src/ports/SkFontMgr_android.cpp

/*
 * Copyright 2014 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "include/core/SkTypes.h"

#include "include/core/SkData.h"
#include "include/core/SkFontMgr.h"
#include "include/core/SkFontStyle.h"
#include "include/core/SkPaint.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkStream.h"
#include "include/core/SkString.h"
#include "include/ports/SkFontMgr_android.h"
#include "include/private/SkFixed.h"
#include "include/private/SkTArray.h"
#include "include/private/SkTDArray.h"
#include "include/private/SkTemplates.h"
#include "src/core/SkFontDescriptor.h"
#include "src/core/SkOSFile.h"
#include "src/core/SkTSearch.h"
#include "src/core/SkTypefaceCache.h"
#include "src/ports/SkFontHost_FreeType_common.h"
#include "src/ports/SkFontMgr_android_parser.h"

#include <algorithm>
#include <limits>

class SkData;

class SkTypeface_Android : public SkTypeface_FreeType {
public:
    SkTypeface_Android(const SkFontStyle& style,
                       bool isFixedPitch,
                       const SkString& familyName)
        : INHERITED(style, isFixedPitch)
        , fFamilyName(familyName)
        { }

protected:
    void onGetFamilyName(SkString* familyName) const override {
        *familyName = fFamilyName;
    }

    SkString fFamilyName;

private:
    using INHERITED = SkTypeface_FreeType;
};

class SkTypeface_AndroidSystem : public SkTypeface_Android {
public:
    SkTypeface_AndroidSystem(const SkString& pathName,
                             const bool cacheFontFiles,
                             int index,
                             const SkFixed* axes, int axesCount,
                             const SkFontStyle& style,
                             bool isFixedPitch,
                             const SkString& familyName,
                             const SkTArray<SkLanguage, true>& lang,
                             FontVariant variantStyle)
        : INHERITED(style, isFixedPitch, familyName)
        , fPathName(pathName)
        , fIndex(index)
        , fAxes(axes, axesCount)
        , fLang(lang)
        , fVariantStyle(variantStyle)
        , fFile(cacheFontFiles ? sk_fopen(fPathName.c_str(), kRead_SkFILE_Flag) : nullptr) {
        if (cacheFontFiles) {
            SkASSERT(fFile);
        }
    }

    std::unique_ptr<SkStreamAsset> makeStream() const {
        if (fFile) {
            sk_sp<SkData> data(SkData::MakeFromFILE(fFile));
            return data ? std::make_unique<SkMemoryStream>(std::move(data)) : nullptr;
        }
        return SkStream::MakeFromFile(fPathName.c_str());
    }

    void onGetFontDescriptor(SkFontDescriptor* desc, bool* serialize) const override {
        SkASSERT(desc);
        SkASSERT(serialize);
        desc->setFamilyName(fFamilyName.c_str());
        desc->setStyle(this->fontStyle());
        *serialize = false;
    }
    std::unique_ptr<SkStreamAsset> onOpenStream(int* ttcIndex) const override {
        *ttcIndex = fIndex;
        return this->makeStream();
    }
    std::unique_ptr<SkFontData> onMakeFontData() const override {
        return std::make_unique<SkFontData>(this->makeStream(), fIndex,
                                              fAxes.begin(), fAxes.count());
    }
    sk_sp<SkTypeface> onMakeClone(const SkFontArguments& args) const override {
        std::unique_ptr<SkFontData> data = this->cloneFontData(args);
        if (!data) {
            return nullptr;
        }
        return sk_make_sp<SkTypeface_AndroidSystem>(fPathName,
                                                    fFile,
                                                    fIndex,
                                                    data->getAxis(),
                                                    data->getAxisCount(),
                                                    this->fontStyle(),
                                                    this->isFixedPitch(),
                                                    fFamilyName,
                                                    fLang,
                                                    fVariantStyle);
    }

    const SkString fPathName;
    int fIndex;
    const SkSTArray<4, SkFixed, true> fAxes;
    const SkSTArray<4, SkLanguage, true> fLang;
    const FontVariant fVariantStyle;
    SkAutoTCallVProc<FILE, sk_fclose> fFile;

    using INHERITED = SkTypeface_Android;
};

class SkTypeface_AndroidStream : public SkTypeface_Android {
public:
    SkTypeface_AndroidStream(std::unique_ptr<SkFontData> data,
                             const SkFontStyle& style,
                             bool isFixedPitch,
                             const SkString& familyName)
        : INHERITED(style, isFixedPitch, familyName)
        , fData(std::move(data))
    { }

    void onGetFontDescriptor(SkFontDescriptor* desc, bool* serialize) const override {
        SkASSERT(desc);
        SkASSERT(serialize);
        desc->setFamilyName(fFamilyName.c_str());
        *serialize = true;
    }

    std::unique_ptr<SkStreamAsset> onOpenStream(int* ttcIndex) const override {
        *ttcIndex = fData->getIndex();
        return fData->getStream()->duplicate();
    }

    std::unique_ptr<SkFontData> onMakeFontData() const override {
        return std::make_unique<SkFontData>(*fData);
    }

    sk_sp<SkTypeface> onMakeClone(const SkFontArguments& args) const override {
        std::unique_ptr<SkFontData> data = this->cloneFontData(args);
        if (!data) {
            return nullptr;
        }
        return sk_make_sp<SkTypeface_AndroidStream>(std::move(data),
                                                    this->fontStyle(),
                                                    this->isFixedPitch(),
                                                    fFamilyName);
    }

private:
    const std::unique_ptr<const SkFontData> fData;
    using INHERITED = SkTypeface_Android;
};

class SkFontStyleSet_Android : public SkFontStyleSet {
    typedef SkTypeface_FreeType::Scanner Scanner;

public:
    explicit SkFontStyleSet_Android(const FontFamily& family, const Scanner& scanner,
                                    const bool cacheFontFiles) {
        const SkString* cannonicalFamilyName = nullptr;
        if (family.fNames.count() > 0) {
            cannonicalFamilyName = &family.fNames[0];
        }
        fFallbackFor = family.fFallbackFor;

        // TODO? make this lazy
        for (int i = 0; i < family.fFonts.count(); ++i) {
            const FontFileInfo& fontFile = family.fFonts[i];

            SkString pathName(family.fBasePath);
            pathName.append(fontFile.fFileName);

            std::unique_ptr<SkStreamAsset> stream = SkStream::MakeFromFile(pathName.c_str());
            if (!stream) {
                SkDEBUGF("Requested font file %s does not exist or cannot be opened.\n",
                         pathName.c_str());
                continue;
            }

            const int ttcIndex = fontFile.fIndex;
            SkString familyName;
            SkFontStyle style;
            bool isFixedWidth;
            Scanner::AxisDefinitions axisDefinitions;
            if (!scanner.scanFont(stream.get(), ttcIndex,
                                  &familyName, &style, &isFixedWidth, &axisDefinitions))
            {
                SkDEBUGF("Requested font file %s exists, but is not a valid font.\n",
                         pathName.c_str());
                continue;
            }

            int weight = fontFile.fWeight != 0 ? fontFile.fWeight : style.weight();
            SkFontStyle::Slant slant = style.slant();
            switch (fontFile.fStyle) {
                case FontFileInfo::Style::kAuto: slant = style.slant(); break;
                case FontFileInfo::Style::kNormal: slant = SkFontStyle::kUpright_Slant; break;
                case FontFileInfo::Style::kItalic: slant = SkFontStyle::kItalic_Slant; break;
                default: SkASSERT(false); break;
            }
            style = SkFontStyle(weight, style.width(), slant);

            uint32_t variant = family.fVariant;
            if (kDefault_FontVariant == variant) {
                variant = kCompact_FontVariant | kElegant_FontVariant;
            }

            // The first specified family name overrides the family name found in the font.
            // TODO: SkTypeface_AndroidSystem::onCreateFamilyNameIterator should return
            // all of the specified family names in addition to the names found in the font.
            if (cannonicalFamilyName != nullptr) {
                familyName = *cannonicalFamilyName;
            }

            SkAutoSTMalloc<4, SkFixed> axisValues(axisDefinitions.count());
            SkFontArguments::VariationPosition position = {
                fontFile.fVariationDesignPosition.begin(),
                fontFile.fVariationDesignPosition.count()
            };
            Scanner::computeAxisValues(axisDefinitions, position,
                                       axisValues, familyName);

            fStyles.push_back().reset(new SkTypeface_AndroidSystem(
                    pathName, cacheFontFiles, ttcIndex, axisValues.get(), axisDefinitions.count(),
                    style, isFixedWidth, familyName, family.fLanguages, variant));
        }
    }

    int count() override {
        return fStyles.count();
    }
    void getStyle(int index, SkFontStyle* style, SkString* name) override {
        if (index < 0 || fStyles.count() <= index) {
            return;
        }
        if (style) {
            *style = fStyles[index]->fontStyle();
        }
        if (name) {
            name->reset();
        }
    }
    SkTypeface_AndroidSystem* createTypeface(int index) override {
        if (index < 0 || fStyles.count() <= index) {
            return nullptr;
        }
        return SkRef(fStyles[index].get());
    }

    SkTypeface_AndroidSystem* matchStyle(const SkFontStyle& pattern) override {
        return static_cast<SkTypeface_AndroidSystem*>(this->matchStyleCSS3(pattern));
    }

private:
    SkTArray<sk_sp<SkTypeface_AndroidSystem>> fStyles;
    SkString fFallbackFor;

    friend struct NameToFamily;
    friend class SkFontMgr_Android;

    using INHERITED = SkFontStyleSet;
};

/** On Android a single family can have many names, but our API assumes unique names.
 *  Map names to the back end so that all names for a given family refer to the same
 *  (non-replicated) set of typefaces.
 *  SkTDict<> doesn't let us do index-based lookup, so we write our own mapping.
 */
struct NameToFamily {
    SkString name;
    SkFontStyleSet_Android* styleSet;
};

class SkFontMgr_Android : public SkFontMgr {
public:
    SkFontMgr_Android(const SkFontMgr_Android_CustomFonts* custom) {
        SkTDArray<FontFamily*> families;
        if (custom && SkFontMgr_Android_CustomFonts::kPreferSystem != custom->fSystemFontUse) {
            SkString base(custom->fBasePath);
            SkFontMgr_Android_Parser::GetCustomFontFamilies(
                families, base, custom->fFontsXml, custom->fFallbackFontsXml);
        }
        if (!custom ||
            (custom && SkFontMgr_Android_CustomFonts::kOnlyCustom != custom->fSystemFontUse))
        {
            SkFontMgr_Android_Parser::GetSystemFontFamilies(families);
        }
        if (custom && SkFontMgr_Android_CustomFonts::kPreferSystem == custom->fSystemFontUse) {
            SkString base(custom->fBasePath);
            SkFontMgr_Android_Parser::GetCustomFontFamilies(
                families, base, custom->fFontsXml, custom->fFallbackFontsXml);
        }
        this->buildNameToFamilyMap(families, custom ? custom->fIsolated : false);
        this->findDefaultStyleSet();
        families.deleteAll();
    }

protected:
    /** Returns not how many families we have, but how many unique names
     *  exist among the families.
     */
    int onCountFamilies() const override {
        return fNameToFamilyMap.count();
    }

    void onGetFamilyName(int index, SkString* familyName) const override {
        if (index < 0 || fNameToFamilyMap.count() <= index) {
            familyName->reset();
            return;
        }
        familyName->set(fNameToFamilyMap[index].name);
    }

    SkFontStyleSet* onCreateStyleSet(int index) const override {
        if (index < 0 || fNameToFamilyMap.count() <= index) {
            return nullptr;
        }
        return SkRef(fNameToFamilyMap[index].styleSet);
    }

    SkFontStyleSet* onMatchFamily(const char familyName[]) const override {
        if (!familyName) {
            return nullptr;
        }
        SkAutoAsciiToLC tolc(familyName);
        for (int i = 0; i < fNameToFamilyMap.count(); ++i) {
            if (fNameToFamilyMap[i].name.equals(tolc.lc())) {
                return SkRef(fNameToFamilyMap[i].styleSet);
            }
        }
        // TODO: eventually we should not need to name fallback families.
        for (int i = 0; i < fFallbackNameToFamilyMap.count(); ++i) {
            if (fFallbackNameToFamilyMap[i].name.equals(tolc.lc())) {
                return SkRef(fFallbackNameToFamilyMap[i].styleSet);
            }
        }
        return nullptr;
    }

    SkTypeface* onMatchFamilyStyle(const char familyName[],
                                   const SkFontStyle& style) const override {
        sk_sp<SkFontStyleSet> sset(this->matchFamily(familyName));
        return sset->matchStyle(style);
    }

    static sk_sp<SkTypeface_AndroidSystem> find_family_style_character(
            const SkString& familyName,
            const SkTArray<NameToFamily, true>& fallbackNameToFamilyMap,
            const SkFontStyle& style, bool elegant,
            const SkString& langTag, SkUnichar character)
    {
        for (int i = 0; i < fallbackNameToFamilyMap.count(); ++i) {
            SkFontStyleSet_Android* family = fallbackNameToFamilyMap[i].styleSet;
            if (familyName != family->fFallbackFor) {
                continue;
            }
            sk_sp<SkTypeface_AndroidSystem> face(family->matchStyle(style));

            if (!langTag.isEmpty() &&
                std::none_of(face->fLang.begin(), face->fLang.end(), [&](SkLanguage lang){
                    return lang.getTag().startsWith(langTag.c_str());
                }))
            {
                continue;
            }

            if (SkToBool(face->fVariantStyle & kElegant_FontVariant) != elegant) {
                continue;
            }

            if (face->unicharToGlyph(character) != 0) {
                return face;
            }
        }
        return nullptr;
    }

    SkTypeface* onMatchFamilyStyleCharacter(const char familyName[],
                                            const SkFontStyle& style,
                                            const char* bcp47[],
                                            int bcp47Count,
                                            SkUnichar character) const override {
        // The variant 'elegant' is 'not squashed', 'compact' is 'stays in ascent/descent'.
        // The variant 'default' means 'compact and elegant'.
        // As a result, it is not possible to know the variant context from the font alone.
        // TODO: add 'is_elegant' and 'is_compact' bits to 'style' request.

        SkString familyNameString(familyName);
        for (const SkString& currentFamilyName : { familyNameString, SkString() }) {
            // The first time match anything elegant, second time anything not elegant.
            for (int elegant = 2; elegant --> 0;) {
                for (int bcp47Index = bcp47Count; bcp47Index --> 0;) {
                    SkLanguage lang(bcp47[bcp47Index]);
                    while (!lang.getTag().isEmpty()) {
                        sk_sp<SkTypeface_AndroidSystem> matchingTypeface =
                            find_family_style_character(currentFamilyName, fFallbackNameToFamilyMap,
                                                        style, SkToBool(elegant),
                                                        lang.getTag(), character);
                        if (matchingTypeface) {
                            return matchingTypeface.release();
                        }

                        lang = lang.getParent();
                    }
                }
                sk_sp<SkTypeface_AndroidSystem> matchingTypeface =
                    find_family_style_character(currentFamilyName, fFallbackNameToFamilyMap,
                                                style, SkToBool(elegant),
                                                SkString(), character);
                if (matchingTypeface) {
                    return matchingTypeface.release();
                }
            }
        }
        return nullptr;
    }

    sk_sp<SkTypeface> onMakeFromData(sk_sp<SkData> data, int ttcIndex) const override {
        return this->makeFromStream(std::unique_ptr<SkStreamAsset>(new SkMemoryStream(std::move(data))),
                                    ttcIndex);
    }

    sk_sp<SkTypeface> onMakeFromFile(const char path[], int ttcIndex) const override {
        std::unique_ptr<SkStreamAsset> stream = SkStream::MakeFromFile(path);
        return stream ? this->makeFromStream(std::move(stream), ttcIndex) : nullptr;
    }

    sk_sp<SkTypeface> onMakeFromStreamIndex(std::unique_ptr<SkStreamAsset> stream,
                                            int ttcIndex) const override {
        bool isFixedPitch;
        SkFontStyle style;
        SkString name;
        if (!fScanner.scanFont(stream.get(), ttcIndex, &name, &style, &isFixedPitch, nullptr)) {
            return nullptr;
        }
        auto data = std::make_unique<SkFontData>(std::move(stream), ttcIndex, nullptr, 0);
        return sk_sp<SkTypeface>(new SkTypeface_AndroidStream(std::move(data),
                                                              style, isFixedPitch, name));
    }

    sk_sp<SkTypeface> onMakeFromStreamArgs(std::unique_ptr<SkStreamAsset> stream,
                                           const SkFontArguments& args) const override {
        using Scanner = SkTypeface_FreeType::Scanner;
        bool isFixedPitch;
        SkFontStyle style;
        SkString name;
        Scanner::AxisDefinitions axisDefinitions;
        if (!fScanner.scanFont(stream.get(), args.getCollectionIndex(),
                               &name, &style, &isFixedPitch, &axisDefinitions))
        {
            return nullptr;
        }

        SkAutoSTMalloc<4, SkFixed> axisValues(axisDefinitions.count());
        Scanner::computeAxisValues(axisDefinitions, args.getVariationDesignPosition(),
                                   axisValues, name);

        auto data = std::make_unique<SkFontData>(std::move(stream), args.getCollectionIndex(),
                                                   axisValues.get(), axisDefinitions.count());
        return sk_sp<SkTypeface>(new SkTypeface_AndroidStream(std::move(data),
                                                              style, isFixedPitch, name));
    }

    sk_sp<SkTypeface> onLegacyMakeTypeface(const char familyName[], SkFontStyle style) const override {
        if (familyName) {
            // On Android, we must return nullptr when we can't find the requested
            // named typeface so that the system/app can provide their own recovery
            // mechanism. On other platforms we'd provide a typeface from the
            // default family instead.
            return sk_sp<SkTypeface>(this->onMatchFamilyStyle(familyName, style));
        }
        return sk_sp<SkTypeface>(fDefaultStyleSet->matchStyle(style));
    }


private:

    SkTypeface_FreeType::Scanner fScanner;

    SkTArray<sk_sp<SkFontStyleSet_Android>> fStyleSets;
    sk_sp<SkFontStyleSet> fDefaultStyleSet;

    SkTArray<NameToFamily, true> fNameToFamilyMap;
    SkTArray<NameToFamily, true> fFallbackNameToFamilyMap;

    void addFamily(FontFamily& family, const bool isolated, int familyIndex) {
        SkTArray<NameToFamily, true>* nameToFamily = &fNameToFamilyMap;
        if (family.fIsFallbackFont) {
            nameToFamily = &fFallbackNameToFamilyMap;

            if (0 == family.fNames.count()) {
                SkString& fallbackName = family.fNames.push_back();
                fallbackName.printf("%.2x##fallback", familyIndex);
            }
        }

        sk_sp<SkFontStyleSet_Android> newSet =
            sk_make_sp<SkFontStyleSet_Android>(family, fScanner, isolated);
        if (0 == newSet->count()) {
            return;
        }

        for (const SkString& name : family.fNames) {
            nameToFamily->emplace_back(NameToFamily{name, newSet.get()});
        }
        fStyleSets.emplace_back(std::move(newSet));
    }
    void buildNameToFamilyMap(SkTDArray<FontFamily*> families, const bool isolated) {
        int familyIndex = 0;
        for (FontFamily* family : families) {
            addFamily(*family, isolated, familyIndex++);
            for (const auto& [unused, fallbackFamily] : family->fallbackFamilies) {
                addFamily(*fallbackFamily, isolated, familyIndex++);
            }
        }
    }

    void findDefaultStyleSet() {
        SkASSERT(!fStyleSets.empty());

        static const char* defaultNames[] = { "sans-serif" };
        for (const char* defaultName : defaultNames) {
            fDefaultStyleSet.reset(this->onMatchFamily(defaultName));
            if (fDefaultStyleSet) {
                break;
            }
        }
        if (nullptr == fDefaultStyleSet) {
            fDefaultStyleSet = fStyleSets[0];
        }
        SkASSERT(fDefaultStyleSet);
    }

    using INHERITED = SkFontMgr;
};

#ifdef SK_DEBUG
static char const * const gSystemFontUseStrings[] = {
    "OnlyCustom", "PreferCustom", "PreferSystem"
};
#endif

sk_sp<SkFontMgr> SkFontMgr_New_Android(const SkFontMgr_Android_CustomFonts* custom) {
    if (custom) {
        SkASSERT(0 <= custom->fSystemFontUse);
        SkASSERT(custom->fSystemFontUse < SK_ARRAY_COUNT(gSystemFontUseStrings));
        SkDEBUGF("SystemFontUse: %s BasePath: %s Fonts: %s FallbackFonts: %s\n",
                 gSystemFontUseStrings[custom->fSystemFontUse],
                 custom->fBasePath,
                 custom->fFontsXml,
                 custom->fFallbackFontsXml);
    }
    return sk_make_sp<SkFontMgr_Android>(custom);
}