flutter_flutter/libs/minikin/FontFamily.cpp

/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#define LOG_TAG "Minikin"

#include <stdint.h>
#include <stdlib.h>
#include <string.h>

#include <log/log.h>
#include <utils/JenkinsHash.h>

#include <hb.h>
#include <hb-ot.h>

#include "FontLanguage.h"
#include "FontLanguageListCache.h"
#include "FontUtils.h"
#include "HbFontCache.h"
#include "MinikinInternal.h"
#include <minikin/CmapCoverage.h>
#include <minikin/MinikinFont.h>
#include <minikin/FontFamily.h>
#include <minikin/MinikinFont.h>

using std::vector;

namespace minikin {

FontStyle::FontStyle(int variant, int weight, bool italic)
        : FontStyle(FontLanguageListCache::kEmptyListId, variant, weight, italic) {
}

FontStyle::FontStyle(uint32_t languageListId, int variant, int weight, bool italic)
        : bits(pack(variant, weight, italic)), mLanguageListId(languageListId) {
}

android::hash_t FontStyle::hash() const {
    uint32_t hash = android::JenkinsHashMix(0, bits);
    hash = android::JenkinsHashMix(hash, mLanguageListId);
    return android::JenkinsHashWhiten(hash);
}

// static
uint32_t FontStyle::registerLanguageList(const std::string& languages) {
    android::AutoMutex _l(gMinikinLock);
    return FontLanguageListCache::getId(languages);
}

// static
uint32_t FontStyle::pack(int variant, int weight, bool italic) {
    return (weight & kWeightMask) | (italic ? kItalicMask : 0) | (variant << kVariantShift);
}

Font::Font(const std::shared_ptr<MinikinFont>& typeface, FontStyle style)
    : typeface(typeface), style(style) {
}

Font::Font(std::shared_ptr<MinikinFont>&& typeface, FontStyle style)
    : typeface(typeface), style(style) {
}

std::unordered_set<AxisTag> Font::getSupportedAxesLocked() const {
    const uint32_t fvarTag = MinikinFont::MakeTag('f', 'v', 'a', 'r');
    HbBlob fvarTable(getFontTable(typeface.get(), fvarTag));
    if (fvarTable.size() == 0) {
        return std::unordered_set<AxisTag>();
    }

    std::unordered_set<AxisTag> supportedAxes;
    analyzeAxes(fvarTable.get(), fvarTable.size(), &supportedAxes);
    return supportedAxes;
}

Font::Font(Font&& o) {
    typeface = std::move(o.typeface);
    style = o.style;
    o.typeface = nullptr;
}

Font::Font(const Font& o) {
    typeface = o.typeface;
    style = o.style;
}

// static
FontFamily::FontFamily(std::vector<Font>&& fonts) : FontFamily(0 /* variant */, std::move(fonts)) {
}

FontFamily::FontFamily(int variant, std::vector<Font>&& fonts)
    : FontFamily(FontLanguageListCache::kEmptyListId, variant, std::move(fonts)) {
}

FontFamily::FontFamily(uint32_t langId, int variant, std::vector<Font>&& fonts)
    : mLangId(langId), mVariant(variant), mFonts(std::move(fonts)), mHasVSTable(false) {
    computeCoverage();
}

FontFamily::FontFamily(std::vector<Font>&& fonts, const uint8_t* acceleratorTable, size_t tableSize)
    : FontFamily(0 /* variant */, std::move(fonts), acceleratorTable, tableSize) {
}

FontFamily::FontFamily(int variant, std::vector<Font>&& fonts, const uint8_t* acceleratorTable,
        size_t tableSize)
    : FontFamily(FontLanguageListCache::kEmptyListId, variant, std::move(fonts), acceleratorTable,
            tableSize) {
}

FontFamily::FontFamily(uint32_t langId, int variant, std::vector<Font>&& fonts,
        const uint8_t* acceleratorTable, size_t tableSize)
    : mLangId(langId), mVariant(variant), mFonts(std::move(fonts)), mHasVSTable(false) {
    readAcceleratorTable(acceleratorTable, tableSize);
}

FontFamily::~FontFamily() {
}

bool FontFamily::analyzeStyle(const std::shared_ptr<MinikinFont>& typeface, int* weight,
        bool* italic) {
    android::AutoMutex _l(gMinikinLock);
    const uint32_t os2Tag = MinikinFont::MakeTag('O', 'S', '/', '2');
    HbBlob os2Table(getFontTable(typeface.get(), os2Tag));
    if (os2Table.get() == nullptr) return false;
    return ::minikin::analyzeStyle(os2Table.get(), os2Table.size(), weight, italic);
}

// Compute a matching metric between two styles - 0 is an exact match
static int computeMatch(FontStyle style1, FontStyle style2) {
    if (style1 == style2) return 0;
    int score = abs(style1.getWeight() - style2.getWeight());
    if (style1.getItalic() != style2.getItalic()) {
        score += 2;
    }
    return score;
}

static FontFakery computeFakery(FontStyle wanted, FontStyle actual) {
    // If desired weight is semibold or darker, and 2 or more grades
    // higher than actual (for example, medium 500 -> bold 700), then
    // select fake bold.
    int wantedWeight = wanted.getWeight();
    bool isFakeBold = wantedWeight >= 6 && (wantedWeight - actual.getWeight()) >= 2;
    bool isFakeItalic = wanted.getItalic() && !actual.getItalic();
    return FontFakery(isFakeBold, isFakeItalic);
}

FakedFont FontFamily::getClosestMatch(FontStyle style) const {
    const Font* bestFont = nullptr;
    int bestMatch = 0;
    for (size_t i = 0; i < mFonts.size(); i++) {
        const Font& font = mFonts[i];
        int match = computeMatch(font.style, style);
        if (i == 0 || match < bestMatch) {
            bestFont = &font;
            bestMatch = match;
        }
    }
    if (bestFont != nullptr) {
        return FakedFont{ bestFont->typeface.get(), computeFakery(style, bestFont->style) };
    }
    return FakedFont{ nullptr, FontFakery() };
}

bool FontFamily::isColorEmojiFamily() const {
    const FontLanguages& languageList = FontLanguageListCache::getById(mLangId);
    for (size_t i = 0; i < languageList.size(); ++i) {
        if (languageList[i].getEmojiStyle() == FontLanguage::EMSTYLE_EMOJI) {
            return true;
        }
    }
    return false;
}

void FontFamily::computeCoverage() {
    android::AutoMutex _l(gMinikinLock);
    const FontStyle defaultStyle;
    const MinikinFont* typeface = getClosestMatch(defaultStyle).font;
    const uint32_t cmapTag = MinikinFont::MakeTag('c', 'm', 'a', 'p');
    HbBlob cmapTable(getFontTable(typeface, cmapTag));
    if (cmapTable.get() == nullptr) {
        ALOGE("Could not get cmap table size!\n");
        return;
    }
    // TODO: Error check?
    CmapCoverage::getCoverage(mCoverage, cmapTable.get(), cmapTable.size(), &mHasVSTable);

    for (size_t i = 0; i < mFonts.size(); ++i) {
        std::unordered_set<AxisTag> supportedAxes = mFonts[i].getSupportedAxesLocked();
        mSupportedAxes.insert(supportedAxes.begin(), supportedAxes.end());
    }
}

bool FontFamily::hasGlyph(uint32_t codepoint, uint32_t variationSelector) const {
    assertMinikinLocked();
    if (variationSelector != 0 && !mHasVSTable) {
        // Early exit if the variation selector is specified but the font doesn't have a cmap format
        // 14 subtable.
        return false;
    }

    const FontStyle defaultStyle;
    hb_font_t* font = getHbFontLocked(getClosestMatch(defaultStyle).font);
    uint32_t unusedGlyph;
    bool result = hb_font_get_glyph(font, codepoint, variationSelector, &unusedGlyph);
    hb_font_destroy(font);
    return result;
}

std::shared_ptr<FontFamily> FontFamily::createFamilyWithVariation(
        const std::vector<FontVariation>& variations) const {
    if (variations.empty() || mSupportedAxes.empty()) {
        return nullptr;
    }

    bool hasSupportedAxis = false;
    for (const FontVariation& variation : variations) {
        if (mSupportedAxes.find(variation.axisTag) != mSupportedAxes.end()) {
            hasSupportedAxis = true;
            break;
        }
    }
    if (!hasSupportedAxis) {
        // None of variation axes are suppored by this family.
        return nullptr;
    }

    std::vector<Font> fonts;
    for (const Font& font : mFonts) {
        bool supportedVariations = false;
        android::AutoMutex _l(gMinikinLock);
        std::unordered_set<AxisTag> supportedAxes = font.getSupportedAxesLocked();
        if (!supportedAxes.empty()) {
            for (const FontVariation& variation : variations) {
                if (supportedAxes.find(variation.axisTag) != supportedAxes.end()) {
                    supportedVariations = true;
                    break;
                }
            }
        }
        std::shared_ptr<MinikinFont> minikinFont;
        if (supportedVariations) {
            minikinFont = font.typeface->createFontWithVariation(variations);
        }
        if (minikinFont == nullptr) {
            minikinFont = font.typeface;
        }
        fonts.push_back(Font(std::move(minikinFont), font.style));
    }

    return std::shared_ptr<FontFamily>(new FontFamily(mLangId, mVariant, std::move(fonts)));
}

size_t FontFamily::writeAcceleratorTable(uint8_t* out) const {
    const size_t axesTableSize = writeSupportedAxes(out);
    if (out != nullptr) {
        out += axesTableSize;
    }
    const size_t coverageTableSize = mCoverage.writeToBuffer(out);
    return axesTableSize + coverageTableSize;
}

void FontFamily::readAcceleratorTable(const uint8_t* data, size_t size) {
    const size_t readSize = readSupportedAxes(data, size);
    data += readSize;
    size -= readSize;
    bool result = mCoverage.initFromBuffer(data, size);
    LOG_ALWAYS_FATAL_IF(!result, "Failed to reconstruct accelerator table from buffer");
}

size_t FontFamily::writeSupportedAxes(uint8_t* out) const {
    LOG_ALWAYS_FATAL_IF(mSupportedAxes.size() > 255, "System fonts may only use up to 255 axes.");
    const uint8_t axesCount = static_cast<uint8_t>(mSupportedAxes.size());
    if (out != nullptr) {
        out[0] = axesCount;
        AxisTag* axisTags = reinterpret_cast<AxisTag*>(out + 1);
        for (const auto& tag : mSupportedAxes) {
            *axisTags++ = tag;
        }
    }
    const size_t axesSizeInbytes = sizeof(AxisTag) * axesCount;
    return axesSizeInbytes + 1 /* 1 for axes count */;
}

size_t FontFamily::readSupportedAxes(const uint8_t* in, size_t inSize) {
    LOG_ALWAYS_FATAL_IF(inSize == 0);
    const uint8_t axesCount = in[0];
    const size_t totalSize = sizeof(AxisTag) * axesCount + 1 /* 1 for axes Count */;
    LOG_ALWAYS_FATAL_IF(inSize < totalSize);
    const AxisTag* axisTags = reinterpret_cast<const AxisTag*>(in + 1);
    mSupportedAxes.clear();
    for (uint8_t i = 0; i < axesCount; ++i) {
        mSupportedAxes.insert(axisTags[i]);
    }
    return totalSize;
}
}  // namespace minikin