angular-touch.js

/**
 * @license AngularJS v1.2.0-rc.2
 * (c) 2010-2012 Google, Inc. http://angularjs.org
 * License: MIT
 */
(function(window, angular, undefined) {'use strict';

/**
 * @ngdoc overview
 * @name ngTouch
 * @description
 *
 * # ngTouch
 *
 * `ngTouch` is the name of the optional Angular module that provides touch events and other
 * helpers for touch-enabled devices.
 * The implementation is based on jQuery Mobile touch event handling
 * ([jquerymobile.com](http://jquerymobile.com/))
 *
 * {@installModule touch}
 *
 * See {@link ngTouch.$swipe `$swipe`} for usage.
 */

// define ngTouch module
var ngTouch = angular.module('ngTouch', []);

/**
     * @ngdoc object
     * @name ngTouch.$swipe
     *
     * @description
     * The `$swipe` service is a service that abstracts the messier details of hold-and-drag swipe
     * behavior, to make implementing swipe-related directives more convenient.
     *
     * Requires the {@link ngTouch `ngTouch`} module to be installed.
     *
     * `$swipe` is used by the `ngSwipeLeft` and `ngSwipeRight` directives in `ngTouch`, and by
     * `ngCarousel` in a separate component.
     *
     * # Usage
     * The `$swipe` service is an object with a single method: `bind`. `bind` takes an element
     * which is to be watched for swipes, and an object with four handler functions. See the
     * documentation for `bind` below.
     */

ngTouch.factory('$swipe', [function() {
  // The total distance in any direction before we make the call on swipe vs. scroll.
  var MOVE_BUFFER_RADIUS = 10;

  function getCoordinates(event) {
    var touches = event.touches && event.touches.length ? event.touches : [event];
    var e = (event.changedTouches && event.changedTouches[0]) ||
        (event.originalEvent && event.originalEvent.changedTouches &&
            event.originalEvent.changedTouches[0]) ||
        touches[0].originalEvent || touches[0];

    return {
      x: e.clientX,
      y: e.clientY
    };
  }

  return {
    /**
     * @ngdoc method
     * @name ngTouch.$swipe#bind
     * @methodOf ngTouch.$swipe
     *
     * @description
     * The main method of `$swipe`. It takes an element to be watched for swipe motions, and an
     * object containing event handlers.
     *
     * The four events are `start`, `move`, `end`, and `cancel`. `start`, `move`, and `end`
     * receive as a parameter a coordinates object of the form `{ x: 150, y: 310 }`.
     *
     * `start` is called on either `mousedown` or `touchstart`. After this event, `$swipe` is
     * watching for `touchmove` or `mousemove` events. These events are ignored until the total
     * distance moved in either dimension exceeds a small threshold.
     *
     * Once this threshold is exceeded, either the horizontal or vertical delta is greater.
     * - If the horizontal distance is greater, this is a swipe and `move` and `end` events follow.
     * - If the vertical distance is greater, this is a scroll, and we let the browser take over.
     *   A `cancel` event is sent.
     *
     * `move` is called on `mousemove` and `touchmove` after the above logic has determined that
     * a swipe is in progress.
     *
     * `end` is called when a swipe is successfully completed with a `touchend` or `mouseup`.
     *
     * `cancel` is called either on a `touchcancel` from the browser, or when we begin scrolling
     * as described above.
     *
     */
    bind: function(element, eventHandlers) {
      // Absolute total movement, used to control swipe vs. scroll.
      var totalX, totalY;
      // Coordinates of the start position.
      var startCoords;
      // Last event's position.
      var lastPos;
      // Whether a swipe is active.
      var active = false;

      element.on('touchstart mousedown', function(event) {
        startCoords = getCoordinates(event);
        active = true;
        totalX = 0;
        totalY = 0;
        lastPos = startCoords;
        eventHandlers['start'] && eventHandlers['start'](startCoords);
      });

      element.on('touchcancel', function(event) {
        active = false;
        eventHandlers['cancel'] && eventHandlers['cancel']();
      });

      element.on('touchmove mousemove', function(event) {
        if (!active) return;

        // Android will send a touchcancel if it thinks we're starting to scroll.
        // So when the total distance (+ or - or both) exceeds 10px in either direction,
        // we either:
        // - On totalX > totalY, we send preventDefault() and treat this as a swipe.
        // - On totalY > totalX, we let the browser handle it as a scroll.

        if (!startCoords) return;
        var coords = getCoordinates(event);

        totalX += Math.abs(coords.x - lastPos.x);
        totalY += Math.abs(coords.y - lastPos.y);

        lastPos = coords;

        if (totalX < MOVE_BUFFER_RADIUS && totalY < MOVE_BUFFER_RADIUS) {
          return;
        }

        // One of totalX or totalY has exceeded the buffer, so decide on swipe vs. scroll.
        if (totalY > totalX) {
          // Allow native scrolling to take over.
          active = false;
          eventHandlers['cancel'] && eventHandlers['cancel']();
          return;
        } else {
          // Prevent the browser from scrolling.
          event.preventDefault();

          eventHandlers['move'] && eventHandlers['move'](coords);
        }
      });

      element.on('touchend mouseup', function(event) {
        if (!active) return;
        active = false;
        eventHandlers['end'] && eventHandlers['end'](getCoordinates(event));
      });
    }
  };
}]);

/**
 * @ngdoc directive
 * @name ngTouch.directive:ngClick
 *
 * @description
 * A more powerful replacement for the default ngClick designed to be used on touchscreen
 * devices. Most mobile browsers wait about 300ms after a tap-and-release before sending
 * the click event. This version handles them immediately, and then prevents the
 * following click event from propagating.
 *
 * Requires the {@link ngTouch `ngTouch`} module to be installed.
 *
 * This directive can fall back to using an ordinary click event, and so works on desktop
 * browsers as well as mobile.
 *
 * This directive also sets the CSS class `ng-click-active` while the element is being held
 * down (by a mouse click or touch) so you can restyle the depressed element if you wish.
 *
 * @element ANY
 * @param {expression} ngClick {@link guide/expression Expression} to evaluate
 * upon tap. (Event object is available as `$event`)
 *
 * @example
    <doc:example>
      <doc:source>
        <button ng-click="count = count + 1" ng-init="count=0">
          Increment
        </button>
        count: {{ count }}
      </doc:source>
    </doc:example>
 */

ngTouch.config(['$provide', function($provide) {
  $provide.decorator('ngClickDirective', ['$delegate', function($delegate) {
    // drop the default ngClick directive
    $delegate.shift();
    return $delegate;
  }]);
}]);

ngTouch.directive('ngClick', ['$parse', '$timeout', '$rootElement',
    function($parse, $timeout, $rootElement) {
  var TAP_DURATION = 750; // Shorter than 750ms is a tap, longer is a taphold or drag.
  var MOVE_TOLERANCE = 12; // 12px seems to work in most mobile browsers.
  var PREVENT_DURATION = 2500; // 2.5 seconds maximum from preventGhostClick call to click
  var CLICKBUSTER_THRESHOLD = 25; // 25 pixels in any dimension is the limit for busting clicks.

  var ACTIVE_CLASS_NAME = 'ng-click-active';
  var lastPreventedTime;
  var touchCoordinates;


  // TAP EVENTS AND GHOST CLICKS
  //
  // Why tap events?
  // Mobile browsers detect a tap, then wait a moment (usually ~300ms) to see if you're
  // double-tapping, and then fire a click event.
  //
  // This delay sucks and makes mobile apps feel unresponsive.
  // So we detect touchstart, touchmove, touchcancel and touchend ourselves and determine when
  // the user has tapped on something.
  //
  // What happens when the browser then generates a click event?
  // The browser, of course, also detects the tap and fires a click after a delay. This results in
  // tapping/clicking twice. So we do "clickbusting" to prevent it.
  //
  // How does it work?
  // We attach global touchstart and click handlers, that run during the capture (early) phase.
  // So the sequence for a tap is:
  // - global touchstart: Sets an "allowable region" at the point touched.
  // - element's touchstart: Starts a touch
  // (- touchmove or touchcancel ends the touch, no click follows)
  // - element's touchend: Determines if the tap is valid (didn't move too far away, didn't hold
  //   too long) and fires the user's tap handler. The touchend also calls preventGhostClick().
  // - preventGhostClick() removes the allowable region the global touchstart created.
  // - The browser generates a click event.
  // - The global click handler catches the click, and checks whether it was in an allowable region.
  //     - If preventGhostClick was called, the region will have been removed, the click is busted.
  //     - If the region is still there, the click proceeds normally. Therefore clicks on links and
  //       other elements without ngTap on them work normally.
  //
  // This is an ugly, terrible hack!
  // Yeah, tell me about it. The alternatives are using the slow click events, or making our users
  // deal with the ghost clicks, so I consider this the least of evils. Fortunately Angular
  // encapsulates this ugly logic away from the user.
  //
  // Why not just put click handlers on the element?
  // We do that too, just to be sure. The problem is that the tap event might have caused the DOM
  // to change, so that the click fires in the same position but something else is there now. So
  // the handlers are global and care only about coordinates and not elements.

  // Checks if the coordinates are close enough to be within the region.
  function hit(x1, y1, x2, y2) {
    return Math.abs(x1 - x2) < CLICKBUSTER_THRESHOLD && Math.abs(y1 - y2) < CLICKBUSTER_THRESHOLD;
  }

  // Checks a list of allowable regions against a click location.
  // Returns true if the click should be allowed.
  // Splices out the allowable region from the list after it has been used.
  function checkAllowableRegions(touchCoordinates, x, y) {
    for (var i = 0; i < touchCoordinates.length; i += 2) {
      if (hit(touchCoordinates[i], touchCoordinates[i+1], x, y)) {
        touchCoordinates.splice(i, i + 2);
        return true; // allowable region
      }
    }
    return false; // No allowable region; bust it.
  }

  // Global click handler that prevents the click if it's in a bustable zone and preventGhostClick
  // was called recently.
  function onClick(event) {
    if (Date.now() - lastPreventedTime > PREVENT_DURATION) {
      return; // Too old.
    }

    var touches = event.touches && event.touches.length ? event.touches : [event];
    var x = touches[0].clientX;
    var y = touches[0].clientY;
    // Work around desktop Webkit quirk where clicking a label will fire two clicks (on the label
    // and on the input element). Depending on the exact browser, this second click we don't want
    // to bust has either (0,0) or negative coordinates.
    if (x < 1 && y < 1) {
      return; // offscreen
    }

    // Look for an allowable region containing this click.
    // If we find one, that means it was created by touchstart and not removed by
    // preventGhostClick, so we don't bust it.
    if (checkAllowableRegions(touchCoordinates, x, y)) {
      return;
    }

    // If we didn't find an allowable region, bust the click.
    event.stopPropagation();
    event.preventDefault();

    // Blur focused form elements
    event.target && event.target.blur();
  }


  // Global touchstart handler that creates an allowable region for a click event.
  // This allowable region can be removed by preventGhostClick if we want to bust it.
  function onTouchStart(event) {
    var touches = event.touches && event.touches.length ? event.touches : [event];
    var x = touches[0].clientX;
    var y = touches[0].clientY;
    touchCoordinates.push(x, y);

    $timeout(function() {
      // Remove the allowable region.
      for (var i = 0; i < touchCoordinates.length; i += 2) {
        if (touchCoordinates[i] == x && touchCoordinates[i+1] == y) {
          touchCoordinates.splice(i, i + 2);
          return;
        }
      }
    }, PREVENT_DURATION, false);
  }

  // On the first call, attaches some event handlers. Then whenever it gets called, it creates a
  // zone around the touchstart where clicks will get busted.
  function preventGhostClick(x, y) {
    if (!touchCoordinates) {
      $rootElement[0].addEventListener('click', onClick, true);
      $rootElement[0].addEventListener('touchstart', onTouchStart, true);
      touchCoordinates = [];
    }

    lastPreventedTime = Date.now();

    checkAllowableRegions(touchCoordinates, x, y);
  }

  // Actual linking function.
  return function(scope, element, attr) {
    var clickHandler = $parse(attr.ngClick),
        tapping = false,
        tapElement,  // Used to blur the element after a tap.
        startTime,   // Used to check if the tap was held too long.
        touchStartX,
        touchStartY;

    function resetState() {
      tapping = false;
      element.removeClass(ACTIVE_CLASS_NAME);
    }

    element.on('touchstart', function(event) {
      tapping = true;
      tapElement = event.target ? event.target : event.srcElement; // IE uses srcElement.
      // Hack for Safari, which can target text nodes instead of containers.
      if(tapElement.nodeType == 3) {
        tapElement = tapElement.parentNode;
      }

      element.addClass(ACTIVE_CLASS_NAME);

      startTime = Date.now();

      var touches = event.touches && event.touches.length ? event.touches : [event];
      var e = touches[0].originalEvent || touches[0];
      touchStartX = e.clientX;
      touchStartY = e.clientY;
    });

    element.on('touchmove', function(event) {
      resetState();
    });

    element.on('touchcancel', function(event) {
      resetState();
    });

    element.on('touchend', function(event) {
      var diff = Date.now() - startTime;

      var touches = (event.changedTouches && event.changedTouches.length) ? event.changedTouches :
          ((event.touches && event.touches.length) ? event.touches : [event]);
      var e = touches[0].originalEvent || touches[0];
      var x = e.clientX;
      var y = e.clientY;
      var dist = Math.sqrt( Math.pow(x - touchStartX, 2) + Math.pow(y - touchStartY, 2) );

      if (tapping && diff < TAP_DURATION && dist < MOVE_TOLERANCE) {
        // Call preventGhostClick so the clickbuster will catch the corresponding click.
        preventGhostClick(x, y);

        // Blur the focused element (the button, probably) before firing the callback.
        // This doesn't work perfectly on Android Chrome, but seems to work elsewhere.
        // I couldn't get anything to work reliably on Android Chrome.
        if (tapElement) {
          tapElement.blur();
        }

        if (!angular.isDefined(attr.disabled) || attr.disabled === false) {
          element.triggerHandler('click', event);
        }
      }

      resetState();
    });

    // Hack for iOS Safari's benefit. It goes searching for onclick handlers and is liable to click
    // something else nearby.
    element.onclick = function(event) { };

    // Actual click handler.
    // There are three different kinds of clicks, only two of which reach this point.
    // - On desktop browsers without touch events, their clicks will always come here.
    // - On mobile browsers, the simulated "fast" click will call this.
    // - But the browser's follow-up slow click will be "busted" before it reaches this handler.
    // Therefore it's safe to use this directive on both mobile and desktop.
    element.on('click', function(event) {
      scope.$apply(function() {
        clickHandler(scope, {$event: event});
      });
    });

    element.on('mousedown', function(event) {
      element.addClass(ACTIVE_CLASS_NAME);
    });

    element.on('mousemove mouseup', function(event) {
      element.removeClass(ACTIVE_CLASS_NAME);
    });

  };
}]);

/**
 * @ngdoc directive
 * @name ngTouch.directive:ngSwipeLeft
 *
 * @description
 * Specify custom behavior when an element is swiped to the left on a touchscreen device.
 * A leftward swipe is a quick, right-to-left slide of the finger.
 * Though ngSwipeLeft is designed for touch-based devices, it will work with a mouse click and drag too.
 *
 * Requires the {@link ngTouch `ngTouch`} module to be installed.
 *
 * @element ANY
 * @param {expression} ngSwipeLeft {@link guide/expression Expression} to evaluate
 * upon left swipe. (Event object is available as `$event`)
 *
 * @example
    <doc:example>
      <doc:source>
        <div ng-show="!showActions" ng-swipe-left="showActions = true">
          Some list content, like an email in the inbox
        </div>
        <div ng-show="showActions" ng-swipe-right="showActions = false">
          <button ng-click="reply()">Reply</button>
          <button ng-click="delete()">Delete</button>
        </div>
      </doc:source>
    </doc:example>
 */

/**
 * @ngdoc directive
 * @name ngTouch.directive:ngSwipeRight
 *
 * @description
 * Specify custom behavior when an element is swiped to the right on a touchscreen device.
 * A rightward swipe is a quick, left-to-right slide of the finger.
 * Though ngSwipeRight is designed for touch-based devices, it will work with a mouse click and drag too.
 *
 * Requires the {@link ngTouch `ngTouch`} module to be installed.
 *
 * @element ANY
 * @param {expression} ngSwipeRight {@link guide/expression Expression} to evaluate
 * upon right swipe. (Event object is available as `$event`)
 *
 * @example
    <doc:example>
      <doc:source>
        <div ng-show="!showActions" ng-swipe-left="showActions = true">
          Some list content, like an email in the inbox
        </div>
        <div ng-show="showActions" ng-swipe-right="showActions = false">
          <button ng-click="reply()">Reply</button>
          <button ng-click="delete()">Delete</button>
        </div>
      </doc:source>
    </doc:example>
 */

function makeSwipeDirective(directiveName, direction, eventName) {
  ngTouch.directive(directiveName, ['$parse', '$swipe', function($parse, $swipe) {
    // The maximum vertical delta for a swipe should be less than 75px.
    var MAX_VERTICAL_DISTANCE = 75;
    // Vertical distance should not be more than a fraction of the horizontal distance.
    var MAX_VERTICAL_RATIO = 0.3;
    // At least a 30px lateral motion is necessary for a swipe.
    var MIN_HORIZONTAL_DISTANCE = 30;

    return function(scope, element, attr) {
      var swipeHandler = $parse(attr[directiveName]);

      var startCoords, valid;

      function validSwipe(coords) {
        // Check that it's within the coordinates.
        // Absolute vertical distance must be within tolerances.
        // Horizontal distance, we take the current X - the starting X.
        // This is negative for leftward swipes and positive for rightward swipes.
        // After multiplying by the direction (-1 for left, +1 for right), legal swipes
        // (ie. same direction as the directive wants) will have a positive delta and
        // illegal ones a negative delta.
        // Therefore this delta must be positive, and larger than the minimum.
        if (!startCoords) return false;
        var deltaY = Math.abs(coords.y - startCoords.y);
        var deltaX = (coords.x - startCoords.x) * direction;
        return valid && // Short circuit for already-invalidated swipes.
            deltaY < MAX_VERTICAL_DISTANCE &&
            deltaX > 0 &&
            deltaX > MIN_HORIZONTAL_DISTANCE &&
            deltaY / deltaX < MAX_VERTICAL_RATIO;
      }

      $swipe.bind(element, {
        'start': function(coords) {
          startCoords = coords;
          valid = true;
        },
        'cancel': function() {
          valid = false;
        },
        'end': function(coords) {
          if (validSwipe(coords)) {
            scope.$apply(function() {
              element.triggerHandler(eventName);
              swipeHandler(scope);
            });
          }
        }
      });
    };
  }]);
}

// Left is negative X-coordinate, right is positive.
makeSwipeDirective('ngSwipeLeft', -1, 'swipeleft');
makeSwipeDirective('ngSwipeRight', 1, 'swiperight');



})(window, window.angular);