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#include "image_io/base/istream_data_source.h"
#include "image_io/base/data_destination.h"
#include "image_io/base/data_segment.h"
namespace photos_editing_formats {
namespace image_io {
void IStreamDataSource::Reset() {
istream_->clear();
istream_->seekg(0);
current_data_segment_.reset();
}
std::shared_ptr<DataSegment> IStreamDataSource::GetDataSegment(
size_t begin, size_t min_size) {
if (current_data_segment_ && current_data_segment_->Contains(begin)) {
return current_data_segment_;
}
current_data_segment_ = Read(begin, min_size);
return current_data_segment_;
}
DataSource::TransferDataResult IStreamDataSource::TransferData(
const DataRange &data_range, size_t best_size,
DataDestination *data_destination) {
bool data_transferred = false;
DataDestination::TransferStatus status = DataDestination::kTransferDone;
if (data_destination && data_range.IsValid()) {
size_t min_size = std::min(data_range.GetLength(), best_size);
if (current_data_segment_ &&
current_data_segment_->GetLength() >= min_size &&
current_data_segment_->GetDataRange().Contains(data_range)) {
status = data_destination->Transfer(data_range, *current_data_segment_);
data_transferred = true;
} else {
istream_->clear();
size_t chunk_size = min_size;
for (size_t begin = data_range.GetBegin(); begin < data_range.GetEnd();
begin += chunk_size) {
size_t segment_length = 0;
size_t end = std::min(data_range.GetEnd(), begin + chunk_size);
std::shared_ptr<DataSegment> data_segment = Read(begin, end - begin);
if (data_segment) {
segment_length = data_segment->GetLength();
if (segment_length) {
status = data_destination->Transfer(data_segment->GetDataRange(),
*data_segment);
data_transferred = true;
}
}
if (status != DataDestination::kTransferOk || segment_length == 0) {
break;
}
}
}
}
if (data_transferred) {
return status == DataDestination::kTransferError ? kTransferDataError
: kTransferDataSuccess;
} else {
return data_destination ? kTransferDataNone : kTransferDataError;
}
}
std::shared_ptr<DataSegment> IStreamDataSource::Read(size_t begin,
size_t count) {
std::shared_ptr<DataSegment> shared_data_segment;
istream_->seekg(begin);
if (istream_->rdstate() == std::ios_base::goodbit) {
Byte *buffer = new Byte[count];
istream_->read(reinterpret_cast<char *>(buffer), count);
size_t bytes_read = istream_->gcount();
shared_data_segment =
DataSegment::Create(DataRange(begin, begin + bytes_read), buffer);
}
return shared_data_segment;
}
} // namespace image_io
} // namespace photos_editing_formats
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