SkFontConfigInterface.h revision d66045ec7d37720309dae4879efc01793c3e746a 
1/*
2 * Copyright 2013 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#ifndef SkFontConfigInterface_DEFINED
9#define SkFontConfigInterface_DEFINED
10
11#include "SkRefCnt.h"
12#include "SkTypeface.h"
13
14/**
15 *  \class SkFontConfigInterface
16 *
17 *  Provides SkFontHost clients with access to fontconfig services. They will
18 *  access the global instance found in RefGlobal().
19 */
20class SK_API SkFontConfigInterface : public SkRefCnt {
21public:
22    /**
23     *  Returns the global SkFontConfigInterface instance, and if it is not
24     *  NULL, calls ref() on it. The caller must balance this with a call to
25     *  unref().
26     */
27    static SkFontConfigInterface* RefGlobal();
28
29    /**
30     *  Replace the current global instance with the specified one, safely
31     *  ref'ing the new instance, and unref'ing the previous. Returns its
32     *  parameter (the new global instance).
33     */
34    static SkFontConfigInterface* SetGlobal(SkFontConfigInterface*);
35
36    /**
37     *  This should be treated as private to the impl of SkFontConfigInterface.
38     *  Callers should not change or expect any particular values. It is meant
39     *  to be a union of possible storage types to aid the impl.
40     */
41    struct FontIdentity {
42        intptr_t    fIntPtr;
43        SkString    fString;
44    };
45
46    /**
47     *  Given a familyName and style, find the best match.
48     *
49     *  If a match is found, return true and set its outFontIdentifier.
50     *      If outFamilyName is not null, assign the found familyName to it
51     *          (which may differ from the requested familyName).
52     *      If outStyle is not null, assign the found style to it
53     *          (which may differ from the requested style).
54     *
55     *  If a match is not found, return false, and ignore all out parameters.
56     */
57    virtual bool matchFamilyName(const char familyName[],
58                                 SkTypeface::Style requested,
59                                 FontIdentity* outFontIdentifier,
60                                 SkString* outFamilyName,
61                                 SkTypeface::Style* outStyle) = 0;
62
63    /**
64     *  Given a FontRef, open a stream to access its data, or return null
65     *  if the FontRef's data is not available. The caller is responsible for
66     *  calling stream->unref() when it is done accessing the data.
67     */
68    virtual SkStream* openStream(const FontIdentity&) = 0;
69
70    /**
71     *  Return a singleton instance of a direct subclass that calls into
72     *  libfontconfig. This does not affect the refcnt of the returned instance.
73     */
74    static SkFontConfigInterface* GetSingletonDirectInterface();
75};
76
77#endif
78