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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 "gfxFT2FontBase.h"
#include "gfxFT2Utils.h"
#include "mozilla/Likely.h"

#ifdef HAVE_FONTCONFIG_FCFREETYPE_H
#include <fontconfig/fcfreetype.h>
#endif

#include "prlink.h"

uint32_t
gfxFT2LockedFace::GetGlyph(uint32_t aCharCode)
{
    if (MOZ_UNLIKELY(!mFace))
        return 0;

#ifdef HAVE_FONTCONFIG_FCFREETYPE_H
    // FcFreeTypeCharIndex will search starting from the most recently
    // selected charmap.  This can cause non-determistic behavior when more
    // than one charmap supports a character but with different glyphs, as
    // with older versions of MS Gothic, for example.  Always prefer a Unicode
    // charmap, if there is one.  (FcFreeTypeCharIndex usually does the
    // appropriate Unicode conversion, but some fonts have non-Roman glyphs
    // for FT_ENCODING_APPLE_ROMAN characters.)
    if (!mFace->charmap || mFace->charmap->encoding != FT_ENCODING_UNICODE) {
        FT_Select_Charmap(mFace, FT_ENCODING_UNICODE);
    }

    return FcFreeTypeCharIndex(mFace, aCharCode);
#else
    return FT_Get_Char_Index(mFace, aCharCode);
#endif
}

typedef FT_UInt (*GetCharVariantFunction)(FT_Face  face,
                                          FT_ULong charcode,
                                          FT_ULong variantSelector);

uint32_t
gfxFT2LockedFace::GetUVSGlyph(uint32_t aCharCode, uint32_t aVariantSelector)
{
    NS_PRECONDITION(aVariantSelector, "aVariantSelector should not be NULL");

    if (MOZ_UNLIKELY(!mFace))
        return 0;

    // This function is available from FreeType 2.3.6 (June 2008).
    static CharVariantFunction sGetCharVariantPtr = FindCharVariantFunction();
    if (!sGetCharVariantPtr)
        return 0;

#ifdef HAVE_FONTCONFIG_FCFREETYPE_H
    // FcFreeTypeCharIndex may have changed the selected charmap.
    // FT_Face_GetCharVariantIndex needs a unicode charmap.
    if (!mFace->charmap || mFace->charmap->encoding != FT_ENCODING_UNICODE) {
        FT_Select_Charmap(mFace, FT_ENCODING_UNICODE);
    }
#endif

    return (*sGetCharVariantPtr)(mFace, aCharCode, aVariantSelector);
}

gfxFT2LockedFace::CharVariantFunction
gfxFT2LockedFace::FindCharVariantFunction()
{
    // This function is available from FreeType 2.3.6 (June 2008).
    PRLibrary *lib = nullptr;
    CharVariantFunction function =
        reinterpret_cast<CharVariantFunction>
        (PR_FindFunctionSymbolAndLibrary("FT_Face_GetCharVariantIndex", &lib));
    if (!lib) {
        return nullptr;
    }

    FT_Int major;
    FT_Int minor;
    FT_Int patch;
    FT_Library_Version(mFace->glyph->library, &major, &minor, &patch);

    // Versions 2.4.0 to 2.4.3 crash if configured with
    // FT_CONFIG_OPTION_OLD_INTERNALS.  Presence of the symbol FT_Alloc
    // indicates FT_CONFIG_OPTION_OLD_INTERNALS.
    if (major == 2 && minor == 4 && patch < 4 &&
        PR_FindFunctionSymbol(lib, "FT_Alloc")) {
        function = nullptr;
    }

    // Decrement the reference count incremented in
    // PR_FindFunctionSymbolAndLibrary.
    PR_UnloadLibrary(lib);

    return function;
}