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//>>built
define("dojox/geo/openlayers/TouchInteractionSupport", ["dojo/_base/kernel",
"dojo/_base/declare",
"dojo/_base/connect",
"dojo/_base/html",
"dojo/_base/lang",
"dojo/_base/event",
"dojo/_base/window"], function(dojo, declare, connect, html, lang, event, window){
return declare("dojox.geo.openlayers.TouchInteractionSupport", null, {
// summary:
// class to handle touch interactions on a OpenLayers.Map widget
// tags:
// private
_map : null,
_centerTouchLocation : null,
_touchMoveListener : null,
_touchEndListener : null,
_initialFingerSpacing : null,
_initialScale : null,
_tapCount : null,
_tapThreshold : null,
_lastTap : null,
constructor : function(/* OpenLayers.Map */map){
// summary:
// Constructs a new TouchInteractionSupport instance
// map: OpenLayers.Map
// the Map widget this class provides touch navigation for.
this._map = map;
this._centerTouchLocation = new OpenLayers.LonLat(0, 0);
var div = this._map.div;
// install touch listeners
connect.connect(div, "touchstart", this, this._touchStartHandler);
connect.connect(div, "touchmove", this, this._touchMoveHandler);
connect.connect(div, "touchend", this, this._touchEndHandler);
this._tapCount = 0;
this._lastTap = {
x : 0,
y : 0
};
this._tapThreshold = 100; // square distance in pixels
},
_getTouchBarycenter : function(touchEvent){
// summary:
// returns the midpoint of the two first fingers (or the first finger location if only one)
// touchEvent: Event
// a touch event
// returns: dojox.gfx.Point
// the midpoint
// tags:
// private
var touches = touchEvent.touches;
var firstTouch = touches[0];
var secondTouch = null;
if (touches.length > 1) {
secondTouch = touches[1];
} else {
secondTouch = touches[0];
}
var marginBox = html.marginBox(this._map.div);
var middleX = (firstTouch.pageX + secondTouch.pageX) / 2.0 - marginBox.l;
var middleY = (firstTouch.pageY + secondTouch.pageY) / 2.0 - marginBox.t;
return {
x : middleX,
y : middleY
};
},
_getFingerSpacing : function(touchEvent){
// summary:
// computes the distance between the first two fingers
// touchEvent: Event
// a touch event
// returns: float
// a distance. -1 if less that 2 fingers
// tags:
// private
var touches = touchEvent.touches;
var spacing = -1;
if (touches.length >= 2) {
var dx = (touches[1].pageX - touches[0].pageX);
var dy = (touches[1].pageY - touches[0].pageY);
spacing = Math.sqrt(dx * dx + dy * dy);
}
return spacing;
},
_isDoubleTap : function(touchEvent){
// summary:
// checks whether the specified touchStart event is a double tap
// (i.e. follows closely a previous touchStart at approximately the same location)
// touchEvent: Event
// a touch event
// returns: boolean
// true if this event is considered a double tap
// tags:
// private
var isDoubleTap = false;
var touches = touchEvent.touches;
if ((this._tapCount > 0) && touches.length == 1) {
// test distance from last tap
var dx = (touches[0].pageX - this._lastTap.x);
var dy = (touches[0].pageY - this._lastTap.y);
var distance = dx * dx + dy * dy;
if (distance < this._tapThreshold) {
isDoubleTap = true;
} else {
this._tapCount = 0;
}
}
this._tapCount++;
this._lastTap.x = touches[0].pageX;
this._lastTap.y = touches[0].pageY;
setTimeout(lang.hitch(this, function(){
this._tapCount = 0;
}), 300);
return isDoubleTap;
},
_doubleTapHandler : function(touchEvent){
// summary:
// action performed on the map when a double tap was triggered
// touchEvent: Event
// a touch event
// tags:
// private
// perform a basic 2x zoom on touch
var touches = touchEvent.touches;
var marginBox = html.marginBox(this._map.div);
var offX = touches[0].pageX - marginBox.l;
var offY = touches[0].pageY - marginBox.t;
// clicked map point before zooming
var mapPoint = this._map.getLonLatFromPixel(new OpenLayers.Pixel(offX, offY));
// zoom increment power
this._map.setCenter(new OpenLayers.LonLat(mapPoint.lon, mapPoint.lat), this._map.getZoom() + 1);
},
_touchStartHandler : function(touchEvent){
// summary:
// action performed on the map when a touch start was triggered
// touchEvent: Event
// a touch event
// tags:
// private
event.stop(touchEvent);
// test double tap
if (this._isDoubleTap(touchEvent)) {
this._doubleTapHandler(touchEvent);
return;
}
// compute map midpoint between fingers
var middlePoint = this._getTouchBarycenter(touchEvent);
this._centerTouchLocation = this._map.getLonLatFromPixel(new OpenLayers.Pixel(middlePoint.x, middlePoint.y));
// store initial finger spacing to compute zoom later
this._initialFingerSpacing = this._getFingerSpacing(touchEvent);
// store initial map scale
this._initialScale = this._map.getScale();
// install touch move and up listeners (if not done by other fingers before)
if (!this._touchMoveListener)
this._touchMoveListener = connect.connect(window.global, "touchmove", this, this._touchMoveHandler);
if (!this._touchEndListener)
this._touchEndListener = connect.connect(window.global, "touchend", this, this._touchEndHandler);
},
_touchEndHandler : function(touchEvent){
// summary:
// action performed on the map when a touch end was triggered
// touchEvent: Event
// a touch event
// tags:
// private
event.stop(touchEvent);
var touches = touchEvent.touches;
if (touches.length == 0) {
// disconnect listeners only when all fingers are up
if (this._touchMoveListener) {
connect.disconnect(this._touchMoveListener);
this._touchMoveListener = null;
}
if (this._touchEndListener) {
connect.disconnect(this._touchEndListener);
this._touchEndListener = null;
}
} else {
// recompute touch center
var middlePoint = this._getTouchBarycenter(touchEvent);
this._centerTouchLocation = this._map.getLonLatFromPixel(new OpenLayers.Pixel(middlePoint.x, middlePoint.y));
}
},
_touchMoveHandler : function(touchEvent){
// summary:
// action performed on the map when a touch move was triggered
// touchEvent: Event
// a touch event
// tags:
// private
// prevent browser interaction
event.stop(touchEvent);
var middlePoint = this._getTouchBarycenter(touchEvent);
// compute map offset
var mapPoint = this._map.getLonLatFromPixel(new OpenLayers.Pixel(middlePoint.x, middlePoint.y));
var mapOffsetLon = mapPoint.lon - this._centerTouchLocation.lon;
var mapOffsetLat = mapPoint.lat - this._centerTouchLocation.lat;
// compute scale factor
var scaleFactor = 1;
var touches = touchEvent.touches;
if (touches.length >= 2) {
var fingerSpacing = this._getFingerSpacing(touchEvent);
scaleFactor = fingerSpacing / this._initialFingerSpacing;
// weird openlayer bug : setting several times the same scale value lead to visual zoom...
this._map.zoomToScale(this._initialScale / scaleFactor);
}
// adjust map center on barycenter
var currentMapCenter = this._map.getCenter();
this._map.setCenter(new OpenLayers.LonLat(currentMapCenter.lon - mapOffsetLon, currentMapCenter.lat
- mapOffsetLat));
}
});
});
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