source: Dev/trunk/src/client/dojox/gesture/tap.js

define([
        "dojo/_base/kernel",
        "dojo/_base/declare",
        "dojo/_base/lang",
        "./Base",
        "../main"
], function(kernel, declare, lang, Base, dojox){
// module:
//              dojox/gesture/tap
        
/*=====
        dojox.gesture.tap = {
                // summary:
                //              This module provides tap gesture event handlers:
                //
                //              1. dojox.gesture.tap: 'tap' event
                //
                //              2. dojox.gesture.tap.hold: 'tap.hold' event
                //
                //              3. dojox.gesture.tap.doubletap: 'tap.doubletap' event
                //
                // example:
                //              A. Used with dojo.connect()
                //              |       dojo.connect(node, dojox.gesture.tap, function(e){});
                //              |       dojo.connect(node, dojox.gesture.tap.hold, function(e){});
                //              |       dojo.connect(node, dojox.gesture.tap.doubletap, function(e){});
                //
                //              B. Used with dojo.on
                //              |       define(['dojo/on', 'dojox/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 dojox.gesture.tap.* directly
                //              |       dojox.gesture.tap(node, function(e){});
                //              |       dojox.gesture.tap.hold(node, function(e){});
                //              |       dojox.gesture.tap.doubletap(node, function(e){});
                //
                //              Though there is always a default gesture instance after being required, e.g
                //              |       require(['dojox/gesture/tap'], function(){...});
                //
                //              It's possible to create a new one with different parameter setting:
                //              |       var myTap = new dojox.gesture.tap.Tap({holdThreshold: 300});
                //              |       dojo.connect(node, myTap, function(e){});
                //              |       dojo.connect(node, myTap.hold, function(e){});
                //              |       dojo.connect(node, myTap.doubletap, function(e){});
        };
=====*/

kernel.experimental("dojox.gesture.tap");

// Declare an internal anonymous class which will only be exported
// by module return value e.g. dojox.gesture.tap.Tap
var clz = declare(/*===== "dojox.gesture.tap", =====*/Base, {
        // defaultEvent: [readonly] String
        //              Default event - 'tap'
        defaultEvent: "tap",

        // subEvents: [readonly] Array
        //              List of sub events, used by being
        //              combined with defaultEvent as 'tap.hold', 'tap.doubletap'.
        subEvents: ["hold", "doubletap"],

        // holdThreshold: Integer
        //              Threshold(in milliseconds) for 'tap.hold'
        holdThreshold: 500,

        // holdThreshold: Integer
        //              Timeout (in milliseconds) for 'tap.doubletap'
        doubleTapTimeout: 250,

        // tapRadius: Integer
        //              Valid tap radius from previous touch point
        tapRadius: 10,

        press: function(/*Object*/data, /*Event*/e){
                // summary:
                //              Overwritten, record initial tap info and register a timeout checker for 'tap.hold'
                if(e.touches && e.touches.length >= 2){
                        //tap gesture is only for single touch
                        clearTimeout(data.tapTimeOut); 
                        delete data.context;
                        return;
                }
                var target = e.target;
                this._initTap(data, e);
                data.tapTimeOut = setTimeout(lang.hitch(this, function(){
                        if(this._isTap(data, e)){
                                this.fire(target, {type: "tap.hold"});
                        }
                        delete data.context;
                }), this.holdThreshold);
        },
        release: function(/*Object*/data, /*Event*/e){
                // summary:
                //              Overwritten, fire matched 'tap' or 'tap.doubletap' during touchend
                if(!data.context){
                        clearTimeout(data.tapTimeOut);
                        return;
                }
                if(this._isTap(data, e)){
                        switch(data.context.c){
                        case 1: 
                                this.fire(e.target, {type: "tap"});
                                break;
                        case 2:
                                this.fire(e.target, {type: "tap.doubletap"});
                                break;
                        }
                }
                clearTimeout(data.tapTimeOut);
        },
        _initTap: function(/*Object*/data, /*Event*/e){
                // summary:
                //              Update the gesture data with new tap info 
                if(!data.context){
                        data.context = {x: 0, y: 0, t: 0, c: 0};
                }
                var ct = new Date().getTime();
                if(ct - data.context.t <= this.doubleTapTimeout){
                        data.context.c++;
                }else{
                        data.context.c = 1;
                        data.context.x = e.screenX;
                        data.context.y = e.screenY;
                }
                data.context.t = ct;
        },
        _isTap: function(/*Object*/data, /*Event*/e){
                // summary:
                //              Check whether it's an valid tap
                var dx = Math.abs(data.context.x - e.screenX);
                var dy = Math.abs(data.context.y - e.screenY);
                return dx <= this.tapRadius && dy <= this.tapRadius;
        }
});

// the default tap instance for handy use
dojox.gesture.tap = new clz();
// Class for creating a new Tap instance
dojox.gesture.tap.Tap = clz;

return dojox.gesture.tap;

});