1
2/*
3 * Copyright 2011 Google Inc.
4 *
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
7 */
8
9
10
11#ifndef SkTypefaceCache_DEFINED
12#define SkTypefaceCache_DEFINED
13
14#include "SkTypeface.h"
15#include "SkTDArray.h"
16
17/*  TODO
18 *  Provide std way to cache name+requestedStyle aliases to the same typeface.
19 *
20 *  The current mechanism ends up create a diff typeface for each one, even if
21 *  they map to the same internal obj (e.g. CTFontRef on the mac)
22 */
23
24class SkTypefaceCache {
25public:
26    SkTypefaceCache();
27    ~SkTypefaceCache();
28
29    /**
30     * Callback for FindByProc. Returns true if the given typeface is a match
31     * for the given context. The passed typeface is owned by the cache and is
32     * not additionally ref()ed. The typeface may be in the disposed state.
33     */
34    typedef bool (*FindProc)(SkTypeface*, SkTypeface::Style, void* context);
35
36    /**
37     *  Add a typeface to the cache. This ref()s the typeface, so that the
38     *  cache is also an owner. Later, if we need to purge the cache, typefaces
39     *  whose refcnt is 1 (meaning only the cache is an owner) will be
40     *  unref()ed.
41     */
42    void add(SkTypeface*, SkTypeface::Style requested, bool strong = true);
43
44    /**
45     *  Search the cache for a typeface with the specified fontID (uniqueID).
46     *  If one is found, return it (its reference count is unmodified). If none
47     *  is found, return NULL. The reference count is unmodified as it is
48     *  assumed that the stack will contain a ref to the typeface.
49     */
50    SkTypeface* findByID(SkFontID findID) const;
51
52    /**
53     *  Iterate through the cache, calling proc(typeface, ctx) with each
54     *  typeface. If proc returns true, then we return that typeface (this
55     *  ref()s the typeface). If it never returns true, we return NULL.
56     */
57    SkTypeface* findByProcAndRef(FindProc proc, void* ctx) const;
58
59    /**
60     *  This will unref all of the typefaces in the cache for which the cache
61     *  is the only owner. Normally this is handled automatically as needed.
62     *  This function is exposed for clients that explicitly want to purge the
63     *  cache (e.g. to look for leaks).
64     */
65    void purgeAll();
66
67    /**
68     *  Helper: returns a unique fontID to pass to the constructor of
69     *  your subclass of SkTypeface
70     */
71    static SkFontID NewFontID();
72
73    // These are static wrappers around a global instance of a cache.
74
75    static void Add(SkTypeface*,
76                    SkTypeface::Style requested,
77                    bool strong = true);
78    static SkTypeface* FindByID(SkFontID fontID);
79    static SkTypeface* FindByProcAndRef(FindProc proc, void* ctx);
80    static void PurgeAll();
81
82    /**
83     *  Debugging only: dumps the status of the typefaces in the cache
84     */
85    static void Dump();
86
87private:
88    static SkTypefaceCache& Get();
89
90    void purge(int count);
91
92    struct Rec {
93        SkTypeface*         fFace;
94        bool                fStrong;
95        SkTypeface::Style   fRequestedStyle;
96    };
97    SkTDArray<Rec> fArray;
98};
99
100#endif
101