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/*
* jwrjfif.c
*
* Copyright (C) 1991, 1992, 1993, Thomas G. Lane.
* This file is part of the Independent JPEG Group's software.
* For conditions of distribution and use, see the accompanying README file.
*
* This file contains routines to write standard JPEG file headers/markers.
* The file format created is a raw JPEG data stream with (optionally) an
* APP0 marker per the JFIF spec. This will handle baseline and
* JFIF-convention JPEG files, although there is currently no provision
* for inserting a thumbnail image in the JFIF header.
*
* These routines may need modification for non-Unix environments or
* specialized applications. As they stand, they assume output to
* an ordinary stdio stream. However, the changes to write to something
* else are localized in the macros appearing just below.
*
* These routines are invoked via the methods write_file_header,
* write_scan_header, write_jpeg_data, write_scan_trailer, and
* write_file_trailer.
*/
#include "jinclude.h"
#ifdef JFIF_SUPPORTED
/*
* To output to something other than a stdio stream, you'd need to redefine
* these macros.
*/
/* Write a single byte */
#define emit_byte(cinfo,x) putc((x), cinfo->output_file)
/* Write some bytes from a (char *) buffer */
#define WRITE_BYTES(cinfo,dataptr,datacount) \
{ if (JFWRITE(cinfo->output_file, dataptr, datacount) \
!= (size_t) (datacount)) \
ERREXIT(cinfo->emethods, "Output file write error --- out of disk space?"); }
/* Clean up and verify successful output */
#define CHECK_OUTPUT(cinfo) \
{ fflush(cinfo->output_file); \
if (ferror(cinfo->output_file)) \
ERREXIT(cinfo->emethods, "Output file write error --- out of disk space?"); }
/* End of stdio-specific code. */
typedef enum { /* JPEG marker codes */
M_SOF0 = 0xc0,
M_SOF1 = 0xc1,
M_SOF2 = 0xc2,
M_SOF3 = 0xc3,
M_SOF5 = 0xc5,
M_SOF6 = 0xc6,
M_SOF7 = 0xc7,
M_JPG = 0xc8,
M_SOF9 = 0xc9,
M_SOF10 = 0xca,
M_SOF11 = 0xcb,
M_SOF13 = 0xcd,
M_SOF14 = 0xce,
M_SOF15 = 0xcf,
M_DHT = 0xc4,
M_DAC = 0xcc,
M_RST0 = 0xd0,
M_RST1 = 0xd1,
M_RST2 = 0xd2,
M_RST3 = 0xd3,
M_RST4 = 0xd4,
M_RST5 = 0xd5,
M_RST6 = 0xd6,
M_RST7 = 0xd7,
M_SOI = 0xd8,
M_EOI = 0xd9,
M_SOS = 0xda,
M_DQT = 0xdb,
M_DNL = 0xdc,
M_DRI = 0xdd,
M_DHP = 0xde,
M_EXP = 0xdf,
M_APP0 = 0xe0,
M_APP15 = 0xef,
M_JPG0 = 0xf0,
M_JPG13 = 0xfd,
M_COM = 0xfe,
M_TEM = 0x01,
M_ERROR = 0x100
} JPEG_MARKER;
LOCAL void
emit_marker (compress_info_ptr cinfo, JPEG_MARKER mark)
/* Emit a marker code */
{
emit_byte(cinfo, 0xFF);
emit_byte(cinfo, mark);
}
LOCAL void
emit_2bytes (compress_info_ptr cinfo, int value)
/* Emit a 2-byte integer; these are always MSB first in JPEG files */
{
emit_byte(cinfo, (value >> 8) & 0xFF);
emit_byte(cinfo, value & 0xFF);
}
LOCAL int
emit_dqt (compress_info_ptr cinfo, int index)
/* Emit a DQT marker */
/* Returns the precision used (0 = 8bits, 1 = 16bits) for baseline checking */
{
QUANT_TBL_PTR data = cinfo->quant_tbl_ptrs[index];
int prec = 0;
int i;
for (i = 0; i < DCTSIZE2; i++) {
if (data[i] > 255)
prec = 1;
}
emit_marker(cinfo, M_DQT);
emit_2bytes(cinfo, prec ? DCTSIZE2*2 + 1 + 2 : DCTSIZE2 + 1 + 2);
emit_byte(cinfo, index + (prec<<4));
for (i = 0; i < DCTSIZE2; i++) {
if (prec)
emit_byte(cinfo, data[i] >> 8);
emit_byte(cinfo, data[i] & 0xFF);
}
return prec;
}
LOCAL void
emit_dht (compress_info_ptr cinfo, int index, boolean is_ac)
/* Emit a DHT marker */
{
HUFF_TBL * htbl;
int length, i;
if (is_ac) {
htbl = cinfo->ac_huff_tbl_ptrs[index];
index += 0x10; /* output index has AC bit set */
} else {
htbl = cinfo->dc_huff_tbl_ptrs[index];
}
if (htbl == NULL)
ERREXIT1(cinfo->emethods, "Huffman table 0x%02x was not defined", index);
if (! htbl->sent_table) {
emit_marker(cinfo, M_DHT);
length = 0;
for (i = 1; i <= 16; i++)
length += htbl->bits[i];
emit_2bytes(cinfo, length + 2 + 1 + 16);
emit_byte(cinfo, index);
for (i = 1; i <= 16; i++)
emit_byte(cinfo, htbl->bits[i]);
for (i = 0; i < length; i++)
emit_byte(cinfo, htbl->huffval[i]);
htbl->sent_table = TRUE;
}
}
LOCAL void
emit_dac (compress_info_ptr cinfo)
/* Emit a DAC marker */
/* Since the useful info is so small, we want to emit all the tables in */
/* one DAC marker. Therefore this routine does its own scan of the table. */
{
char dc_in_use[NUM_ARITH_TBLS];
char ac_in_use[NUM_ARITH_TBLS];
int length, i;
for (i = 0; i < NUM_ARITH_TBLS; i++)
dc_in_use[i] = ac_in_use[i] = 0;
for (i = 0; i < cinfo->num_components; i++) {
dc_in_use[cinfo->comp_info[i].dc_tbl_no] = 1;
ac_in_use[cinfo->comp_info[i].ac_tbl_no] = 1;
}
length = 0;
for (i = 0; i < NUM_ARITH_TBLS; i++)
length += dc_in_use[i] + ac_in_use[i];
emit_marker(cinfo, M_DAC);
emit_2bytes(cinfo, length*2 + 2);
for (i = 0; i < NUM_ARITH_TBLS; i++) {
if (dc_in_use[i]) {
emit_byte(cinfo, i);
emit_byte(cinfo, cinfo->arith_dc_L[i] + (cinfo->arith_dc_U[i]<<4));
}
if (ac_in_use[i]) {
emit_byte(cinfo, i + 0x10);
emit_byte(cinfo, cinfo->arith_ac_K[i]);
}
}
}
LOCAL void
emit_dri (compress_info_ptr cinfo)
/* Emit a DRI marker */
{
emit_marker(cinfo, M_DRI);
emit_2bytes(cinfo, 4); /* fixed length */
emit_2bytes(cinfo, (int) cinfo->restart_interval);
}
LOCAL void
emit_sof (compress_info_ptr cinfo, JPEG_MARKER code)
/* Emit a SOF marker */
{
int i;
emit_marker(cinfo, code);
emit_2bytes(cinfo, 3 * cinfo->num_components + 2 + 5 + 1); /* length */
if (cinfo->image_height > 65535L || cinfo->image_width > 65535L)
ERREXIT(cinfo->emethods, "Maximum image dimension for JFIF is 65535 pixels");
emit_byte(cinfo, cinfo->data_precision);
emit_2bytes(cinfo, (int) cinfo->image_height);
emit_2bytes(cinfo, (int) cinfo->image_width);
emit_byte(cinfo, cinfo->num_components);
for (i = 0; i < cinfo->num_components; i++) {
emit_byte(cinfo, cinfo->comp_info[i].component_id);
emit_byte(cinfo, (cinfo->comp_info[i].h_samp_factor << 4)
+ cinfo->comp_info[i].v_samp_factor);
emit_byte(cinfo, cinfo->comp_info[i].quant_tbl_no);
}
}
LOCAL void
emit_sos (compress_info_ptr cinfo)
/* Emit a SOS marker */
{
int i;
emit_marker(cinfo, M_SOS);
emit_2bytes(cinfo, 2 * cinfo->comps_in_scan + 2 + 1 + 3); /* length */
emit_byte(cinfo, cinfo->comps_in_scan);
for (i = 0; i < cinfo->comps_in_scan; i++) {
emit_byte(cinfo, cinfo->cur_comp_info[i]->component_id);
emit_byte(cinfo, (cinfo->cur_comp_info[i]->dc_tbl_no << 4)
+ cinfo->cur_comp_info[i]->ac_tbl_no);
}
emit_byte(cinfo, 0); /* Spectral selection start */
emit_byte(cinfo, DCTSIZE2-1); /* Spectral selection end */
emit_byte(cinfo, 0); /* Successive approximation */
}
LOCAL void
emit_jfif_app0 (compress_info_ptr cinfo)
/* Emit a JFIF-compliant APP0 marker */
{
/*
* Length of APP0 block (2 bytes)
* Block ID (4 bytes - ASCII "JFIF")
* Zero byte (1 byte to terminate the ID string)
* Version Major, Minor (2 bytes - 0x01, 0x01)
* Units (1 byte - 0x00 = none, 0x01 = inch, 0x02 = cm)
* Xdpu (2 bytes - dots per unit horizontal)
* Ydpu (2 bytes - dots per unit vertical)
* Thumbnail X size (1 byte)
* Thumbnail Y size (1 byte)
*/
emit_marker(cinfo, M_APP0);
emit_2bytes(cinfo, 2 + 4 + 1 + 2 + 1 + 2 + 2 + 1 + 1); /* length */
emit_byte(cinfo, 0x4A); /* Identifier: ASCII "JFIF" */
emit_byte(cinfo, 0x46);
emit_byte(cinfo, 0x49);
emit_byte(cinfo, 0x46);
emit_byte(cinfo, 0);
emit_byte(cinfo, 1); /* Major version */
emit_byte(cinfo, 1); /* Minor version */
emit_byte(cinfo, cinfo->density_unit); /* Pixel size information */
emit_2bytes(cinfo, (int) cinfo->X_density);
emit_2bytes(cinfo, (int) cinfo->Y_density);
emit_byte(cinfo, 0); /* No thumbnail image */
emit_byte(cinfo, 0);
}
LOCAL void
emit_com (compress_info_ptr cinfo, char * dataptr, size_t datalen)
/* Emit a COM marker */
{
if ((unsigned) datalen <= (unsigned) 65533) { /* safety check */
emit_marker(cinfo, M_COM);
emit_2bytes(cinfo, (int) (datalen + 2)); /* length */
while (datalen--) {
emit_byte(cinfo, *dataptr);
dataptr++;
}
}
}
/*
* Write the file header.
*/
METHODDEF void
write_file_header (compress_info_ptr cinfo)
{
char qt_in_use[NUM_QUANT_TBLS];
int i, prec;
boolean is_baseline;
emit_marker(cinfo, M_SOI); /* first the SOI */
if (cinfo->write_JFIF_header) /* next an optional JFIF APP0 */
emit_jfif_app0(cinfo);
if (cinfo->comment_text != NULL) /* and an optional COM block */
emit_com(cinfo, cinfo->comment_text,
(size_t) (strlen(cinfo->comment_text)));
/* Emit DQT for each quantization table. */
/* Note that doing it here means we can't adjust the QTs on-the-fly. */
/* If we did want to do that, we'd have a problem with checking precision */
/* for the is_baseline determination. */
for (i = 0; i < NUM_QUANT_TBLS; i++)
qt_in_use[i] = 0;
for (i = 0; i < cinfo->num_components; i++)
qt_in_use[cinfo->comp_info[i].quant_tbl_no] = 1;
prec = 0;
for (i = 0; i < NUM_QUANT_TBLS; i++) {
if (qt_in_use[i])
prec += emit_dqt(cinfo, i);
}
/* now prec is nonzero iff there are any 16-bit quant tables. */
/* Check for a non-baseline specification. */
/* Note we assume that Huffman table numbers won't be changed later. */
is_baseline = TRUE;
if (cinfo->arith_code || (cinfo->data_precision != 8))
is_baseline = FALSE;
for (i = 0; i < cinfo->num_components; i++) {
if (cinfo->comp_info[i].dc_tbl_no > 1 || cinfo->comp_info[i].ac_tbl_no > 1)
is_baseline = FALSE;
}
if (prec && is_baseline) {
is_baseline = FALSE;
/* If it's baseline except for quantizer size, warn the user */
TRACEMS(cinfo->emethods, 0,
"Caution: quantization tables are too coarse for baseline JPEG");
}
/* Emit the proper SOF marker */
if (cinfo->arith_code)
emit_sof(cinfo, M_SOF9); /* SOF code for arithmetic coding */
else if (is_baseline)
emit_sof(cinfo, M_SOF0); /* SOF code for baseline implementation */
else
emit_sof(cinfo, M_SOF1); /* SOF code for non-baseline Huffman file */
}
/*
* Write the start of a scan (everything through the SOS marker).
*/
METHODDEF void
write_scan_header (compress_info_ptr cinfo)
{
int i;
if (cinfo->arith_code) {
/* Emit arith conditioning info. We will have some duplication
* if the file has multiple scans, but it's so small it's hardly
* worth worrying about.
*/
emit_dac(cinfo);
} else {
/* Emit Huffman tables. Note that emit_dht takes care of
* suppressing duplicate tables.
*/
for (i = 0; i < cinfo->comps_in_scan; i++) {
emit_dht(cinfo, cinfo->cur_comp_info[i]->dc_tbl_no, FALSE);
emit_dht(cinfo, cinfo->cur_comp_info[i]->ac_tbl_no, TRUE);
}
}
/* Emit DRI if required --- note that DRI value could change for each scan.
* If it doesn't, a tiny amount of space is wasted in multiple-scan files.
* We assume DRI will never be nonzero for one scan and zero for a later one.
*/
if (cinfo->restart_interval)
emit_dri(cinfo);
emit_sos(cinfo);
}
/*
* Write some bytes of compressed data within a scan.
*/
METHODDEF void
write_jpeg_data (compress_info_ptr cinfo, char *dataptr, int datacount)
{
WRITE_BYTES(cinfo, dataptr, datacount);
}
/*
* Finish up after a compressed scan (series of write_jpeg_data calls).
*/
METHODDEF void
write_scan_trailer (compress_info_ptr cinfo)
{
/* no work needed in this format */
}
/*
* Finish up at the end of the file.
*/
METHODDEF void
write_file_trailer (compress_info_ptr cinfo)
{
emit_marker(cinfo, M_EOI);
/* Make sure we wrote the output file OK */
CHECK_OUTPUT(cinfo);
}
/*
* The method selection routine for standard JPEG header writing.
* This should be called from c_ui_method_selection if appropriate.
*/
GLOBAL void
jselwjfif (compress_info_ptr cinfo)
{
cinfo->methods->write_file_header = write_file_header;
cinfo->methods->write_scan_header = write_scan_header;
cinfo->methods->write_jpeg_data = write_jpeg_data;
cinfo->methods->write_scan_trailer = write_scan_trailer;
cinfo->methods->write_file_trailer = write_file_trailer;
}
#endif /* JFIF_SUPPORTED */
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