FREE_IMAGE_FORMAT FreeImage_GetFileType(const char *filename, int size);

Investigates the given bitmap and returns the type of it using an abstract i/o structure and a fi_handle.

FREE_IMAGE_FORMAT format;
format = FreeImage_GetFileType("test.bmp", 16);

FREE_IMAGE_FORMAT FreeImage_GetFileTypeFromHandle(FreeImageIO *io, fi_handle handle, int size);

Investigates the given bitmap and returns the type of it. FreeImage_GetFileType can return the following values:

Type	Bitmap
FIF_BMP	Windows/OS/2 Bitmap
FIF_ICO	Windows Icon
FIF_JPEG	JPEG/JIF
FIF_KOALA	C64 KOALA
FIF_PBM	Portable Bitmap
FIF_PCD	Kodak PhotoCD
FIF_PCX	PCX
FIF_PGM	Portable Greymap
FIF_PNG	Portable Network Graphics
FIF_PPM	Portable Pixmap
FIF_RAS	Sun Rasterfile
FIF_TARGA	Targa
FIF_TIFF	TIFF

unsigned
_ReadProc(void *buffer, unsigned s, unsigned c, fi_handle handle) {
return fread(buffer, s, c, (FILE *)handle);
}

unsigned
_WriteProc(void *buffer, unsigned s, unsigned c, fi_handle handle){
return fwrite(buffer, s, c, (FILE *)handle);
}

int
_SeekProc(fi_handle handle, long offset, int origin) {
return fseek((FILE *)handle, offset, origin);
}

long
_TellProc(fi_handle handle) {
return ftell((FILE *)handle);
}

FreeImageIO io;
io.read_proc = _ReadProc;
io.write_proc = _WriteProc;
io.seek_proc = _SeekProc;
io.tell_proc = _TellProc;

FILE *file = fopen("test.bmp", "rb");

FREE_IMAGE_TYPE type;
type = FreeImage_GetFileTypeFromHandle(&io, (fi_handle)file, 16);

FREE_IMAGE_FORMAT FreeImage_GetFileTypeFromExt(const char *ext);

Investigates the given file extension and returns the corresponding format. For example "bmp" would return FIF_BMP.

FREE_IMAGE_FORMAT format;
format = FreeImage_GetFileTypeFromExt("bmp");