skia2/include/core/SkFontMgr.h

/*
 * Copyright 2013 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkFontMgr_DEFINED
#define SkFontMgr_DEFINED

#include "include/core/SkFontArguments.h"
#include "include/core/SkFontStyle.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkTypes.h"

class SkData;
class SkFontData;
class SkStreamAsset;
class SkString;
class SkTypeface;

class SK_API SkFontStyleSet : public SkRefCnt {
public:
    virtual int count() = 0;
    virtual void getStyle(int index, SkFontStyle*, SkString* style) = 0;
    virtual SkTypeface* createTypeface(int index) = 0;
    virtual SkTypeface* matchStyle(const SkFontStyle& pattern) = 0;

    static SkFontStyleSet* CreateEmpty();

protected:
    SkTypeface* matchStyleCSS3(const SkFontStyle& pattern);

private:
    using INHERITED = SkRefCnt;
};

class SK_API SkFontMgr : public SkRefCnt {
public:
    int countFamilies() const;
    void getFamilyName(int index, SkString* familyName) const;
    SkFontStyleSet* createStyleSet(int index) const;

    /**
     *  The caller must call unref() on the returned object.
     *  Never returns NULL; will return an empty set if the name is not found.
     *
     *  Passing nullptr as the parameter will return the default system family.
     *  Note that most systems don't have a default system family, so passing nullptr will often
     *  result in the empty set.
     *
     *  It is possible that this will return a style set not accessible from
     *  createStyleSet(int) due to hidden or auto-activated fonts.
     */
    SkFontStyleSet* matchFamily(const char familyName[]) const;

    /**
     *  Find the closest matching typeface to the specified familyName and style
     *  and return a ref to it. The caller must call unref() on the returned
     *  object. Will return nullptr if no 'good' match is found.
     *
     *  Passing |nullptr| as the parameter for |familyName| will return the
     *  default system font.
     *
     *  It is possible that this will return a style set not accessible from
     *  createStyleSet(int) or matchFamily(const char[]) due to hidden or
     *  auto-activated fonts.
     */
    SkTypeface* matchFamilyStyle(const char familyName[], const SkFontStyle&) const;

    /**
     *  Use the system fallback to find a typeface for the given character.
     *  Note that bcp47 is a combination of ISO 639, 15924, and 3166-1 codes,
     *  so it is fine to just pass a ISO 639 here.
     *
     *  Will return NULL if no family can be found for the character
     *  in the system fallback.
     *
     *  Passing |nullptr| as the parameter for |familyName| will return the
     *  default system font.
     *
     *  bcp47[0] is the least significant fallback, bcp47[bcp47Count-1] is the
     *  most significant. If no specified bcp47 codes match, any font with the
     *  requested character will be matched.
     */
    SkTypeface* matchFamilyStyleCharacter(const char familyName[], const SkFontStyle&,
                                          const char* bcp47[], int bcp47Count,
                                          SkUnichar character) const;

    /**
     *  Create a typeface for the specified data and TTC index (pass 0 for none)
     *  or NULL if the data is not recognized. The caller must call unref() on
     *  the returned object if it is not null.
     */
    sk_sp<SkTypeface> makeFromData(sk_sp<SkData>, int ttcIndex = 0) const;

    /**
     *  Create a typeface for the specified stream and TTC index
     *  (pass 0 for none) or NULL if the stream is not recognized. The caller
     *  must call unref() on the returned object if it is not null.
     */
    sk_sp<SkTypeface> makeFromStream(std::unique_ptr<SkStreamAsset>, int ttcIndex = 0) const;

    /* Experimental, API subject to change. */
    sk_sp<SkTypeface> makeFromStream(std::unique_ptr<SkStreamAsset>, const SkFontArguments&) const;

    /**
     *  Create a typeface for the specified fileName and TTC index
     *  (pass 0 for none) or NULL if the file is not found, or its contents are
     *  not recognized. The caller must call unref() on the returned object
     *  if it is not null.
     */
    sk_sp<SkTypeface> makeFromFile(const char path[], int ttcIndex = 0) const;

    sk_sp<SkTypeface> legacyMakeTypeface(const char familyName[], SkFontStyle style) const;

    /** Return the default fontmgr. */
    static sk_sp<SkFontMgr> RefDefault();

protected:
    virtual int onCountFamilies() const = 0;
    virtual void onGetFamilyName(int index, SkString* familyName) const = 0;
    virtual SkFontStyleSet* onCreateStyleSet(int index)const  = 0;

    /** May return NULL if the name is not found. */
    virtual SkFontStyleSet* onMatchFamily(const char familyName[]) const = 0;

    virtual SkTypeface* onMatchFamilyStyle(const char familyName[],
                                           const SkFontStyle&) const = 0;
    virtual SkTypeface* onMatchFamilyStyleCharacter(const char familyName[], const SkFontStyle&,
                                                    const char* bcp47[], int bcp47Count,
                                                    SkUnichar character) const = 0;

    virtual sk_sp<SkTypeface> onMakeFromData(sk_sp<SkData>, int ttcIndex) const = 0;
    virtual sk_sp<SkTypeface> onMakeFromStreamIndex(std::unique_ptr<SkStreamAsset>,
                                                    int ttcIndex) const = 0;
    virtual sk_sp<SkTypeface> onMakeFromStreamArgs(std::unique_ptr<SkStreamAsset>,
                                                   const SkFontArguments&) const = 0;
    virtual sk_sp<SkTypeface> onMakeFromFile(const char path[], int ttcIndex) const = 0;

    virtual sk_sp<SkTypeface> onLegacyMakeTypeface(const char familyName[], SkFontStyle) const = 0;

    // this method is never called -- will be removed
    virtual SkTypeface* onMatchFaceStyle(const SkTypeface*,
                                         const SkFontStyle&) const {
        return nullptr;
    }

private:

    /** Implemented by porting layer to return the default factory. */
    static sk_sp<SkFontMgr> Factory();

    using INHERITED = SkRefCnt;
};

#endif