1 files changed, 48 insertions, 11 deletions

diff --git a/src/j2k_transcode.cc b/src/j2k_transcode.cc
index 664d18a3..4fc48042 100644
--- a/src/j2k_transcode.cc
+++ b/src/j2k_transcode.cc
@@ -57,16 +57,16 @@ using namespace dcp;
 
 
 shared_ptr<dcp::OpenJPEGImage>
-dcp::decompress_j2k (Data const& data, int reduce)
+dcp::decompress_j2k(Data const& data, int reduce, shared_ptr<OpenJPEGCancel> cancel)
 {
-	return dcp::decompress_j2k (data.data(), data.size(), reduce);
+	return dcp::decompress_j2k(data.data(), data.size(), reduce, cancel);
 }
 
 
 shared_ptr<dcp::OpenJPEGImage>
-dcp::decompress_j2k (shared_ptr<const Data> data, int reduce)
+dcp::decompress_j2k(shared_ptr<const Data> data, int reduce, shared_ptr<OpenJPEGCancel> cancel)
 {
-	return dcp::decompress_j2k (data->data(), data->size(), reduce);
+	return dcp::decompress_j2k (data->data(), data->size(), reduce, cancel);
 }
 
 
@@ -123,7 +123,7 @@ compress_error_callback (char const * msg, void *)
 
 
 shared_ptr<dcp::OpenJPEGImage>
-dcp::decompress_j2k (uint8_t const * data, int64_t size, int reduce)
+dcp::decompress_j2k(uint8_t const * data, int64_t size, int reduce, shared_ptr<OpenJPEGCancel> cancel)
 {
 	DCP_ASSERT (reduce >= 0);
 
@@ -152,6 +152,10 @@ dcp::decompress_j2k (uint8_t const * data, int64_t size, int reduce)
 	parameters.cp_reduce = reduce;
 	opj_setup_decoder (decoder, &parameters);
 
+	if (cancel) {
+		opj_set_cancel(decoder, cancel->opj_cancel());
+	}
+
 	auto stream = opj_stream_default_create (OPJ_TRUE);
 	if (!stream) {
 		throw MiscError ("could not create JPEG2000 stream");
@@ -166,19 +170,24 @@ dcp::decompress_j2k (uint8_t const * data, int64_t size, int reduce)
 
 	opj_image_t* image = 0;
 	opj_read_header (stream, decoder, &image);
-	if (opj_decode (decoder, stream, image) == OPJ_FALSE) {
-		opj_destroy_codec (decoder);
-		opj_stream_destroy (stream);
+	auto const result = opj_decode(decoder, stream, image);
+	opj_destroy_codec (decoder);
+	opj_stream_destroy (stream);
+
+	switch (result) {
+	case OPJ_FAILURE:
 		if (format == OPJ_CODEC_J2K) {
 			boost::throw_exception (ReadError (String::compose ("could not decode JPEG2000 codestream of %1 bytes.", size)));
 		} else {
 			boost::throw_exception (ReadError (String::compose ("could not decode JP2 file of %1 bytes.", size)));
 		}
+		break;
+	case OPJ_CANCEL:
+		boost::throw_exception(Cancelled{});
+	default:
+		break;
 	}
 
-	opj_destroy_codec (decoder);
-	opj_stream_destroy (stream);
-
 	image->x1 = rint (float(image->x1) / pow (2.0f, reduce));
 	image->y1 = rint (float(image->y1) / pow (2.0f, reduce));
 	return std::make_shared<OpenJPEGImage>(image);
@@ -332,3 +341,31 @@ dcp::compress_j2k (shared_ptr<const OpenJPEGImage> xyz, int bandwidth, int frame
 	return enc;
 }
 
+
+OpenJPEGCancel::OpenJPEGCancel()
+{
+	_cancel = opj_create_cancel();
+}
+
+
+OpenJPEGCancel::~OpenJPEGCancel()
+{
+	opj_destroy_cancel(_cancel);
+}
+
+
+void
+OpenJPEGCancel::cancel()
+{
+	::opj_cancel(_cancel);
+}
+
+
+void
+OpenJPEGCancel::reset()
+{
+	::opj_reset(_cancel);
+}
+
+
+