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1 /* | |
2 * Copyright 2015 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 SkRWBuffer_DEFINED | |
9 #define SkRWBuffer_DEFINED | |
10 | |
11 #include "SkRefCnt.h" | |
12 | |
13 struct SkBufferBlock; | |
14 struct SkBufferHead; | |
15 class SkRWBuffer; | |
16 class SkStreamAsset; | |
17 | |
18 /** | |
19 * Contains a read-only, thread-sharable block of memory. To access the memory,
the caller must | |
20 * instantiate a local iterator, as the memory is stored in 1 or more contiguou
s blocks. | |
21 */ | |
22 class SkROBuffer : public SkRefCnt { | |
23 public: | |
24 /** | |
25 * Return the logical length of the data owned/shared by this buffer. It ma
y be stored in | |
26 * multiple contiguous blocks, accessible via the iterator. | |
27 */ | |
28 size_t size() const { return fUsed; } | |
29 | |
30 class Iter { | |
31 public: | |
32 Iter(const SkROBuffer*); | |
33 | |
34 void reset(const SkROBuffer*); | |
35 | |
36 /** | |
37 * Return the current continuous block of memory, or nullptr if the ite
rator is exhausted | |
38 */ | |
39 const void* data() const; | |
40 | |
41 /** | |
42 * Returns the number of bytes in the current continguous block of memo
ry, or 0 if the | |
43 * iterator is exhausted. | |
44 */ | |
45 size_t size() const; | |
46 | |
47 /** | |
48 * Advance to the next contiguous block of memory, returning true if th
ere is another | |
49 * block, or false if the iterator is exhausted. | |
50 */ | |
51 bool next(); | |
52 | |
53 private: | |
54 const SkBufferBlock* fBlock; | |
55 size_t fRemaining; | |
56 }; | |
57 | |
58 private: | |
59 SkROBuffer(const SkBufferHead* head, size_t used); | |
60 virtual ~SkROBuffer(); | |
61 | |
62 const SkBufferHead* fHead; | |
63 const size_t fUsed; | |
64 | |
65 friend class SkRWBuffer; | |
66 }; | |
67 | |
68 /** | |
69 * Accumulates bytes of memory that are "appended" to it, growing internal stor
age as needed. | |
70 * The growth is done such that at any time, a RBuffer or StreamAsset can be sn
apped off, which | |
71 * can see the previously stored bytes, but which will be unaware of any future
writes. | |
72 */ | |
73 class SkRWBuffer { | |
74 public: | |
75 SkRWBuffer(size_t initialCapacity = 0); | |
76 ~SkRWBuffer(); | |
77 | |
78 size_t size() const { return fTotalUsed; } | |
79 void append(const void* buffer, size_t length); | |
80 void* append(size_t length); | |
81 | |
82 SkROBuffer* newRBufferSnapshot() const; | |
83 SkStreamAsset* newStreamSnapshot() const; | |
84 | |
85 #ifdef SK_DEBUG | |
86 void validate() const; | |
87 #else | |
88 void validate() const {} | |
89 #endif | |
90 | |
91 private: | |
92 SkBufferHead* fHead; | |
93 SkBufferBlock* fTail; | |
94 size_t fTotalUsed; | |
95 }; | |
96 | |
97 #endif | |
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