115 lines
3.9 KiB
C
115 lines
3.9 KiB
C
#include "bmp.h"
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#include <stdio.h>
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#include <stdlib.h>
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#define HEADER_SIZE 54
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void write_str(unsigned char *buffer, unsigned int offset, unsigned int size,
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unsigned char *value) {
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unsigned int i;
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for (i = 0; i < size; i++) {
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buffer[offset + i] = (unsigned char)value[i];
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}
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}
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void write_num(unsigned char *buffer, unsigned int offset, unsigned int size,
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unsigned int value) {
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unsigned int i;
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for (i = 0; i < size; i++) {
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buffer[offset + i] = (unsigned char)((value >> (8 * i)) & 0xFFu);
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}
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}
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void write_nul(unsigned char *buffer, unsigned int offset, unsigned int size) {
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unsigned int i;
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for (i = 0; i < size; i++) {
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buffer[offset + i] = 0;
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}
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}
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unsigned char *bmp_header(unsigned short width, unsigned short height,
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unsigned char color_depth) {
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unsigned char *output = (unsigned char *)malloc(HEADER_SIZE);
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unsigned int data_length = ((unsigned int)width) * ((unsigned int)height) *
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((unsigned int)color_depth);
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// 0x00(2) BM
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write_str(output, 0x00, 0x02, (unsigned char *)"BM");
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// 0x02(4) file size
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write_num(output, 0x02, 0x04, HEADER_SIZE + data_length);
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// 0x06(4) application reserved
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write_nul(output, 0x06, 0x04);
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// 0x0A(4) data offset
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write_num(output, 0x0A, 0x04, HEADER_SIZE);
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// 0x0E(4) DIB header size
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write_num(output, 0x0E, 0x04, 40);
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// 0x12(4) width
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write_num(output, 0x12, 0x04, width);
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// 0x16(4) height
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write_num(output, 0x16, 0x04, height);
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// 0x1A(2) color panes
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write_num(output, 0x1A, 0x04, 1);
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// 0x1C(2) bits per pixel
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write_num(output, 0x1C, 0x02, color_depth * 8);
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// 0x1E(4) BI_RGB, no compression
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write_nul(output, 0x1E, 0x04);
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// 0x22(4) size of raw bitmap data
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write_num(output, 0x22, 0x04, data_length);
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// 0x26(4) horizontal print resolution
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write_num(output, 0x26, 0x04, 2835);
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// 0x2A(4) vertical print resolution
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write_num(output, 0x2A, 0x04, 2835);
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// 0x2E(4) color in palette (0)
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write_nul(output, 0x2E, 0x04);
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// 0x32(4) important colors (0)
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write_nul(output, 0x32, 0x04);
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return output;
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}
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unsigned int bmp_data_line_length(unsigned short width,
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unsigned char color_depth) {
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unsigned int data_length =
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((unsigned int)width) * ((unsigned int)color_depth);
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unsigned int line_offset = data_length % 4;
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unsigned short line_padding = line_offset > 0 ? 4 - line_offset : 0;
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return data_length + line_padding;
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}
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void bmp_data_line(unsigned char *buffer, unsigned short width,
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unsigned char color_depth, unsigned char *data) {
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unsigned int data_length =
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((unsigned int)width) * ((unsigned int)color_depth);
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unsigned int line_offset = data_length % 4;
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unsigned short line_padding = line_offset > 0 ? 4 - line_offset : 0;
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write_str(buffer, 0, data_length, data);
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if (line_padding > 0) {
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write_nul(buffer, width * color_depth, line_padding);
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}
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}
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void bmp_generate(unsigned short width, unsigned short height,
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unsigned char color_depth, bool descending, char *file_path,
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line_fn generate_line) {
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FILE *fptr;
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fptr = fopen(file_path, "w");
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unsigned char *header = bmp_header(width, height, color_depth);
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fwrite(header, HEADER_SIZE, 1, fptr);
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free(header);
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unsigned int data_length =
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((unsigned int)width) * ((unsigned int)color_depth);
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unsigned int line_length = bmp_data_line_length(width, color_depth);
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unsigned char *data_buffer = (unsigned char *)malloc(data_length);
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unsigned char *line_buffer = (unsigned char *)malloc(line_length);
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unsigned short y;
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for (y = 0; y < height; y++) {
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generate_line(y, data_buffer, data_length);
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bmp_data_line(line_buffer, width, color_depth, data_buffer);
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if (descending) {
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fseek(fptr, HEADER_SIZE + (height - y - 1) * line_length, SEEK_SET);
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}
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fwrite(line_buffer, line_length, 1, fptr);
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}
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free(line_buffer);
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free(data_buffer);
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fclose(fptr);
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} |