gecko-dev/gfx/thebes/gfxFT2Utils.cpp

/* -*- 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 "ft2build.h"
#include FT_MULTIPLE_MASTERS_H

#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)
{
    MOZ_ASSERT(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;
}

/*static*/
void
gfxFT2Utils::GetVariationAxes(const FT_MM_Var* aMMVar,
                              nsTArray<gfxFontVariationAxis>& aAxes)
{
    MOZ_ASSERT(aAxes.IsEmpty());
    if (!aMMVar) {
        return;
    }
    aAxes.SetCapacity(aMMVar->num_axis);
    for (unsigned i = 0; i < aMMVar->num_axis; i++) {
        const auto& a = aMMVar->axis[i];
        gfxFontVariationAxis axis;
        axis.mMinValue = a.minimum / 65536.0;
        axis.mMaxValue = a.maximum / 65536.0;
        axis.mDefaultValue = a.def / 65536.0;
        axis.mTag = a.tag;
        axis.mName = a.name;
        aAxes.AppendElement(axis);
    }
}

/*static*/
void
gfxFT2Utils::GetVariationInstances(
    gfxFontEntry* aFontEntry,
    const FT_MM_Var* aMMVar,
    nsTArray<gfxFontVariationInstance>& aInstances)
{
    MOZ_ASSERT(aInstances.IsEmpty());
    if (!aMMVar) {
        return;
    }
    hb_blob_t* nameTable =
        aFontEntry->GetFontTable(TRUETYPE_TAG('n','a','m','e'));
    if (!nameTable) {
        return;
    }
    aInstances.SetCapacity(aMMVar->num_namedstyles);
    for (unsigned i = 0; i < aMMVar->num_namedstyles; i++) {
        const auto& ns = aMMVar->namedstyle[i];
        gfxFontVariationInstance inst;
        nsresult rv =
            gfxFontUtils::ReadCanonicalName(nameTable, ns.strid, inst.mName);
        if (NS_FAILED(rv)) {
            continue;
        }
        inst.mValues.SetCapacity(aMMVar->num_axis);
        for (unsigned j = 0; j < aMMVar->num_axis; j++) {
            gfxFontVariationValue value;
            value.mAxis = aMMVar->axis[j].tag;
            value.mValue = ns.coords[j] / 65536.0;
            inst.mValues.AppendElement(value);
        }
        aInstances.AppendElement(inst);
    }
    hb_blob_destroy(nameTable);
}