Use a per-element gesture registration system.

This provides better ergonomics for touch, removes a global per-shadowroot MutationObserver, and only generates gestures
that are being listened for.

Need metadata for event -> dependency mappings

Remove ShadowDOM Polyfill logic

Handling gestures at the element level rather than the scope level should be a much cleaner fix for #4

Remove MutationObserver and Installer

Per-element tracking removes need for watching DOM

addGesture and removeGesture

only set touch-action if one is given

remove installer from karma config

build.json

@@ -5,7 +5,6 @@
   "src/eventFactory.js",
   "src/pointermap.js",
   "src/dispatcher.js",
-  "src/installer.js",
   "src/mouse.js",
   "src/touch.js",
   "src/ms.js",

conf/karma.conf.js

@@ -13,7 +13,6 @@ module.exports = function(karma) {
       'polymer-gestures/src/eventFactory.js',
       'polymer-gestures/src/pointermap.js',
       'polymer-gestures/src/dispatcher.js',
-      'polymer-gestures/src/installer.js',
       'polymer-gestures/src/mouse.js',
       'polymer-gestures/src/touch.js',
       'polymer-gestures/src/ms.js',

polymer-gestures.html

@@ -11,7 +11,6 @@
 <script src="src/eventFactory.js"></script>
 <script src="src/pointermap.js"></script>
 <script src="src/dispatcher.js"></script>
-<script src="src/installer.js"></script>
 <script src="src/mouse.js"></script>
 <script src="src/touch.js"></script>
 <script src="src/ms.js"></script>

polymer-gestures.js

@@ -16,7 +16,6 @@
     'src/eventFactory.js',
     'src/pointermap.js',
     'src/dispatcher.js',
-    'src/installer.js',
     'src/mouse.js',
     'src/touch.js',
     'src/ms.js',

src/dispatcher.js

@@ -94,9 +94,6 @@
 
   var eventFactory = scope.eventFactory;
 
-  var hasSDPolyfill = scope.hasSDPolyfill;
-  var wrap = scope.wrap;
-
   /**
    * This module is for normalizing events. Mouse and Touch events will be
    * collected here, and fire PointerEvents that have the same semantics, no
@@ -117,6 +114,8 @@
     eventSources: Object.create(null),
     eventSourceList: [],
     gestures: [],
+    // map gesture event -> {listeners: int, index: gestures[int]}
+    dependencyMap: Object.create(null),
     gestureQueue: [],
     /**
      * Add a new event source that will generate pointer events.
@@ -140,6 +139,13 @@
       }
     },
     registerGesture: function(name, source) {
+      var obj = Object.create(null);
+      obj.listeners = 0;
+      obj.index = this.gestures.length;
+      for (var i = 0, g; i < source.exposes.length; i++) {
+        g = source.exposes[i];
+        this.dependencyMap[g] = obj;
+      }
       this.gestures.push(source);
     },
     register: function(element) {
@@ -177,6 +183,9 @@
       // This is used to prevent multiple dispatch of events from
       // platform events. This can happen when two elements in different scopes
       // are set up to create pointer events, which is relevant to Shadow DOM.
+
+      // TODO(dfreedm): make this check more granular, allow for minimal event generation
+      // e.g inEvent._handledByPG['tap'] and inEvent._handledByPG['track'], etc
       if (inEvent._handledByPG) {
         return;
       }
@@ -200,20 +209,10 @@
       }
     },
     addEvent: function(target, eventName) {
-      // NOTE: Work around for #4, use native event listener in SD Polyfill
-      if (hasSDPolyfill) {
-        target.addEventListener_(eventName, this.boundHandler);
-      } else {
-        target.addEventListener(eventName, this.boundHandler);
-      }
+      target.addEventListener(eventName, this.boundHandler);
     },
     removeEvent: function(target, eventName) {
-      // NOTE: Work around for #4, use native event listener in SD Polyfill
-      if (hasSDPolyfill) {
-        target.removeEventListener_(eventName, this.boundHandler);
-      } else {
-        target.removeEventListener(eventName, this.boundHandler);
-      }
+      target.removeEventListener(eventName, this.boundHandler);
     },
     // EVENT CREATION AND TRACKING
     /**
@@ -255,7 +254,6 @@
           if (HAS_SVG_INSTANCE && eventCopy[p] instanceof SVGElementInstance) {
             eventCopy[p] = eventCopy[p].correspondingUseElement;
           }
-          eventCopy[p] = wrap(eventCopy[p]);
         }
       }
       // keep the semantics of preventDefault
@@ -288,7 +286,7 @@
         for (var j = 0, g, fn; j < this.gestures.length; j++) {
           g = this.gestures[j];
           fn = g[e.type];
-          if (fn) {
+          if (g.enabled && fn) {
             fn.call(g, e);
           }
         }
@@ -306,9 +304,61 @@
   dispatcher.boundHandler = dispatcher.eventHandler.bind(dispatcher);
   dispatcher.boundGestureTrigger = dispatcher.gestureTrigger.bind(dispatcher);
   scope.dispatcher = dispatcher;
-  scope.register = function(root) {
-    dispatcher.register(root);
+
+  /**
+   *
+   * Initializes `node` for receiving events of type `gesture`
+   *
+   * Optionally, `touchAction` will set the touch-action of the node.
+   * The default is `auto`.
+   *
+   * If `gesture` is the only listener set up, the underlying gesture is then enabled.
+   *
+   * @param {Element} node
+   * @param {string} gesture
+   * @param {string} touchAction
+   */
+  scope.addGesture = function(node, gesture, touchAction) {
+    var dep = dispatcher.dependencyMap[gesture];
+    if (dep) {
+      if (touchAction && !node.hasAttribute('touch-action')) {
+        node.setAttribute('touch-action', touchAction);
+      }
+      if (dep.listeners === 0) {
+        dispatcher.gestures[dep.index].enabled = true;
+      }
+      dep.listeners++;
+      if (!node._pgListeners) {
+        dispatcher.register(node);
+        node._pgListeners = 0;
+      }
+      node._pgListeners++;
+    }
+  };
+
+  /**
+   * Tears down the gesture configuration for `node`
+   *
+   * If no more listeners for `gesture` exist, the underlying gesture recognizer is disabled.
+   *
+   * @param {Element} node
+   * @param {string} gesture
+   */
+  scope.removeGesture = function(node, gesture) {
+    var dep = dispatcher.dependencyMap[gesture];
+    if (dep) {
+      if (dep.listeners > 0) {
+        dep.listeners--;
+      }
+      if (dep.listeners === 0) {
+        dispatcher.gestures[dep.index].enabled = false;
+      }
+      if (node._pgListeners > 0) {
+        node._pgListeners--;
+      }
+      if (node._pgListeners === 0) {
+        dispatcher.unregister(node);
+      }
+    }
   };
-  scope.unregister = dispatcher.unregister.bind(dispatcher);
-  scope.wrap = wrap;
 })(window.PolymerGestures);

src/hold.js

@@ -64,6 +64,11 @@
       'move',
       'up',
     ],
+    exposes: [
+      'hold',
+      'holdpulse',
+      'release'
+    ],
     heldPointer: null,
     holdJob: null,
     pulse: function() {

src/mouse.js

@@ -29,10 +29,12 @@
       'mousemove',
       'mouseup'
     ],
+    exposes: [
+      'down',
+      'up',
+      'move'
+    ],
     register: function(target) {
-      if (target !== document) {
-        return;
-      }
       dispatcher.listen(target, this.events);
     },
     unregister: function(target) {
@@ -71,7 +73,7 @@
           this.mouseup(inEvent);
         }
         var e = this.prepareEvent(inEvent);
-        e.target = scope.wrap(scope.findTarget(inEvent));
+        e.target = scope.findTarget(inEvent);
         pointermap.set(this.POINTER_ID, e.target);
         dispatcher.down(e);
       }
@@ -95,7 +97,7 @@
     mouseup: function(inEvent) {
       if (!this.isEventSimulatedFromTouch(inEvent)) {
         var e = this.prepareEvent(inEvent);
-        e.relatedTarget = scope.wrap(scope.findTarget(inEvent));
+        e.relatedTarget = scope.findTarget(inEvent);
         e.target = pointermap.get(this.POINTER_ID);
         dispatcher.up(e);
         this.cleanupMouse();

src/ms.js

@@ -48,7 +48,7 @@
     },
     MSPointerDown: function(inEvent) {
       var e = this.prepareEvent(inEvent);
-      e.target = scope.wrap(scope.findTarget(inEvent));
+      e.target = scope.findTarget(inEvent);
       pointermap.set(inEvent.pointerId, e.target);
       dispatcher.down(e);
     },
@@ -59,14 +59,14 @@
     },
     MSPointerUp: function(inEvent) {
       var e = this.prepareEvent(inEvent);
-      e.relatedTarget = scope.wrap(scope.findTarget(inEvent));
+      e.relatedTarget = scope.findTarget(inEvent);
       e.target = pointermap.get(e.pointerId);
       dispatcher.up(e);
       this.cleanup(inEvent.pointerId);
     },
     MSPointerCancel: function(inEvent) {
       var e = this.prepareEvent(inEvent);
-      e.relatedTarget = scope.wrap(scope.findTarget(inEvent));
+      e.relatedTarget = scope.findTarget(inEvent);
       e.target = pointermap.get(e.pointerId);
       dispatcher.cancel(e);
       this.cleanup(inEvent.pointerId);