A remotable font management interface and DirectWrite implementation.

include/ports/SkRemotableFontMgr.h

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkRemotableFontMgr_DEFINED
+#define SkRemotableFontMgr_DEFINED
+
+#include "SkFontStyle.h"
+#include "SkRefCnt.h"
+#include "SkTemplates.h"
+
+class SkDataTable;
+class SkStreamAsset;
+class SkString;
+
+struct SK_API SkFontIdentity {
+    static const uint32_t kInvalidDataId = 0xFFFFFFFF;
+
+    // Note that fDataId is a data identifier, not a font identifier.
+    // (fDataID, fTtcIndex) can be seen as a font identifier.
+    uint32_t fDataId;
+    uint32_t fTtcIndex;
+
+    // On Linux/FontConfig there is also the ability to specify preferences for rendering
+    // antialias, embedded bitmaps, autohint, hinting, hintstyle, lcd rendering
+    // may all be set or set to no-preference
+    // (No-preference is resolved against globals set by the platform)
+    // Since they may be selected against, these are really 'extensions' to SkFontStyle.
+    // SkFontStyle should pick these up.
+    SkFontStyle fFontStyle;
+};
+
+class SK_API SkRemotableFontIdentitySet : public SkRefCnt {
+public:
+    SK_DECLARE_INST_COUNT(SkRemotableFontIdentitySet)
+
+    SkRemotableFontIdentitySet(int count, SkFontIdentity** data);
+
+    int count() const { return fCount; }
+    const SkFontIdentity& at(int index) const { return fData[index]; }
+
+    static SkRemotableFontIdentitySet* NewEmpty();
+
+private:
+    SkRemotableFontIdentitySet() : fCount(0), fData() { }
+    static void NewEmptyImpl(int);
+
+    int fCount;
+    SkAutoTMalloc<SkFontIdentity> fData;
+
+    typedef SkRefCnt INHERITED;
+};
+
+class SK_API SkRemotableFontMgr : public SkRefCnt {
+public:
+    SK_DECLARE_INST_COUNT(SkRemotableFontMgr)
+
+    /**
+     *  Returns the names of the known fonts on the system.
+     *  Will not return NULL, will return an empty table if no families exist.
+     *
+     *  The indexes may be used with getIndex(int) and
+     *  matchIndexStyle(int, SkFontStyle).
+     *
+     *  The caller must unref() the returned object.
+     */
+    virtual SkDataTable* getFamilyNames() const = 0;
+
+    /**
+     *  Returns all of the fonts with the given familyIndex.
+     *  Returns NULL if the index is out of bounds.
+     *  Returns empty if there are no fonts at the given index.
+     *
+     *  The caller must unref() the returned object.
+     */
+    virtual SkRemotableFontIdentitySet* getIndex(int familyIndex) const = 0;
+
+    /**
+     *  Returns the closest match to the given style in the given index.
+     *  If there are no available fonts at the given index, the return value's
+     *  data id will be kInvalidDataId.
+     */
+    virtual SkFontIdentity matchIndexStyle(int familyIndex, const SkFontStyle&) const = 0;
+
+    /**
+     *  Returns all the fonts on the system with the given name.
+     *  If the given name is NULL, will return the default font family.
+     *  Never returns NULL; will return an empty set if the name is not found.
+     *
+     *  It is possible that this will return fonts not accessible from
+     *  getIndex(int) or matchIndexStyle(int, SkFontStyle) due to
+     *  hidden or auto-activated fonts.
+     *
+     *  The matching may be done in a system dependent way. The name may be
+     *  matched case-insensitive, there may be system aliases which resolve,
+     *  and names outside the current locale may be considered. However, this
+     *  should only return fonts which are somehow associated with the requested
+     *  name.
+     *
+     *  The caller must unref() the returned object.
+     */
+    virtual SkRemotableFontIdentitySet* matchName(const char familyName[]) const = 0;
+
+    /**
+     *  Returns the closest matching font to the specified name and style.
+     *  If there are no available fonts which match the name, the return value's
+     *  data id will be kInvalidDataId.
+     *  If the given name is NULL, the match will be against any default fonts.
+     *
+     *  It is possible that this will return a font identity not accessible from
+     *  methods returning sets due to hidden or auto-activated fonts.
+     *
+     *  The matching may be done in a system dependent way. The name may be
+     *  matched case-insensitive, there may be system aliases which resolve,
+     *  and names outside the current locale may be considered. However, this
+     *  should only return a font which is somehow associated with the requested
+     *  name.
+     *
+     *  The caller must unref() the returned object.
+     */
+    virtual SkFontIdentity matchNameStyle(const char familyName[], const SkFontStyle&) const = 0;
+
+    /**
+     *  Use the system fall-back to find a font for the given character.
+     *  If no font can be found for the character, the return value's data id
+     *  will be kInvalidDataId.
+     *  If the name is NULL, the match will start against any default fonts.
+     *  If the bpc47 is NULL, a default locale will be assumed.
+     *
+     *  Note that bpc47 is a combination of ISO 639, 15924, and 3166-1 codes,
+     *  so it is fine to just pass a ISO 639 here.
+     */
+    virtual SkFontIdentity matchNameStyleCharacter(const char familyName[], const SkFontStyle&,
+                                                   const char bpc47[], SkUnichar character) const=0;
+
+    /**
+     *  Returns the data for the given data id.
+     *  Will return NULL if the data id is invalid.
+     *  Note that this is a data id, not a font id.
+     *
+     *  The caller must unref() the returned object.
+     */
+    virtual SkStreamAsset* getData(int dataId) const = 0;
+
+private:
+    typedef SkRefCnt INHERITED;
+};
+
+#endif
+