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      1 /*
      2  * wrppm.c
      3  *
      4  * Copyright (C) 1991-1996, 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 routines to write output images in PPM/PGM format.
      9  * The extended 2-byte-per-sample raw PPM/PGM formats are supported.
     10  * The PBMPLUS library is NOT required to compile this software
     11  * (but it is highly useful as a set of PPM image manipulation programs).
     12  *
     13  * These routines may need modification for non-Unix environments or
     14  * specialized applications.  As they stand, they assume output to
     15  * an ordinary stdio stream.
     16  */
     17 
     18 #include "cdjpeg.h"		/* Common decls for cjpeg/djpeg applications */
     19 
     20 #ifdef PPM_SUPPORTED
     21 
     22 
     23 /*
     24  * For 12-bit JPEG data, we either downscale the values to 8 bits
     25  * (to write standard byte-per-sample PPM/PGM files), or output
     26  * nonstandard word-per-sample PPM/PGM files.  Downscaling is done
     27  * if PPM_NORAWWORD is defined (this can be done in the Makefile
     28  * or in jconfig.h).
     29  * (When the core library supports data precision reduction, a cleaner
     30  * implementation will be to ask for that instead.)
     31  */
     32 
     33 #if BITS_IN_JSAMPLE == 8
     34 #define PUTPPMSAMPLE(ptr,v)  *ptr++ = (char) (v)
     35 #define BYTESPERSAMPLE 1
     36 #define PPM_MAXVAL 255
     37 #else
     38 #ifdef PPM_NORAWWORD
     39 #define PUTPPMSAMPLE(ptr,v)  *ptr++ = (char) ((v) >> (BITS_IN_JSAMPLE-8))
     40 #define BYTESPERSAMPLE 1
     41 #define PPM_MAXVAL 255
     42 #else
     43 /* The word-per-sample format always puts the LSB first. */
     44 #define PUTPPMSAMPLE(ptr,v)			\
     45 	{ register int val_ = v;		\
     46 	  *ptr++ = (char) (val_ & 0xFF);	\
     47 	  *ptr++ = (char) ((val_ >> 8) & 0xFF);	\
     48 	}
     49 #define BYTESPERSAMPLE 2
     50 #define PPM_MAXVAL ((1<<BITS_IN_JSAMPLE)-1)
     51 #endif
     52 #endif
     53 
     54 
     55 /*
     56  * When JSAMPLE is the same size as char, we can just fwrite() the
     57  * decompressed data to the PPM or PGM file.  On PCs, in order to make this
     58  * work the output buffer must be allocated in near data space, because we are
     59  * assuming small-data memory model wherein fwrite() can't reach far memory.
     60  * If you need to process very wide images on a PC, you might have to compile
     61  * in large-memory model, or else replace fwrite() with a putc() loop ---
     62  * which will be much slower.
     63  */
     64 
     65 
     66 /* Private version of data destination object */
     67 
     68 typedef struct {
     69   struct djpeg_dest_struct pub;	/* public fields */
     70 
     71   /* Usually these two pointers point to the same place: */
     72   char *iobuffer;		/* fwrite's I/O buffer */
     73   JSAMPROW pixrow;		/* decompressor output buffer */
     74   size_t buffer_width;		/* width of I/O buffer */
     75   JDIMENSION samples_per_row;	/* JSAMPLEs per output row */
     76 } ppm_dest_struct;
     77 
     78 typedef ppm_dest_struct * ppm_dest_ptr;
     79 
     80 
     81 /*
     82  * Write some pixel data.
     83  * In this module rows_supplied will always be 1.
     84  *
     85  * put_pixel_rows handles the "normal" 8-bit case where the decompressor
     86  * output buffer is physically the same as the fwrite buffer.
     87  */
     88 
     89 METHODDEF(void)
     90 put_pixel_rows (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
     91 		JDIMENSION rows_supplied)
     92 {
     93   ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
     94 
     95   (void) JFWRITE(dest->pub.output_file, dest->iobuffer, dest->buffer_width);
     96 }
     97 
     98 
     99 /*
    100  * This code is used when we have to copy the data and apply a pixel
    101  * format translation.  Typically this only happens in 12-bit mode.
    102  */
    103 
    104 METHODDEF(void)
    105 copy_pixel_rows (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
    106 		 JDIMENSION rows_supplied)
    107 {
    108   ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
    109   register char * bufferptr;
    110   register JSAMPROW ptr;
    111   register JDIMENSION col;
    112 
    113   ptr = dest->pub.buffer[0];
    114   bufferptr = dest->iobuffer;
    115   for (col = dest->samples_per_row; col > 0; col--) {
    116     PUTPPMSAMPLE(bufferptr, GETJSAMPLE(*ptr++));
    117   }
    118   (void) JFWRITE(dest->pub.output_file, dest->iobuffer, dest->buffer_width);
    119 }
    120 
    121 
    122 /*
    123  * Write some pixel data when color quantization is in effect.
    124  * We have to demap the color index values to straight data.
    125  */
    126 
    127 METHODDEF(void)
    128 put_demapped_rgb (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
    129 		  JDIMENSION rows_supplied)
    130 {
    131   ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
    132   register char * bufferptr;
    133   register int pixval;
    134   register JSAMPROW ptr;
    135   register JSAMPROW color_map0 = cinfo->colormap[0];
    136   register JSAMPROW color_map1 = cinfo->colormap[1];
    137   register JSAMPROW color_map2 = cinfo->colormap[2];
    138   register JDIMENSION col;
    139 
    140   ptr = dest->pub.buffer[0];
    141   bufferptr = dest->iobuffer;
    142   for (col = cinfo->output_width; col > 0; col--) {
    143     pixval = GETJSAMPLE(*ptr++);
    144     PUTPPMSAMPLE(bufferptr, GETJSAMPLE(color_map0[pixval]));
    145     PUTPPMSAMPLE(bufferptr, GETJSAMPLE(color_map1[pixval]));
    146     PUTPPMSAMPLE(bufferptr, GETJSAMPLE(color_map2[pixval]));
    147   }
    148   (void) JFWRITE(dest->pub.output_file, dest->iobuffer, dest->buffer_width);
    149 }
    150 
    151 
    152 METHODDEF(void)
    153 put_demapped_gray (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
    154 		   JDIMENSION rows_supplied)
    155 {
    156   ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
    157   register char * bufferptr;
    158   register JSAMPROW ptr;
    159   register JSAMPROW color_map = cinfo->colormap[0];
    160   register JDIMENSION col;
    161 
    162   ptr = dest->pub.buffer[0];
    163   bufferptr = dest->iobuffer;
    164   for (col = cinfo->output_width; col > 0; col--) {
    165     PUTPPMSAMPLE(bufferptr, GETJSAMPLE(color_map[GETJSAMPLE(*ptr++)]));
    166   }
    167   (void) JFWRITE(dest->pub.output_file, dest->iobuffer, dest->buffer_width);
    168 }
    169 
    170 
    171 /*
    172  * Startup: write the file header.
    173  */
    174 
    175 METHODDEF(void)
    176 start_output_ppm (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo)
    177 {
    178   ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
    179 
    180   /* Emit file header */
    181   switch (cinfo->out_color_space) {
    182   case JCS_GRAYSCALE:
    183     /* emit header for raw PGM format */
    184     fprintf(dest->pub.output_file, "P5\n%ld %ld\n%d\n",
    185 	    (long) cinfo->output_width, (long) cinfo->output_height,
    186 	    PPM_MAXVAL);
    187     break;
    188   case JCS_RGB:
    189     /* emit header for raw PPM format */
    190     fprintf(dest->pub.output_file, "P6\n%ld %ld\n%d\n",
    191 	    (long) cinfo->output_width, (long) cinfo->output_height,
    192 	    PPM_MAXVAL);
    193     break;
    194   default:
    195     ERREXIT(cinfo, JERR_PPM_COLORSPACE);
    196   }
    197 }
    198 
    199 
    200 /*
    201  * Finish up at the end of the file.
    202  */
    203 
    204 METHODDEF(void)
    205 finish_output_ppm (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo)
    206 {
    207   /* Make sure we wrote the output file OK */
    208   fflush(dinfo->output_file);
    209   if (ferror(dinfo->output_file))
    210     ERREXIT(cinfo, JERR_FILE_WRITE);
    211 }
    212 
    213 
    214 /*
    215  * The module selection routine for PPM format output.
    216  */
    217 
    218 GLOBAL(djpeg_dest_ptr)
    219 jinit_write_ppm (j_decompress_ptr cinfo)
    220 {
    221   ppm_dest_ptr dest;
    222 
    223   /* Create module interface object, fill in method pointers */
    224   dest = (ppm_dest_ptr)
    225       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
    226 				  SIZEOF(ppm_dest_struct));
    227   dest->pub.start_output = start_output_ppm;
    228   dest->pub.finish_output = finish_output_ppm;
    229 
    230   /* Calculate output image dimensions so we can allocate space */
    231   jpeg_calc_output_dimensions(cinfo);
    232 
    233   /* Create physical I/O buffer.  Note we make this near on a PC. */
    234   dest->samples_per_row = cinfo->output_width * cinfo->out_color_components;
    235   dest->buffer_width = dest->samples_per_row * (BYTESPERSAMPLE * SIZEOF(char));
    236   dest->iobuffer = (char *) (*cinfo->mem->alloc_small)
    237     ((j_common_ptr) cinfo, JPOOL_IMAGE, dest->buffer_width);
    238 
    239   if (cinfo->quantize_colors || BITS_IN_JSAMPLE != 8 ||
    240       SIZEOF(JSAMPLE) != SIZEOF(char)) {
    241     /* When quantizing, we need an output buffer for colormap indexes
    242      * that's separate from the physical I/O buffer.  We also need a
    243      * separate buffer if pixel format translation must take place.
    244      */
    245     dest->pub.buffer = (*cinfo->mem->alloc_sarray)
    246       ((j_common_ptr) cinfo, JPOOL_IMAGE,
    247        cinfo->output_width * cinfo->output_components, (JDIMENSION) 1);
    248     dest->pub.buffer_height = 1;
    249     if (! cinfo->quantize_colors)
    250       dest->pub.put_pixel_rows = copy_pixel_rows;
    251     else if (cinfo->out_color_space == JCS_GRAYSCALE)
    252       dest->pub.put_pixel_rows = put_demapped_gray;
    253     else
    254       dest->pub.put_pixel_rows = put_demapped_rgb;
    255   } else {
    256     /* We will fwrite() directly from decompressor output buffer. */
    257     /* Synthesize a JSAMPARRAY pointer structure */
    258     /* Cast here implies near->far pointer conversion on PCs */
    259     dest->pixrow = (JSAMPROW) dest->iobuffer;
    260     dest->pub.buffer = & dest->pixrow;
    261     dest->pub.buffer_height = 1;
    262     dest->pub.put_pixel_rows = put_pixel_rows;
    263   }
    264 
    265   return (djpeg_dest_ptr) dest;
    266 }
    267 
    268 #endif /* PPM_SUPPORTED */
    269