char* webpGetXMP(const uint8_t* data, size_t data_size, size_t* metadata_size) {
char* metadata = NULL;
WebPData webp_data = {data, data_size};
WebPDemuxer* demux = WebPDemux(&webp_data);
uint32_t flags = WebPDemuxGetI(demux, WEBP_FF_FORMAT_FLAGS);
*metadata_size = 0;
if(flags & XMP_FLAG) {
WebPChunkIterator it;
memset(&it, 0, sizeof(it));
if(WebPDemuxGetChunk(demux, "XMP ", 1, &it)) {
if(it.chunk.bytes != NULL && it.chunk.size > 0) {
metadata = (char*)malloc(it.chunk.size);
memcpy(metadata, it.chunk.bytes, it.chunk.size);
*metadata_size = it.chunk.size;
}
}
WebPDemuxReleaseChunkIterator(&it);
}
WebPDemuxDelete(demux);
return metadata;
}
/**
* Uses libwebp to extract xmp metadata.
*/
const std::vector<uint8_t> extractMetadata(
JNIEnv* env,
std::vector<uint8_t>& image_data) {
// Create WebPDemux from provided data.
// It is "index" of all chunks. It stores
// list of pointers to particular chunks, but does
// not copy memory from provided WebPData.
WebPData webpdata = {image_data.data(), image_data.size()};
// Thsnks to using RAII we do not need to worry about
// releasing WebPDemuxer structure
auto demux = std::unique_ptr<WebPDemuxer, decltype(&WebPDemuxDelete)>{
WebPDemux(&webpdata),
WebPDemuxDelete};
THROW_AND_RETURNVAL_IF(
demux == nullptr,
"Could not create WebPDemux from image. This webp might be malformed.",
{});
// find xmp chunk
WebPChunkIterator chunk_iterator;
if (!WebPDemuxGetChunk(demux.get(), "XMP ", 1, &chunk_iterator)) {
// we failed to find "XMP " chunk - don't worry, maybe it was not
// there. Let the transcode proceed
WebPDemuxReleaseChunkIterator(&chunk_iterator);
return {};
}
// we managed to find "XMP " chunk, let's return its size and pointer to it
const unsigned int metadata_length = chunk_iterator.chunk.size;
const uint8_t* metadata_ptr = chunk_iterator.chunk.bytes;
WebPDemuxReleaseChunkIterator(&chunk_iterator);
// If XMP chunk contains no data then return nullptr.
if (metadata_length == 0) {
return {};
}
return {metadata_ptr, metadata_ptr + metadata_length};
}
bool QWebpHandler::ensureScanned() const
{
if (m_scanState != ScanNotScanned)
return m_scanState == ScanSuccess;
m_scanState = ScanError;
if (device()->isSequential()) {
qWarning() << "Sequential devices are not supported";
return false;
}
QWebpHandler *that = const_cast<QWebpHandler *>(this);
// FIXME: should not read all when scanning
that->m_rawData = device()->readAll();
that->m_webpData.bytes = reinterpret_cast<const uint8_t *>(m_rawData.data());
that->m_webpData.size = m_rawData.size();
that->m_demuxer = WebPDemux(&m_webpData);
if (m_demuxer == NULL)
return false;
that->m_flags = WebPDemuxGetI(m_demuxer, WEBP_FF_FORMAT_FLAGS);
that->m_width = WebPDemuxGetI(m_demuxer, WEBP_FF_CANVAS_WIDTH);
that->m_height = WebPDemuxGetI(m_demuxer, WEBP_FF_CANVAS_HEIGHT);
that->m_loop = WebPDemuxGetI(m_demuxer, WEBP_FF_LOOP_COUNT);
that->m_frameCount = WebPDemuxGetI(m_demuxer, WEBP_FF_FRAME_COUNT);
if (!WebPDemuxGetFrame(m_demuxer, 1, &(that->m_iter))) {
return false;
}
m_scanState = ScanSuccess;
return true;
}
