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src/Source/FreeImage/PluginJ2K.cpp  view on Meta::CPAN

static const char * DLL_CALLCONV
MimeType() {
	return "image/j2k";
}

static BOOL DLL_CALLCONV
Validate(FreeImageIO *io, fi_handle handle) {
	BYTE jpc_signature[] = { 0xFF, 0x4F };
	BYTE signature[2] = { 0, 0 };

	long tell = io->tell_proc(handle);
	io->read_proc(signature, 1, sizeof(jpc_signature), handle);
	io->seek_proc(handle, tell, SEEK_SET);

	return (memcmp(jpc_signature, signature, sizeof(jpc_signature)) == 0);
}

static BOOL DLL_CALLCONV
SupportsExportDepth(int depth) {
	return (
		(depth == 8) ||
		(depth == 24) || 
		(depth == 32)
	);
}

static BOOL DLL_CALLCONV 
SupportsExportType(FREE_IMAGE_TYPE type) {
	return (
		(type == FIT_BITMAP)  ||
		(type == FIT_UINT16)  ||
		(type == FIT_RGB16) || 
		(type == FIT_RGBA16)
	);
}

// ----------------------------------------------------------

static void * DLL_CALLCONV
Open(FreeImageIO *io, fi_handle handle, BOOL read) {
	// create the stream wrapper
	J2KFIO_t *fio = opj_freeimage_stream_create(io, handle, read);
	return fio;
}

static void DLL_CALLCONV
Close(FreeImageIO *io, fi_handle handle, void *data) {
	// destroy the stream wrapper
	J2KFIO_t *fio = (J2KFIO_t*)data;
	opj_freeimage_stream_destroy(fio);
}

// ----------------------------------------------------------

static FIBITMAP * DLL_CALLCONV
Load(FreeImageIO *io, fi_handle handle, int page, int flags, void *data) {
	J2KFIO_t *fio = (J2KFIO_t*)data;
	if (handle && fio) {
		opj_codec_t *d_codec = NULL;	// handle to a decompressor
		opj_dparameters_t parameters;	// decompression parameters
		opj_image_t *image = NULL;		// decoded image 

		FIBITMAP *dib = NULL;

		// check the file format
		if(!Validate(io, handle)) {
			return NULL;
		}

		BOOL header_only = (flags & FIF_LOAD_NOPIXELS) == FIF_LOAD_NOPIXELS;

		// get the OpenJPEG stream
		opj_stream_t *d_stream = fio->stream;

		// set decoding parameters to default values 
		opj_set_default_decoder_parameters(&parameters);

		try {
			// decode the JPEG-2000 codestream

			// get a decoder handle
			d_codec = opj_create_decompress(OPJ_CODEC_J2K);
			
			// configure the event callbacks
			// catch events using our callbacks (no local context needed here)
			opj_set_info_handler(d_codec, NULL, NULL);
			opj_set_warning_handler(d_codec, j2k_warning_callback, NULL);
			opj_set_error_handler(d_codec, j2k_error_callback, NULL);

			// setup the decoder decoding parameters using user parameters
			if( !opj_setup_decoder(d_codec, &parameters) ) {
				throw "Failed to setup the decoder\n";
			}
			
			// read the main header of the codestream and if necessary the JP2 boxes
			if( !opj_read_header(d_stream, d_codec, &image)) {
				throw "Failed to read the header\n";
			}

			// --- header only mode

			if (header_only) {
				// create output image 
				dib = J2KImageToFIBITMAP(s_format_id, image, header_only);
				if(!dib) {
					throw "Failed to import JPEG2000 image";
				}
				// clean-up and return header data
				opj_destroy_codec(d_codec);
				opj_image_destroy(image);
				return dib;
			}

			// decode the stream and fill the image structure 
			if( !( opj_decode(d_codec, d_stream, image) && opj_end_decompress(d_codec, d_stream) ) ) {
				throw "Failed to decode image!\n";
			}

			// free the codec context
			opj_destroy_codec(d_codec);
			d_codec = NULL;