/**************************************************************************** * gif.c * * Gif-format file reader. * * NOTE: Portions of this module were written by Steve Bennett and are used * here with his permission. * * from Persistence of Vision(tm) Ray Tracer * Copyright 1996,1999 Persistence of Vision Team *--------------------------------------------------------------------------- * NOTICE: This source code file is provided so that users may experiment * with enhancements to POV-Ray and to port the software to platforms other * than those supported by the POV-Ray Team. There are strict rules under * which you are permitted to use this file. The rules are in the file * named POVLEGAL.DOC which should be distributed with this file. * If POVLEGAL.DOC is not available or for more info please contact the POV-Ray * Team Coordinator by email to team-coord@povray.org or visit us on the web at * http://www.povray.org. The latest version of POV-Ray may be found at this site. * * This program is based on the popular DKB raytracer version 2.12. * DKBTrace was originally written by David K. Buck. * DKBTrace Ver 2.0-2.12 were written by David K. Buck & Aaron A. Collins. * * Modification by Hans-Deltev Fink, January 1999, used with permission * *****************************************************************************/ /* * The following routines were borrowed freely from FRACTINT, and represent * a generalized GIF file decoder. This once seemed the best, most universal * format for reading in Bitmapped images, until Unisys began enforcing * its patent on the LZ compression that GIF uses. POV-Ray, as freeware, is * exempt from GIF licensing fees. GIF is a Copyright of Compuserve, Inc. * * Swiped and converted to entirely "C" coded routines by AAC for the most * in future portability! */ #include "frame.h" #include "povproto.h" #include "gif.h" #include "gifdecod.h" #include "povray.h" /***************************************************************************** * Local preprocessor defines ******************************************************************************/ /***************************************************************************** * Local typedefs ******************************************************************************/ /***************************************************************************** * Local variables ******************************************************************************/ static IMAGE *Current_Image; static int Bitmap_Line; static FILE *Bit_File; unsigned char *decoderline /* [2049] */ ; /* write-line routines use this */ static IMAGE_COLOUR *gif_colour_map; static int colourmap_size; /***************************************************************************** * Static functions ******************************************************************************/ /***************************************************************************** * * FUNCTION * * out_line * * INPUT * * OUTPUT * * RETURNS * * AUTHOR * * POV-Ray Team * * DESCRIPTION * * - * * CHANGES * * - * ******************************************************************************/ int out_line (unsigned char *pixels, int linelen) { register int x; register unsigned char *line; if (Bitmap_Line == Current_Image->iheight) { Warning (0.0, "Extra data at end of GIF image.\n"); return (0) ; } line = Current_Image->data.map_lines[Bitmap_Line++]; for (x = 0; x < linelen; x++) { if ((int)(*pixels) > Current_Image->Colour_Map_Size) { Error ("Error - GIF image map color out of range.\n"); } line[x] = *pixels; pixels++; } return (0); } /***************************************************************************** * * FUNCTION * * gif_get_byte * * INPUT * * OUTPUT * * RETURNS * * AUTHOR * * POV-Ray Team * * DESCRIPTION * * Get byte from file, return the next byte or an error. * * CHANGES * * - * ******************************************************************************/ int gif_get_byte() { register int byte; if ((byte = getc(Bit_File)) != EOF) { return (byte); } else { Error ("Error reading data from GIF image.\n"); } /* Keep the compiler happy. */ return(0); } /***************************************************************************** * * FUNCTION * * Read_Gif_Image * * INPUT * * OUTPUT * * RETURNS * * AUTHOR * * POV-Ray Team * * DESCRIPTION * * Main GIF file decoder. * * CHANGES * * - * ******************************************************************************/ void Read_Gif_Image(IMAGE *Image, char *filename) { register int i, j, status; unsigned finished, planes; unsigned char buffer[16]; status = 0; Current_Image = Image; if ((Bit_File = Locate_File(filename, READ_BINFILE_STRING, ".gif", ".GIF",NULL,TRUE)) == NULL) { Error ("Error opening GIF image.\n"); } /* Get the screen description. */ for (i = 0; i < 13; i++) { buffer[i] = (unsigned char)gif_get_byte(); } /* Use updated GIF specs. */ if (strncmp((char *) buffer,"GIF",3) == 0) /* Allow only GIF87 and GIF89 */ { if ((buffer[3] != '8') || ((buffer[4] != '7') && (buffer[4]) != '9') || (buffer[5] < 'A') || (buffer[5]) > 'z') { Error ("Unsupported GIF version %c%c%c.\n", buffer[3], buffer[4], buffer[5]); } } else { Error ("File is not in GIF format.\n"); } planes = ((unsigned)buffer[10] & 0x0F) + 1; colourmap_size = (int)(1 << planes); gif_colour_map = (IMAGE_COLOUR *)POV_CALLOC((size_t)colourmap_size, sizeof(IMAGE_COLOUR), "GIF color map"); /* Color map (better be!) */ if ((buffer[10] & 0x80) == 0) { Error ("Error in GIF color map.\n"); } for (i = 0; i < colourmap_size ; i++) { gif_colour_map[i].Red = (unsigned char)gif_get_byte(); gif_colour_map[i].Green = (unsigned char)gif_get_byte(); gif_colour_map[i].Blue = (unsigned char)gif_get_byte(); gif_colour_map[i].Filter = 0; gif_colour_map[i].Transmit = 0; } /* Now display one or more GIF objects. */ finished = FALSE; while (!finished) { switch (gif_get_byte()) { /* End of the GIF dataset. */ case ';': finished = TRUE; status = 0; break; /* GIF Extension Block. */ case '!': /* Read (and ignore) the ID. */ gif_get_byte(); /* Get data len. */ while ((i = gif_get_byte()) > 0) { for (j = 0; j < i; j++) { /* Flush data. */ gif_get_byte(); } } break; /* Start of image object. Get description. */ case ',': for (i = 0; i < 9; i++) { /* EOF test (?).*/ if ((j = gif_get_byte()) < 0) { status = -1; break; } buffer[i] = (unsigned char) j; } /* Check "interlaced" bit. */ if (j & 0x40) { Error ("Interlacing in GIF image unsupported.\n"); } if (status < 0) { finished = TRUE; break; } Image->iwidth = buffer[4] | (buffer[5] << 8); Image->iheight = buffer[6] | (buffer[7] << 8); Image->width = (DBL) Image->iwidth; Image->height = (DBL) Image->iheight; Bitmap_Line = 0; Image->Colour_Map_Size = colourmap_size; Image->Colour_Map = gif_colour_map; Image->data.map_lines = (unsigned char **)POV_MALLOC(Image->iheight * sizeof(unsigned char *), "GIF image"); for (i = 0 ; i < Image->iheight ; i++) { Image->data.map_lines[i] = (unsigned char *)POV_CALLOC((size_t)Image->iwidth, sizeof(unsigned char), "GIF image line"); } /* Setup the color palette for the image. */ decoderline = (unsigned char *)POV_CALLOC(Image->iwidth, sizeof(unsigned char), "GIF decoder line"); /* Put bytes in Buf. */ status = decoder(Image->iwidth); POV_FREE (decoderline); decoderline = NULL; finished = TRUE; break; default: status = -1; finished = TRUE; break; } } if (Bit_File != NULL) /* -hdf99- */ { fclose(Bit_File); } }