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/*
* Copyright 2016 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkStreamBuffer.h"
SkStreamBuffer::SkStreamBuffer(SkStream* stream)
: fStream(stream)
, fPosition(0)
, fBytesBuffered(0)
, fHasLengthAndPosition(stream->hasLength() && stream->hasPosition())
, fTrulyBuffered(0)
{}
SkStreamBuffer::~SkStreamBuffer() {
fMarkedData.foreach([](size_t, SkData** data) { (*data)->unref(); });
}
const char* SkStreamBuffer::get() const {
SkASSERT(fBytesBuffered >= 1);
if (fHasLengthAndPosition && fTrulyBuffered < fBytesBuffered) {
const size_t bytesToBuffer = fBytesBuffered - fTrulyBuffered;
char* dst = SkTAddOffset<char>(const_cast<char*>(fBuffer), fTrulyBuffered);
SkDEBUGCODE(const size_t bytesRead =)
// This stream is rewindable, so it should be safe to call the non-const
// read()
const_cast<SkStream*>(fStream.get())->read(dst, bytesToBuffer);
SkASSERT(bytesRead == bytesToBuffer);
fTrulyBuffered = fBytesBuffered;
}
return fBuffer;
}
bool SkStreamBuffer::buffer(size_t totalBytesToBuffer) {
// FIXME (scroggo): What should we do if the client tries to read too much?
// Should not be a problem in GIF.
SkASSERT(totalBytesToBuffer <= kMaxSize);
if (totalBytesToBuffer <= fBytesBuffered) {
return true;
}
if (fHasLengthAndPosition) {
const size_t remaining = fStream->getLength() - fStream->getPosition() + fTrulyBuffered;
fBytesBuffered = SkTMin(remaining, totalBytesToBuffer);
} else {
const size_t extraBytes = totalBytesToBuffer - fBytesBuffered;
const size_t bytesBuffered = fStream->read(fBuffer + fBytesBuffered, extraBytes);
fBytesBuffered += bytesBuffered;
}
return fBytesBuffered == totalBytesToBuffer;
}
size_t SkStreamBuffer::markPosition() {
SkASSERT(fBytesBuffered >= 1);
if (!fHasLengthAndPosition) {
sk_sp<SkData> data(SkData::MakeWithCopy(fBuffer, fBytesBuffered));
SkASSERT(nullptr == fMarkedData.find(fPosition));
fMarkedData.set(fPosition, data.release());
}
return fPosition;
}
sk_sp<SkData> SkStreamBuffer::getDataAtPosition(size_t position, size_t length) {
if (!fHasLengthAndPosition) {
SkData** data = fMarkedData.find(position);
SkASSERT(data);
SkASSERT((*data)->size() == length);
return sk_ref_sp<SkData>(*data);
}
SkASSERT(position + length <= fStream->getLength());
const size_t oldPosition = fStream->getPosition();
if (!fStream->seek(position)) {
return nullptr;
}
sk_sp<SkData> data(SkData::MakeUninitialized(length));
void* dst = data->writable_data();
const bool success = fStream->read(dst, length) == length;
fStream->seek(oldPosition);
return success ? data : nullptr;
}
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