3rdparty/libjpeg/jdatadst.c

/*
 * jdatadst.c
 *
 * Copyright (C) 1994-1996, 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 compression data destination routines for the case of
 * emitting JPEG data to a file (or any stdio stream).  While these routines
 * are sufficient for most applications, some will want to use a different
 * destination manager.
 * IMPORTANT: we assume that fwrite() will correctly transcribe an array of
 * JOCTETs into 8-bit-wide elements on external storage.  If char is wider
 * than 8 bits on your machine, you may need to do some tweaking.
 */

/* this is not a core library module, so it doesn't define JPEG_INTERNALS */
#include "jinclude.h"
#include "jpeglib.h"
#include "jerror.h"


/* Expanded data destination object for stdio output */

typedef struct {
  struct jpeg_destination_mgr pub; /* public fields */

  FILE * outfile;               /* target stream */
  JOCTET * buffer;              /* start of buffer */
} my_destination_mgr;

typedef my_destination_mgr * my_dest_ptr;

#define OUTPUT_BUF_SIZE  4096   /* choose an efficiently fwrite'able size */


/*
 * Initialize destination --- called by jpeg_start_compress
 * before any data is actually written.
 */

METHODDEF(void)
init_destination (j_compress_ptr cinfo)
{
  my_dest_ptr dest = (my_dest_ptr) cinfo->dest;

  /* Allocate the output buffer --- it will be released when done with image */
  dest->buffer = (JOCTET *)
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
                                  OUTPUT_BUF_SIZE * SIZEOF(JOCTET));

  dest->pub.next_output_byte = dest->buffer;
  dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
}


/*
 * Empty the output buffer --- called whenever buffer fills up.
 *
 * In typical applications, this should write the entire output buffer
 * (ignoring the current state of next_output_byte & free_in_buffer),
 * reset the pointer & count to the start of the buffer, and return TRUE
 * indicating that the buffer has been dumped.
 *
 * In applications that need to be able to suspend compression due to output
 * overrun, a FALSE return indicates that the buffer cannot be emptied now.
 * In this situation, the compressor will return to its caller (possibly with
 * an indication that it has not accepted all the supplied scanlines).  The
 * application should resume compression after it has made more room in the
 * output buffer.  Note that there are substantial restrictions on the use of
 * suspension --- see the documentation.
 *
 * When suspending, the compressor will back up to a convenient restart point
 * (typically the start of the current MCU). next_output_byte & free_in_buffer
 * indicate where the restart point will be if the current call returns FALSE.
 * Data beyond this point will be regenerated after resumption, so do not
 * write it out when emptying the buffer externally.
 */

METHODDEF(boolean)
empty_output_buffer (j_compress_ptr cinfo)
{
  my_dest_ptr dest = (my_dest_ptr) cinfo->dest;

  if (JFWRITE(dest->outfile, dest->buffer, OUTPUT_BUF_SIZE) !=
      (size_t) OUTPUT_BUF_SIZE)
    ERREXIT(cinfo, JERR_FILE_WRITE);

  dest->pub.next_output_byte = dest->buffer;
  dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;

  return TRUE;
}


/*
 * Terminate destination --- called by jpeg_finish_compress
 * after all data has been written.  Usually needs to flush buffer.
 *
 * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
 * application must deal with any cleanup that should happen even
 * for error exit.
 */

METHODDEF(void)
term_destination (j_compress_ptr cinfo)
{
  my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
  size_t datacount = OUTPUT_BUF_SIZE - dest->pub.free_in_buffer;

  /* Write any data remaining in the buffer */
  if (datacount > 0) {
    if (JFWRITE(dest->outfile, dest->buffer, datacount) != datacount)
      ERREXIT(cinfo, JERR_FILE_WRITE);
  }
  fflush(dest->outfile);
  /* Make sure we wrote the output file OK */
  if (ferror(dest->outfile))
    ERREXIT(cinfo, JERR_FILE_WRITE);
}


/*
 * Prepare for output to a stdio stream.
 * The caller must have already opened the stream, and is responsible
 * for closing it after finishing compression.
 */

GLOBAL(void)
jpeg_stdio_dest (j_compress_ptr cinfo, FILE * outfile)
{
  my_dest_ptr dest;

  /* The destination object is made permanent so that multiple JPEG images
   * can be written to the same file without re-executing jpeg_stdio_dest.
   * This makes it dangerous to use this manager and a different destination
   * manager serially with the same JPEG object, because their private object
   * sizes may be different.  Caveat programmer.
   */
  if (cinfo->dest == NULL) {    /* first time for this JPEG object? */
    cinfo->dest = (struct jpeg_destination_mgr *)
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
                                  SIZEOF(my_destination_mgr));
  }

  dest = (my_dest_ptr) cinfo->dest;
  dest->pub.init_destination = init_destination;
  dest->pub.empty_output_buffer = empty_output_buffer;
  dest->pub.term_destination = term_destination;
  dest->outfile = outfile;
}
1	/*
2	* jdatadst.c
3	*
4	* Copyright (C) 1994-1996, Thomas G. Lane.
5	* This file is part of the Independent JPEG Group's software.
6	* For conditions of distribution and use, see the accompanying README file.
7	*
8	* This file contains compression data destination routines for the case of
9	* emitting JPEG data to a file (or any stdio stream). While these routines
10	* are sufficient for most applications, some will want to use a different
11	* destination manager.
12	* IMPORTANT: we assume that fwrite() will correctly transcribe an array of
13	* JOCTETs into 8-bit-wide elements on external storage. If char is wider
14	* than 8 bits on your machine, you may need to do some tweaking.
15	*/
16
17	/* this is not a core library module, so it doesn't define JPEG_INTERNALS */
18	#include "jinclude.h"
19	#include "jpeglib.h"
20	#include "jerror.h"
21
22
23	/* Expanded data destination object for stdio output */
24
25	typedef struct {
26	struct jpeg_destination_mgr pub; /* public fields */
27
28	FILE * outfile; /* target stream */
29	JOCTET * buffer; /* start of buffer */
30	} my_destination_mgr;
31
32	typedef my_destination_mgr * my_dest_ptr;
33
34	#define OUTPUT_BUF_SIZE 4096 /* choose an efficiently fwrite'able size */
35
36
37	/*
38	* Initialize destination --- called by jpeg_start_compress
39	* before any data is actually written.
40	*/
41
42	METHODDEF(void)
43	init_destination (j_compress_ptr cinfo)
44	{
45	my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
46
47	/* Allocate the output buffer --- it will be released when done with image */
48	dest->buffer = (JOCTET *)
49	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
50	OUTPUT_BUF_SIZE * SIZEOF(JOCTET));
51
52	dest->pub.next_output_byte = dest->buffer;
53	dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
54	}
55
56
57	/*
58	* Empty the output buffer --- called whenever buffer fills up.
59	*
60	* In typical applications, this should write the entire output buffer
61	* (ignoring the current state of next_output_byte & free_in_buffer),
62	* reset the pointer & count to the start of the buffer, and return TRUE
63	* indicating that the buffer has been dumped.
64	*
65	* In applications that need to be able to suspend compression due to output
66	* overrun, a FALSE return indicates that the buffer cannot be emptied now.
67	* In this situation, the compressor will return to its caller (possibly with
68	* an indication that it has not accepted all the supplied scanlines). The
69	* application should resume compression after it has made more room in the
70	* output buffer. Note that there are substantial restrictions on the use of
71	* suspension --- see the documentation.
72	*
73	* When suspending, the compressor will back up to a convenient restart point
74	* (typically the start of the current MCU). next_output_byte & free_in_buffer
75	* indicate where the restart point will be if the current call returns FALSE.
76	* Data beyond this point will be regenerated after resumption, so do not
77	* write it out when emptying the buffer externally.
78	*/
79
80	METHODDEF(boolean)
81	empty_output_buffer (j_compress_ptr cinfo)
82	{
83	my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
84
85	if (JFWRITE(dest->outfile, dest->buffer, OUTPUT_BUF_SIZE) !=
86	(size_t) OUTPUT_BUF_SIZE)
87	ERREXIT(cinfo, JERR_FILE_WRITE);
88
89	dest->pub.next_output_byte = dest->buffer;
90	dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
91
92	return TRUE;
93	}
94
95
96	/*
97	* Terminate destination --- called by jpeg_finish_compress
98	* after all data has been written. Usually needs to flush buffer.
99	*
100	* NB: not called by jpeg_abort or jpeg_destroy; surrounding
101	* application must deal with any cleanup that should happen even
102	* for error exit.
103	*/
104
105	METHODDEF(void)
106	term_destination (j_compress_ptr cinfo)
107	{
108	my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
109	size_t datacount = OUTPUT_BUF_SIZE - dest->pub.free_in_buffer;
110
111	/* Write any data remaining in the buffer */
112	if (datacount > 0) {
113	if (JFWRITE(dest->outfile, dest->buffer, datacount) != datacount)
114	ERREXIT(cinfo, JERR_FILE_WRITE);
115	}
116	fflush(dest->outfile);
117	/* Make sure we wrote the output file OK */
118	if (ferror(dest->outfile))
119	ERREXIT(cinfo, JERR_FILE_WRITE);
120	}
121
122
123	/*
124	* Prepare for output to a stdio stream.
125	* The caller must have already opened the stream, and is responsible
126	* for closing it after finishing compression.
127	*/
128
129	GLOBAL(void)
130	jpeg_stdio_dest (j_compress_ptr cinfo, FILE * outfile)
131	{
132	my_dest_ptr dest;
133
134	/* The destination object is made permanent so that multiple JPEG images
135	* can be written to the same file without re-executing jpeg_stdio_dest.
136	* This makes it dangerous to use this manager and a different destination
137	* manager serially with the same JPEG object, because their private object
138	* sizes may be different. Caveat programmer.
139	*/
140	if (cinfo->dest == NULL) { /* first time for this JPEG object? */
141	cinfo->dest = (struct jpeg_destination_mgr *)
142	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
143	SIZEOF(my_destination_mgr));
144	}
145
146	dest = (my_dest_ptr) cinfo->dest;
147	dest->pub.init_destination = init_destination;
148	dest->pub.empty_output_buffer = empty_output_buffer;
149	dest->pub.term_destination = term_destination;
150	dest->outfile = outfile;
151	}