Home | History | Annotate | Download | only in jpeg-6b
      1 /*
      2  * rdtarga.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 read input images in Targa format.
      9  *
     10  * These routines may need modification for non-Unix environments or
     11  * specialized applications.  As they stand, they assume input from
     12  * an ordinary stdio stream.  They further assume that reading begins
     13  * at the start of the file; start_input may need work if the
     14  * user interface has already read some data (e.g., to determine that
     15  * the file is indeed Targa format).
     16  *
     17  * Based on code contributed by Lee Daniel Crocker.
     18  */
     19 
     20 #include "cdjpeg.h"		/* Common decls for cjpeg/djpeg applications */
     21 
     22 #ifdef TARGA_SUPPORTED
     23 
     24 
     25 /* Macros to deal with unsigned chars as efficiently as compiler allows */
     26 
     27 #ifdef HAVE_UNSIGNED_CHAR
     28 typedef unsigned char U_CHAR;
     29 #define UCH(x)	((int) (x))
     30 #else /* !HAVE_UNSIGNED_CHAR */
     31 #ifdef CHAR_IS_UNSIGNED
     32 typedef char U_CHAR;
     33 #define UCH(x)	((int) (x))
     34 #else
     35 typedef char U_CHAR;
     36 #define UCH(x)	((int) (x) & 0xFF)
     37 #endif
     38 #endif /* HAVE_UNSIGNED_CHAR */
     39 
     40 
     41 #define	ReadOK(file,buffer,len)	(JFREAD(file,buffer,len) == ((size_t) (len)))
     42 
     43 
     44 /* Private version of data source object */
     45 
     46 typedef struct _tga_source_struct * tga_source_ptr;
     47 
     48 typedef struct _tga_source_struct {
     49   struct cjpeg_source_struct pub; /* public fields */
     50 
     51   j_compress_ptr cinfo;		/* back link saves passing separate parm */
     52 
     53   JSAMPARRAY colormap;		/* Targa colormap (converted to my format) */
     54 
     55   jvirt_sarray_ptr whole_image;	/* Needed if funny input row order */
     56   JDIMENSION current_row;	/* Current logical row number to read */
     57 
     58   /* Pointer to routine to extract next Targa pixel from input file */
     59   JMETHOD(void, read_pixel, (tga_source_ptr sinfo));
     60 
     61   /* Result of read_pixel is delivered here: */
     62   U_CHAR tga_pixel[4];
     63 
     64   int pixel_size;		/* Bytes per Targa pixel (1 to 4) */
     65 
     66   /* State info for reading RLE-coded pixels; both counts must be init to 0 */
     67   int block_count;		/* # of pixels remaining in RLE block */
     68   int dup_pixel_count;		/* # of times to duplicate previous pixel */
     69 
     70   /* This saves the correct pixel-row-expansion method for preload_image */
     71   JMETHOD(JDIMENSION, get_pixel_rows, (j_compress_ptr cinfo,
     72 				       cjpeg_source_ptr sinfo));
     73 } tga_source_struct;
     74 
     75 
     76 /* For expanding 5-bit pixel values to 8-bit with best rounding */
     77 
     78 static const UINT8 c5to8bits[32] = {
     79     0,   8,  16,  25,  33,  41,  49,  58,
     80    66,  74,  82,  90,  99, 107, 115, 123,
     81   132, 140, 148, 156, 165, 173, 181, 189,
     82   197, 206, 214, 222, 230, 239, 247, 255
     83 };
     84 
     85 
     86 
     87 LOCAL(int)
     88 read_byte (tga_source_ptr sinfo)
     89 /* Read next byte from Targa file */
     90 {
     91   register FILE *infile = sinfo->pub.input_file;
     92   register int c;
     93 
     94   if ((c = getc(infile)) == EOF)
     95     ERREXIT(sinfo->cinfo, JERR_INPUT_EOF);
     96   return c;
     97 }
     98 
     99 
    100 LOCAL(void)
    101 read_colormap (tga_source_ptr sinfo, int cmaplen, int mapentrysize)
    102 /* Read the colormap from a Targa file */
    103 {
    104   int i;
    105 
    106   /* Presently only handles 24-bit BGR format */
    107   if (mapentrysize != 24)
    108     ERREXIT(sinfo->cinfo, JERR_TGA_BADCMAP);
    109 
    110   for (i = 0; i < cmaplen; i++) {
    111     sinfo->colormap[2][i] = (JSAMPLE) read_byte(sinfo);
    112     sinfo->colormap[1][i] = (JSAMPLE) read_byte(sinfo);
    113     sinfo->colormap[0][i] = (JSAMPLE) read_byte(sinfo);
    114   }
    115 }
    116 
    117 
    118 /*
    119  * read_pixel methods: get a single pixel from Targa file into tga_pixel[]
    120  */
    121 
    122 METHODDEF(void)
    123 read_non_rle_pixel (tga_source_ptr sinfo)
    124 /* Read one Targa pixel from the input file; no RLE expansion */
    125 {
    126   register FILE *infile = sinfo->pub.input_file;
    127   register int i;
    128 
    129   for (i = 0; i < sinfo->pixel_size; i++) {
    130     sinfo->tga_pixel[i] = (U_CHAR) getc(infile);
    131   }
    132 }
    133 
    134 
    135 METHODDEF(void)
    136 read_rle_pixel (tga_source_ptr sinfo)
    137 /* Read one Targa pixel from the input file, expanding RLE data as needed */
    138 {
    139   register FILE *infile = sinfo->pub.input_file;
    140   register int i;
    141 
    142   /* Duplicate previously read pixel? */
    143   if (sinfo->dup_pixel_count > 0) {
    144     sinfo->dup_pixel_count--;
    145     return;
    146   }
    147 
    148   /* Time to read RLE block header? */
    149   if (--sinfo->block_count < 0) { /* decrement pixels remaining in block */
    150     i = read_byte(sinfo);
    151     if (i & 0x80) {		/* Start of duplicate-pixel block? */
    152       sinfo->dup_pixel_count = i & 0x7F; /* number of dups after this one */
    153       sinfo->block_count = 0;	/* then read new block header */
    154     } else {
    155       sinfo->block_count = i & 0x7F; /* number of pixels after this one */
    156     }
    157   }
    158 
    159   /* Read next pixel */
    160   for (i = 0; i < sinfo->pixel_size; i++) {
    161     sinfo->tga_pixel[i] = (U_CHAR) getc(infile);
    162   }
    163 }
    164 
    165 
    166 /*
    167  * Read one row of pixels.
    168  *
    169  * We provide several different versions depending on input file format.
    170  */
    171 
    172 
    173 METHODDEF(JDIMENSION)
    174 get_8bit_gray_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
    175 /* This version is for reading 8-bit grayscale pixels */
    176 {
    177   tga_source_ptr source = (tga_source_ptr) sinfo;
    178   register JSAMPROW ptr;
    179   register JDIMENSION col;
    180 
    181   ptr = source->pub.buffer[0];
    182   for (col = cinfo->image_width; col > 0; col--) {
    183     (*source->read_pixel) (source); /* Load next pixel into tga_pixel */
    184     *ptr++ = (JSAMPLE) UCH(source->tga_pixel[0]);
    185   }
    186   return 1;
    187 }
    188 
    189 METHODDEF(JDIMENSION)
    190 get_8bit_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
    191 /* This version is for reading 8-bit colormap indexes */
    192 {
    193   tga_source_ptr source = (tga_source_ptr) sinfo;
    194   register int t;
    195   register JSAMPROW ptr;
    196   register JDIMENSION col;
    197   register JSAMPARRAY colormap = source->colormap;
    198 
    199   ptr = source->pub.buffer[0];
    200   for (col = cinfo->image_width; col > 0; col--) {
    201     (*source->read_pixel) (source); /* Load next pixel into tga_pixel */
    202     t = UCH(source->tga_pixel[0]);
    203     *ptr++ = colormap[0][t];
    204     *ptr++ = colormap[1][t];
    205     *ptr++ = colormap[2][t];
    206   }
    207   return 1;
    208 }
    209 
    210 METHODDEF(JDIMENSION)
    211 get_16bit_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
    212 /* This version is for reading 16-bit pixels */
    213 {
    214   tga_source_ptr source = (tga_source_ptr) sinfo;
    215   register int t;
    216   register JSAMPROW ptr;
    217   register JDIMENSION col;
    218 
    219   ptr = source->pub.buffer[0];
    220   for (col = cinfo->image_width; col > 0; col--) {
    221     (*source->read_pixel) (source); /* Load next pixel into tga_pixel */
    222     t = UCH(source->tga_pixel[0]);
    223     t += UCH(source->tga_pixel[1]) << 8;
    224     /* We expand 5 bit data to 8 bit sample width.
    225      * The format of the 16-bit (LSB first) input word is
    226      *     xRRRRRGGGGGBBBBB
    227      */
    228     ptr[2] = (JSAMPLE) c5to8bits[t & 0x1F];
    229     t >>= 5;
    230     ptr[1] = (JSAMPLE) c5to8bits[t & 0x1F];
    231     t >>= 5;
    232     ptr[0] = (JSAMPLE) c5to8bits[t & 0x1F];
    233     ptr += 3;
    234   }
    235   return 1;
    236 }
    237 
    238 METHODDEF(JDIMENSION)
    239 get_24bit_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
    240 /* This version is for reading 24-bit pixels */
    241 {
    242   tga_source_ptr source = (tga_source_ptr) sinfo;
    243   register JSAMPROW ptr;
    244   register JDIMENSION col;
    245 
    246   ptr = source->pub.buffer[0];
    247   for (col = cinfo->image_width; col > 0; col--) {
    248     (*source->read_pixel) (source); /* Load next pixel into tga_pixel */
    249     *ptr++ = (JSAMPLE) UCH(source->tga_pixel[2]); /* change BGR to RGB order */
    250     *ptr++ = (JSAMPLE) UCH(source->tga_pixel[1]);
    251     *ptr++ = (JSAMPLE) UCH(source->tga_pixel[0]);
    252   }
    253   return 1;
    254 }
    255 
    256 /*
    257  * Targa also defines a 32-bit pixel format with order B,G,R,A.
    258  * We presently ignore the attribute byte, so the code for reading
    259  * these pixels is identical to the 24-bit routine above.
    260  * This works because the actual pixel length is only known to read_pixel.
    261  */
    262 
    263 #define get_32bit_row  get_24bit_row
    264 
    265 
    266 /*
    267  * This method is for re-reading the input data in standard top-down
    268  * row order.  The entire image has already been read into whole_image
    269  * with proper conversion of pixel format, but it's in a funny row order.
    270  */
    271 
    272 METHODDEF(JDIMENSION)
    273 get_memory_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
    274 {
    275   tga_source_ptr source = (tga_source_ptr) sinfo;
    276   JDIMENSION source_row;
    277 
    278   /* Compute row of source that maps to current_row of normal order */
    279   /* For now, assume image is bottom-up and not interlaced. */
    280   /* NEEDS WORK to support interlaced images! */
    281   source_row = cinfo->image_height - source->current_row - 1;
    282 
    283   /* Fetch that row from virtual array */
    284   source->pub.buffer = (*cinfo->mem->access_virt_sarray)
    285     ((j_common_ptr) cinfo, source->whole_image,
    286      source_row, (JDIMENSION) 1, FALSE);
    287 
    288   source->current_row++;
    289   return 1;
    290 }
    291 
    292 
    293 /*
    294  * This method loads the image into whole_image during the first call on
    295  * get_pixel_rows.  The get_pixel_rows pointer is then adjusted to call
    296  * get_memory_row on subsequent calls.
    297  */
    298 
    299 METHODDEF(JDIMENSION)
    300 preload_image (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
    301 {
    302   tga_source_ptr source = (tga_source_ptr) sinfo;
    303   JDIMENSION row;
    304   cd_progress_ptr progress = (cd_progress_ptr) cinfo->progress;
    305 
    306   /* Read the data into a virtual array in input-file row order. */
    307   for (row = 0; row < cinfo->image_height; row++) {
    308     if (progress != NULL) {
    309       progress->pub.pass_counter = (long) row;
    310       progress->pub.pass_limit = (long) cinfo->image_height;
    311       (*progress->pub.progress_monitor) ((j_common_ptr) cinfo);
    312     }
    313     source->pub.buffer = (*cinfo->mem->access_virt_sarray)
    314       ((j_common_ptr) cinfo, source->whole_image, row, (JDIMENSION) 1, TRUE);
    315     (*source->get_pixel_rows) (cinfo, sinfo);
    316   }
    317   if (progress != NULL)
    318     progress->completed_extra_passes++;
    319 
    320   /* Set up to read from the virtual array in unscrambled order */
    321   source->pub.get_pixel_rows = get_memory_row;
    322   source->current_row = 0;
    323   /* And read the first row */
    324   return get_memory_row(cinfo, sinfo);
    325 }
    326 
    327 
    328 /*
    329  * Read the file header; return image size and component count.
    330  */
    331 
    332 METHODDEF(void)
    333 start_input_tga (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
    334 {
    335   tga_source_ptr source = (tga_source_ptr) sinfo;
    336   U_CHAR targaheader[18];
    337   int idlen, cmaptype, subtype, flags, interlace_type, components;
    338   unsigned int width, height, maplen;
    339   boolean is_bottom_up;
    340 
    341 #define GET_2B(offset)	((unsigned int) UCH(targaheader[offset]) + \
    342 			 (((unsigned int) UCH(targaheader[offset+1])) << 8))
    343 
    344   if (! ReadOK(source->pub.input_file, targaheader, 18))
    345     ERREXIT(cinfo, JERR_INPUT_EOF);
    346 
    347   /* Pretend "15-bit" pixels are 16-bit --- we ignore attribute bit anyway */
    348   if (targaheader[16] == 15)
    349     targaheader[16] = 16;
    350 
    351   idlen = UCH(targaheader[0]);
    352   cmaptype = UCH(targaheader[1]);
    353   subtype = UCH(targaheader[2]);
    354   maplen = GET_2B(5);
    355   width = GET_2B(12);
    356   height = GET_2B(14);
    357   source->pixel_size = UCH(targaheader[16]) >> 3;
    358   flags = UCH(targaheader[17]);	/* Image Descriptor byte */
    359 
    360   is_bottom_up = ((flags & 0x20) == 0);	/* bit 5 set => top-down */
    361   interlace_type = flags >> 6;	/* bits 6/7 are interlace code */
    362 
    363   if (cmaptype > 1 ||		/* cmaptype must be 0 or 1 */
    364       source->pixel_size < 1 || source->pixel_size > 4 ||
    365       (UCH(targaheader[16]) & 7) != 0 || /* bits/pixel must be multiple of 8 */
    366       interlace_type != 0)	/* currently don't allow interlaced image */
    367     ERREXIT(cinfo, JERR_TGA_BADPARMS);
    368 
    369   if (subtype > 8) {
    370     /* It's an RLE-coded file */
    371     source->read_pixel = read_rle_pixel;
    372     source->block_count = source->dup_pixel_count = 0;
    373     subtype -= 8;
    374   } else {
    375     /* Non-RLE file */
    376     source->read_pixel = read_non_rle_pixel;
    377   }
    378 
    379   /* Now should have subtype 1, 2, or 3 */
    380   components = 3;		/* until proven different */
    381   cinfo->in_color_space = JCS_RGB;
    382 
    383   switch (subtype) {
    384   case 1:			/* Colormapped image */
    385     if (source->pixel_size == 1 && cmaptype == 1)
    386       source->get_pixel_rows = get_8bit_row;
    387     else
    388       ERREXIT(cinfo, JERR_TGA_BADPARMS);
    389     TRACEMS2(cinfo, 1, JTRC_TGA_MAPPED, width, height);
    390     break;
    391   case 2:			/* RGB image */
    392     switch (source->pixel_size) {
    393     case 2:
    394       source->get_pixel_rows = get_16bit_row;
    395       break;
    396     case 3:
    397       source->get_pixel_rows = get_24bit_row;
    398       break;
    399     case 4:
    400       source->get_pixel_rows = get_32bit_row;
    401       break;
    402     default:
    403       ERREXIT(cinfo, JERR_TGA_BADPARMS);
    404       break;
    405     }
    406     TRACEMS2(cinfo, 1, JTRC_TGA, width, height);
    407     break;
    408   case 3:			/* Grayscale image */
    409     components = 1;
    410     cinfo->in_color_space = JCS_GRAYSCALE;
    411     if (source->pixel_size == 1)
    412       source->get_pixel_rows = get_8bit_gray_row;
    413     else
    414       ERREXIT(cinfo, JERR_TGA_BADPARMS);
    415     TRACEMS2(cinfo, 1, JTRC_TGA_GRAY, width, height);
    416     break;
    417   default:
    418     ERREXIT(cinfo, JERR_TGA_BADPARMS);
    419     break;
    420   }
    421 
    422   if (is_bottom_up) {
    423     /* Create a virtual array to buffer the upside-down image. */
    424     source->whole_image = (*cinfo->mem->request_virt_sarray)
    425       ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
    426        (JDIMENSION) width * components, (JDIMENSION) height, (JDIMENSION) 1);
    427     if (cinfo->progress != NULL) {
    428       cd_progress_ptr progress = (cd_progress_ptr) cinfo->progress;
    429       progress->total_extra_passes++; /* count file input as separate pass */
    430     }
    431     /* source->pub.buffer will point to the virtual array. */
    432     source->pub.buffer_height = 1; /* in case anyone looks at it */
    433     source->pub.get_pixel_rows = preload_image;
    434   } else {
    435     /* Don't need a virtual array, but do need a one-row input buffer. */
    436     source->whole_image = NULL;
    437     source->pub.buffer = (*cinfo->mem->alloc_sarray)
    438       ((j_common_ptr) cinfo, JPOOL_IMAGE,
    439        (JDIMENSION) width * components, (JDIMENSION) 1);
    440     source->pub.buffer_height = 1;
    441     source->pub.get_pixel_rows = source->get_pixel_rows;
    442   }
    443 
    444   while (idlen--)		/* Throw away ID field */
    445     (void) read_byte(source);
    446 
    447   if (maplen > 0) {
    448     if (maplen > 256 || GET_2B(3) != 0)
    449       ERREXIT(cinfo, JERR_TGA_BADCMAP);
    450     /* Allocate space to store the colormap */
    451     source->colormap = (*cinfo->mem->alloc_sarray)
    452       ((j_common_ptr) cinfo, JPOOL_IMAGE, (JDIMENSION) maplen, (JDIMENSION) 3);
    453     /* and read it from the file */
    454     read_colormap(source, (int) maplen, UCH(targaheader[7]));
    455   } else {
    456     if (cmaptype)		/* but you promised a cmap! */
    457       ERREXIT(cinfo, JERR_TGA_BADPARMS);
    458     source->colormap = NULL;
    459   }
    460 
    461   cinfo->input_components = components;
    462   cinfo->data_precision = 8;
    463   cinfo->image_width = width;
    464   cinfo->image_height = height;
    465 }
    466 
    467 
    468 /*
    469  * Finish up at the end of the file.
    470  */
    471 
    472 METHODDEF(void)
    473 finish_input_tga (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
    474 {
    475   /* no work */
    476 }
    477 
    478 
    479 /*
    480  * The module selection routine for Targa format input.
    481  */
    482 
    483 GLOBAL(cjpeg_source_ptr)
    484 jinit_read_targa (j_compress_ptr cinfo)
    485 {
    486   tga_source_ptr source;
    487 
    488   /* Create module interface object */
    489   source = (tga_source_ptr)
    490       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
    491 				  SIZEOF(tga_source_struct));
    492   source->cinfo = cinfo;	/* make back link for subroutines */
    493   /* Fill in method ptrs, except get_pixel_rows which start_input sets */
    494   source->pub.start_input = start_input_tga;
    495   source->pub.finish_input = finish_input_tga;
    496 
    497   return (cjpeg_source_ptr) source;
    498 }
    499 
    500 #endif /* TARGA_SUPPORTED */
    501