io_bmp.h和io_bmp.cpp

/*****************************************************************************/ // File: io_bmp.cpp // Author: David Taubman // Last Revised: 30 July, 2007 /*****************************************************************************/ // Copyright 2007, David Taubman, The University of New South Wales (UNSW) /*****************************************************************************/ #include <string.h> // Import `memset' function #include "io_bmp.h" /* ========================================================================= */ /* Internal Functions */ /* ========================================================================= */ /*****************************************************************************/ /* STATIC to_little_endian */ /*****************************************************************************/ static void to_little_endian(io_int32 *words, int num_words) { io_int32 test = 1; io_byte *first_byte = (io_byte *) &test; if (*first_byte) return; // Machine uses little-endian architecture already. io_int32 tmp; for (; num_words--; words++) { tmp = *words; *words = ((tmp >> 24) & 0x000000FF) + ((tmp >> 8) & 0x0000FF00) + ((tmp << 8) & 0x00FF0000) + ((tmp << 24) & 0xFF000000); } } /*****************************************************************************/ /* INLINE from_little_endian */ /*****************************************************************************/ static inline void from_little_endian(io_int32 *words, int num_words) { to_little_endian(words,num_words); } /* ========================================================================= */ /* bmp_in */ /* ========================================================================= */ /*****************************************************************************/ /* bmp_in__open */ /*****************************************************************************/ int bmp_in__open(bmp_in *state, const char *fname) { memset(state,0,sizeof(bmp_in)); // Start by reseting everything if ((state->in = fopen(fname,"rb")) == NULL) return(IO_ERR_NO_FILE); io_byte magic[14]; bmp_header header; fread(magic,1,14,state->in); if ((magic[0] != 'B') || (magic[1] != 'M')) return(IO_ERR_FILE_HEADER); if (fread(&header,1,40,state->in) != 40) return(IO_ERR_FILE_TRUNC); from_little_endian((io_int32 *) &header,10); state->cols = header.width; state->rows = header.height; int bit_count = (header.planes_bits>>16); if (bit_count == 24) state->num_components = 3; else if (bit_count == 8) state->num_components = 1; else return(IO_ERR_UNSUPPORTED); int palette_entries_used = header.num_colours_used; if (state->num_components != 1) palette_entries_used = 0; else if (header.num_colours_used == 0) palette_entries_used = (1<<bit_count); int header_size = 54 + 4*palette_entries_used; int offset = magic[13]; offset <<= 8; offset += magic[12]; offset <<= 8; offset += magic[11]; offset <<= 8; offset += magic[10]; if (offset < header_size) return(IO_ERR_FILE_HEADER); if (palette_entries_used) fseek(state->in,palette_entries_used*4,SEEK_CUR); // Skip over palette if (offset > header_size) fseek(state->in,offset-header_size,SEEK_CUR); state->num_unread_rows = state->rows; state->line_bytes = state->num_components * state->cols; state->alignment_bytes = (4-state->line_bytes) & 3; // Pad to a multiple of 4 bytes return 0; } /*****************************************************************************/ /* bmp_in__close */ /*****************************************************************************/ void bmp_in__close(bmp_in *state) { if (state->in != NULL) fclose(state->in); memset(state,0,sizeof(bmp_in)); } /*****************************************************************************/ /* bmp_in__get_line */ /*****************************************************************************/ int bmp_in__get_line(bmp_in *state, io_byte *line) { if ((state->in == NULL) || (state->num_unread_rows <= 0)) return(IO_ERR_FILE_NOT_OPEN); state->num_unread_rows--; if (fread(line,1,(size_t) state->line_bytes,state->in) != (size_t) state->line_bytes) return(IO_ERR_FILE_TRUNC); if (state->alignment_bytes > 0) { io_byte buf[3]; fread(buf,1,(size_t) state->alignment_bytes,state->in); } return 0; } /* ========================================================================= */ /* bmp_out */ /* ========================================================================= */ /*****************************************************************************/ /* bmp_out__open */ /*****************************************************************************/ int bmp_out__open(bmp_out *state, const char *fname, int width, int height, int num_components) { memset(state,0,sizeof(bmp_out)); // Start by reseting everything state->num_components = num_components; state->rows = state->num_unwritten_rows = height; state->cols = width; io_byte magic[14]; bmp_header header; int header_bytes = 14+sizeof(header); assert(header_bytes == 54); if (num_components == 1) header_bytes += 1024; // Need colour LUT. else if (num_components != 3) return(IO_ERR_UNSUPPORTED); state->line_bytes = num_components * width; state->alignment_bytes = (4-state->line_bytes) & 3; int file_bytes = header_bytes + (state->line_bytes+state->alignment_bytes)*state->rows; magic[0] = 'B'; magic[1] = 'M'; magic[2] = (io_byte) file_bytes; magic[3] = (io_byte)(file_bytes>>8); magic[4] = (io_byte)(file_bytes>>16); magic[5] = (io_byte)(file_bytes>>24); magic[6] = magic[7] = magic[8] = magic[9] = 0; magic[10] = (io_byte) header_bytes; magic[11] = (io_byte)(header_bytes>>8); magic[12] = (io_byte)(header_bytes>>16); magic[13] = (io_byte)(header_bytes>>24); header.size = 40; header.width = width; header.height = height; header.planes_bits = 1; // Set `planes'=1 (mandatory) header.planes_bits |= ((num_components==1)?8:24) << 16; // Set bits per pel. header.compression = 0; header.image_size = 0; header.xpels_per_metre = header.ypels_per_metre = 0; header.num_colours_used = header.num_colours_important = 0; to_little_endian((io_int32 *) &header,10); if ((state->out = fopen(fname,"wb")) == NULL) return(IO_ERR_NO_FILE); fwrite(magic,1,14,state->out); fwrite(&header,1,40,state->out); if (num_components == 1) for (int n=0; n < 256; n++) { fputc(n,state->out); fputc(n,state->out); fputc(n,state->out); fputc(0,state->out); } return 0; } /*****************************************************************************/ /* bmp_out__close */ /*****************************************************************************/ void bmp_out__close(bmp_out *state) { if (state->out != NULL) fclose(state->out); memset(state,0,sizeof(bmp_out)); } /*****************************************************************************/ /* bmp_out__put_line */ /******************************************