tap.js

define(["./base/lang"], function(lang){
// module:
//		dojo/gesture/tap
// summary:
//		This module provides tap gesture event handlers
//		- dojo.gesture.tap -> to fire 'tap' event
//		- dojo.gesture.tap.hold -> to fire 'tap.hold' event
//		- dojo.gesture.tap.doubletap -> to fire 'tap.doubletap' event
// example:
//		A. Used with dojo.connect()
//		|	dojo.connect(node, dojo.gesture.tap, function(e){});
//		|	dojo.connect(node, dojo.gesture.tap.hold, function(e){});
//		|	dojo.connect(node, dojo.gesture.tap.doubletap, function(e){});		
//
//		B. Used with dojo.on
//		|	define(["dojo/on", "dojo/gesture/tap"], function(on, tap){
//		|		on(node, tap, function(e){});
//		|		on(node, tap.hold, function(e){});
//		|		on(node, tap.doubletap, function(e){});
//
//		C. Used with dojo.gesture.tap.* directly
//		|	dojo.gesture.tap(node, function(e){});
//		|	dojo.gesture.tap.hold(node, function(e){});
//		|	dojo.gesture.tap.doubletap(node, function(e){});
//
//		Though there is always a default singleton gesture instance after being required, e.g 
//		|	require(["dojo/gesture/tap"], function(){...});
//		It's possible to unRegister it and create a new one with different parameter setting:
//		|	dojo.gesture.unRegister(dojo.gesture.tap);
//		|	var myTap = new dojo.gesture.tap.Tap({holdThreshold: 300});
//		|	dojo.gesture.register(myTap);
//		|	dojo.connect(node, myTap, function(e){});
//		|	dojo.connect(node, myTap.hold, function(e){});
//		|	dojo.connect(node, myTap.doubletap, function(e){});

function Tap(settings){
	settings = lang.mixin({
		holdThreshold: 500,
		doubleTapTimeout: 250,
		tapRadius: 10,
		type: "tap"
	}, settings);
	var data = {};
	function isTap(data, e){
		var dx = Math.abs(data.tapContext.x - e.screenX);
		var dy = Math.abs(data.tapContext.y - e.screenY);
		return dx <= this.tapRadius && dy <= this.tapRadius;
	}
	return function(node, listener){
		on(node, "touchstart", function(){
			if(e.touches && e.touches.length >= 2){
				//tap gesture is only for single touch
				delete data.tapContext;
				return;
			}
			var target = e.currentTarget;
			if(!data.tapContext){
				data.tapContext = {x: 0, y: 0, t: 0, c: 0};
			}
			var ct = new Date().getTime();
			if(ct - data.tapContext.t <= this.doubleTapTimeout){
				data.tapContext.c++;
			}else{
				data.tapContext.c = 1;
				data.tapContext.x = e.screenX;
				data.tapContext.y = e.screenY;
			}
			data.tapContext.t = ct;
			clearTimeout(data.tapTimeOut);
			data.tapTimeOut = setTimeout(function(){
				if(type == "hold" && isTap(data, e)){
					listener(e);
				}
				clearTimeout(data.tapTimeOut);
				delete data.tapContext;
			}, settings.holdThreshold);
		});
		on(node, "touchend", function(e){
			if(!data.tapContext){
				clearTimeout(data.tapTimeOut);
				return;
			}
			switch(data.tapContext.c){
			case 1: 
				if(type == 'tap'){
					listener(e);
				}
				break;
			case 2:
				if(isTap(data, e) && type == "doubletap"){
					listener(e);
				}
				break;
			}
		});
	}
}
var tap = new Tap();
tap.Tap = Tap;
tap.doubletap = Tap({type:"doubletap"});
tap.hold = Tap({type:"hold"});
});