/**
* Uses jpeg library api to write APP01 segment consisting
* of JPEG_XMP_SEGMENT_HEADER and metadata associated with
* given image. If there is no metadata, or its size exceeds
* JPEG_METADATA_LIMIT, then nothing is written.
*
* @param cinfo
* @param decoded_image
*/
static void writeMetadata(
jpeg_compress_struct& cinfo,
const DecodedImage& decoded_image) {
const unsigned metadata_length = decoded_image.getMetadataLength();
if (metadata_length == 0 || metadata_length > JPEG_METADATA_LIMIT) {
return;
}
jpeg_write_m_header(
&cinfo,
JPEG_APP0 + 1,
JPEG_XMP_SEGMENT_HEADER_LENGTH + metadata_length);
auto jpeg_metadata_writer = [&] (int c) { jpeg_write_m_byte(&cinfo, c); };
// Write xmp header
std::for_each(
JPEG_XMP_SEGMENT_HEADER,
JPEG_XMP_SEGMENT_HEADER + JPEG_XMP_SEGMENT_HEADER_LENGTH,
jpeg_metadata_writer);
// Write xmp data
std::for_each(
decoded_image.getMetadataPtr(),
decoded_image.getMetadataPtr() + metadata_length,
jpeg_metadata_writer);
}
static void
write_icc_profile (j_compress_ptr cinfo,
const JOCTET *icc_data_ptr,
unsigned int icc_data_len)
{
unsigned int num_markers; /* total number of markers we'll write */
int cur_marker = 1; /* per spec, counting starts at 1 */
unsigned int length; /* number of bytes to write in this marker */
/* Calculate the number of markers we'll need, rounding up of course */
num_markers = icc_data_len / MAX_DATA_BYTES_IN_MARKER;
if (num_markers * MAX_DATA_BYTES_IN_MARKER != icc_data_len)
num_markers++;
while (icc_data_len > 0)
{
/* length of profile to put in this marker */
length = icc_data_len;
if (length > MAX_DATA_BYTES_IN_MARKER)
length = MAX_DATA_BYTES_IN_MARKER;
icc_data_len -= length;
/* Write the JPEG marker header (APP2 code and marker length) */
jpeg_write_m_header(cinfo, ICC_MARKER,
(unsigned int) (length + ICC_OVERHEAD_LEN));
/* Write the marker identifying string "ICC_PROFILE" (null-terminated).
* We code it in this less-than-transparent way so that the code works
* even if the local character set is not ASCII.
*/
jpeg_write_m_byte(cinfo, 0x49);
jpeg_write_m_byte(cinfo, 0x43);
jpeg_write_m_byte(cinfo, 0x43);
jpeg_write_m_byte(cinfo, 0x5F);
jpeg_write_m_byte(cinfo, 0x50);
jpeg_write_m_byte(cinfo, 0x52);
jpeg_write_m_byte(cinfo, 0x4F);
jpeg_write_m_byte(cinfo, 0x46);
jpeg_write_m_byte(cinfo, 0x49);
jpeg_write_m_byte(cinfo, 0x4C);
jpeg_write_m_byte(cinfo, 0x45);
jpeg_write_m_byte(cinfo, 0x0);
/* Add the sequencing info */
jpeg_write_m_byte(cinfo, cur_marker);
jpeg_write_m_byte(cinfo, (int) num_markers);
/* Add the profile data */
while (length--)
{
jpeg_write_m_byte(cinfo, *icc_data_ptr);
icc_data_ptr++;
}
cur_marker++;
}
}
static
void jcopy_markers_execute(j_decompress_ptr srcinfo, j_compress_ptr dstinfo)
{
jpeg_saved_marker_ptr marker;
/* In the current implementation, we don't actually need to examine the
* option flag here; we just copy everything that got saved.
* But to avoid confusion, we do not output JFIF and Adobe APP14 markers
* if the encoder library already wrote one.
*/
for (marker = srcinfo->marker_list; marker != NULL; marker = marker->next) {
if (dstinfo->write_JFIF_header &&
marker->marker == JPEG_APP0 &&
marker->data_length >= 5 &&
GETJOCTET(marker->data[0]) == 0x4A &&
GETJOCTET(marker->data[1]) == 0x46 &&
GETJOCTET(marker->data[2]) == 0x49 &&
GETJOCTET(marker->data[3]) == 0x46 &&
GETJOCTET(marker->data[4]) == 0)
continue; /* reject duplicate JFIF */
if (dstinfo->write_Adobe_marker &&
marker->marker == JPEG_APP0+14 &&
marker->data_length >= 5 &&
GETJOCTET(marker->data[0]) == 0x41 &&
GETJOCTET(marker->data[1]) == 0x64 &&
GETJOCTET(marker->data[2]) == 0x6F &&
GETJOCTET(marker->data[3]) == 0x62 &&
GETJOCTET(marker->data[4]) == 0x65)
continue; /* reject duplicate Adobe */
#ifdef NEED_FAR_POINTERS
/* We could use jpeg_write_marker if the data weren't FAR... */
{
unsigned int i;
jpeg_write_m_header(dstinfo, marker->marker, marker->data_length);
for (i = 0; i < marker->data_length; i++)
jpeg_write_m_byte(dstinfo, marker->data[i]);
}
#else
jpeg_write_marker(dstinfo, marker->marker,
marker->data, marker->data_length);
#endif
}
}
