mouse.js

/*
 * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
 * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
 * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
 * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
 * Code distributed by Google as part of the polymer project is also
 * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
 */

(function(scope) {
  var dispatcher = scope.dispatcher;
  var pointermap = dispatcher.pointermap;
  // radius around touchend that swallows mouse events
  var DEDUP_DIST = 25;

  var WHICH_TO_BUTTONS = [0, 1, 4, 2];

  var currentButtons = 0;

  var FIREFOX_LINUX = /Linux.*Firefox\//i;

  var HAS_BUTTONS = (function() {
    // firefox on linux returns spec-incorrect values for mouseup.buttons
    // https://developer.mozilla.org/en-US/docs/Web/API/MouseEvent.buttons#See_also
    // https://codereview.chromium.org/727593003/#msg16
    if (FIREFOX_LINUX.test(navigator.userAgent)) {
      return false;
    }
    try {
      return new MouseEvent('test', {buttons: 1}).buttons === 1;
    } catch (e) {
      return false;
    }
  })();

  // handler block for native mouse events
  var mouseEvents = {
    POINTER_ID: 1,
    POINTER_TYPE: 'mouse',
    events: [
      'mousedown',
      'mousemove',
      'mouseup'
    ],
    exposes: [
      'down',
      'up',
      'move'
    ],
    register: function(target) {
      dispatcher.listen(target, this.events);
    },
    unregister: function(target) {
      if (target.nodeType === Node.DOCUMENT_NODE) {
        return;
      }
      dispatcher.unlisten(target, this.events);
    },
    lastTouches: [],
    // collide with the global mouse listener
    isEventSimulatedFromTouch: function(inEvent) {
      var lts = this.lastTouches;
      var x = inEvent.clientX, y = inEvent.clientY;
      for (var i = 0, l = lts.length, t; i < l && (t = lts[i]); i++) {
        // simulated mouse events will be swallowed near a primary touchend
        var dx = Math.abs(x - t.x), dy = Math.abs(y - t.y);
        if (dx <= DEDUP_DIST && dy <= DEDUP_DIST) {
          return true;
        }
      }
    },
    prepareEvent: function(inEvent) {
      var e = dispatcher.cloneEvent(inEvent);
      e.pointerId = this.POINTER_ID;
      e.isPrimary = true;
      e.pointerType = this.POINTER_TYPE;
      e._source = 'mouse';
      if (!HAS_BUTTONS) {
        var type = inEvent.type;
        var bit = WHICH_TO_BUTTONS[inEvent.which] || 0;
        if (type === 'mousedown') {
          currentButtons |= bit;
        } else if (type === 'mouseup') {
          currentButtons &= ~bit;
        }
        e.buttons = currentButtons;
      }
      return e;
    },
    mousedown: function(inEvent) {
      if (!this.isEventSimulatedFromTouch(inEvent)) {
        var p = pointermap.has(this.POINTER_ID);
        var e = this.prepareEvent(inEvent);
        e.target = scope.findTarget(inEvent);
        pointermap.set(this.POINTER_ID, e.target);
        dispatcher.down(e);
      }
    },
    mousemove: function(inEvent) {
      if (!this.isEventSimulatedFromTouch(inEvent)) {
        var target = pointermap.get(this.POINTER_ID);
        if (target) {
          var e = this.prepareEvent(inEvent);
          e.target = target;
          // handle case where we missed a mouseup
          if ((HAS_BUTTONS ? e.buttons : e.which) === 0) {
            if (!HAS_BUTTONS) {
              currentButtons = e.buttons = 0;
            }
            dispatcher.cancel(e);
            this.cleanupMouse(e.buttons);
          } else {
            dispatcher.move(e);
          }
        }
      }
    },
    mouseup: function(inEvent) {
      if (!this.isEventSimulatedFromTouch(inEvent)) {
        var e = this.prepareEvent(inEvent);
        e.relatedTarget = scope.findTarget(inEvent);
        e.target = pointermap.get(this.POINTER_ID);
        dispatcher.up(e);
        this.cleanupMouse(e.buttons);
      }
    },
    cleanupMouse: function(buttons) {
      if (buttons === 0) {
        pointermap.delete(this.POINTER_ID);
      }
    }
  };

  scope.mouseEvents = mouseEvents;
})(window.PolymerGestures);