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// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "platform/image-decoders/SegmentReader.h"
#include "platform/SharedBuffer.h"
#include "third_party/skia/include/core/SkData.h"
#include "wtf/Assertions.h"
#include "wtf/Noncopyable.h"
#include "wtf/PassRefPtr.h"
#include "wtf/RefPtr.h"
#include "wtf/ThreadingPrimitives.h"
namespace blink {
// SharedBufferSegmentReader ---------------------------------------------------
// Interface for ImageDecoder to read a SharedBuffer.
class SharedBufferSegmentReader final : public SegmentReader {
WTF_MAKE_NONCOPYABLE(SharedBufferSegmentReader);
public:
SharedBufferSegmentReader(PassRefPtr<SharedBuffer>);
size_t size() const override;
size_t getSomeData(const char*& data, size_t position) const override;
sk_sp<SkData> getAsSkData() const override;
private:
RefPtr<SharedBuffer> m_sharedBuffer;
};
SharedBufferSegmentReader::SharedBufferSegmentReader(
PassRefPtr<SharedBuffer> buffer)
: m_sharedBuffer(buffer) {}
size_t SharedBufferSegmentReader::size() const {
return m_sharedBuffer->size();
}
size_t SharedBufferSegmentReader::getSomeData(const char*& data,
size_t position) const {
return m_sharedBuffer->getSomeData(data, position);
}
sk_sp<SkData> SharedBufferSegmentReader::getAsSkData() const {
return m_sharedBuffer->getAsSkData();
}
// DataSegmentReader -----------------------------------------------------------
// Interface for ImageDecoder to read an SkData.
class DataSegmentReader final : public SegmentReader {
WTF_MAKE_NONCOPYABLE(DataSegmentReader);
public:
DataSegmentReader(sk_sp<SkData>);
size_t size() const override;
size_t getSomeData(const char*& data, size_t position) const override;
sk_sp<SkData> getAsSkData() const override;
private:
sk_sp<SkData> m_data;
};
DataSegmentReader::DataSegmentReader(sk_sp<SkData> data)
: m_data(std::move(data)) {}
size_t DataSegmentReader::size() const {
return m_data->size();
}
size_t DataSegmentReader::getSomeData(const char*& data,
size_t position) const {
if (position >= m_data->size())
return 0;
data = reinterpret_cast<const char*>(m_data->bytes() + position);
return m_data->size() - position;
}
sk_sp<SkData> DataSegmentReader::getAsSkData() const {
return m_data;
}
// ROBufferSegmentReader -------------------------------------------------------
class ROBufferSegmentReader final : public SegmentReader {
WTF_MAKE_NONCOPYABLE(ROBufferSegmentReader);
public:
ROBufferSegmentReader(sk_sp<SkROBuffer>);
size_t size() const override;
size_t getSomeData(const char*& data, size_t position) const override;
sk_sp<SkData> getAsSkData() const override;
private:
sk_sp<SkROBuffer> m_roBuffer;
// Protects access to mutable fields.
mutable Mutex m_readMutex;
// Position of the first char in the current block of m_iter.
mutable size_t m_positionOfBlock;
mutable SkROBuffer::Iter m_iter;
};
ROBufferSegmentReader::ROBufferSegmentReader(sk_sp<SkROBuffer> buffer)
: m_roBuffer(std::move(buffer)),
m_positionOfBlock(0),
m_iter(m_roBuffer.get()) {}
size_t ROBufferSegmentReader::size() const {
return m_roBuffer ? m_roBuffer->size() : 0;
}
size_t ROBufferSegmentReader::getSomeData(const char*& data,
size_t position) const {
if (!m_roBuffer)
return 0;
MutexLocker lock(m_readMutex);
if (position < m_positionOfBlock) {
// SkROBuffer::Iter only iterates forwards. Start from the beginning.
m_iter.reset(m_roBuffer.get());
m_positionOfBlock = 0;
}
for (size_t sizeOfBlock = m_iter.size(); sizeOfBlock != 0;
m_positionOfBlock += sizeOfBlock, sizeOfBlock = m_iter.size()) {
ASSERT(m_positionOfBlock <= position);
if (m_positionOfBlock + sizeOfBlock > position) {
// |position| is in this block.
const size_t positionInBlock = position - m_positionOfBlock;
data = static_cast<const char*>(m_iter.data()) + positionInBlock;
return sizeOfBlock - positionInBlock;
}
// Move to next block.
if (!m_iter.next()) {
// Reset to the beginning, so future calls can succeed.
m_iter.reset(m_roBuffer.get());
m_positionOfBlock = 0;
return 0;
}
}
return 0;
}
static void unrefROBuffer(const void* ptr, void* context) {
static_cast<SkROBuffer*>(context)->unref();
}
sk_sp<SkData> ROBufferSegmentReader::getAsSkData() const {
if (!m_roBuffer)
return nullptr;
// Check to see if the data is already contiguous.
SkROBuffer::Iter iter(m_roBuffer.get());
const bool multipleBlocks = iter.next();
iter.reset(m_roBuffer.get());
if (!multipleBlocks) {
// Contiguous data. No need to copy.
m_roBuffer->ref();
return SkData::MakeWithProc(iter.data(), iter.size(), &unrefROBuffer,
m_roBuffer.get());
}
sk_sp<SkData> data = SkData::MakeUninitialized(m_roBuffer->size());
char* dst = static_cast<char*>(data->writable_data());
do {
size_t size = iter.size();
memcpy(dst, iter.data(), size);
dst += size;
} while (iter.next());
return data;
}
// SegmentReader ---------------------------------------------------------------
PassRefPtr<SegmentReader> SegmentReader::createFromSharedBuffer(
PassRefPtr<SharedBuffer> buffer) {
return adoptRef(new SharedBufferSegmentReader(std::move(buffer)));
}
PassRefPtr<SegmentReader> SegmentReader::createFromSkData(sk_sp<SkData> data) {
return adoptRef(new DataSegmentReader(std::move(data)));
}
PassRefPtr<SegmentReader> SegmentReader::createFromSkROBuffer(
sk_sp<SkROBuffer> buffer) {
return adoptRef(new ROBufferSegmentReader(std::move(buffer)));
}
} // namespace blink
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