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105 lines
4 KiB
C
105 lines
4 KiB
C
/*
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* jcicc.c
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*
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* Copyright (C) 1997-1998, Thomas G. Lane, Todd Newman.
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* Copyright (C) 2017, D. R. Commander.
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* For conditions of distribution and use, see the accompanying README.ijg
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* file.
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*
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* This file provides code to write International Color Consortium (ICC) device
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* profiles embedded in JFIF JPEG image files. The ICC has defined a standard
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* for including such data in JPEG "APP2" markers. The code given here does
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* not know anything about the internal structure of the ICC profile data; it
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* just knows how to embed the profile data in a JPEG file while writing it.
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*/
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#define JPEG_INTERNALS
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#include "jinclude.h"
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#include "jpeglib.h"
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#include "jerror.h"
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/*
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* Since an ICC profile can be larger than the maximum size of a JPEG marker
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* (64K), we need provisions to split it into multiple markers. The format
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* defined by the ICC specifies one or more APP2 markers containing the
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* following data:
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* Identifying string ASCII "ICC_PROFILE\0" (12 bytes)
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* Marker sequence number 1 for first APP2, 2 for next, etc (1 byte)
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* Number of markers Total number of APP2's used (1 byte)
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* Profile data (remainder of APP2 data)
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* Decoders should use the marker sequence numbers to reassemble the profile,
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* rather than assuming that the APP2 markers appear in the correct sequence.
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*/
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#define ICC_MARKER (JPEG_APP0 + 2) /* JPEG marker code for ICC */
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#define ICC_OVERHEAD_LEN 14 /* size of non-profile data in APP2 */
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#define MAX_BYTES_IN_MARKER 65533 /* maximum data len of a JPEG marker */
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#define MAX_DATA_BYTES_IN_MARKER (MAX_BYTES_IN_MARKER - ICC_OVERHEAD_LEN)
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/*
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* This routine writes the given ICC profile data into a JPEG file. It *must*
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* be called AFTER calling jpeg_start_compress() and BEFORE the first call to
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* jpeg_write_scanlines(). (This ordering ensures that the APP2 marker(s) will
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* appear after the SOI and JFIF or Adobe markers, but before all else.)
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*/
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GLOBAL(void)
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jpeg_write_icc_profile(j_compress_ptr cinfo, const JOCTET *icc_data_ptr,
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unsigned int icc_data_len)
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{
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unsigned int num_markers; /* total number of markers we'll write */
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int cur_marker = 1; /* per spec, counting starts at 1 */
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unsigned int length; /* number of bytes to write in this marker */
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if (icc_data_ptr == NULL || icc_data_len == 0)
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ERREXIT(cinfo, JERR_BUFFER_SIZE);
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if (cinfo->global_state < CSTATE_SCANNING)
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ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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/* Calculate the number of markers we'll need, rounding up of course */
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num_markers = icc_data_len / MAX_DATA_BYTES_IN_MARKER;
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if (num_markers * MAX_DATA_BYTES_IN_MARKER != icc_data_len)
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num_markers++;
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while (icc_data_len > 0) {
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/* length of profile to put in this marker */
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length = icc_data_len;
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if (length > MAX_DATA_BYTES_IN_MARKER)
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length = MAX_DATA_BYTES_IN_MARKER;
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icc_data_len -= length;
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/* Write the JPEG marker header (APP2 code and marker length) */
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jpeg_write_m_header(cinfo, ICC_MARKER,
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(unsigned int)(length + ICC_OVERHEAD_LEN));
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/* Write the marker identifying string "ICC_PROFILE" (null-terminated). We
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* code it in this less-than-transparent way so that the code works even if
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* the local character set is not ASCII.
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*/
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jpeg_write_m_byte(cinfo, 0x49);
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jpeg_write_m_byte(cinfo, 0x43);
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jpeg_write_m_byte(cinfo, 0x43);
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jpeg_write_m_byte(cinfo, 0x5F);
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jpeg_write_m_byte(cinfo, 0x50);
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jpeg_write_m_byte(cinfo, 0x52);
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jpeg_write_m_byte(cinfo, 0x4F);
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jpeg_write_m_byte(cinfo, 0x46);
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jpeg_write_m_byte(cinfo, 0x49);
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jpeg_write_m_byte(cinfo, 0x4C);
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jpeg_write_m_byte(cinfo, 0x45);
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jpeg_write_m_byte(cinfo, 0x0);
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/* Add the sequencing info */
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jpeg_write_m_byte(cinfo, cur_marker);
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jpeg_write_m_byte(cinfo, (int)num_markers);
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/* Add the profile data */
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while (length--) {
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jpeg_write_m_byte(cinfo, *icc_data_ptr);
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icc_data_ptr++;
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}
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cur_marker++;
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}
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}
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