1 files changed, 180 insertions, 0 deletions
diff --git a/src/lib/startAudioContext.js b/src/lib/startAudioContext.js
new file mode 100644
index 0000000..5a339a2
--- /dev/null
+++ b/src/lib/startAudioContext.js
@@ -0,0 +1,180 @@
+/**
+ *  StartAudioContext.js
+ *  @author Yotam Mann
+ *  @license http://opensource.org/licenses/MIT MIT License
+ *  @copyright 2016 Yotam Mann
+ */
+
+(function (root, factory) {
+  if (typeof define === "function" && define.amd) {
+    define([], factory);
+  } else if (typeof module === "object" && module.exports) {
+    module.exports = factory();
+  } else {
+    root.StartAudioContext = factory();
+  }
+})(this, function () {
+  /**
+   * The StartAudioContext object
+   */
+  var StartAudioContext = {
+    /**
+     * The audio context passed in by the user
+     * @type {AudioContext}
+     */
+    context: null,
+    /**
+     * The TapListeners bound to the elements
+     * @type {Array}
+     * @private
+     */
+    _tapListeners: [],
+    /**
+     * Callbacks to invoke when the audio context is started
+     * @type {Array}
+     * @private
+     */
+    _onStarted: [],
+  };
+
+  /**
+   * Set the context
+   * @param {AudioContext} ctx
+   * @returns {StartAudioContext}
+   */
+  StartAudioContext.setContext = function (ctx) {
+    StartAudioContext.context = ctx;
+    return StartAudioContext;
+  };
+
+  /**
+   * Add a tap listener to the audio context
+   * @param  {Array|Element|String|jQuery} element
+   * @returns {StartAudioContext}
+   */
+  StartAudioContext.on = function (element) {
+    if (Array.isArray(element) || (NodeList && element instanceof NodeList)) {
+      for (var i = 0; i < element.length; i++) {
+        StartAudioContext.on(element[i]);
+      }
+    } else if (typeof element === "string") {
+      StartAudioContext.on(document.querySelectorAll(element));
+    } else if (element.jquery && typeof element.toArray === "function") {
+      StartAudioContext.on(element.toArray());
+    } else if (Element && element instanceof Element) {
+      //if it's an element, create a TapListener
+      var tap = new TapListener(element, onTap);
+      StartAudioContext._tapListeners.push(tap);
+    }
+    return StartAudioContext;
+  };
+
+  /**
+   * Bind a callback to when the audio context is started.
+   * @param {Function} cb
+   * @return {StartAudioContext}
+   */
+  StartAudioContext.onStarted = function (cb) {
+    //if it's already started, invoke the callback
+    if (StartAudioContext.isStarted()) {
+      cb();
+    } else {
+      StartAudioContext._onStarted.push(cb);
+    }
+    return StartAudioContext;
+  };
+
+  /**
+   * returns true if the context is started
+   * @return {Boolean}
+   */
+  StartAudioContext.isStarted = function () {
+    return (
+      StartAudioContext.context !== null &&
+      StartAudioContext.context.state === "running"
+    );
+  };
+
+  /**
+   * @class  Listens for non-dragging tap ends on the given element
+   * @param {Element} element
+   * @internal
+   */
+  var TapListener = function (element) {
+    this._dragged = false;
+
+    this._element = element;
+
+    this._bindedMove = this._moved.bind(this);
+    this._bindedEnd = this._ended.bind(this);
+
+    element.addEventListener("touchmove", this._bindedMove);
+    element.addEventListener("touchend", this._bindedEnd);
+    element.addEventListener("mouseup", this._bindedEnd);
+  };
+
+  /**
+   * drag move event
+   */
+  TapListener.prototype._moved = function (e) {
+    this._dragged = true;
+  };
+
+  /**
+   * tap ended listener
+   */
+  TapListener.prototype._ended = function (e) {
+    if (!this._dragged) {
+      onTap();
+    }
+    this._dragged = false;
+  };
+
+  /**
+   * remove all the bound events
+   */
+  TapListener.prototype.dispose = function () {
+    this._element.removeEventListener("touchmove", this._bindedMove);
+    this._element.removeEventListener("touchend", this._bindedEnd);
+    this._element.removeEventListener("mouseup", this._bindedEnd);
+    this._bindedMove = null;
+    this._bindedEnd = null;
+    this._element = null;
+  };
+
+  /**
+   * Invoked the first time of the elements is tapped.
+   * Creates a silent oscillator when a non-dragging touchend
+   * event has been triggered.
+   */
+  function onTap() {
+    //start the audio context with a silent oscillator
+    if (StartAudioContext.context && !StartAudioContext.isStarted()) {
+      var osc = StartAudioContext.context.createOscillator();
+      var silent = StartAudioContext.context.createGain();
+      silent.gain.value = 0;
+      osc.connect(silent);
+      silent.connect(StartAudioContext.context.destination);
+      var now = StartAudioContext.context.currentTime;
+      osc.start(now);
+      osc.stop(now + 0.5);
+    }
+
+    //dispose all the tap listeners
+    if (StartAudioContext._tapListeners) {
+      for (var i = 0; i < StartAudioContext._tapListeners.length; i++) {
+        StartAudioContext._tapListeners[i].dispose();
+      }
+      StartAudioContext._tapListeners = null;
+    }
+    //the onstarted callbacks
+    if (StartAudioContext._onStarted) {
+      for (var j = 0; j < StartAudioContext._onStarted.length; j++) {
+        StartAudioContext._onStarted[j]();
+      }
+      StartAudioContext._onStarted = null;
+    }
+  }
+
+  return StartAudioContext;
+});