60 lines
2.1 KiB
C
60 lines
2.1 KiB
C
#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include "bmp.h"
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uint32_t calc_bitmap_pixel_array_size_bytes(bitmap *bitmap_in) {
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/* We will assume that the bitmap bits per pixel is always a multiple of 8 and sizeof byte is always 8 */
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uint32_t bytes_unpadded = (bitmap_in->image_width * bitmap_in->image_height * bitmap_in->bits_per_pixel) / 8;
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return bytes_unpadded + (bytes_unpadded % 8); /* Add padding to ensure 4 byte allignment */
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};
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uint32_t calc_bitmap_file_size_bytes(bitmap *bitmap_in) {
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/* We will assume that the bitmap bits per pixel is always a multiple of 8 and sizeof byte is always 8 */
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return sizeof(bitmap) + calc_bitmap_pixel_array_size_bytes(bitmap_in) - 2 ; /* Take away two to account for compiler padding struct */
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};
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bitmap init_bitmap(int32_t image_width_in, int32_t image_height_in) {
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bitmap new_bitmap;
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/* Bitmap Info Header */
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new_bitmap.info_header_size_bytes = 40;
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new_bitmap.image_width = image_width_in;
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new_bitmap.image_height = image_height_in;
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new_bitmap.color_planes_used = 1;
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new_bitmap.bits_per_pixel = 24;
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new_bitmap.compression_method = 0;
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new_bitmap.image_size = calc_bitmap_pixel_array_size_bytes(&new_bitmap);
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new_bitmap.horizontal_resolution_pixels_per_metre = 2835; /* Approx 72DPI */
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new_bitmap.vertical_resolution_pixels_per_metre = 2835;
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new_bitmap.colors_in_palette = 0;
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new_bitmap.important_colors = 0;
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/* File Header */
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new_bitmap.header_field[0] = 'B';
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new_bitmap.header_field[1] = 'M';
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new_bitmap.file_size_bytes = calc_bitmap_file_size_bytes(&new_bitmap);
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new_bitmap.reserved1 = 0;
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new_bitmap.reserved2 = 0;
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new_bitmap.image_data_start_offset = 54;
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return new_bitmap;
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};
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int write_to_bitmap(bitmap *bitmap_in, char *filename) {
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int8_t write_status;
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uint8_t *bitmap_in_byte_ptr = (uint8_t *)bitmap_in + 2; /* Offset by two to account for padding */
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int8_t fd = open(filename, O_WRONLY | O_CREAT);
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if (fd == -1)
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return -1;
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/* This is writing out of bounds (bitmap < bitmap_file_size), please fix */
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write_status = write(fd, bitmap_in_byte_ptr, calc_bitmap_file_size_bytes(bitmap_in));
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if (fd == -1) {
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close(fd);
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return -1;
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}
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close(fd);
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return 0;
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};
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