GUACAMOLE-377: Use ImageDecoder to decode images while they are being received (if possible).

guacamole-common-js/src/main/webapp/modules/InputStream.js

@@ -76,4 +76,66 @@ Guacamole.InputStream = function(client, index) {
         client.sendAck(guac_stream.index, message, code);
     };
 
+    /**
+     * Creates a new ReadableStream that receives the data sent to this stream
+     * by the Guacamole server. This function may be invoked at most once per
+     * stream, and invoking this function will overwrite any installed event
+     * handlers on this stream.
+     * 
+     * A ReadableStream is a JavaScript object defined by the "Streams"
+     * standard. It is supported by most browsers, but not necessarily all
+     * browsers. The caller should verify this support is present before
+     * invoking this function. The behavior of this function when the browser
+     * does not support ReadableStream is not defined.
+     *
+     * @see {@link https://streams.spec.whatwg.org/#rs-class}
+     *
+     * @returns {!ReadableStream}
+     *     A new ReadableStream that receives the bytes sent along this stream
+     *     by the Guacamole server.
+     */
+    this.toReadableStream = function toReadableStream() {
+        return new ReadableStream({
+            type: 'bytes',
+            start: function startStream(controller) {
+
+                var reader = new Guacamole.ArrayBufferReader(guac_stream);
+
+                // Provide any received blocks of data to the ReadableStream
+                // controller, such that they will be read by whatever is
+                // consuming the ReadableStream
+                reader.ondata = function dataReceived(data) {
+
+                    if (controller.byobRequest) {
+
+                        var view = controller.byobRequest.view;
+                        var length = Math.min(view.byteLength, data.byteLength);
+                        var byobBlock = new Uint8Array(data, 0, length);
+
+                        view.buffer.set(byobBlock);
+                        controller.byobRequest.respond(length);
+
+                        if (length < data.byteLength) {
+                            controller.enqueue(data.slice(length));
+                        }
+
+                    }
+
+                    else {
+                        controller.enqueue(new Uint8Array(data));
+                    }
+
+                };
+
+                // Notify the ReadableStream when the end of the stream is
+                // reached
+                reader.onend = function dataComplete() {
+                    controller.close();
+                };
+
+            }
+        });
+
+    };
+
 };