BlobReader.js

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

var Guacamole = Guacamole || {};

/**
 * A reader which automatically handles the given input stream, assembling all
 * received blobs into a single blob by appending them to each other in order.
 * Note that this object will overwrite any installed event handlers on the
 * given Guacamole.InputStream.
 * 
 * @constructor
 * @param {!Guacamole.InputStream} stream
 *     The stream that data will be read from.
 *
 * @param {!string} mimetype
 *     The mimetype of the blob being built.
 */
Guacamole.BlobReader = function(stream, mimetype) {

    /**
     * Reference to this Guacamole.InputStream.
     *
     * @private
     * @type {!Guacamole.BlobReader}
     */
    var guac_reader = this;

    /**
     * The length of this Guacamole.InputStream in bytes.
     *
     * @private
     * @type {!number}
     */
    var length = 0;

    // Get blob builder
    var blob_builder;
    if      (window.BlobBuilder)       blob_builder = new BlobBuilder();
    else if (window.WebKitBlobBuilder) blob_builder = new WebKitBlobBuilder();
    else if (window.MozBlobBuilder)    blob_builder = new MozBlobBuilder();
    else
        blob_builder = new (function() {

            var blobs = [];

            /** @ignore */
            this.append = function(data) {
                blobs.push(new Blob([data], {"type": mimetype}));
            };

            /** @ignore */
            this.getBlob = function() {
                return new Blob(blobs, {"type": mimetype});
            };

        })();

    // Append received blobs
    stream.onblob = function(data) {

        // Convert to ArrayBuffer
        var binary = window.atob(data);
        var arrayBuffer = new ArrayBuffer(binary.length);
        var bufferView = new Uint8Array(arrayBuffer);

        for (var i=0; i<binary.length; i++)
            bufferView[i] = binary.charCodeAt(i);

        blob_builder.append(arrayBuffer);
        length += arrayBuffer.byteLength;

        // Call handler, if present
        if (guac_reader.onprogress)
            guac_reader.onprogress(arrayBuffer.byteLength);

        // Send success response
        stream.sendAck("OK", 0x0000);

    };

    // Simply call onend when end received
    stream.onend = function() {
        if (guac_reader.onend)
            guac_reader.onend();
    };

    /**
     * Returns the current length of this Guacamole.InputStream, in bytes.
     *
     * @return {!number}
     *     The current length of this Guacamole.InputStream.
     */
    this.getLength = function() {
        return length;
    };

    /**
     * Returns the contents of this Guacamole.BlobReader as a Blob.
     *
     * @return {!Blob}
     *     The contents of this Guacamole.BlobReader.
     */
    this.getBlob = function() {
        return blob_builder.getBlob();
    };

    /**
     * Fired once for every blob of data received.
     * 
     * @event
     * @param {!number} length
     *     The number of bytes received.
     */
    this.onprogress = null;

    /**
     * Fired once this stream is finished and no further data will be written.
     * @event
     */
    this.onend = null;

};