https://gladstonehs.sa.edu.au/app/js/jSignature/src/plugins/jSignature.UndoButton.js

1/** @license
2jSignature v2 jSignature's Undo Button and undo functionality plugin
3
4*/
5/**
6Copyright (c) 2011 Willow Systems Corp http://willow-systems.com
7MIT License <http://www.opensource.org/licenses/mit-license.php>
8*/
9
10;(function(){
11
12	var apinamespace = 'jSignature'
13
14	function attachHandlers(buttonRenderer, apinamespace, extensionName) {
15		var $undoButton = buttonRenderer.call(this)
16
17		;(function(jSignatureInstance, $undoButton, apinamespace) {
18			jSignatureInstance.events.subscribe(
19				apinamespace + '.change'
20				, function(){
21					if (jSignatureInstance.dataEngine.data.length) {
22						$undoButton.show()
23					} else {
24						$undoButton.hide()
25					}
26				}
27			)
28		})( this, $undoButton, apinamespace )
29
30		;(function(jSignatureInstance, $undoButton, apinamespace) {
31
32			var eventName = apinamespace + '.undo'
33
34			$undoButton.bind('click', function(){
35				jSignatureInstance.events.publish(eventName)
36			})
37
38			// This one creates new "undo" event listener to jSignature instance
39			// It handles the actual undo-ing.
40			jSignatureInstance.events.subscribe(
41				eventName
42				, function(){
43					var data = jSignatureInstance.dataEngine.data
44					if (data.length) {
45						data.pop()
46						jSignatureInstance.resetCanvas(data)
47					}
48				}
49			)
50		})( 
51			this
52			, $undoButton
53			, this.events.topics.hasOwnProperty( apinamespace + '.undo' ) ? 
54				// oops, seems some other plugin or code has already claimed "jSignature.undo" event
55				// we will use this extension's name for event name prefix
56				extensionName :
57				// Great! we will use 'jSignature' for event name prefix.
58				apinamespace
59		)
60	}
61
62	function ExtensionInitializer(extensionName){
63		// we are called very early in instance's life.
64		// right after the settings are resolved and 
65		// jSignatureInstance.events is created 
66		// and right before first ("jSignature.initializing") event is called.
67		// You don't really need to manupilate 
68		// jSignatureInstance directly, just attach
69		// a bunch of events to jSignatureInstance.events
70		// (look at the source of jSignatureClass to see when these fire)
71		// and your special pieces of code will attach by themselves.
72
73		// this function runs every time a new instance is set up.
74		// this means every var you create will live only for one instance
75		// unless you attach it to something outside, like "window."
76		// and pick it up later from there.
77
78		// when globalEvents' events fire, 'this' is globalEvents object
79		// when jSignatureInstance's events fire, 'this' is jSignatureInstance
80
81		// Here,
82		// this = is new jSignatureClass's instance.
83
84		// The way you COULD approch setting this up is:
85		// if you have multistep set up, attach event to "jSignature.initializing"
86		// that attaches other events to be fired further lower the init stream.
87		// Or, if you know for sure you rely on only one jSignatureInstance's event,
88		// just attach to it directly
89
90		var apinamespace = 'jSignature'
91
92		this.events.subscribe(
93			// name of the event
94			apinamespace + '.attachingEventHandlers'
95			// event handlers, can pass args too, but in majority of cases,
96			// 'this' which is jSignatureClass object instance pointer is enough to get by.
97			, function(){
98
99				// hooking up "undo" button	to lower edge of Canvas.
100				// but only when options passed to jSignature('init', options)
101				// contain "undoButton":renderingFunction pair.
102				// or "undoButton":true (in which case default, internal rendering fn is used)
103				if (this.settings[extensionName]) {
104					var oursettings = this.settings[extensionName]
105					if (typeof oursettings !== 'function') {
106						// we make it a function.
107
108						// we allow people to override the button rendering code,
109						// but when developler is OK with default look (and just passes "truthy" value)
110						// this defines default look for the button:
111						// centered against canvas, hanging on its lower side.
112						oursettings = function(){
113							// this === jSignatureInstance 
114							var undoButtonSytle = 'position:absolute;display:none;margin:0 !important;top:auto'
115							, $undoButton = $('<input type="button" value="Undo last stroke" style="'+undoButtonSytle+'" />')
116								.appendTo(this.$controlbarLower)
117
118							// this centers the button against the canvas.
119							var buttonWidth = $undoButton.width()
120							$undoButton.css(
121								'left'
122								, Math.round(( this.canvas.width - buttonWidth ) / 2)
123							)
124							// IE 7 grows the button. Correcting for that.
125							if ( buttonWidth !== $undoButton.width() ) {
126								$undoButton.width(buttonWidth)
127							}
128
129							return $undoButton
130						}
131					}
132
133					attachHandlers.call( 
134						this
135						, oursettings
136						, apinamespace
137						, extensionName
138					)
139				}
140			}
141		)
142	}
143
144	var ExtensionAttacher = function(){
145		$.fn[apinamespace](
146			'addPlugin'
147			,'instance' // type of plugin
148			,'UndoButton' // extension name
149			,ExtensionInitializer
150		)
151	}
152	
153
154//  //Because plugins are minified together with jSignature, multiple defines per (minified) file blow up and dont make sense
155//	//Need to revisit this later.
156	
157//	if ( typeof define === "function" && define.amd != null) {
158//		// AMD-loader compatible resource declaration
159//		// you need to call this one with jQuery as argument.
160//		define(function(){return Initializer} )
161//	} else {
162		ExtensionAttacher()
163//	}
164
165})();