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/* Copyright (c) 2006-2013 by OpenLayers Contributors (see authors.txt for
* full list of contributors). Published under the 2-clause BSD license.
* See license.txt in the OpenLayers distribution or repository for the
* full text of the license. */
/**
* @requires OpenLayers/Handler.js
*/
/**
* Class: OpenLayers.Handler.Pinch
* The pinch handler is used to deal with sequences of browser events related
* to pinch gestures. The handler is used by controls that want to know
* when a pinch sequence begins, when a pinch is happening, and when it has
* finished.
*
* Controls that use the pinch handler typically construct it with callbacks
* for 'start', 'move', and 'done'. Callbacks for these keys are
* called when the pinch begins, with each change, and when the pinch is
* done.
*
* Create a new pinch handler with the <OpenLayers.Handler.Pinch> constructor.
*
* Inherits from:
* - <OpenLayers.Handler>
*/
OpenLayers.Handler.Pinch = OpenLayers.Class(OpenLayers.Handler, {
/**
* Property: started
* {Boolean} When a touchstart event is received, we want to record it,
* but not set 'pinching' until the touchmove get started after
* starting.
*/
started: false,
/**
* Property: stopDown
* {Boolean} Stop propagation of touchstart events from getting to
* listeners on the same element. Default is false.
*/
stopDown: false,
/**
* Property: pinching
* {Boolean}
*/
pinching: false,
/**
* Property: last
* {Object} Object that store informations related to pinch last touch.
*/
last: null,
/**
* Property: start
* {Object} Object that store informations related to pinch touchstart.
*/
start: null,
/**
* Constructor: OpenLayers.Handler.Pinch
* Returns OpenLayers.Handler.Pinch
*
* Parameters:
* control - {<OpenLayers.Control>} The control that is making use of
* this handler. If a handler is being used without a control, the
* handlers setMap method must be overridden to deal properly with
* the map.
* callbacks - {Object} An object containing functions to be called when
* the pinch operation start, change, or is finished. The callbacks
* should expect to receive an object argument, which contains
* information about scale, distance, and position of touch points.
* options - {Object}
*/
/**
* Method: touchstart
* Handle touchstart events
*
* Parameters:
* evt - {Event}
*
* Returns:
* {Boolean} Let the event propagate.
*/
touchstart: function(evt) {
var propagate = true;
this.pinching = false;
if (OpenLayers.Event.isMultiTouch(evt)) {
this.started = true;
this.last = this.start = {
distance: this.getDistance(evt.touches),
delta: 0,
scale: 1
};
this.callback("start", [evt, this.start]);
propagate = !this.stopDown;
} else if (this.started) {
// Some webkit versions send fake single-touch events during
// multitouch, which cause the drag handler to trigger
return false;
} else {
this.started = false;
this.start = null;
this.last = null;
}
// prevent document dragging
OpenLayers.Event.preventDefault(evt);
return propagate;
},
/**
* Method: touchmove
* Handle touchmove events
*
* Parameters:
* evt - {Event}
*
* Returns:
* {Boolean} Let the event propagate.
*/
touchmove: function(evt) {
if (this.started && OpenLayers.Event.isMultiTouch(evt)) {
this.pinching = true;
var current = this.getPinchData(evt);
this.callback("move", [evt, current]);
this.last = current;
// prevent document dragging
OpenLayers.Event.stop(evt);
} else if (this.started) {
// Some webkit versions send fake single-touch events during
// multitouch, which cause the drag handler to trigger
return false;
}
return true;
},
/**
* Method: touchend
* Handle touchend events
*
* Parameters:
* evt - {Event}
*
* Returns:
* {Boolean} Let the event propagate.
*/
touchend: function(evt) {
if (this.started && !OpenLayers.Event.isMultiTouch(evt)) {
this.started = false;
this.pinching = false;
this.callback("done", [evt, this.start, this.last]);
this.start = null;
this.last = null;
return false;
}
return true;
},
/**
* Method: activate
* Activate the handler.
*
* Returns:
* {Boolean} The handler was successfully activated.
*/
activate: function() {
var activated = false;
if (OpenLayers.Handler.prototype.activate.apply(this, arguments)) {
this.pinching = false;
activated = true;
}
return activated;
},
/**
* Method: deactivate
* Deactivate the handler.
*
* Returns:
* {Boolean} The handler was successfully deactivated.
*/
deactivate: function() {
var deactivated = false;
if (OpenLayers.Handler.prototype.deactivate.apply(this, arguments)) {
this.started = false;
this.pinching = false;
this.start = null;
this.last = null;
deactivated = true;
}
return deactivated;
},
/**
* Method: getDistance
* Get the distance in pixels between two touches.
*
* Parameters:
* touches - {Array(Object)}
*
* Returns:
* {Number} The distance in pixels.
*/
getDistance: function(touches) {
var t0 = touches[0];
var t1 = touches[1];
return Math.sqrt(
Math.pow(t0.olClientX - t1.olClientX, 2) +
Math.pow(t0.olClientY - t1.olClientY, 2)
);
},
/**
* Method: getPinchData
* Get informations about the pinch event.
*
* Parameters:
* evt - {Event}
*
* Returns:
* {Object} Object that contains data about the current pinch.
*/
getPinchData: function(evt) {
var distance = this.getDistance(evt.touches);
var scale = distance / this.start.distance;
return {
distance: distance,
delta: this.last.distance - distance,
scale: scale
};
},
CLASS_NAME: "OpenLayers.Handler.Pinch"
});
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