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/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "gfxGDIFont.h"

#include "mozilla/MemoryReporting.h"
#include "mozilla/Sprintf.h"
#include "mozilla/WindowsVersion.h"

#include <algorithm>
#include "gfxWindowsPlatform.h"
#include "gfxContext.h"
#include "mozilla/Preferences.h"
#include "nsUnicodeProperties.h"
#include "gfxFontConstants.h"
#include "gfxTextRun.h"

#include "cairo-win32.h"

#define ROUND(x) floor((x) + 0.5)

using namespace mozilla;
using namespace mozilla::gfx;
using namespace mozilla::unicode;

static inline cairo_antialias_t
GetCairoAntialiasOption(gfxFont::AntialiasOption anAntialiasOption)
{
    switch (anAntialiasOption) {
    default:
    case gfxFont::kAntialiasDefault:
        return CAIRO_ANTIALIAS_DEFAULT;
    case gfxFont::kAntialiasNone:
        return CAIRO_ANTIALIAS_NONE;
    case gfxFont::kAntialiasGrayscale:
        return CAIRO_ANTIALIAS_GRAY;
    case gfxFont::kAntialiasSubpixel:
        return CAIRO_ANTIALIAS_SUBPIXEL;
    }
}

gfxGDIFont::gfxGDIFont(GDIFontEntry *aFontEntry,
                       const gfxFontStyle *aFontStyle,
                       bool aNeedsBold,
                       AntialiasOption anAAOption)
    : gfxFont(nullptr, aFontEntry, aFontStyle, anAAOption),
      mFont(nullptr),
      mFontFace(nullptr),
      mMetrics(nullptr),
      mSpaceGlyph(0),
      mNeedsBold(aNeedsBold),
      mScriptCache(nullptr)
{
    Initialize();

    if (mFont) {
        mUnscaledFont = aFontEntry->LookupUnscaledFont(mFont);
    }
}

gfxGDIFont::~gfxGDIFont()
{
    if (mScaledFont) {
        cairo_scaled_font_destroy(mScaledFont);
    }
    if (mFontFace) {
        cairo_font_face_destroy(mFontFace);
    }
    if (mFont) {
        ::DeleteObject(mFont);
    }
    if (mScriptCache) {
        ScriptFreeCache(&mScriptCache);
    }
    delete mMetrics;
}

UniquePtr<gfxFont>
gfxGDIFont::CopyWithAntialiasOption(AntialiasOption anAAOption)
{
    auto entry = static_cast<GDIFontEntry*>(mFontEntry.get());
    return MakeUnique<gfxGDIFont>(entry, &mStyle, mNeedsBold, anAAOption);
}

bool
gfxGDIFont::ShapeText(DrawTarget     *aDrawTarget,
                      const char16_t *aText,
                      uint32_t        aOffset,
                      uint32_t        aLength,
                      Script          aScript,
                      bool            aVertical,
                      RoundingFlags   aRounding,
                      gfxShapedText  *aShapedText)
{
    if (!mIsValid) {
        NS_WARNING("invalid font! expect incorrect text rendering");
        return false;
    }

    // Ensure the cairo font is set up, so there's no risk it'll fall back to
    // creating a "toy" font internally (see bug 544617).
    // We must check that this succeeded, otherwise we risk cairo creating the
    // wrong kind of font internally as a fallback (bug 744480).
    if (!SetupCairoFont(aDrawTarget)) {
        return false;
    }

    return gfxFont::ShapeText(aDrawTarget, aText, aOffset, aLength, aScript,
                              aVertical, aRounding, aShapedText);
}

const gfxFont::Metrics&
gfxGDIFont::GetHorizontalMetrics()
{
    return *mMetrics;
}

uint32_t
gfxGDIFont::GetSpaceGlyph()
{
    return mSpaceGlyph;
}

bool
gfxGDIFont::SetupCairoFont(DrawTarget* aDrawTarget)
{
    if (!mScaledFont ||
        cairo_scaled_font_status(mScaledFont) != CAIRO_STATUS_SUCCESS) {
        // Don't cairo_set_scaled_font as that would propagate the error to
        // the cairo_t, precluding any further drawing.
        return false;
    }
    cairo_set_scaled_font(gfxFont::RefCairo(aDrawTarget), mScaledFont);
    return true;
}

already_AddRefed<ScaledFont>
gfxGDIFont::GetScaledFont(DrawTarget *aTarget)
{
    if (!mAzureScaledFont) {
        NativeFont nativeFont;
        nativeFont.mType = NativeFontType::GDI_FONT_FACE;
        LOGFONT lf;
        GetObject(GetHFONT(), sizeof(LOGFONT), &lf);
        nativeFont.mFont = &lf;

        mAzureScaledFont =
          Factory::CreateScaledFontWithCairo(nativeFont,
                                             GetUnscaledFont(),
                                             GetAdjustedSize(),
                                             GetCairoScaledFont());
    }

    RefPtr<ScaledFont> scaledFont(mAzureScaledFont);
    return scaledFont.forget();
}

gfxFont::RunMetrics
gfxGDIFont::Measure(const gfxTextRun *aTextRun,
                    uint32_t aStart, uint32_t aEnd,
                    BoundingBoxType aBoundingBoxType,
                    DrawTarget *aRefDrawTarget,
                    Spacing *aSpacing,
                    gfx::ShapedTextFlags aOrientation)
{
    gfxFont::RunMetrics metrics =
        gfxFont::Measure(aTextRun, aStart, aEnd, aBoundingBoxType,
                         aRefDrawTarget, aSpacing, aOrientation);

    // if aBoundingBoxType is LOOSE_INK_EXTENTS
    // and the underlying cairo font may be antialiased,
    // we can't trust Windows to have considered all the pixels
    // so we need to add "padding" to the bounds.
    // (see bugs 475968, 439831, compare also bug 445087)
    if (aBoundingBoxType == LOOSE_INK_EXTENTS &&
        mAntialiasOption != kAntialiasNone &&
        metrics.mBoundingBox.width > 0) {
        metrics.mBoundingBox.x -= aTextRun->GetAppUnitsPerDevUnit();
        metrics.mBoundingBox.width += aTextRun->GetAppUnitsPerDevUnit() * 3;
    }

    return metrics;
}

void
gfxGDIFont::Initialize()
{
    NS_ASSERTION(!mMetrics, "re-creating metrics? this will leak");

    LOGFONTW logFont;

    // Figure out if we want to do synthetic oblique styling.
    GDIFontEntry* fe = static_cast<GDIFontEntry*>(GetFontEntry());
    bool wantFakeItalic = mStyle.style != NS_FONT_STYLE_NORMAL &&
                          fe->IsUpright() && mStyle.allowSyntheticStyle;

    // If the font's family has an actual italic face (but font matching
    // didn't choose it), we have to use a cairo transform instead of asking
    // GDI to italicize, because that would use a different face and result
    // in a possible glyph ID mismatch between shaping and rendering.
    //
    // We use the mFamilyHasItalicFace flag in the entry in case of user fonts,
    // where the *CSS* family may not know about italic faces that are present
    // in the *GDI* family, and which GDI would use if we asked it to perform
    // the "italicization".
    bool useCairoFakeItalic = wantFakeItalic && fe->mFamilyHasItalicFace;

    if (mAdjustedSize == 0.0) {
        mAdjustedSize = mStyle.size;
        if (mStyle.sizeAdjust > 0.0 && mAdjustedSize > 0.0) {
            // to implement font-size-adjust, we first create the "unadjusted" font
            FillLogFont(logFont, mAdjustedSize,
                        wantFakeItalic && !useCairoFakeItalic);
            mFont = ::CreateFontIndirectW(&logFont);

            // initialize its metrics so we can calculate size adjustment
            Initialize();

            // Unless the font was so small that GDI metrics rounded to zero,
            // calculate the properly adjusted size, and then proceed
            // to recreate mFont and recalculate metrics
            if (mMetrics->xHeight > 0.0 && mMetrics->emHeight > 0.0) {
                gfxFloat aspect = mMetrics->xHeight / mMetrics->emHeight;
                mAdjustedSize = mStyle.GetAdjustedSize(aspect);
            }

            // delete the temporary font and metrics
            ::DeleteObject(mFont);
            mFont = nullptr;
            delete mMetrics;
            mMetrics = nullptr;
        } else if (mStyle.sizeAdjust == 0.0) {
            mAdjustedSize = 0.0;
        }
    }

    // (bug 724231) for local user fonts, we don't use GDI's synthetic bold,
    // as it could lead to a different, incompatible face being used
    // but instead do our own multi-striking
    if (mNeedsBold && GetFontEntry()->IsLocalUserFont()) {
        mApplySyntheticBold = true;
    }

    // this may end up being zero
    mAdjustedSize = ROUND(mAdjustedSize);
    FillLogFont(logFont, mAdjustedSize, wantFakeItalic && !useCairoFakeItalic);
    mFont = ::CreateFontIndirectW(&logFont);

    mMetrics = new gfxFont::Metrics;
    ::memset(mMetrics, 0, sizeof(*mMetrics));

    if (!mFont) {
        NS_WARNING("Failed creating GDI font");
        mIsValid = false;
        return;
    }

    AutoDC dc;
    SetGraphicsMode(dc.GetDC(), GM_ADVANCED);
    AutoSelectFont selectFont(dc.GetDC(), mFont);

    // Get font metrics if size > 0
    if (mAdjustedSize > 0.0) {

        OUTLINETEXTMETRIC oMetrics;
        TEXTMETRIC& metrics = oMetrics.otmTextMetrics;

        if (0 < GetOutlineTextMetrics(dc.GetDC(), sizeof(oMetrics), &oMetrics)) {
            mMetrics->strikeoutSize = (double)oMetrics.otmsStrikeoutSize;
            mMetrics->strikeoutOffset = (double)oMetrics.otmsStrikeoutPosition;
            mMetrics->underlineSize = (double)oMetrics.otmsUnderscoreSize;
            mMetrics->underlineOffset = (double)oMetrics.otmsUnderscorePosition;

            const MAT2 kIdentityMatrix = { {0, 1}, {0, 0}, {0, 0}, {0, 1} };
            GLYPHMETRICS gm;
            DWORD len = GetGlyphOutlineW(dc.GetDC(), char16_t('x'), GGO_METRICS, &gm, 0, nullptr, &kIdentityMatrix);
            if (len == GDI_ERROR || gm.gmptGlyphOrigin.y <= 0) {
                // 56% of ascent, best guess for true type
                mMetrics->xHeight =
                    ROUND((double)metrics.tmAscent * DEFAULT_XHEIGHT_FACTOR);
            } else {
                mMetrics->xHeight = gm.gmptGlyphOrigin.y;
            }
            len = GetGlyphOutlineW(dc.GetDC(), char16_t('H'), GGO_METRICS, &gm, 0, nullptr, &kIdentityMatrix);
            if (len == GDI_ERROR || gm.gmptGlyphOrigin.y <= 0) {
                mMetrics->capHeight = metrics.tmAscent - metrics.tmInternalLeading;
            } else {
                mMetrics->capHeight = gm.gmptGlyphOrigin.y;
            }
            mMetrics->emHeight = metrics.tmHeight - metrics.tmInternalLeading;
            gfxFloat typEmHeight = (double)oMetrics.otmAscent - (double)oMetrics.otmDescent;
            mMetrics->emAscent = ROUND(mMetrics->emHeight * (double)oMetrics.otmAscent / typEmHeight);
            mMetrics->emDescent = mMetrics->emHeight - mMetrics->emAscent;
            if (oMetrics.otmEMSquare > 0) {
                mFUnitsConvFactor = float(mAdjustedSize / oMetrics.otmEMSquare);
            }
        } else {
            // Make a best-effort guess at extended metrics
            // this is based on general typographic guidelines

            // GetTextMetrics can fail if the font file has been removed
            // or corrupted recently.
            BOOL result = GetTextMetrics(dc.GetDC(), &metrics);
            if (!result) {
                NS_WARNING("Missing or corrupt font data, fasten your seatbelt");
                mIsValid = false;
                memset(mMetrics, 0, sizeof(*mMetrics));
                return;
            }

            mMetrics->xHeight =
                ROUND((float)metrics.tmAscent * DEFAULT_XHEIGHT_FACTOR);
            mMetrics->strikeoutSize = 1;
            mMetrics->strikeoutOffset = ROUND(mMetrics->xHeight * 0.5f); // 50% of xHeight
            mMetrics->underlineSize = 1;
            mMetrics->underlineOffset = -ROUND((float)metrics.tmDescent * 0.30f); // 30% of descent
            mMetrics->emHeight = metrics.tmHeight - metrics.tmInternalLeading;
            mMetrics->emAscent = metrics.tmAscent - metrics.tmInternalLeading;
            mMetrics->emDescent = metrics.tmDescent;
            mMetrics->capHeight = mMetrics->emAscent;
        }

        mMetrics->internalLeading = metrics.tmInternalLeading;
        mMetrics->externalLeading = metrics.tmExternalLeading;
        mMetrics->maxHeight = metrics.tmHeight;
        mMetrics->maxAscent = metrics.tmAscent;
        mMetrics->maxDescent = metrics.tmDescent;
        mMetrics->maxAdvance = metrics.tmMaxCharWidth;
        mMetrics->aveCharWidth = std::max<gfxFloat>(1, metrics.tmAveCharWidth);
        // The font is monospace when TMPF_FIXED_PITCH is *not* set!
        // See http://msdn2.microsoft.com/en-us/library/ms534202(VS.85).aspx
        if (!(metrics.tmPitchAndFamily & TMPF_FIXED_PITCH)) {
            mMetrics->maxAdvance = mMetrics->aveCharWidth;
        }

        // For fonts with USE_TYPO_METRICS set in the fsSelection field,
        // let the OS/2 sTypo* metrics override the previous values.
        // (see http://www.microsoft.com/typography/otspec/os2.htm#fss)
        // Using the equivalent values from oMetrics provides inconsistent
        // results with CFF fonts, so we instead rely on OS2Table.
        gfxFontEntry::AutoTable os2Table(mFontEntry,
                                         TRUETYPE_TAG('O','S','/','2'));
        if (os2Table) {
            uint32_t len;
            const OS2Table *os2 =
                reinterpret_cast<const OS2Table*>(hb_blob_get_data(os2Table,
                                                                   &len));
            if (len >= offsetof(OS2Table, sTypoLineGap) + sizeof(int16_t)) {
                const uint16_t kUseTypoMetricsMask = 1 << 7;
                if ((uint16_t(os2->fsSelection) & kUseTypoMetricsMask)) {
                    double ascent = int16_t(os2->sTypoAscender);
                    double descent = int16_t(os2->sTypoDescender);
                    double lineGap = int16_t(os2->sTypoLineGap);
                    mMetrics->maxAscent = ROUND(ascent * mFUnitsConvFactor);
                    mMetrics->maxDescent = -ROUND(descent * mFUnitsConvFactor);
                    mMetrics->maxHeight =
                        mMetrics->maxAscent + mMetrics->maxDescent;
                    mMetrics->internalLeading =
                        mMetrics->maxHeight - mMetrics->emHeight;
                    gfxFloat lineHeight =
                        ROUND((ascent - descent + lineGap) * mFUnitsConvFactor);
                    lineHeight = std::max(lineHeight, mMetrics->maxHeight);
                    mMetrics->externalLeading =
                        lineHeight - mMetrics->maxHeight;
                }
            }
            // although sxHeight and sCapHeight are signed fields, we consider
            // negative values to be erroneous and just ignore them
            if (uint16_t(os2->version) >= 2) {
                // version 2 and later includes the x-height and cap-height fields
                if (len >= offsetof(OS2Table, sxHeight) + sizeof(int16_t) &&
                    int16_t(os2->sxHeight) > 0) {
                    mMetrics->xHeight = ROUND(int16_t(os2->sxHeight) * mFUnitsConvFactor);
                }
                if (len >= offsetof(OS2Table, sCapHeight) + sizeof(int16_t) &&
                    int16_t(os2->sCapHeight) > 0) {
                    mMetrics->capHeight = ROUND(int16_t(os2->sCapHeight) * mFUnitsConvFactor);
                }
            }
        }

        WORD glyph;
        SIZE size;
        DWORD ret = GetGlyphIndicesW(dc.GetDC(), L" ", 1, &glyph,
                                     GGI_MARK_NONEXISTING_GLYPHS);
        if (ret != GDI_ERROR && glyph != 0xFFFF) {
            mSpaceGlyph = glyph;
            // Cache the width of a single space.
            GetTextExtentPoint32W(dc.GetDC(), L" ", 1, &size);
            mMetrics->spaceWidth = ROUND(size.cx);
        } else {
            mMetrics->spaceWidth = mMetrics->aveCharWidth;
        }

        // Cache the width of digit zero, if available.
        ret = GetGlyphIndicesW(dc.GetDC(), L"0", 1, &glyph,
                               GGI_MARK_NONEXISTING_GLYPHS);
        if (ret != GDI_ERROR && glyph != 0xFFFF) {
            GetTextExtentPoint32W(dc.GetDC(), L"0", 1, &size);
            mMetrics->zeroOrAveCharWidth = ROUND(size.cx);
        } else {
            mMetrics->zeroOrAveCharWidth = mMetrics->aveCharWidth;
        }

        SanitizeMetrics(mMetrics, GetFontEntry()->mIsBadUnderlineFont);
    } else {
        mFUnitsConvFactor = 0.0; // zero-sized font: all values scale to zero
    }

    if (IsSyntheticBold()) {
        mMetrics->aveCharWidth += GetSyntheticBoldOffset();
        mMetrics->maxAdvance += GetSyntheticBoldOffset();
    }

    mFontFace = cairo_win32_font_face_create_for_logfontw_hfont(&logFont,
                                                                mFont);

    cairo_matrix_t sizeMatrix, ctm;
    cairo_matrix_init_identity(&ctm);
    cairo_matrix_init_scale(&sizeMatrix, mAdjustedSize, mAdjustedSize);

    if (useCairoFakeItalic) {
        // Skew the matrix to do fake italic if it wasn't already applied
        // via the LOGFONT
        double skewfactor = OBLIQUE_SKEW_FACTOR;
        cairo_matrix_t style;
        cairo_matrix_init(&style,
                          1,                //xx
                          0,                //yx
                          -1 * skewfactor,  //xy
                          1,                //yy
                          0,                //x0
                          0);               //y0
        cairo_matrix_multiply(&sizeMatrix, &sizeMatrix, &style);
    }

    cairo_font_options_t *fontOptions = cairo_font_options_create();
    if (mAntialiasOption != kAntialiasDefault) {
        cairo_font_options_set_antialias(fontOptions,
            GetCairoAntialiasOption(mAntialiasOption));
    }
    mScaledFont = cairo_scaled_font_create(mFontFace, &sizeMatrix,
                                           &ctm, fontOptions);
    cairo_font_options_destroy(fontOptions);

    if (!mScaledFont ||
        cairo_scaled_font_status(mScaledFont) != CAIRO_STATUS_SUCCESS) {
#ifdef DEBUG
        char warnBuf[1024];
        SprintfLiteral(warnBuf, "Failed to create scaled font: %s status: %d",
                       NS_ConvertUTF16toUTF8(mFontEntry->Name()).get(),
                       mScaledFont ? cairo_scaled_font_status(mScaledFont) : 0);
        NS_WARNING(warnBuf);
#endif
        mIsValid = false;
    } else {
        mIsValid = true;
    }

#if 0
    printf("Font: %p (%s) size: %f adjusted size: %f valid: %s\n", this,
           NS_ConvertUTF16toUTF8(GetName()).get(), mStyle.size, mAdjustedSize, (mIsValid ? "yes" : "no"));
    printf("    emHeight: %f emAscent: %f emDescent: %f\n", mMetrics->emHeight, mMetrics->emAscent, mMetrics->emDescent);
    printf("    maxAscent: %f maxDescent: %f maxAdvance: %f\n", mMetrics->maxAscent, mMetrics->maxDescent, mMetrics->maxAdvance);
    printf("    internalLeading: %f externalLeading: %f\n", mMetrics->internalLeading, mMetrics->externalLeading);
    printf("    spaceWidth: %f aveCharWidth: %f\n", mMetrics->spaceWidth, mMetrics->aveCharWidth);
    printf("    xHeight: %f capHeight: %f\n", mMetrics->xHeight, mMetrics->capHeight);
    printf("    uOff: %f uSize: %f stOff: %f stSize: %f\n",
           mMetrics->underlineOffset, mMetrics->underlineSize, mMetrics->strikeoutOffset, mMetrics->strikeoutSize);
#endif
}

void
gfxGDIFont::FillLogFont(LOGFONTW& aLogFont, gfxFloat aSize,
                        bool aUseGDIFakeItalic)
{
    GDIFontEntry *fe = static_cast<GDIFontEntry*>(GetFontEntry());

    uint16_t weight;
    if (fe->IsUserFont()) {
        if (fe->IsLocalUserFont()) {
            // for local user fonts, don't change the original weight
            // in the entry's logfont, because that could alter the
            // choice of actual face used (bug 724231)
            weight = 0;
        } else {
            // avoid GDI synthetic bold which occurs when weight
            // specified is >= font data weight + 200
            weight = mNeedsBold ? 700 : 200;
        }
    } else {
        weight = mNeedsBold ? 700 : fe->Weight();
    }

    fe->FillLogFont(&aLogFont, weight, aSize);

    // If GDI synthetic italic is wanted, force the lfItalic field to true
    if (aUseGDIFakeItalic) {
        aLogFont.lfItalic = 1;
    }
}

uint32_t
gfxGDIFont::GetGlyph(uint32_t aUnicode, uint32_t aVarSelector)
{
    // Callback used only for fonts that lack a 'cmap' table.

    // We don't support variation selector sequences or non-BMP characters
    // in the legacy bitmap, vector or postscript fonts that might use
    // this code path.
    if (aUnicode > 0xffff || aVarSelector) {
        return 0;
    }

    if (!mGlyphIDs) {
        mGlyphIDs = MakeUnique<nsDataHashtable<nsUint32HashKey,uint32_t>>(64);
    }

    uint32_t gid;
    if (mGlyphIDs->Get(aUnicode, &gid)) {
        return gid;
    }

    wchar_t ch = aUnicode;
    WORD glyph;
    DWORD ret = ScriptGetCMap(nullptr, &mScriptCache, &ch, 1, 0, &glyph);
    if (ret != S_OK) {
        AutoDC dc;
        AutoSelectFont fs(dc.GetDC(), GetHFONT());
        if (ret == E_PENDING) {
            // Try ScriptGetCMap again now that we've set up the font.
            ret = ScriptGetCMap(dc.GetDC(), &mScriptCache, &ch, 1, 0, &glyph);
        }
        if (ret != S_OK) {
            // If ScriptGetCMap still failed, fall back to GetGlyphIndicesW
            // (see bug 1105807).
            ret = GetGlyphIndicesW(dc.GetDC(), &ch, 1, &glyph,
                                   GGI_MARK_NONEXISTING_GLYPHS);
            if (ret == GDI_ERROR || glyph == 0xFFFF) {
                glyph = 0;
            }
        }
    }

    mGlyphIDs->Put(aUnicode, glyph);
    return glyph;
}

int32_t
gfxGDIFont::GetGlyphWidth(DrawTarget& aDrawTarget, uint16_t aGID)
{
    if (!mGlyphWidths) {
        mGlyphWidths = MakeUnique<nsDataHashtable<nsUint32HashKey,int32_t>>(128);
    }

    int32_t width;
    if (mGlyphWidths->Get(aGID, &width)) {
        return width;
    }

    DCFromDrawTarget dc(aDrawTarget);
    AutoSelectFont fs(dc, GetHFONT());

    int devWidth;
    if (GetCharWidthI(dc, aGID, 1, nullptr, &devWidth)) {
        // clamp value to range [0..0x7fff], and convert to 16.16 fixed-point
        devWidth = std::min(std::max(0, devWidth), 0x7fff);
        width = devWidth << 16;
        mGlyphWidths->Put(aGID, width);
        return width;
    }

    return -1;
}

void
gfxGDIFont::AddSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf,
                                   FontCacheSizes* aSizes) const
{
    gfxFont::AddSizeOfExcludingThis(aMallocSizeOf, aSizes);
    aSizes->mFontInstances += aMallocSizeOf(mMetrics);
    if (mGlyphWidths) {
        aSizes->mFontInstances +=
            mGlyphWidths->ShallowSizeOfIncludingThis(aMallocSizeOf);
    }
}

void
gfxGDIFont::AddSizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf,
                                   FontCacheSizes* aSizes) const
{
    aSizes->mFontInstances += aMallocSizeOf(this);
    AddSizeOfExcludingThis(aMallocSizeOf, aSizes);
}