wrgif.c
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1 /*
2  * wrgif.c
3  *
4  * Copyright (C) 1991-1997, 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 routines to write output images in GIF format.
9  *
10  **************************************************************************
11  * NOTE: to avoid entanglements with Unisys' patent on LZW compression, *
12  * this code has been modified to output "uncompressed GIF" files. *
13  * There is no trace of the LZW algorithm in this file. *
14  **************************************************************************
15  *
16  * These routines may need modification for non-Unix environments or
17  * specialized applications. As they stand, they assume output to
18  * an ordinary stdio stream.
19  */
20 
21 /*
22  * This code is loosely based on ppmtogif from the PBMPLUS distribution
23  * of Feb. 1991. That file contains the following copyright notice:
24  * Based on GIFENCODE by David Rowley <mgardi@watdscu.waterloo.edu>.
25  * Lempel-Ziv compression based on "compress" by Spencer W. Thomas et al.
26  * Copyright (C) 1989 by Jef Poskanzer.
27  * Permission to use, copy, modify, and distribute this software and its
28  * documentation for any purpose and without fee is hereby granted, provided
29  * that the above copyright notice appear in all copies and that both that
30  * copyright notice and this permission notice appear in supporting
31  * documentation. This software is provided "as is" without express or
32  * implied warranty.
33  *
34  * We are also required to state that
35  * "The Graphics Interchange Format(c) is the Copyright property of
36  * CompuServe Incorporated. GIF(sm) is a Service Mark property of
37  * CompuServe Incorporated."
38  */
39 
40 #include "cdjpeg.h" /* Common decls for cjpeg/djpeg applications */
41 
42 #ifdef GIF_SUPPORTED
43 
44 
45 /* Private version of data destination object */
46 
47 typedef struct {
48  struct djpeg_dest_struct pub; /* public fields */
49 
50  j_decompress_ptr cinfo; /* back link saves passing separate parm */
51 
52  /* State for packing variable-width codes into a bitstream */
53  int n_bits; /* current number of bits/code */
54  int maxcode; /* maximum code, given n_bits */
55  INT32 cur_accum; /* holds bits not yet output */
56  int cur_bits; /* # of bits in cur_accum */
57 
58  /* State for GIF code assignment */
59  int ClearCode; /* clear code (doesn't change) */
60  int EOFCode; /* EOF code (ditto) */
61  int code_counter; /* counts output symbols */
62 
63  /* GIF data packet construction buffer */
64  int bytesinpkt; /* # of bytes in current packet */
65  char packetbuf[256]; /* workspace for accumulating packet */
66 
68 
70 
71 /* Largest value that will fit in N bits */
72 #define MAXCODE(n_bits) ((1 << (n_bits)) - 1)
73 
74 
75 /*
76  * Routines to package finished data bytes into GIF data blocks.
77  * A data block consists of a count byte (1..255) and that many data bytes.
78  */
79 
80 LOCAL(void)
82 /* flush any accumulated data */
83 {
84  if (dinfo->bytesinpkt > 0) { /* never write zero-length packet */
85  dinfo->packetbuf[0] = (char) dinfo->bytesinpkt++;
86  if (JFWRITE(dinfo->pub.output_file, dinfo->packetbuf, dinfo->bytesinpkt)
87  != (size_t) dinfo->bytesinpkt)
88  ERREXIT(dinfo->cinfo, JERR_FILE_WRITE);
89  dinfo->bytesinpkt = 0;
90  }
91 }
92 
93 
94 /* Add a character to current packet; flush to disk if necessary */
95 #define CHAR_OUT(dinfo,c) \
96  { (dinfo)->packetbuf[++(dinfo)->bytesinpkt] = (char) (c); \
97  if ((dinfo)->bytesinpkt >= 255) \
98  flush_packet(dinfo); \
99  }
100 
101 
102 /* Routine to convert variable-width codes into a byte stream */
103 
104 LOCAL(void)
106 /* Emit a code of n_bits bits */
107 /* Uses cur_accum and cur_bits to reblock into 8-bit bytes */
108 {
109  dinfo->cur_accum |= ((INT32) code) << dinfo->cur_bits;
110  dinfo->cur_bits += dinfo->n_bits;
111 
112  while (dinfo->cur_bits >= 8) {
113  CHAR_OUT(dinfo, dinfo->cur_accum & 0xFF);
114  dinfo->cur_accum >>= 8;
115  dinfo->cur_bits -= 8;
116  }
117 }
118 
119 
120 /* The pseudo-compression algorithm.
121  *
122  * In this module we simply output each pixel value as a separate symbol;
123  * thus, no compression occurs. In fact, there is expansion of one bit per
124  * pixel, because we use a symbol width one bit wider than the pixel width.
125  *
126  * GIF ordinarily uses variable-width symbols, and the decoder will expect
127  * to ratchet up the symbol width after a fixed number of symbols.
128  * To simplify the logic and keep the expansion penalty down, we emit a
129  * GIF Clear code to reset the decoder just before the width would ratchet up.
130  * Thus, all the symbols in the output file will have the same bit width.
131  * Note that emitting the Clear codes at the right times is a mere matter of
132  * counting output symbols and is in no way dependent on the LZW patent.
133  *
134  * With a small basic pixel width (low color count), Clear codes will be
135  * needed very frequently, causing the file to expand even more. So this
136  * simplistic approach wouldn't work too well on bilevel images, for example.
137  * But for output of JPEG conversions the pixel width will usually be 8 bits
138  * (129 to 256 colors), so the overhead added by Clear symbols is only about
139  * one symbol in every 256.
140  */
141 
142 LOCAL(void)
143 compress_init (gif_dest_ptr dinfo, int i_bits)
144 /* Initialize pseudo-compressor */
145 {
146  /* init all the state variables */
147  dinfo->n_bits = i_bits;
148  dinfo->maxcode = MAXCODE(dinfo->n_bits);
149  dinfo->ClearCode = (1 << (i_bits - 1));
150  dinfo->EOFCode = dinfo->ClearCode + 1;
151  dinfo->code_counter = dinfo->ClearCode + 2;
152  /* init output buffering vars */
153  dinfo->bytesinpkt = 0;
154  dinfo->cur_accum = 0;
155  dinfo->cur_bits = 0;
156  /* GIF specifies an initial Clear code */
157  output(dinfo, dinfo->ClearCode);
158 }
159 
160 
161 LOCAL(void)
163 /* Accept and "compress" one pixel value.
164  * The given value must be less than n_bits wide.
165  */
166 {
167  /* Output the given pixel value as a symbol. */
168  output(dinfo, c);
169  /* Issue Clear codes often enough to keep the reader from ratcheting up
170  * its symbol size.
171  */
172  if (dinfo->code_counter < dinfo->maxcode) {
173  dinfo->code_counter++;
174  } else {
175  output(dinfo, dinfo->ClearCode);
176  dinfo->code_counter = dinfo->ClearCode + 2; /* reset the counter */
177  }
178 }
179 
180 
181 LOCAL(void)
183 /* Clean up at end */
184 {
185  /* Send an EOF code */
186  output(dinfo, dinfo->EOFCode);
187  /* Flush the bit-packing buffer */
188  if (dinfo->cur_bits > 0) {
189  CHAR_OUT(dinfo, dinfo->cur_accum & 0xFF);
190  }
191  /* Flush the packet buffer */
192  flush_packet(dinfo);
193 }
194 
195 
196 /* GIF header construction */
197 
198 
199 LOCAL(void)
200 put_word (gif_dest_ptr dinfo, unsigned int w)
201 /* Emit a 16-bit word, LSB first */
202 {
203  putc(w & 0xFF, dinfo->pub.output_file);
204  putc((w >> 8) & 0xFF, dinfo->pub.output_file);
205 }
206 
207 
208 LOCAL(void)
210 /* Emit 3 copies of same byte value --- handy subr for colormap construction */
211 {
212  putc(val, dinfo->pub.output_file);
213  putc(val, dinfo->pub.output_file);
214  putc(val, dinfo->pub.output_file);
215 }
216 
217 
218 LOCAL(void)
219 emit_header (gif_dest_ptr dinfo, int num_colors, JSAMPARRAY colormap)
220 /* Output the GIF file header, including color map */
221 /* If colormap==NULL, synthesize a gray-scale colormap */
222 {
223  int BitsPerPixel, ColorMapSize, InitCodeSize, FlagByte;
224  int cshift = dinfo->cinfo->data_precision - 8;
225  int i;
226 
227  if (num_colors > 256)
228  ERREXIT1(dinfo->cinfo, JERR_TOO_MANY_COLORS, num_colors);
229  /* Compute bits/pixel and related values */
230  BitsPerPixel = 1;
231  while (num_colors > (1 << BitsPerPixel))
232  BitsPerPixel++;
233  ColorMapSize = 1 << BitsPerPixel;
234  if (BitsPerPixel <= 1)
235  InitCodeSize = 2;
236  else
237  InitCodeSize = BitsPerPixel;
238  /*
239  * Write the GIF header.
240  * Note that we generate a plain GIF87 header for maximum compatibility.
241  */
242  putc('G', dinfo->pub.output_file);
243  putc('I', dinfo->pub.output_file);
244  putc('F', dinfo->pub.output_file);
245  putc('8', dinfo->pub.output_file);
246  putc('7', dinfo->pub.output_file);
247  putc('a', dinfo->pub.output_file);
248  /* Write the Logical Screen Descriptor */
249  put_word(dinfo, (unsigned int) dinfo->cinfo->output_width);
250  put_word(dinfo, (unsigned int) dinfo->cinfo->output_height);
251  FlagByte = 0x80; /* Yes, there is a global color table */
252  FlagByte |= (BitsPerPixel-1) << 4; /* color resolution */
253  FlagByte |= (BitsPerPixel-1); /* size of global color table */
254  putc(FlagByte, dinfo->pub.output_file);
255  putc(0, dinfo->pub.output_file); /* Background color index */
256  putc(0, dinfo->pub.output_file); /* Reserved (aspect ratio in GIF89) */
257  /* Write the Global Color Map */
258  /* If the color map is more than 8 bits precision, */
259  /* we reduce it to 8 bits by shifting */
260  for (i=0; i < ColorMapSize; i++) {
261  if (i < num_colors) {
262  if (colormap != NULL) {
263  if (dinfo->cinfo->out_color_space == JCS_RGB) {
264  /* Normal case: RGB color map */
265  putc(GETJSAMPLE(colormap[0][i]) >> cshift, dinfo->pub.output_file);
266  putc(GETJSAMPLE(colormap[1][i]) >> cshift, dinfo->pub.output_file);
267  putc(GETJSAMPLE(colormap[2][i]) >> cshift, dinfo->pub.output_file);
268  } else {
269  /* Grayscale "color map": possible if quantizing grayscale image */
270  put_3bytes(dinfo, GETJSAMPLE(colormap[0][i]) >> cshift);
271  }
272  } else {
273  /* Create a gray-scale map of num_colors values, range 0..255 */
274  put_3bytes(dinfo, (i * 255 + (num_colors-1)/2) / (num_colors-1));
275  }
276  } else {
277  /* fill out the map to a power of 2 */
278  put_3bytes(dinfo, 0);
279  }
280  }
281  /* Write image separator and Image Descriptor */
282  putc(',', dinfo->pub.output_file); /* separator */
283  put_word(dinfo, 0); /* left/top offset */
284  put_word(dinfo, 0);
285  put_word(dinfo, (unsigned int) dinfo->cinfo->output_width); /* image size */
286  put_word(dinfo, (unsigned int) dinfo->cinfo->output_height);
287  /* flag byte: not interlaced, no local color map */
288  putc(0x00, dinfo->pub.output_file);
289  /* Write Initial Code Size byte */
290  putc(InitCodeSize, dinfo->pub.output_file);
291 
292  /* Initialize for "compression" of image data */
293  compress_init(dinfo, InitCodeSize+1);
294 }
295 
296 
297 /*
298  * Startup: write the file header.
299  */
300 
301 METHODDEF(void)
303 {
304  gif_dest_ptr dest = (gif_dest_ptr) dinfo;
305 
306  if (cinfo->quantize_colors)
307  emit_header(dest, cinfo->actual_number_of_colors, cinfo->colormap);
308  else
309  emit_header(dest, 256, (JSAMPARRAY) NULL);
310 }
311 
312 
313 /*
314  * Write some pixel data.
315  * In this module rows_supplied will always be 1.
316  */
317 
318 METHODDEF(void)
320  JDIMENSION rows_supplied)
321 {
322  gif_dest_ptr dest = (gif_dest_ptr) dinfo;
323  register JSAMPROW ptr;
324  register JDIMENSION col;
325 
326  ptr = dest->pub.buffer[0];
327  for (col = cinfo->output_width; col > 0; col--) {
328  compress_pixel(dest, GETJSAMPLE(*ptr++));
329  }
330 }
331 
332 
333 /*
334  * Finish up at the end of the file.
335  */
336 
337 METHODDEF(void)
339 {
340  gif_dest_ptr dest = (gif_dest_ptr) dinfo;
341 
342  /* Flush "compression" mechanism */
343  compress_term(dest);
344  /* Write a zero-length data block to end the series */
345  putc(0, dest->pub.output_file);
346  /* Write the GIF terminator mark */
347  putc(';', dest->pub.output_file);
348  /* Make sure we wrote the output file OK */
349  fflush(dest->pub.output_file);
350  if (ferror(dest->pub.output_file))
351  ERREXIT(cinfo, JERR_FILE_WRITE);
352 }
353 
354 
355 /*
356  * The module selection routine for GIF format output.
357  */
358 
361 {
362  gif_dest_ptr dest;
363 
364  /* Create module interface object, fill in method pointers */
365  dest = (gif_dest_ptr)
366  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
368  dest->cinfo = cinfo; /* make back link for subroutines */
369  dest->pub.start_output = start_output_gif;
370  dest->pub.put_pixel_rows = put_pixel_rows;
371  dest->pub.finish_output = finish_output_gif;
372 
373  if (cinfo->out_color_space != JCS_GRAYSCALE &&
374  cinfo->out_color_space != JCS_RGB)
375  ERREXIT(cinfo, JERR_GIF_COLORSPACE);
376 
377  /* Force quantization if color or if > 8 bits input */
378  if (cinfo->out_color_space != JCS_GRAYSCALE || cinfo->data_precision > 8) {
379  /* Force quantization to at most 256 colors */
380  cinfo->quantize_colors = TRUE;
381  if (cinfo->desired_number_of_colors > 256)
382  cinfo->desired_number_of_colors = 256;
383  }
384 
385  /* Calculate output image dimensions so we can allocate space */
387 
388  if (cinfo->output_components != 1) /* safety check: just one component? */
389  ERREXIT(cinfo, JERR_GIF_BUG);
390 
391  /* Create decompressor output buffer. */
392  dest->pub.buffer = (*cinfo->mem->alloc_sarray)
393  ((j_common_ptr) cinfo, JPOOL_IMAGE, cinfo->output_width, (JDIMENSION) 1);
394  dest->pub.buffer_height = 1;
395 
396  return (djpeg_dest_ptr) dest;
397 }
398 
399 #endif /* GIF_SUPPORTED */
JSAMPARRAY buffer
Definition: cdjpeg.h:68
int c
Definition: autoplay.py:16
int maxcode
Definition: wrgif.c:54
JSAMPLE FAR * JSAMPROW
Definition: jpeglib.h:66
int cur_bits
Definition: wrgif.c:56
j_decompress_ptr cinfo
Definition: wrgif.c:50
emit_header(gif_dest_ptr dinfo, int num_colors, JSAMPARRAY colormap)
Definition: wrgif.c:219
png_voidp ptr
Definition: png.h:2063
struct jpeg_common_struct * j_common_ptr
Definition: jpeglib.h:261
#define GETJSAMPLE(value)
Definition: jmorecfg.h:68
finish_output_gif(j_decompress_ptr cinfo, djpeg_dest_ptr dinfo)
Definition: wrgif.c:338
put_3bytes(gif_dest_ptr dinfo, int val)
Definition: wrgif.c:209
#define ERREXIT(cinfo, code)
Definition: jerror.h:205
#define TRUE
Definition: OPC_IceHook.h:13
#define SIZEOF(object)
Definition: jinclude.h:80
#define CHAR_OUT(dinfo, c)
Definition: wrgif.c:95
put_word(gif_dest_ptr dinfo, unsigned int w)
Definition: wrgif.c:200
long INT32
Definition: jmorecfg.h:161
w
png_uint_32 i
Definition: png.h:2735
start_output_gif(j_decompress_ptr cinfo, djpeg_dest_ptr dinfo)
Definition: wrgif.c:302
#define JFWRITE(file, buf, sizeofbuf)
Definition: jinclude.h:90
jpeg_calc_output_dimensions(j_decompress_ptr cinfo)
Definition: jdmaster.c:84
#define JPOOL_IMAGE
Definition: jpeglib.h:749
jinit_write_gif(j_decompress_ptr cinfo)
Definition: wrgif.c:360
int n_bits
Definition: wrgif.c:53
#define LOCAL(type)
Definition: jmorecfg.h:186
FILE * output_file
Definition: cdjpeg.h:62
compress_init(gif_dest_ptr dinfo, int i_bits)
Definition: wrgif.c:143
#define MAXCODE(n_bits)
Definition: wrgif.c:72
compress_pixel(gif_dest_ptr dinfo, int c)
Definition: wrgif.c:162
int val
Definition: jpeglib.h:956
#define ERREXIT1(cinfo, code, p1)
Definition: jerror.h:208
compress_term(gif_dest_ptr dinfo)
Definition: wrgif.c:182
Definition: inftrees.h:24
JSAMPROW * JSAMPARRAY
Definition: jpeglib.h:67
int EOFCode
Definition: wrgif.c:60
#define GLOBAL(type)
Definition: jmorecfg.h:188
int bytesinpkt
Definition: wrgif.c:64
#define METHODDEF(type)
Definition: jmorecfg.h:184
JDIMENSION buffer_height
Definition: cdjpeg.h:69
put_pixel_rows(j_decompress_ptr cinfo, djpeg_dest_ptr dinfo, JDIMENSION rows_supplied)
Definition: wrgif.c:319
unsigned int JDIMENSION
Definition: jmorecfg.h:171
int code_counter
Definition: wrgif.c:61
struct djpeg_dest_struct pub
Definition: wrgif.c:48
gif_dest_struct * gif_dest_ptr
Definition: wrgif.c:69
int ClearCode
Definition: wrgif.c:59
INT32 cur_accum
Definition: wrgif.c:55
output(gif_dest_ptr dinfo, int code)
Definition: wrgif.c:105
flush_packet(gif_dest_ptr dinfo)
Definition: wrgif.c:81


openhrp3
Author(s): AIST, General Robotix Inc., Nakamura Lab of Dept. of Mechano Informatics at University of Tokyo
autogenerated on Sat Apr 13 2019 02:14:26