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xrdp-proprietary/xorg/tests/xdemo/bmp_parser.c

205 lines
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#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdint.h>
#include "common.h"
// multi byte values are stored in little endian
struct bmp_magic
{
char magic[2];
};
struct bmp_hdr
{
uint32_t size; // file size in bytes
uint16_t reserved1;
uint16_t reserved2;
uint32_t offset; // offset to image data, in bytes
};
struct dib_hdr
{
uint32_t hdr_size;
int32_t width;
int32_t height;
uint16_t nplanes;
uint16_t bpp;
uint32_t compress_type;
uint32_t image_size;
int32_t hres;
int32_t vres;
uint32_t ncolors;
uint32_t nimpcolors;
};
// forward declarations
int parse_bmp(char *filename, struct pic_info *pic_info);
int parse_bmp_24(struct bmp_hdr *bmp_hdr, struct dib_hdr *dib_hdr, int fd, struct pic_info *pic_info);
int parse_bmp(char *filename, struct pic_info *pic_info)
{
int got_magic;
int fd;
int rval;
struct bmp_magic magic;
struct bmp_hdr bmp_hdr;
struct dib_hdr dib_hdr;
if ((fd = open(filename, O_RDONLY)) < 0) {
printf("error opeing %s\n", filename);
return -1;
}
// read BMP magic...
if ((rval = read(fd, magic.magic, 2)) != 2) {
fprintf(stderr, "error reading BMP signature from file %s\n", filename);
return -1;
}
got_magic = 0;
// ...and confirm that this is indeed a BMP file
if ((magic.magic[0] == 'B') && (magic.magic[1] == 'M')) {
// BM Windows 3.1x, 95, NT, ... etc
got_magic = 1;
}
else if ((magic.magic[0] == 'B') && (magic.magic[1] == 'A')) {
// BA OS/2 struct Bitmap Array
got_magic = 1;
}
else if ((magic.magic[0] == 'C') && (magic.magic[1] == 'I')) {
// CI OS/2 struct Color Icon
got_magic = 1;
}
else if ((magic.magic[0] == 'C') && (magic.magic[1] == 'P')) {
// CP OS/2 const Color Pointer
got_magic = 1;
}
else if ((magic.magic[0] == 'I') && (magic.magic[1] == 'C')) {
// IC OS/2 struct Icon
got_magic = 1;
}
else if ((magic.magic[0] == 'P') && (magic.magic[1] == 'T')) {
// PT OS/2 Pointer
got_magic = 1;
}
if (!got_magic) {
fprintf(stderr, "%s is not a valid BMP file\n", filename);
return -1;
}
// read BMP header
if ((rval = read(fd, &bmp_hdr, sizeof(bmp_hdr))) < sizeof(bmp_hdr)) {
fprintf(stderr, "error BMP header from file %s\n", filename);
return -1;
}
// read DIB header
if ((rval = read(fd, &dib_hdr, sizeof(dib_hdr))) < sizeof(dib_hdr)) {
fprintf(stderr, "error reading DIB header from file %s\n", filename);
return -1;
}
#if 0
printf("header size: %d\n", dib_hdr.hdr_size);
printf("width: %d\n", dib_hdr.width);
printf("height: %d\n", dib_hdr.height);
printf("num planes: %d\n", dib_hdr.nplanes);
printf("bpp: %d\n", dib_hdr.bpp);
printf("comp type: %d\n", dib_hdr.compress_type);
printf("image size: %d\n", dib_hdr.image_size);
printf("hres: %d\n", dib_hdr.hres);
printf("vres: %d\n", dib_hdr.vres);
printf("ncolors: %d\n", dib_hdr.ncolors);
printf("nimpcolors: %d\n", dib_hdr.nimpcolors);
#endif
if (dib_hdr.compress_type) {
printf("TODO: compressed images not yet supported\n");
return -1;
}
pic_info->width = dib_hdr.width;
pic_info->height = dib_hdr.height;
if (dib_hdr.bpp == 24) {
rval = parse_bmp_24(&bmp_hdr, &dib_hdr, fd, pic_info);
}
close(fd);
return rval;
}
/**
* extract 24bit BMP data from image file
*
* @return 0 on success
* @return -1 on failure
*/
int parse_bmp_24(
struct bmp_hdr *bmp_hdr,
struct dib_hdr *dib_hdr,
int fd,
struct pic_info *pic_info
)
{
char *file_data;
char *ptr_file_data;
char *mem_data;
char *ptr_mem_data;
char *cptr;
int w = dib_hdr->width; // picture width
int h = dib_hdr->height; // picture height
int bpl; // bytes per line
int bytes;
int i;
int j;
// bytes per image line = width x bytes_per_pixel + padding
i = (w * 3) % 4;
j = (i == 0) ? 0 : 4 - i;
bpl = w * 3 + j;
// 24 bit depth, no alpha channel
file_data = (char *) malloc(h * bpl);
// point to first line in image data, which is stored in reverse order
ptr_file_data = (file_data + dib_hdr->image_size) - bpl;
// 24 bit depth, with alpha channel
mem_data = (char *) malloc(w * h * 4);
ptr_mem_data = mem_data;
pic_info->pixel_data = ptr_mem_data;
// seek to beginning of pixel data
lseek(fd, bmp_hdr->offset, SEEK_SET);
// read all pixel data
bytes = read(fd, file_data, dib_hdr->image_size);
// convert 24bit to 24 bit with alpha and store in reverse
for (i = 0; i < h; i ++)
{
cptr = ptr_file_data;
for (j = 0; j < w; j++)
{
*ptr_mem_data++ = *cptr++; // blue value
*ptr_mem_data++ = *cptr++; // green value
*ptr_mem_data++ = *cptr++; // red value
*ptr_mem_data++ = 0; // alpha channel
}
ptr_file_data -= bpl;
}
free(file_data);
return 0;
}