BMP_Image *BMP_load(const char *filename)
{
// read the header from the file
FILE *input_file = fopen(filename,"rb");//use rb to read binary file
if (input_file == NULL)//check if it's opened
{
return NULL;
}
BMP_Header input_header;//input header file
if (fread(&input_header, sizeof(BMP_Header), 1, input_file) != 1)//check if the input file has been successfully read or not
{
fclose(input_file);
return NULL;
}
// print the header information (use BMP_printHeader)
BMP_printHeader(&input_header);//print the header information to the screen
// make sure the header is valid before proceeding (use BMP_checkValid)
if(BMP_checkValid(&input_header) != 1)//check if the header information is valid or not
{
return NULL;
}
// create the image structure (BMP_create)
BMP_Image *input_image = BMP_create(&input_header);//use BMP_create to create a output_image structure
// read all of the image data
if(fread(input_image -> data, sizeof(char), input_image -> data_size, input_file) != input_image -> data_size)//use fread to read all the image data
{
fclose(input_file);//if not successful, close the file
return NULL;
}
// return the image
fclose(input_file);
return input_image;
}
Image * Image_loadbmp(const char * filename)
{
FILE * fp = NULL;
size_t read;
BMP_Header header;
Image * tmp_im = NULL, * im = NULL;
size_t n_bytes = 0;
int err = FALSE;
if(!err) { // Open filename
fp = fopen(filename, "rb");
if(!fp) {
fprintf(stderr, "Failed to open file '%s'\n", filename);
err = TRUE;
}
}
if(!err) { // Read the header
read = fread(&header, sizeof(BMP_Header), 1, fp);
if(read != 1) {
fprintf(stderr, "Failed to read header from '%s'\n", filename);
err = TRUE;
}
}
if(!err) { // Print the header
BMP_printHeader(&header);
}
if(!err) { // We're only interested in a subset of valid bmp files
if(!BMP_checkValid(&header)) {
fprintf(stderr, "Invalid header in '%s'\n", filename);
err = TRUE;
}
}
if(!err) { // Allocate Image struct
tmp_im = malloc(sizeof(Image));
if(tmp_im == NULL) {
fprintf(stderr, "Failed to allocate im structure\n");
err = TRUE;
}
}
if(!err) { // Init the Image struct
tmp_im->width = header.width;
tmp_im->height = header.height;
// Handle the comment
char * filename_cpy = strdup(filename); // we want to call basename
char * file_basename = basename(filename_cpy); // requires editable str
const char * prefix = "Original BMP file: ";
n_bytes = sizeof(char) * (strlen(prefix) + strlen(file_basename) + 1);
tmp_im->comment = malloc(n_bytes);
if(tmp_im->comment == NULL) {
fprintf(stderr, "Failed to allocate %zd bytes for comment\n",
n_bytes);
err = TRUE;
} else {
sprintf(tmp_im->comment, "%s%s", prefix, file_basename);
}
free(filename_cpy); // this also takes care of file_basename
// Handle image data
n_bytes = sizeof(uint8_t) * header.width * header.height;
tmp_im->data = malloc(n_bytes);
if(tmp_im->data == NULL) {
fprintf(stderr, "Failed to allocate %zd bytes for image data\n",
n_bytes);
err = TRUE;
}
}
if(!err) { // Seek the start of the pixel data
if(fseek(fp, header.offset, SEEK_SET) != 0) {
fprintf(stderr, "Failed to seek %d, the data of the image data\n",
header.offset);
err = TRUE;
}
}
if(!err) { // Read pixel data
size_t bytes_per_row = ((header.bits * header.width + 31)/32) * 4;
n_bytes = bytes_per_row * header.height;
uint8_t * rawbmp = malloc(n_bytes);
if(rawbmp == NULL) {
fprintf(stderr, "Could not allocate %zd bytes of image data\n",
n_bytes);
err = TRUE;
} else {
read = fread(rawbmp, sizeof(uint8_t), n_bytes, fp);
if(n_bytes != read) {
fprintf(stderr, "Only read %zd of %zd bytes of image data\n",
read, n_bytes);
err = TRUE;
} else {
// Must convert RGB to grayscale
uint8_t * write_ptr = tmp_im->data;
uint8_t * read_ptr;
int intensity;
int row, col; // row and column
for(row = 0; row < header.height; ++row) {
read_ptr = &rawbmp[row * bytes_per_row];
for(col = 0; col < header.width; ++col) {
intensity = *read_ptr++; // blue
intensity += *read_ptr++; // green
intensity += *read_ptr++; // red
*write_ptr++ = intensity / 3; // now grayscale
}
}
}
}
free(rawbmp);
}
if(!err) { // We should be at the end of the file now
uint8_t byte;
read = fread(&byte, sizeof(uint8_t), 1, fp);
if(read != 0) {
fprintf(stderr, "Stray bytes at the end of bmp file '%s'\n",
filename);
err = TRUE;
}
}
if(!err) { // We're winners...
im = tmp_im; // bmp will be returned
tmp_im = NULL; // and not cleaned up
}
// Cleanup
if(tmp_im != NULL) {
free(tmp_im->comment); // Remember, you can always free(NULL)
free(tmp_im->data);
free(tmp_im);
}
if(fp) {
fclose(fp);
}
return im;
}
Image * Image_load(const char * filename)
{
FILE * fp = NULL;
ImageHeader header;
size_t read;
Image * tmp_im = NULL, * im = NULL;
int err = FALSE;
if(!err){
fp = fopen(filename, "rb");
if(!fp){
fprintf(stderr, "Failed to open file '%s'\n",filename);
err = TRUE;
}
}
if(!err){
read = fread(&header, sizeof(ImageHeader), 1, fp);
if(read != 1){
fprintf(stderr, "Failed to read header from '%s'\n", filename);
err = TRUE;
}
}
if(!err){
if(!BMP_checkValid(&header)) {
fprintf(stderr, "Invalid header in '%s'\n", filename);
err = TRUE;
}
}
if(!err){
tmp_im = malloc(sizeof(Image));
tmp_im->comment = NULL;
tmp_im->data = NULL;
if(tmp_im == NULL){
fprintf(stderr, "Failed to allocate im structure\n");
err = TRUE;
}
}
if(!err){
tmp_im->width = header.width;
tmp_im->height = header.height;
tmp_im->comment = malloc(sizeof(char*) *header.comment_len);
if(tmp_im->comment == NULL){
fprintf(stderr, "Fail to allocate comment\n");
err = TRUE;
}
}
if(!err){
read = fread(tmp_im->comment, sizeof(char), header.comment_len, fp);
if(read != header.comment_len || tmp_im->comment[header.comment_len-1] != '\0'){
fprintf(stderr, "Comment does not end with null byte\n");
err = TRUE;
}
}
if(!err){
tmp_im-> data = malloc(sizeof(uint8_t) * header.width * header.height);
if(tmp_im-> data == NULL){
fprintf(stderr, "Fail to allocate memory to data\n");
err = TRUE;
}
}
if(!err) {
read = fread(tmp_im-> data, sizeof(uint8_t), header.width * header.height,fp);
if(read != header.width * header.height){
fprintf(stderr, "could not read all image data\n");
err = TRUE;
}
}
if(!err){
if(fgetc(fp) != EOF){
fprintf(stderr, "Have not reach the end of file\n");
err = TRUE;
}
}
if(!err){
im = tmp_im;
tmp_im = NULL;
}
Image_free(tmp_im);
if(fp != NULL)
fclose(fp);
if(err)
return NULL;
else
return im;
}
