1
2 /*
3 * Copyright 2010 The Android Open Source Project
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 #include "SkData.h"
11 #include "SkDeflate.h"
12 #include "SkStream.h"
13
14 #ifdef ZLIB_INCLUDE
15 #include ZLIB_INCLUDE
16 #else
17 #include "zlib.h"
18 #endif
19
20 namespace {
21
22 // Different zlib implementations use different T.
23 // We've seen size_t and unsigned.
skia_alloc_func(void *,T items,T size)24 template <typename T> void* skia_alloc_func(void*, T items, T size) {
25 return sk_calloc_throw(SkToSizeT(items) * SkToSizeT(size));
26 }
27
skia_free_func(void *,void * address)28 void skia_free_func(void*, void* address) { sk_free(address); }
29
30 } // namespace
31
32 #define SKDEFLATEWSTREAM_INPUT_BUFFER_SIZE 4096
33 #define SKDEFLATEWSTREAM_OUTPUT_BUFFER_SIZE 4224 // 4096 + 128, usually big
34 // enough to always do a
35 // single loop.
36
37 // called by both write() and finalize()
do_deflate(int flush,z_stream * zStream,SkWStream * out,unsigned char * inBuffer,size_t inBufferSize)38 static void do_deflate(int flush,
39 z_stream* zStream,
40 SkWStream* out,
41 unsigned char* inBuffer,
42 size_t inBufferSize) {
43 zStream->next_in = inBuffer;
44 zStream->avail_in = SkToInt(inBufferSize);
45 unsigned char outBuffer[SKDEFLATEWSTREAM_OUTPUT_BUFFER_SIZE];
46 SkDEBUGCODE(int returnValue;)
47 do {
48 zStream->next_out = outBuffer;
49 zStream->avail_out = sizeof(outBuffer);
50 SkDEBUGCODE(returnValue =) deflate(zStream, flush);
51 SkASSERT(!zStream->msg);
52
53 out->write(outBuffer, sizeof(outBuffer) - zStream->avail_out);
54 } while (zStream->avail_in || !zStream->avail_out);
55 SkASSERT(flush == Z_FINISH
56 ? returnValue == Z_STREAM_END
57 : returnValue == Z_OK);
58 }
59
60 // Hide all zlib impl details.
61 struct SkDeflateWStream::Impl {
62 SkWStream* fOut;
63 unsigned char fInBuffer[SKDEFLATEWSTREAM_INPUT_BUFFER_SIZE];
64 size_t fInBufferIndex;
65 z_stream fZStream;
66 };
67
SkDeflateWStream(SkWStream * out,int compressionLevel,bool gzip)68 SkDeflateWStream::SkDeflateWStream(SkWStream* out,
69 int compressionLevel,
70 bool gzip)
71 : fImpl(new SkDeflateWStream::Impl) {
72 fImpl->fOut = out;
73 fImpl->fInBufferIndex = 0;
74 if (!fImpl->fOut) {
75 return;
76 }
77 fImpl->fZStream.next_in = nullptr;
78 fImpl->fZStream.zalloc = &skia_alloc_func;
79 fImpl->fZStream.zfree = &skia_free_func;
80 fImpl->fZStream.opaque = nullptr;
81 SkASSERT(compressionLevel <= 9 && compressionLevel >= -1);
82 SkDEBUGCODE(int r =) deflateInit2(&fImpl->fZStream, compressionLevel,
83 Z_DEFLATED, gzip ? 0x1F : 0x0F,
84 8, Z_DEFAULT_STRATEGY);
85 SkASSERT(Z_OK == r);
86 }
87
~SkDeflateWStream()88 SkDeflateWStream::~SkDeflateWStream() { this->finalize(); }
89
finalize()90 void SkDeflateWStream::finalize() {
91 if (!fImpl->fOut) {
92 return;
93 }
94 do_deflate(Z_FINISH, &fImpl->fZStream, fImpl->fOut, fImpl->fInBuffer,
95 fImpl->fInBufferIndex);
96 (void)deflateEnd(&fImpl->fZStream);
97 fImpl->fOut = nullptr;
98 }
99
write(const void * void_buffer,size_t len)100 bool SkDeflateWStream::write(const void* void_buffer, size_t len) {
101 if (!fImpl->fOut) {
102 return false;
103 }
104 const char* buffer = (const char*)void_buffer;
105 while (len > 0) {
106 size_t tocopy =
107 SkTMin(len, sizeof(fImpl->fInBuffer) - fImpl->fInBufferIndex);
108 memcpy(fImpl->fInBuffer + fImpl->fInBufferIndex, buffer, tocopy);
109 len -= tocopy;
110 buffer += tocopy;
111 fImpl->fInBufferIndex += tocopy;
112 SkASSERT(fImpl->fInBufferIndex <= sizeof(fImpl->fInBuffer));
113
114 // if the buffer isn't filled, don't call into zlib yet.
115 if (sizeof(fImpl->fInBuffer) == fImpl->fInBufferIndex) {
116 do_deflate(Z_NO_FLUSH, &fImpl->fZStream, fImpl->fOut,
117 fImpl->fInBuffer, fImpl->fInBufferIndex);
118 fImpl->fInBufferIndex = 0;
119 }
120 }
121 return true;
122 }
123
bytesWritten() const124 size_t SkDeflateWStream::bytesWritten() const {
125 return fImpl->fZStream.total_in + fImpl->fInBufferIndex;
126 }
127