openEventsPlatformApp/plugins/cordova-plugin-file/www/blackberry10/truncate.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.
 *
*/

/* 
 * truncate
 * 
 * IN:
 *  args
 *   0 - URL of file to truncate
 *   1 - start position
 * OUT:
 *  success - new length of file
 *  fail - FileError
 */

var resolve = cordova.require('cordova-plugin-file.resolveLocalFileSystemURIProxy'),
    requestAnimationFrame = cordova.require('cordova-plugin-file.bb10RequestAnimationFrame');

module.exports = function (success, fail, args) {
    var uri = args[0],
        length = args[1],
        onSuccess = function (data) {
            if (typeof success === 'function') {
                success(data.loaded);
            }
        },
        onFail = function (error) {
            if (typeof fail === 'function') {
                if (error && error.code) {
                    fail(error.code);
                } else {
                    fail(error);
                }
            }
        };
    resolve(function (fs) {
        requestAnimationFrame(function () {
            fs.nativeEntry.file(function (file) {
                var reader = new FileReader()._realReader;
                reader.onloadend = function () {
                    var contents = new Uint8Array(this.result).subarray(0, length),
                        blob = new Blob([contents]);
                    window.requestAnimationFrame(function () {
                        fs.nativeEntry.createWriter(function (fileWriter) {
                            fileWriter.onwriteend = onSuccess;
                            fileWriter.onerror = onFail;
                            fileWriter.write(blob);
                        }, onFail);
                    });
                };
                reader.onerror = onFail;
                reader.readAsArrayBuffer(file);
            }, onFail);
        });
    }, onFail, [uri]);
};