handle drag-n-drop on touch interfaces

test plan:
try to drag drop things (like on the discussions
index page) on an iPad or other touch interface

make sure it works

Change-Id: I4bfc443569846afa0ab07f7c818a8fd2ab9c0943
Reviewed-on: https://gerrit.instructure.com/12161
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Zach Pendleton <zachp@instructure.com>

public/javascripts/vendor/jquery.ui.touch-punch.js

@@ -0,0 +1,161 @@
+// from: https://raw.github.com/furf/jquery-ui-touch-punch/master/jquery.ui.touch-punch.js
+/*!
+ * jQuery UI Touch Punch 0.2.2
+ *
+ * Copyright 2011, Dave Furfero
+ * Dual licensed under the MIT or GPL Version 2 licenses.
+ *
+ * Depends:
+ *  jquery.ui.widget.js
+ *  jquery.ui.mouse.js
+ */
+define(['jquery', 'jqueryui/draggable-unpatched'], function ($) {
+
+  // Detect touch support
+  $.support.touch = 'ontouchend' in document;
+
+  // Ignore browsers without touch support
+  if (!$.support.touch) {
+    return;
+  }
+
+  var mouseProto = $.ui.mouse.prototype,
+      _mouseInit = mouseProto._mouseInit,
+      touchHandled;
+
+  /**
+   * Simulate a mouse event based on a corresponding touch event
+   * @param {Object} event A touch event
+   * @param {String} simulatedType The corresponding mouse event
+   */
+  function simulateMouseEvent (event, simulatedType) {
+
+    // Ignore multi-touch events
+    if (event.originalEvent.touches.length > 1) {
+      return;
+    }
+
+    event.preventDefault();
+
+    var touch = event.originalEvent.changedTouches[0],
+        simulatedEvent = document.createEvent('MouseEvents');
+    
+    // Initialize the simulated mouse event using the touch event's coordinates
+    simulatedEvent.initMouseEvent(
+      simulatedType,    // type
+      true,             // bubbles                    
+      true,             // cancelable                 
+      window,           // view                       
+      1,                // detail                     
+      touch.screenX,    // screenX                    
+      touch.screenY,    // screenY                    
+      touch.clientX,    // clientX                    
+      touch.clientY,    // clientY                    
+      false,            // ctrlKey                    
+      false,            // altKey                     
+      false,            // shiftKey                   
+      false,            // metaKey                    
+      0,                // button                     
+      null              // relatedTarget              
+    );
+
+    // Dispatch the simulated event to the target element
+    event.target.dispatchEvent(simulatedEvent);
+  }
+
+  /**
+   * Handle the jQuery UI widget's touchstart events
+   * @param {Object} event The widget element's touchstart event
+   */
+  mouseProto._touchStart = function (event) {
+
+    var self = this;
+
+    // Ignore the event if another widget is already being handled
+    if (touchHandled || !self._mouseCapture(event.originalEvent.changedTouches[0])) {
+      return;
+    }
+
+    // Set the flag to prevent other widgets from inheriting the touch event
+    touchHandled = true;
+
+    // Track movement to determine if interaction was a click
+    self._touchMoved = false;
+
+    // Simulate the mouseover event
+    simulateMouseEvent(event, 'mouseover');
+
+    // Simulate the mousemove event
+    simulateMouseEvent(event, 'mousemove');
+
+    // Simulate the mousedown event
+    simulateMouseEvent(event, 'mousedown');
+  };
+
+  /**
+   * Handle the jQuery UI widget's touchmove events
+   * @param {Object} event The document's touchmove event
+   */
+  mouseProto._touchMove = function (event) {
+
+    // Ignore event if not handled
+    if (!touchHandled) {
+      return;
+    }
+
+    // Interaction was not a click
+    this._touchMoved = true;
+
+    // Simulate the mousemove event
+    simulateMouseEvent(event, 'mousemove');
+  };
+
+  /**
+   * Handle the jQuery UI widget's touchend events
+   * @param {Object} event The document's touchend event
+   */
+  mouseProto._touchEnd = function (event) {
+
+    // Ignore event if not handled
+    if (!touchHandled) {
+      return;
+    }
+
+    // Simulate the mouseup event
+    simulateMouseEvent(event, 'mouseup');
+
+    // Simulate the mouseout event
+    simulateMouseEvent(event, 'mouseout');
+
+    // If the touch interaction did not move, it should trigger a click
+    if (!this._touchMoved) {
+
+      // Simulate the click event
+      simulateMouseEvent(event, 'click');
+    }
+
+    // Unset the flag to allow other widgets to inherit the touch event
+    touchHandled = false;
+  };
+
+  /**
+   * A duck punch of the $.ui.mouse _mouseInit method to support touch events.
+   * This method extends the widget with bound touch event handlers that
+   * translate touch events to mouse events and pass them to the widget's
+   * original mouse event handling methods.
+   */
+  mouseProto._mouseInit = function () {
+    
+    var self = this;
+
+    // Delegate the touch handlers to the widget's element
+    self.element
+      .bind('touchstart', $.proxy(self, '_touchStart'))
+      .bind('touchmove', $.proxy(self, '_touchMove'))
+      .bind('touchend', $.proxy(self, '_touchEnd'));
+
+    // Call the original $.ui.mouse init method
+    _mouseInit.call(self);
+  };
+
+});

public/javascripts/vendor/jqueryui/draggable.js

@@ -1,4 +1,4 @@
-define(['jquery', 'jqueryui/draggable-unpatched'], function ($, returnValueOfUnpatchedDraggable) {
+define(['jquery', 'jqueryui/draggable-unpatched', 'vendor/jquery.ui.touch-punch'], function ($, returnValueOfUnpatchedDraggable) {
 
   var _mouseMove = $.ui.draggable.prototype._mouseMove;
   $.ui.draggable.prototype._mouseMove = function() {