nicholas@1: /**
nicholas@1:  * core.js
nicholas@1:  * 
nicholas@1:  * Main script to run, calls all other core functions and manages loading/store to backend.
nicholas@1:  * Also contains all global variables.
nicholas@1:  */
nicholas@1: 
nicholas@1: /* create the web audio API context and store in audioContext*/
nicholas@1: var audioContext;
nicholas@2: var projectXML;
nicholas@1: var audioEngineContext;
nicholas@7: var projectReturn;
n@23: var preTestQuestions = document.createElement('PreTest');
n@23: var postTestQuestions = document.createElement('PostTest');
nicholas@1: 
nicholas@1: window.onload = function() {
nicholas@1: 	// Function called once the browser has loaded all files.
nicholas@1: 	// This should perform any initial commands such as structure / loading documents
nicholas@1: 	
nicholas@1: 	// Create a web audio API context
nicholas@21: 	// Fixed for cross-browser support
nicholas@21: 	var AudioContext = window.AudioContext || window.webkitAudioContext;
nicholas@7: 	audioContext = new AudioContext;
nicholas@1: 	
nicholas@1: 	// Create the audio engine object
nicholas@1: 	audioEngineContext = new AudioEngine();
n@16: };
nicholas@1: 
nicholas@1: function loadProjectSpec(url) {
nicholas@1: 	// Load the project document from the given URL, decode the XML and instruct audioEngine to get audio data
nicholas@1: 	// If url is null, request client to upload project XML document
nicholas@2: 	var r = new XMLHttpRequest();
nicholas@2: 	r.open('GET',url,true);
nicholas@2: 	r.onload = function() {
nicholas@2: 		loadProjectSpecCallback(r.response);
n@16: 	};
nicholas@2: 	r.send();
n@16: };
nicholas@2: 
nicholas@2: function loadProjectSpecCallback(response) {
nicholas@2: 	// Function called after asynchronous download of XML project specification
nicholas@2: 	var decode = $.parseXML(response);
nicholas@2: 	projectXML = $(decode);
nicholas@2: 	
nicholas@2: 	// Now extract the setup tag
nicholas@2: 	var xmlSetup = projectXML.find('setup');
n@16: 	// Detect the interface to use and load the relevant javascripts.
nicholas@2: 	var interfaceType = xmlSetup[0].attributes['interface'];
nicholas@2: 	var interfaceJS = document.createElement('script');
nicholas@2: 	interfaceJS.setAttribute("type","text/javascript");
nicholas@2: 	if (interfaceType.value == 'APE') {
nicholas@2: 		interfaceJS.setAttribute("src","ape.js");
nicholas@2: 	}
nicholas@2: 	document.getElementsByTagName("head")[0].appendChild(interfaceJS);
nicholas@1: }
nicholas@1: 
nicholas@1: function createProjectSave(destURL) {
nicholas@1: 	// Save the data from interface into XML and send to destURL
nicholas@1: 	// If destURL is null then download XML in client
nicholas@7: 	// Now time to render file locally
nicholas@7: 	var xmlDoc = interfaceXMLSave();
nicholas@7: 	if (destURL == "null" || destURL == undefined) {
nicholas@7: 		var parent = document.createElement("div");
nicholas@7: 		parent.appendChild(xmlDoc);
nicholas@7: 		var file = [parent.innerHTML];
nicholas@7: 		var bb = new Blob(file,{type : 'application/xml'});
nicholas@7: 		var dnlk = window.URL.createObjectURL(bb);
nicholas@7: 		var a = document.createElement("a");
nicholas@7: 		a.hidden = '';
nicholas@7: 		a.href = dnlk;
nicholas@7: 		a.download = "save.xml";
nicholas@7: 		a.textContent = "Save File";
nicholas@7: 		
nicholas@7: 		var submitDiv = document.getElementById('download-point');
nicholas@7: 		submitDiv.appendChild(a);
nicholas@7: 	}
nicholas@1: }
nicholas@1: 
nicholas@1: function AudioEngine() {
nicholas@1: 	
nicholas@1: 	// Create two output paths, the main outputGain and fooGain.
nicholas@1: 	// Output gain is default to 1 and any items for playback route here
nicholas@1: 	// Foo gain is used for analysis to ensure paths get processed, but are not heard
nicholas@1: 	// because web audio will optimise and any route which does not go to the destination gets ignored.
nicholas@1: 	this.outputGain = audioContext.createGain();
nicholas@1: 	this.fooGain = audioContext.createGain();
nicholas@1: 	this.fooGain.gain = 0;
nicholas@1: 	
nicholas@7: 	// Use this to detect playback state: 0 - stopped, 1 - playing
nicholas@7: 	this.status = 0;
nicholas@7: 	
nicholas@1: 	// Connect both gains to output
nicholas@1: 	this.outputGain.connect(audioContext.destination);
nicholas@1: 	this.fooGain.connect(audioContext.destination);
nicholas@1: 	
nicholas@1: 	// Create store for new audioObjects
nicholas@1: 	this.audioObjects = [];
nicholas@1: 	
nicholas@1: 	this.play = function() {
nicholas@1: 		// Send play command to all playback buffers for synchronised start
nicholas@1: 		// Also start timer callbacks to detect if playback has finished
nicholas@7: 		if (this.status == 0) {
nicholas@7: 			// First get current clock
nicholas@7: 			var timer = audioContext.currentTime;
nicholas@7: 			// Add 3 seconds
nicholas@7: 			timer += 3.0;
nicholas@7: 			
nicholas@7: 			// Send play to all tracks
nicholas@7: 			for (var i=0; i<this.audioObjects.length; i++)
nicholas@7: 			{
nicholas@7: 				this.audioObjects[i].play(timer);
nicholas@7: 			}
nicholas@7: 			this.status = 1;
nicholas@7: 		}
n@16: 	};
nicholas@1: 	
nicholas@1: 	this.stop = function() {
nicholas@1: 		// Send stop and reset command to all playback buffers
nicholas@7: 		if (this.status == 1) {
nicholas@7: 			for (var i=0; i<this.audioObjects.length; i++)
nicholas@7: 			{
nicholas@7: 				this.audioObjects[i].stop();
nicholas@7: 			}
nicholas@7: 			this.status = 0;
nicholas@7: 		}
n@16: 	};
nicholas@1: 	
nicholas@8: 	this.selectedTrack = function(id) {
nicholas@8: 		for (var i=0; i<this.audioObjects.length; i++)
nicholas@8: 		{
nicholas@8: 			if (id == i) {
nicholas@8: 				this.audioObjects[i].outputGain.gain.value = 1.0;
nicholas@8: 			} else {
nicholas@8: 				this.audioObjects[i].outputGain.gain.value = 0.0;
nicholas@8: 			}
nicholas@8: 		}
n@16: 	};
nicholas@8: 	
nicholas@8: 	
nicholas@1: 	this.newTrack = function(url) {
nicholas@1: 		// Pull data from given URL into new audio buffer
nicholas@1: 		// URLs must either be from the same source OR be setup to 'Access-Control-Allow-Origin'
nicholas@7: 		
nicholas@1: 		// Create the audioObject with ID of the new track length;
nicholas@1: 		audioObjectId = this.audioObjects.length
nicholas@1: 		this.audioObjects[audioObjectId] = new audioObject(audioObjectId);
nicholas@7: 
nicholas@7: 		// AudioObject will get track itself.
nicholas@7: 		this.audioObjects[audioObjectId].constructTrack(url);
n@16: 	};
nicholas@1: 	
nicholas@1: }
nicholas@1: 
nicholas@1: function audioObject(id) {
nicholas@1: 	// The main buffer object with common control nodes to the AudioEngine
nicholas@1: 	
nicholas@1: 	this.id = id;
nicholas@1: 	this.state = 0; // 0 - no data, 1 - ready
nicholas@1: 	
nicholas@1: 	// Create a buffer and external gain control to allow internal patching of effects and volume leveling.
nicholas@1: 	this.bufferNode = audioContext.createBufferSource();
nicholas@1: 	this.outputGain = audioContext.createGain();
nicholas@1: 	
nicholas@8: 	// Default output gain to be zero
nicholas@8: 	this.outputGain.gain.value = 0.0;
nicholas@8: 	
nicholas@1: 	// Connect buffer to the audio graph
nicholas@1: 	this.bufferNode.connect(this.outputGain);
nicholas@1: 	this.outputGain.connect(audioEngineContext.outputGain);
nicholas@1: 	
nicholas@1: 	// the audiobuffer is not designed for multi-start playback
nicholas@1: 	// When stopeed, the buffer node is deleted and recreated with the stored buffer.
nicholas@1: 	this.buffer;
nicholas@1: 	
nicholas@1: 	this.play = function(startTime) {
nicholas@1: 		this.bufferNode.start(startTime);
n@16: 	};
nicholas@1: 	
nicholas@1: 	this.stop = function() {
nicholas@1: 		this.bufferNode.stop(0);
nicholas@1: 		this.bufferNode = audioContext.createBufferSource();
nicholas@1: 		this.bufferNode.connect(this.outputGain);
nicholas@1: 		this.bufferNode.buffer = this.buffer;
nicholas@7: 		this.bufferNode.loop = true;
n@16: 	};
nicholas@8: 
nicholas@7: 	this.constructTrack = function(url) {
nicholas@7: 		var request = new XMLHttpRequest();
nicholas@7: 		request.open('GET',url,true);
nicholas@7: 		request.responseType = 'arraybuffer';
nicholas@7: 		
nicholas@7: 		var audioObj = this;
nicholas@7: 		
nicholas@7: 		// Create callback to decode the data asynchronously
nicholas@7: 		request.onloadend = function() {
nicholas@7: 			audioContext.decodeAudioData(request.response, function(decodedData) {
nicholas@7: 				audioObj.buffer = decodedData;
nicholas@7: 				audioObj.bufferNode.buffer = audioObj.buffer;
nicholas@7: 				audioObj.bufferNode.loop = true;
nicholas@7: 				audioObj.state = 1;
nicholas@7: 			}, function(){
nicholas@7: 				// Should only be called if there was an error, but sometimes gets called continuously
nicholas@7: 				// Check here if the error is genuine
nicholas@7: 				if (audioObj.state == 0 || audioObj.buffer == undefined) {
nicholas@7: 					// Genuine error
nicholas@7: 					console.log('FATAL - Error loading buffer on '+audioObj.id);
nicholas@7: 				}
nicholas@7: 			});
n@16: 		};
nicholas@7: 		request.send();
n@16: 	};
nicholas@7: 	
nicholas@7: }