aboutsummaryrefslogtreecommitdiffhomepage
path: root/include/core/SkWriter32.h
blob: 793e815b3d12a2df0ff5e8658941656065772238 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208

/*
 * Copyright 2008 The Android Open Source Project
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */


#ifndef SkWriter32_DEFINED
#define SkWriter32_DEFINED

#include "SkTypes.h"

#include "SkScalar.h"
#include "SkPath.h"
#include "SkPoint.h"
#include "SkRect.h"
#include "SkMatrix.h"
#include "SkRegion.h"

class SkStream;
class SkWStream;

class SkWriter32 : SkNoncopyable {
public:
    /**
     *  The caller can specify an initial block of storage, which the caller manages.
     *  SkWriter32 will not attempt to free this in its destructor. It is up to the
     *  implementation to decide if, and how much, of the storage to utilize, and it
     *  is possible that it may be ignored entirely.
     */
    SkWriter32(size_t minSize, void* initialStorage, size_t storageSize);

    SkWriter32(size_t minSize)
        : fMinSize(minSize),
          fSize(0),
          fSingleBlock(NULL),
          fSingleBlockSize(0),
          fHead(NULL),
          fTail(NULL),
          fHeadIsExternalStorage(false) {}

    ~SkWriter32();

    /**
     *  Returns the single block backing the writer, or NULL if the memory is
     *  to be dynamically allocated.
     */
    void* getSingleBlock() const { return fSingleBlock; }

    /**
     *  Specify the single block to back the writer, rathern than dynamically
     *  allocating the memory. If block == NULL, then the writer reverts to
     *  dynamic allocation (and resets).
     */
    void reset(void* block, size_t size);

    bool writeBool(bool value) {
        this->writeInt(value);
        return value;
    }
    
    void writeInt(int32_t value) {
        *(int32_t*)this->reserve(sizeof(value)) = value;
    }
    
    void write8(int32_t value) {
        *(int32_t*)this->reserve(sizeof(value)) = value & 0xFF;
    }
    
    void write16(int32_t value) {
        *(int32_t*)this->reserve(sizeof(value)) = value & 0xFFFF;
    }
    
    void write32(int32_t value) {
        *(int32_t*)this->reserve(sizeof(value)) = value;
    }
    
    void writePtr(void* ptr) {
        // Since we "know" that we're always 4-byte aligned, we can tell the
        // compiler that here, by assigning to an int32 ptr.
        int32_t* addr = (int32_t*)this->reserve(sizeof(void*));
        if (4 == sizeof(void*)) {
            *(void**)addr = ptr;
        } else {
            memcpy(addr, &ptr, sizeof(void*));
        }
    }

    void writeScalar(SkScalar value) {
        *(SkScalar*)this->reserve(sizeof(value)) = value;
    }
    
    void writePoint(const SkPoint& pt) {
        *(SkPoint*)this->reserve(sizeof(pt)) = pt;
    }
    
    void writeRect(const SkRect& rect) {
        *(SkRect*)this->reserve(sizeof(rect)) = rect;
    }

    void writePath(const SkPath& path) {
        size_t size = path.writeToMemory(NULL);
        SkASSERT(SkAlign4(size) == size);
        path.writeToMemory(this->reserve(size));
    }

    void writeMatrix(const SkMatrix& matrix) {
        size_t size = matrix.writeToMemory(NULL);
        SkASSERT(SkAlign4(size) == size);
        matrix.writeToMemory(this->reserve(size));
    }
    
    void writeRegion(const SkRegion& rgn) {
        size_t size = rgn.writeToMemory(NULL);
        SkASSERT(SkAlign4(size) == size);
        rgn.writeToMemory(this->reserve(size));
    }

    // write count bytes (must be a multiple of 4)
    void writeMul4(const void* values, size_t size) {
        this->write(values, size);
    }

    /**
     *  Write size bytes from values. size must be a multiple of 4, though
     *  values need not be 4-byte aligned.
     */
    void write(const void* values, size_t size) {
        SkASSERT(SkAlign4(size) == size);
        // if we could query how much is avail in the current block, we might
        // copy that much, and then alloc the rest. That would reduce the waste
        // in the current block
        memcpy(this->reserve(size), values, size);
    }
    
    void writePad(const void* src, size_t size);

    /**
     *  Writes a string to the writer, which can be retrieved with
     *  SkReader32::readString().
     *  The length can be specified, or if -1 is passed, it will be computed by
     *  calling strlen(). The length must be < 0xFFFF
     */
    void writeString(const char* str, size_t len = (size_t)-1);

    /**
     *  Computes the size (aligned to multiple of 4) need to write the string
     *  in a call to writeString(). If the length is not specified, it will be
     *  computed by calling strlen().
     */
    static size_t WriteStringSize(const char* str, size_t len = (size_t)-1);

    // return the current offset (will always be a multiple of 4)
    uint32_t  size() const { return fSize; }
    void      reset();
    uint32_t* reserve(size_t size); // size MUST be multiple of 4

    // return the address of the 4byte int at the specified offset (which must
    // be a multiple of 4. This does not allocate any new space, so the returned
    // address is only valid for 1 int.
    uint32_t* peek32(size_t offset);
    
    // copy into a single buffer (allocated by caller). Must be at least size()
    void flatten(void* dst) const;
    
    // read from the stream, and write up to length bytes. Return the actual
    // number of bytes written.
    size_t readFromStream(SkStream*, size_t length);
    
    bool writeToStream(SkWStream*);

private:
    size_t      fMinSize;
    uint32_t    fSize;

    char*       fSingleBlock;
    uint32_t    fSingleBlockSize;

    struct Block;
    Block*  fHead;
    Block*  fTail;

    bool fHeadIsExternalStorage;

    Block* newBlock(size_t bytes);
};

/**
 *  Helper class to allocated SIZE bytes as part of the writer, and to provide
 *  that storage to the constructor as its initial storage buffer.
 *
 *  This wrapper ensures proper alignment rules are met for the storage.
 */
template <size_t SIZE> class SkSWriter32 : public SkWriter32 {
public:
    SkSWriter32(size_t minSize) : SkWriter32(minSize, fData.fStorage, SIZE) {}
    
private:
    union {
        void*   fPtrAlignment;
        double  fDoubleAlignment;
        char    fStorage[SIZE];
    } fData;
};

#endif