTypeface* onMatchFaceStyle(const SkTypeface* familyMember,
                                         const SkFontStyle& fontstyle) SK_OVERRIDE {
        // could be in base impl
        SkString familyName;
        ((LogFontTypeface*)familyMember)->getFamilyName(&familyName);
        return this->matchFamilyStyle(familyName.c_str(), fontstyle);
    }

    virtual SkTypeface* onCreateFromStream(SkStream* stream, int ttcIndex) SK_OVERRIDE {
        return create_from_stream(stream);
    }

    virtual SkTypeface* onCreateFromData(SkData* data, int ttcIndex) SK_OVERRIDE {
        // could be in base impl
        SkAutoTUnref<SkStream> stream(SkNEW_ARGS(SkMemoryStream, (data)));
        return this->createFromStream(stream);
    }

    virtual SkTypeface* onCreateFromFile(const char path[], int ttcIndex) SK_OVERRIDE {
        // could be in base impl
        SkAutoTUnref<SkStream> stream(SkStream::NewFromFile(path));
        return this->createFromStream(stream);
    }

    virtual SkTypeface* onLegacyCreateTypeface(const char familyName[],
                                               unsigned styleBits) SK_OVERRIDE {
        return create_typeface(NULL, familyName, styleBits);
    }

private:
    SkTDArray<ENUMLOGFONTEX> fLogFontArray;
};

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

#ifndef SK_FONTHOST_USES_FONTMGR

SkTypeface* SkFontHost::CreateTypeface(const SkTypeface* familyFace,
                                       const char familyName[],
                                       SkTypeface::Style styleBits) {
    return create_typeface(familyFace, familyName, styleBits);
}

SkTypeface* SkFontHost::CreateTypefaceFromFile(const char path[]) {
    SkAutoTUnref<SkStream> stream(SkStream::NewFromFile(path));
    return stream.get() ? CreateTypefaceFromStream(stream) : NULL;
}

SkTypeface* SkFontHost::CreateTypefaceFromStream(SkStream* stream) {
    return create_from_stream(stream);
}

#endif

extern SkFontMgr* SkFontMgr_New_GDI();
SkFontMgr* SkFontMgr_New_GDI() {
    return SkNEW(SkFontMgrGDI);
}