1*c8dee2aaSAndroid Build Coastguard Worker /*
2*c8dee2aaSAndroid Build Coastguard Worker * Copyright 2013 Google Inc.
3*c8dee2aaSAndroid Build Coastguard Worker *
4*c8dee2aaSAndroid Build Coastguard Worker * Use of this source code is governed by a BSD-style license that can be
5*c8dee2aaSAndroid Build Coastguard Worker * found in the LICENSE file.
6*c8dee2aaSAndroid Build Coastguard Worker */
7*c8dee2aaSAndroid Build Coastguard Worker
8*c8dee2aaSAndroid Build Coastguard Worker #include "include/codec/SkCodec.h"
9*c8dee2aaSAndroid Build Coastguard Worker #include "include/core/SkStream.h"
10*c8dee2aaSAndroid Build Coastguard Worker #include "FrontBufferedStream.h"
11*c8dee2aaSAndroid Build Coastguard Worker
12*c8dee2aaSAndroid Build Coastguard Worker #include <algorithm>
13*c8dee2aaSAndroid Build Coastguard Worker #include <memory>
14*c8dee2aaSAndroid Build Coastguard Worker
15*c8dee2aaSAndroid Build Coastguard Worker namespace {
16*c8dee2aaSAndroid Build Coastguard Worker class FrontBufferedStream : public SkStreamRewindable {
17*c8dee2aaSAndroid Build Coastguard Worker public:
18*c8dee2aaSAndroid Build Coastguard Worker // Called by Make.
19*c8dee2aaSAndroid Build Coastguard Worker FrontBufferedStream(std::unique_ptr<SkStream>, size_t bufferSize);
20*c8dee2aaSAndroid Build Coastguard Worker ~FrontBufferedStream() override;
21*c8dee2aaSAndroid Build Coastguard Worker
failedToAllocateBuffer() const22*c8dee2aaSAndroid Build Coastguard Worker bool failedToAllocateBuffer() const { return !fBuffer; }
23*c8dee2aaSAndroid Build Coastguard Worker
24*c8dee2aaSAndroid Build Coastguard Worker size_t read(void* buffer, size_t size) override;
25*c8dee2aaSAndroid Build Coastguard Worker
26*c8dee2aaSAndroid Build Coastguard Worker size_t peek(void* buffer, size_t size) const override;
27*c8dee2aaSAndroid Build Coastguard Worker
28*c8dee2aaSAndroid Build Coastguard Worker bool isAtEnd() const override;
29*c8dee2aaSAndroid Build Coastguard Worker
30*c8dee2aaSAndroid Build Coastguard Worker bool rewind() override;
31*c8dee2aaSAndroid Build Coastguard Worker
hasLength() const32*c8dee2aaSAndroid Build Coastguard Worker bool hasLength() const override { return fHasLength; }
33*c8dee2aaSAndroid Build Coastguard Worker
getLength() const34*c8dee2aaSAndroid Build Coastguard Worker size_t getLength() const override { return fLength; }
35*c8dee2aaSAndroid Build Coastguard Worker
36*c8dee2aaSAndroid Build Coastguard Worker private:
onDuplicate() const37*c8dee2aaSAndroid Build Coastguard Worker SkStreamRewindable* onDuplicate() const override { return nullptr; }
38*c8dee2aaSAndroid Build Coastguard Worker
39*c8dee2aaSAndroid Build Coastguard Worker std::unique_ptr<SkStream> fStream;
40*c8dee2aaSAndroid Build Coastguard Worker const bool fHasLength;
41*c8dee2aaSAndroid Build Coastguard Worker const size_t fLength;
42*c8dee2aaSAndroid Build Coastguard Worker // Current offset into the stream. Always >= 0.
43*c8dee2aaSAndroid Build Coastguard Worker size_t fOffset;
44*c8dee2aaSAndroid Build Coastguard Worker // Amount that has been buffered by calls to read. Will always be less than
45*c8dee2aaSAndroid Build Coastguard Worker // fBufferSize.
46*c8dee2aaSAndroid Build Coastguard Worker size_t fBufferedSoFar;
47*c8dee2aaSAndroid Build Coastguard Worker // Total size of the buffer.
48*c8dee2aaSAndroid Build Coastguard Worker const size_t fBufferSize;
49*c8dee2aaSAndroid Build Coastguard Worker char* fBuffer;
50*c8dee2aaSAndroid Build Coastguard Worker inline static constexpr size_t kStorageSize = SkCodec::MinBufferedBytesNeeded();
51*c8dee2aaSAndroid Build Coastguard Worker char fStorage[kStorageSize];
52*c8dee2aaSAndroid Build Coastguard Worker
53*c8dee2aaSAndroid Build Coastguard Worker // Read up to size bytes from already buffered data, and copy to
54*c8dee2aaSAndroid Build Coastguard Worker // dst, if non-nullptr. Updates fOffset. Assumes that fOffset is less
55*c8dee2aaSAndroid Build Coastguard Worker // than fBufferedSoFar.
56*c8dee2aaSAndroid Build Coastguard Worker size_t readFromBuffer(char* dst, size_t size);
57*c8dee2aaSAndroid Build Coastguard Worker
58*c8dee2aaSAndroid Build Coastguard Worker // Buffer up to size bytes from the stream, and copy to dst if non-
59*c8dee2aaSAndroid Build Coastguard Worker // nullptr. Updates fOffset and fBufferedSoFar. Assumes that fOffset is
60*c8dee2aaSAndroid Build Coastguard Worker // less than fBufferedSoFar, and size is greater than 0.
61*c8dee2aaSAndroid Build Coastguard Worker size_t bufferAndWriteTo(char* dst, size_t size);
62*c8dee2aaSAndroid Build Coastguard Worker
63*c8dee2aaSAndroid Build Coastguard Worker // Read up to size bytes directly from the stream and into dst if non-
64*c8dee2aaSAndroid Build Coastguard Worker // nullptr. Updates fOffset. Assumes fOffset is at or beyond the buffered
65*c8dee2aaSAndroid Build Coastguard Worker // data, and size is greater than 0.
66*c8dee2aaSAndroid Build Coastguard Worker size_t readDirectlyFromStream(char* dst, size_t size);
67*c8dee2aaSAndroid Build Coastguard Worker
68*c8dee2aaSAndroid Build Coastguard Worker using INHERITED = SkStream;
69*c8dee2aaSAndroid Build Coastguard Worker };
70*c8dee2aaSAndroid Build Coastguard Worker } // anonymous namespace
71*c8dee2aaSAndroid Build Coastguard Worker
72*c8dee2aaSAndroid Build Coastguard Worker namespace android {
73*c8dee2aaSAndroid Build Coastguard Worker namespace skia {
74*c8dee2aaSAndroid Build Coastguard Worker
Make(std::unique_ptr<SkStream> stream,size_t bufferSize)75*c8dee2aaSAndroid Build Coastguard Worker std::unique_ptr<SkStreamRewindable> FrontBufferedStream::Make(std::unique_ptr<SkStream> stream,
76*c8dee2aaSAndroid Build Coastguard Worker size_t bufferSize) {
77*c8dee2aaSAndroid Build Coastguard Worker if (!stream) {
78*c8dee2aaSAndroid Build Coastguard Worker return nullptr;
79*c8dee2aaSAndroid Build Coastguard Worker }
80*c8dee2aaSAndroid Build Coastguard Worker auto frontBufferedStream = std::make_unique<::FrontBufferedStream>(
81*c8dee2aaSAndroid Build Coastguard Worker std::move(stream), bufferSize);
82*c8dee2aaSAndroid Build Coastguard Worker if (frontBufferedStream->failedToAllocateBuffer()) {
83*c8dee2aaSAndroid Build Coastguard Worker return nullptr;
84*c8dee2aaSAndroid Build Coastguard Worker }
85*c8dee2aaSAndroid Build Coastguard Worker
86*c8dee2aaSAndroid Build Coastguard Worker return frontBufferedStream;
87*c8dee2aaSAndroid Build Coastguard Worker }
88*c8dee2aaSAndroid Build Coastguard Worker } // namespace skia
89*c8dee2aaSAndroid Build Coastguard Worker } // namespace android
90*c8dee2aaSAndroid Build Coastguard Worker
91*c8dee2aaSAndroid Build Coastguard Worker namespace {
FrontBufferedStream(std::unique_ptr<SkStream> stream,size_t bufferSize)92*c8dee2aaSAndroid Build Coastguard Worker FrontBufferedStream::FrontBufferedStream(std::unique_ptr<SkStream> stream, size_t bufferSize)
93*c8dee2aaSAndroid Build Coastguard Worker : fStream(std::move(stream))
94*c8dee2aaSAndroid Build Coastguard Worker , fHasLength(fStream->hasPosition() && fStream->hasLength())
95*c8dee2aaSAndroid Build Coastguard Worker , fLength(fStream->getLength() - fStream->getPosition())
96*c8dee2aaSAndroid Build Coastguard Worker , fOffset(0)
97*c8dee2aaSAndroid Build Coastguard Worker , fBufferedSoFar(0)
98*c8dee2aaSAndroid Build Coastguard Worker , fBufferSize(bufferSize)
99*c8dee2aaSAndroid Build Coastguard Worker , fBuffer(bufferSize <= kStorageSize ? fStorage
100*c8dee2aaSAndroid Build Coastguard Worker : reinterpret_cast<char*>(malloc(bufferSize))) {}
101*c8dee2aaSAndroid Build Coastguard Worker
~FrontBufferedStream()102*c8dee2aaSAndroid Build Coastguard Worker FrontBufferedStream::~FrontBufferedStream() {
103*c8dee2aaSAndroid Build Coastguard Worker if (fBuffer != fStorage) {
104*c8dee2aaSAndroid Build Coastguard Worker free(fBuffer);
105*c8dee2aaSAndroid Build Coastguard Worker }
106*c8dee2aaSAndroid Build Coastguard Worker }
107*c8dee2aaSAndroid Build Coastguard Worker
isAtEnd() const108*c8dee2aaSAndroid Build Coastguard Worker bool FrontBufferedStream::isAtEnd() const {
109*c8dee2aaSAndroid Build Coastguard Worker if (fOffset < fBufferedSoFar) {
110*c8dee2aaSAndroid Build Coastguard Worker // Even if the underlying stream is at the end, this stream has been
111*c8dee2aaSAndroid Build Coastguard Worker // rewound after buffering, so it is not at the end.
112*c8dee2aaSAndroid Build Coastguard Worker return false;
113*c8dee2aaSAndroid Build Coastguard Worker }
114*c8dee2aaSAndroid Build Coastguard Worker
115*c8dee2aaSAndroid Build Coastguard Worker return fStream->isAtEnd();
116*c8dee2aaSAndroid Build Coastguard Worker }
117*c8dee2aaSAndroid Build Coastguard Worker
rewind()118*c8dee2aaSAndroid Build Coastguard Worker bool FrontBufferedStream::rewind() {
119*c8dee2aaSAndroid Build Coastguard Worker // Only allow a rewind if we have not exceeded the buffer.
120*c8dee2aaSAndroid Build Coastguard Worker if (fOffset <= fBufferSize) {
121*c8dee2aaSAndroid Build Coastguard Worker fOffset = 0;
122*c8dee2aaSAndroid Build Coastguard Worker return true;
123*c8dee2aaSAndroid Build Coastguard Worker }
124*c8dee2aaSAndroid Build Coastguard Worker return false;
125*c8dee2aaSAndroid Build Coastguard Worker }
126*c8dee2aaSAndroid Build Coastguard Worker
readFromBuffer(char * dst,size_t size)127*c8dee2aaSAndroid Build Coastguard Worker size_t FrontBufferedStream::readFromBuffer(char* dst, size_t size) {
128*c8dee2aaSAndroid Build Coastguard Worker SkASSERT(fOffset < fBufferedSoFar);
129*c8dee2aaSAndroid Build Coastguard Worker // Some data has already been copied to fBuffer. Read up to the
130*c8dee2aaSAndroid Build Coastguard Worker // lesser of the size requested and the remainder of the buffered
131*c8dee2aaSAndroid Build Coastguard Worker // data.
132*c8dee2aaSAndroid Build Coastguard Worker const size_t bytesToCopy = std::min(size, fBufferedSoFar - fOffset);
133*c8dee2aaSAndroid Build Coastguard Worker if (dst != nullptr) {
134*c8dee2aaSAndroid Build Coastguard Worker memcpy(dst, fBuffer + fOffset, bytesToCopy);
135*c8dee2aaSAndroid Build Coastguard Worker }
136*c8dee2aaSAndroid Build Coastguard Worker
137*c8dee2aaSAndroid Build Coastguard Worker // Update fOffset to the new position. It is guaranteed to be
138*c8dee2aaSAndroid Build Coastguard Worker // within the buffered data.
139*c8dee2aaSAndroid Build Coastguard Worker fOffset += bytesToCopy;
140*c8dee2aaSAndroid Build Coastguard Worker SkASSERT(fOffset <= fBufferedSoFar);
141*c8dee2aaSAndroid Build Coastguard Worker
142*c8dee2aaSAndroid Build Coastguard Worker return bytesToCopy;
143*c8dee2aaSAndroid Build Coastguard Worker }
144*c8dee2aaSAndroid Build Coastguard Worker
bufferAndWriteTo(char * dst,size_t size)145*c8dee2aaSAndroid Build Coastguard Worker size_t FrontBufferedStream::bufferAndWriteTo(char* dst, size_t size) {
146*c8dee2aaSAndroid Build Coastguard Worker SkASSERT(size > 0);
147*c8dee2aaSAndroid Build Coastguard Worker SkASSERT(fOffset >= fBufferedSoFar);
148*c8dee2aaSAndroid Build Coastguard Worker SkASSERT(fBuffer);
149*c8dee2aaSAndroid Build Coastguard Worker // Data needs to be buffered. Buffer up to the lesser of the size requested
150*c8dee2aaSAndroid Build Coastguard Worker // and the remainder of the max buffer size.
151*c8dee2aaSAndroid Build Coastguard Worker const size_t bytesToBuffer = std::min(size, fBufferSize - fBufferedSoFar);
152*c8dee2aaSAndroid Build Coastguard Worker char* buffer = fBuffer + fOffset;
153*c8dee2aaSAndroid Build Coastguard Worker const size_t buffered = fStream->read(buffer, bytesToBuffer);
154*c8dee2aaSAndroid Build Coastguard Worker
155*c8dee2aaSAndroid Build Coastguard Worker fBufferedSoFar += buffered;
156*c8dee2aaSAndroid Build Coastguard Worker fOffset = fBufferedSoFar;
157*c8dee2aaSAndroid Build Coastguard Worker SkASSERT(fBufferedSoFar <= fBufferSize);
158*c8dee2aaSAndroid Build Coastguard Worker
159*c8dee2aaSAndroid Build Coastguard Worker // Copy the buffer to the destination buffer and update the amount read.
160*c8dee2aaSAndroid Build Coastguard Worker if (dst != nullptr) {
161*c8dee2aaSAndroid Build Coastguard Worker memcpy(dst, buffer, buffered);
162*c8dee2aaSAndroid Build Coastguard Worker }
163*c8dee2aaSAndroid Build Coastguard Worker
164*c8dee2aaSAndroid Build Coastguard Worker return buffered;
165*c8dee2aaSAndroid Build Coastguard Worker }
166*c8dee2aaSAndroid Build Coastguard Worker
readDirectlyFromStream(char * dst,size_t size)167*c8dee2aaSAndroid Build Coastguard Worker size_t FrontBufferedStream::readDirectlyFromStream(char* dst, size_t size) {
168*c8dee2aaSAndroid Build Coastguard Worker SkASSERT(size > 0);
169*c8dee2aaSAndroid Build Coastguard Worker // If we get here, we have buffered all that can be buffered.
170*c8dee2aaSAndroid Build Coastguard Worker SkASSERT(fBufferSize == fBufferedSoFar && fOffset >= fBufferSize);
171*c8dee2aaSAndroid Build Coastguard Worker
172*c8dee2aaSAndroid Build Coastguard Worker const size_t bytesReadDirectly = fStream->read(dst, size);
173*c8dee2aaSAndroid Build Coastguard Worker fOffset += bytesReadDirectly;
174*c8dee2aaSAndroid Build Coastguard Worker
175*c8dee2aaSAndroid Build Coastguard Worker // If we have read past the end of the buffer, rewinding is no longer
176*c8dee2aaSAndroid Build Coastguard Worker // supported, so we can go ahead and free the memory.
177*c8dee2aaSAndroid Build Coastguard Worker if (bytesReadDirectly > 0 && fBuffer != fStorage) {
178*c8dee2aaSAndroid Build Coastguard Worker free(fBuffer);
179*c8dee2aaSAndroid Build Coastguard Worker fBuffer = nullptr;
180*c8dee2aaSAndroid Build Coastguard Worker }
181*c8dee2aaSAndroid Build Coastguard Worker
182*c8dee2aaSAndroid Build Coastguard Worker return bytesReadDirectly;
183*c8dee2aaSAndroid Build Coastguard Worker }
184*c8dee2aaSAndroid Build Coastguard Worker
peek(void * dst,size_t size) const185*c8dee2aaSAndroid Build Coastguard Worker size_t FrontBufferedStream::peek(void* dst, size_t size) const {
186*c8dee2aaSAndroid Build Coastguard Worker // Keep track of the offset so we can return to it.
187*c8dee2aaSAndroid Build Coastguard Worker const size_t start = fOffset;
188*c8dee2aaSAndroid Build Coastguard Worker
189*c8dee2aaSAndroid Build Coastguard Worker if (start >= fBufferSize) {
190*c8dee2aaSAndroid Build Coastguard Worker // This stream is not able to buffer.
191*c8dee2aaSAndroid Build Coastguard Worker return 0;
192*c8dee2aaSAndroid Build Coastguard Worker }
193*c8dee2aaSAndroid Build Coastguard Worker
194*c8dee2aaSAndroid Build Coastguard Worker size = std::min(size, fBufferSize - start);
195*c8dee2aaSAndroid Build Coastguard Worker FrontBufferedStream* nonConstThis = const_cast<FrontBufferedStream*>(this);
196*c8dee2aaSAndroid Build Coastguard Worker const size_t bytesRead = nonConstThis->read(dst, size);
197*c8dee2aaSAndroid Build Coastguard Worker nonConstThis->fOffset = start;
198*c8dee2aaSAndroid Build Coastguard Worker return bytesRead;
199*c8dee2aaSAndroid Build Coastguard Worker }
200*c8dee2aaSAndroid Build Coastguard Worker
read(void * voidDst,size_t size)201*c8dee2aaSAndroid Build Coastguard Worker size_t FrontBufferedStream::read(void* voidDst, size_t size) {
202*c8dee2aaSAndroid Build Coastguard Worker // Cast voidDst to a char* for easy addition.
203*c8dee2aaSAndroid Build Coastguard Worker char* dst = reinterpret_cast<char*>(voidDst);
204*c8dee2aaSAndroid Build Coastguard Worker SkDEBUGCODE(const size_t totalSize = size;)
205*c8dee2aaSAndroid Build Coastguard Worker const size_t start = fOffset;
206*c8dee2aaSAndroid Build Coastguard Worker
207*c8dee2aaSAndroid Build Coastguard Worker // First, read any data that was previously buffered.
208*c8dee2aaSAndroid Build Coastguard Worker if (fOffset < fBufferedSoFar) {
209*c8dee2aaSAndroid Build Coastguard Worker const size_t bytesCopied = this->readFromBuffer(dst, size);
210*c8dee2aaSAndroid Build Coastguard Worker
211*c8dee2aaSAndroid Build Coastguard Worker // Update the remaining number of bytes needed to read
212*c8dee2aaSAndroid Build Coastguard Worker // and the destination buffer.
213*c8dee2aaSAndroid Build Coastguard Worker size -= bytesCopied;
214*c8dee2aaSAndroid Build Coastguard Worker SkASSERT(size + (fOffset - start) == totalSize);
215*c8dee2aaSAndroid Build Coastguard Worker if (dst != nullptr) {
216*c8dee2aaSAndroid Build Coastguard Worker dst += bytesCopied;
217*c8dee2aaSAndroid Build Coastguard Worker }
218*c8dee2aaSAndroid Build Coastguard Worker }
219*c8dee2aaSAndroid Build Coastguard Worker
220*c8dee2aaSAndroid Build Coastguard Worker // Buffer any more data that should be buffered, and copy it to the
221*c8dee2aaSAndroid Build Coastguard Worker // destination.
222*c8dee2aaSAndroid Build Coastguard Worker if (size > 0 && fBufferedSoFar < fBufferSize && !fStream->isAtEnd()) {
223*c8dee2aaSAndroid Build Coastguard Worker const size_t buffered = this->bufferAndWriteTo(dst, size);
224*c8dee2aaSAndroid Build Coastguard Worker
225*c8dee2aaSAndroid Build Coastguard Worker // Update the remaining number of bytes needed to read
226*c8dee2aaSAndroid Build Coastguard Worker // and the destination buffer.
227*c8dee2aaSAndroid Build Coastguard Worker size -= buffered;
228*c8dee2aaSAndroid Build Coastguard Worker SkASSERT(size + (fOffset - start) == totalSize);
229*c8dee2aaSAndroid Build Coastguard Worker if (dst != nullptr) {
230*c8dee2aaSAndroid Build Coastguard Worker dst += buffered;
231*c8dee2aaSAndroid Build Coastguard Worker }
232*c8dee2aaSAndroid Build Coastguard Worker }
233*c8dee2aaSAndroid Build Coastguard Worker
234*c8dee2aaSAndroid Build Coastguard Worker if (size > 0 && !fStream->isAtEnd()) {
235*c8dee2aaSAndroid Build Coastguard Worker SkDEBUGCODE(const size_t bytesReadDirectly =) this->readDirectlyFromStream(dst, size);
236*c8dee2aaSAndroid Build Coastguard Worker SkDEBUGCODE(size -= bytesReadDirectly;)
237*c8dee2aaSAndroid Build Coastguard Worker SkASSERT(size + (fOffset - start) == totalSize);
238*c8dee2aaSAndroid Build Coastguard Worker }
239*c8dee2aaSAndroid Build Coastguard Worker
240*c8dee2aaSAndroid Build Coastguard Worker return fOffset - start;
241*c8dee2aaSAndroid Build Coastguard Worker }
242*c8dee2aaSAndroid Build Coastguard Worker } // anonymous namespace
243