wrppm.c

00001 /*
00002  * wrppm.c
00003  *
00004  * Copyright (C) 1991-1996, Thomas G. Lane.
00005  * Modified 2009 by Guido Vollbeding.
00006  * This file is part of the Independent JPEG Group's software.
00007  * For conditions of distribution and use, see the accompanying README file.
00008  *
00009  * This file contains routines to write output images in PPM/PGM format.
00010  * The extended 2-byte-per-sample raw PPM/PGM formats are supported.
00011  * The PBMPLUS library is NOT required to compile this software
00012  * (but it is highly useful as a set of PPM image manipulation programs).
00013  *
00014  * These routines may need modification for non-Unix environments or
00015  * specialized applications.  As they stand, they assume output to
00016  * an ordinary stdio stream.
00017  */
00018 
00019 #include "cdjpeg.h"     /* Common decls for cjpeg/djpeg applications */
00020 
00021 #ifdef PPM_SUPPORTED
00022 
00023 
00024 /*
00025  * For 12-bit JPEG data, we either downscale the values to 8 bits
00026  * (to write standard byte-per-sample PPM/PGM files), or output
00027  * nonstandard word-per-sample PPM/PGM files.  Downscaling is done
00028  * if PPM_NORAWWORD is defined (this can be done in the Makefile
00029  * or in jconfig.h).
00030  * (When the core library supports data precision reduction, a cleaner
00031  * implementation will be to ask for that instead.)
00032  */
00033 
00034 #if BITS_IN_JSAMPLE == 8
00035 #define PUTPPMSAMPLE(ptr,v)  *ptr++ = (char) (v)
00036 #define BYTESPERSAMPLE 1
00037 #define PPM_MAXVAL 255
00038 #else
00039 #ifdef PPM_NORAWWORD
00040 #define PUTPPMSAMPLE(ptr,v)  *ptr++ = (char) ((v) >> (BITS_IN_JSAMPLE-8))
00041 #define BYTESPERSAMPLE 1
00042 #define PPM_MAXVAL 255
00043 #else
00044 /* The word-per-sample format always puts the MSB first. */
00045 #define PUTPPMSAMPLE(ptr,v)         \
00046     { register int val_ = v;        \
00047       *ptr++ = (char) ((val_ >> 8) & 0xFF); \
00048       *ptr++ = (char) (val_ & 0xFF);    \
00049     }
00050 #define BYTESPERSAMPLE 2
00051 #define PPM_MAXVAL ((1<<BITS_IN_JSAMPLE)-1)
00052 #endif
00053 #endif
00054 
00055 
00056 /*
00057  * When JSAMPLE is the same size as char, we can just fwrite() the
00058  * decompressed data to the PPM or PGM file.  On PCs, in order to make this
00059  * work the output buffer must be allocated in near data space, because we are
00060  * assuming small-data memory model wherein fwrite() can't reach far memory.
00061  * If you need to process very wide images on a PC, you might have to compile
00062  * in large-memory model, or else replace fwrite() with a putc() loop ---
00063  * which will be much slower.
00064  */
00065 
00066 
00067 /* Private version of data destination object */
00068 
00069 typedef struct {
00070   struct djpeg_dest_struct pub; /* public fields */
00071 
00072   /* Usually these two pointers point to the same place: */
00073   char *iobuffer;       /* fwrite's I/O buffer */
00074   JSAMPROW pixrow;      /* decompressor output buffer */
00075   size_t buffer_width;      /* width of I/O buffer */
00076   JDIMENSION samples_per_row;   /* JSAMPLEs per output row */
00077 } ppm_dest_struct;
00078 
00079 typedef ppm_dest_struct * ppm_dest_ptr;
00080 
00081 
00082 /*
00083  * Write some pixel data.
00084  * In this module rows_supplied will always be 1.
00085  *
00086  * put_pixel_rows handles the "normal" 8-bit case where the decompressor
00087  * output buffer is physically the same as the fwrite buffer.
00088  */
00089 
00090 METHODDEF(void)
00091 put_pixel_rows (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
00092         JDIMENSION rows_supplied)
00093 {
00094   ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
00095 
00096   (void) JFWRITE(dest->pub.output_file, dest->iobuffer, dest->buffer_width);
00097 }
00098 
00099 
00100 /*
00101  * This code is used when we have to copy the data and apply a pixel
00102  * format translation.  Typically this only happens in 12-bit mode.
00103  */
00104 
00105 METHODDEF(void)
00106 copy_pixel_rows (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
00107          JDIMENSION rows_supplied)
00108 {
00109   ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
00110   register char * bufferptr;
00111   register JSAMPROW ptr;
00112   register JDIMENSION col;
00113 
00114   ptr = dest->pub.buffer[0];
00115   bufferptr = dest->iobuffer;
00116   for (col = dest->samples_per_row; col > 0; col--) {
00117     PUTPPMSAMPLE(bufferptr, GETJSAMPLE(*ptr++));
00118   }
00119   (void) JFWRITE(dest->pub.output_file, dest->iobuffer, dest->buffer_width);
00120 }
00121 
00122 
00123 /*
00124  * Write some pixel data when color quantization is in effect.
00125  * We have to demap the color index values to straight data.
00126  */
00127 
00128 METHODDEF(void)
00129 put_demapped_rgb (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
00130           JDIMENSION rows_supplied)
00131 {
00132   ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
00133   register char * bufferptr;
00134   register int pixval;
00135   register JSAMPROW ptr;
00136   register JSAMPROW color_map0 = cinfo->colormap[0];
00137   register JSAMPROW color_map1 = cinfo->colormap[1];
00138   register JSAMPROW color_map2 = cinfo->colormap[2];
00139   register JDIMENSION col;
00140 
00141   ptr = dest->pub.buffer[0];
00142   bufferptr = dest->iobuffer;
00143   for (col = cinfo->output_width; col > 0; col--) {
00144     pixval = GETJSAMPLE(*ptr++);
00145     PUTPPMSAMPLE(bufferptr, GETJSAMPLE(color_map0[pixval]));
00146     PUTPPMSAMPLE(bufferptr, GETJSAMPLE(color_map1[pixval]));
00147     PUTPPMSAMPLE(bufferptr, GETJSAMPLE(color_map2[pixval]));
00148   }
00149   (void) JFWRITE(dest->pub.output_file, dest->iobuffer, dest->buffer_width);
00150 }
00151 
00152 
00153 METHODDEF(void)
00154 put_demapped_gray (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
00155            JDIMENSION rows_supplied)
00156 {
00157   ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
00158   register char * bufferptr;
00159   register JSAMPROW ptr;
00160   register JSAMPROW color_map = cinfo->colormap[0];
00161   register JDIMENSION col;
00162 
00163   ptr = dest->pub.buffer[0];
00164   bufferptr = dest->iobuffer;
00165   for (col = cinfo->output_width; col > 0; col--) {
00166     PUTPPMSAMPLE(bufferptr, GETJSAMPLE(color_map[GETJSAMPLE(*ptr++)]));
00167   }
00168   (void) JFWRITE(dest->pub.output_file, dest->iobuffer, dest->buffer_width);
00169 }
00170 
00171 
00172 /*
00173  * Startup: write the file header.
00174  */
00175 
00176 METHODDEF(void)
00177 start_output_ppm (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo)
00178 {
00179   ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
00180 
00181   /* Emit file header */
00182   switch (cinfo->out_color_space) {
00183   case JCS_GRAYSCALE:
00184     /* emit header for raw PGM format */
00185     fprintf(dest->pub.output_file, "P5\n%ld %ld\n%d\n",
00186         (long) cinfo->output_width, (long) cinfo->output_height,
00187         PPM_MAXVAL);
00188     break;
00189   case JCS_RGB:
00190     /* emit header for raw PPM format */
00191     fprintf(dest->pub.output_file, "P6\n%ld %ld\n%d\n",
00192         (long) cinfo->output_width, (long) cinfo->output_height,
00193         PPM_MAXVAL);
00194     break;
00195   default:
00196     ERREXIT(cinfo, JERR_PPM_COLORSPACE);
00197   }
00198 }
00199 
00200 
00201 /*
00202  * Finish up at the end of the file.
00203  */
00204 
00205 METHODDEF(void)
00206 finish_output_ppm (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo)
00207 {
00208   /* Make sure we wrote the output file OK */
00209   fflush(dinfo->output_file);
00210   if (ferror(dinfo->output_file))
00211     ERREXIT(cinfo, JERR_FILE_WRITE);
00212 }
00213 
00214 
00215 /*
00216  * The module selection routine for PPM format output.
00217  */
00218 
00219 GLOBAL(djpeg_dest_ptr)
00220 jinit_write_ppm (j_decompress_ptr cinfo)
00221 {
00222   ppm_dest_ptr dest;
00223 
00224   /* Create module interface object, fill in method pointers */
00225   dest = (ppm_dest_ptr)
00226       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
00227                   SIZEOF(ppm_dest_struct));
00228   dest->pub.start_output = start_output_ppm;
00229   dest->pub.finish_output = finish_output_ppm;
00230 
00231   /* Calculate output image dimensions so we can allocate space */
00232   jpeg_calc_output_dimensions(cinfo);
00233 
00234   /* Create physical I/O buffer.  Note we make this near on a PC. */
00235   dest->samples_per_row = cinfo->output_width * cinfo->out_color_components;
00236   dest->buffer_width = dest->samples_per_row * (BYTESPERSAMPLE * SIZEOF(char));
00237   dest->iobuffer = (char *) (*cinfo->mem->alloc_small)
00238     ((j_common_ptr) cinfo, JPOOL_IMAGE, dest->buffer_width);
00239 
00240   if (cinfo->quantize_colors || BITS_IN_JSAMPLE != 8 ||
00241       SIZEOF(JSAMPLE) != SIZEOF(char)) {
00242     /* When quantizing, we need an output buffer for colormap indexes
00243      * that's separate from the physical I/O buffer.  We also need a
00244      * separate buffer if pixel format translation must take place.
00245      */
00246     dest->pub.buffer = (*cinfo->mem->alloc_sarray)
00247       ((j_common_ptr) cinfo, JPOOL_IMAGE,
00248        cinfo->output_width * cinfo->output_components, (JDIMENSION) 1);
00249     dest->pub.buffer_height = 1;
00250     if (! cinfo->quantize_colors)
00251       dest->pub.put_pixel_rows = copy_pixel_rows;
00252     else if (cinfo->out_color_space == JCS_GRAYSCALE)
00253       dest->pub.put_pixel_rows = put_demapped_gray;
00254     else
00255       dest->pub.put_pixel_rows = put_demapped_rgb;
00256   } else {
00257     /* We will fwrite() directly from decompressor output buffer. */
00258     /* Synthesize a JSAMPARRAY pointer structure */
00259     /* Cast here implies near->far pointer conversion on PCs */
00260     dest->pixrow = (JSAMPROW) dest->iobuffer;
00261     dest->pub.buffer = & dest->pixrow;
00262     dest->pub.buffer_height = 1;
00263     dest->pub.put_pixel_rows = put_pixel_rows;
00264   }
00265 
00266   return (djpeg_dest_ptr) dest;
00267 }
00268 
00269 #endif /* PPM_SUPPORTED */