rulimine/stage23/lib/bmp.c

97 lines
2.5 KiB
C

#include <stdint.h>
#include <fs/file.h>
#include <lib/image.h>
#include <lib/bmp.h>
#include <lib/libc.h>
#include <lib/blib.h>
#include <mm/pmm.h>
struct bmp_header {
uint16_t bf_signature;
uint32_t bf_size;
uint32_t reserved;
uint32_t bf_offset;
uint32_t bi_size;
uint32_t bi_width;
uint32_t bi_height;
uint16_t bi_planes;
uint16_t bi_bpp;
uint32_t bi_compression;
uint32_t bi_image_size;
uint32_t bi_xcount;
uint32_t bi_ycount;
uint32_t bi_clr_used;
uint32_t bi_clr_important;
uint32_t red_mask;
uint32_t green_mask;
uint32_t blue_mask;
} __attribute__((packed));
struct bmp_local {
uint8_t *image;
uint32_t pitch;
struct bmp_header header;
};
static uint32_t get_pixel(struct image *this, int x, int y) {
struct bmp_local *local = this->local;
struct bmp_header *header = &local->header;
switch (this->type) {
case IMAGE_TILED: {
x %= header->bi_width;
y %= header->bi_height;
break;
}
case IMAGE_CENTERED: {
x -= this->x_displacement;
y -= this->y_displacement;
if (x < 0 || y < 0 || x >= this->x_size || y >= this->y_size)
return this->back_colour;
break;
}
case IMAGE_STRETCHED: {
x = (x * this->old_x_size) / this->x_size;
y = (y * this->old_y_size) / this->y_size;
break;
}
}
size_t pixel_offset = local->pitch * (header->bi_height - y - 1) + x * (header->bi_bpp / 8);
// TODO: Perhaps use masks here, they're there for a reason
uint32_t composite = 0;
for (int i = 0; i < header->bi_bpp / 8; i++)
composite |= (uint32_t)local->image[pixel_offset + i] << (i * 8);
return composite;
}
int bmp_open_image(struct image *image, struct file_handle *file) {
struct bmp_header header;
fread(file, &header, 0, sizeof(struct bmp_header));
if (memcmp(&header.bf_signature, "BM", 2) != 0)
return -1;
// We don't support bpp lower than 8
if (header.bi_bpp < 8)
return -1;
struct bmp_local *local = ext_mem_alloc(sizeof(struct bmp_local));
local->image = ext_mem_alloc(header.bf_size);
fread(file, local->image, header.bf_offset, header.bf_size);
local->pitch = ALIGN_UP(header.bi_width * header.bi_bpp, 32) / 8;
local->header = header;
image->x_size = header.bi_width;
image->y_size = header.bi_height;
image->get_pixel = get_pixel;
image->local = local;
return 0;
}