ALKMaps.Event

Utility functions for event handling.

Summary

ALKMaps.Event	Utility functions for event handling.
Properties
observers	{Object} A hashtable cache of the event observers.
Constants
KEY_SPACE	{int}
KEY_BACKSPACE	{int}
KEY_TAB	{int}
KEY_RETURN	{int}
KEY_ESC	{int}
KEY_LEFT	{int}
KEY_UP	{int}
KEY_RIGHT	{int}
KEY_DOWN	{int}
KEY_DELETE	{int}
Functions
element	Cross browser event element detection.
isSingleTouch	Determine whether event was caused by a single touch
isMultiTouch	Determine whether event was caused by a multi touch
isLeftClick	Determine whether event was caused by a left click.
isRightClick	Determine whether event was caused by a right mouse click.
stop	Stops an event from propagating.
findElement
observe
stopObservingElement	Given the id of an element to stop observing, cycle through the element’s cached observers, calling stopObserving on each one, skipping those entries which can no longer be removed.
_removeElementObservers
stopObserving
unloadCache	Cycle through all the element entries in the events cache and call stopObservingElement on each.
ALKMaps.Events
Constants
BROWSER_EVENTS	{Array(String)} supported events
Properties
listeners	{Object} Hashtable of Array(Function): events listener functions
object	{Object} the code object issuing application events
element	{DOMElement} the DOM element receiving browser events
fallThrough	{Boolean}
includeXY	{Boolean} Should the .xy property automatically be created for browser mouse events?
extensions	{Object} Event extensions registered with this instance.
extensionCount	{Object} Keys are event types (like in listeners), values are the number of extension listeners for each event type.
Functions
clearMouseListener	A version of clearMouseCache that is bound to this instance so that it can be used with ALKMaps.Event.observe and ALKMaps.Event.stopObserving.
Constructor
ALKMaps.Events	Construct an ALKMaps.Events object.
Functions
destroy
addEventType	Deprecated.
attachToElement
on	Convenience method for registering listeners with a common scope.
register	Register an event on the events object.
registerPriority	Same as register() but adds the new listener to the front of the events queue instead of to the end.
un	Convenience method for unregistering listeners with a common scope.
unregister
remove	Remove all listeners for a given event type.
triggerEvent	Trigger a specified registered event.
handleBrowserEvent	Basically just a wrapper to the triggerEvent() function, but takes care to set a property ‘xy’ on the event with the current mouse position.
clearMouseCache	Clear cached data about the mouse position.
getMousePosition

Properties

observers

{Object} A hashtable cache of the event observers. Keyed by element._eventCacheID

Constants

KEY_SPACE

{int}

KEY_BACKSPACE

{int}

KEY_TAB

{int}

KEY_RETURN

{int}

KEY_ESC

{int}

KEY_LEFT

{int}

KEY_UP

{int}

KEY_RIGHT

{int}

KEY_DOWN

{int}

KEY_DELETE

{int}

Functions

element

element: function( event )

Cross browser event element detection.

Parameters

event

{Event}

Returns

{DOMElement} The element that caused the event

isSingleTouch

isSingleTouch: function( event )

Determine whether event was caused by a single touch

Parameters

event

{Event}

Returns

{Boolean}

isMultiTouch

isMultiTouch: function( event )

Determine whether event was caused by a multi touch

Parameters

event

{Event}

Returns

{Boolean}

isLeftClick

isLeftClick: function( event )

Determine whether event was caused by a left click.

Parameters

event

{Event}

Returns

{Boolean}

isRightClick

isRightClick: function( event )

Determine whether event was caused by a right mouse click.

Parameters

event

{Event}

Returns

{Boolean}

stop

stop: function( event,
allowDefault )

Stops an event from propagating.

Parameters

event	{Event}
allowDefault	{Boolean} If true, we stop the event chain but still allow the default browser behavior (text selection, radio-button clicking, etc). Default is false.

findElement

findElement: function( event,
tagName )

Parameters

event	{Event}
tagName	{String}

Returns

{DOMElement} The first node with the given tagName, starting from the node the event was triggered on and traversing the DOM upwards

observe

observe: function( elementParam,
name,
observer,
useCapture )

Parameters

elementParam	{DOMElement \|\| String}
name	{String}
observer	{function}
useCapture	{Boolean}

stopObservingElement

stopObservingElement: function( elementParam )

Given the id of an element to stop observing, cycle through the element’s cached observers, calling stopObserving on each one, skipping those entries which can no longer be removed.

parameters

elementParam

{DOMElement || String}

_removeElementObservers

_removeElementObservers: function( elementObservers )

Parameters

elementObservers

{Array(Object)} Array of (element, name, observer, usecapture) objects, taken directly from hashtable

stopObserving

stopObserving: function( elementParam,
name,
observer,
useCapture )

Parameters

elementParam	{DOMElement \|\| String}
name	{String}
observer	{function}
useCapture	{Boolean}

Returns

{Boolean} Whether or not the event observer was removed

unloadCache

unloadCache: function()

Cycle through all the element entries in the events cache and call stopObservingElement on each.

ALKMaps.Events

Summary

Constants
BROWSER_EVENTS	{Array(String)} supported events
Properties
listeners	{Object} Hashtable of Array(Function): events listener functions
object	{Object} the code object issuing application events
element	{DOMElement} the DOM element receiving browser events
fallThrough	{Boolean}
includeXY	{Boolean} Should the .xy property automatically be created for browser mouse events?
extensions	{Object} Event extensions registered with this instance.
extensionCount	{Object} Keys are event types (like in listeners), values are the number of extension listeners for each event type.
Functions
clearMouseListener	A version of clearMouseCache that is bound to this instance so that it can be used with ALKMaps.Event.observe and ALKMaps.Event.stopObserving.
Constructor
ALKMaps.Events	Construct an ALKMaps.Events object.
Functions
destroy
addEventType	Deprecated.
attachToElement
on	Convenience method for registering listeners with a common scope.
register	Register an event on the events object.
registerPriority	Same as register() but adds the new listener to the front of the events queue instead of to the end.
un	Convenience method for unregistering listeners with a common scope.
unregister
remove	Remove all listeners for a given event type.
triggerEvent	Trigger a specified registered event.
handleBrowserEvent	Basically just a wrapper to the triggerEvent() function, but takes care to set a property ‘xy’ on the event with the current mouse position.
clearMouseCache	Clear cached data about the mouse position.
getMousePosition

Constants

BROWSER_EVENTS

{Array(String)} supported events

Properties

listeners

{Object} Hashtable of Array(Function): events listener functions

object

{Object} the code object issuing application events

element

{DOMElement} the DOM element receiving browser events

fallThrough

{Boolean}

includeXY

{Boolean} Should the .xy property automatically be created for browser mouse events? In general, this should be false. If it is true, then mouse events will automatically generate a ‘.xy’ property on the event object that is passed. (Prior to ALKMaps 2.7, this was true by default.) Otherwise, you can call the getMousePosition on the relevant events handler on the object available via the ‘evt.object’ property of the evt object. So, for most events, you can call: function named(evt) { this.xy = this.object.events.getMousePosition(evt) }

This option typically defaults to false for performance reasons

when creating an events object whose primary purpose is to manage relatively positioned mouse events within a div, it may make sense to set it to true.

This option is also used to control whether the events object caches offsets. If this is false, it will not: the reason for this is that it is only expected to be called many times if the includeXY property is set to true. If you set this to true, you are expected to clear the offset cache manually (using this.clearMouseCache()) if: the border of the element changes the location of the element in the page changes

extensions

{Object} Event extensions registered with this instance. Keys are event types, values are {ALKMaps.Events.*} extension instances or {Boolean} for events that an instantiated extension provides in addition to the one it was created for.

Extensions create an event in addition to browser events, which usually fires when a sequence of browser events is completed. Extensions are automatically instantiated when a listener is registered for an event provided by an extension.

Extensions are created in the ALKMaps.Events namespace using <ALKMaps.Class>, and named after the event they provide. The constructor receives the target ALKMaps.Events instance as argument. Extensions that need to capture browser events before they propagate can register their listeners events using register, with {extension: true} as 4th argument.

If an extension creates more than one event, an alias for each event type should be created and reference the same class. The constructor should set a reference in the target’s extensions registry to itself.

Below is a minimal extension that provides the “foostart” and “fooend” event types, which replace the native “click” event type if clicked on an element with the css class “foo”:

ALKMaps.Events.foostart = ALKMaps.Class({
    initialize: function(target) {
        this.target = target;
        this.target.register("click", this, this.doStuff, {extension: true});
        // only required if extension provides more than one event type
        this.target.extensions["foostart"] = true;
        this.target.extensions["fooend"] = true;
    },
    destroy: function() {
        var target = this.target;
        target.unregister("click", this, this.doStuff);
        delete this.target;
        // only required if extension provides more than one event type
        delete target.extensions["foostart"];
        delete target.extensions["fooend"];
    },
    doStuff: function(evt) {
        var propagate = true;
        if (ALKMaps.Event.element(evt).className === "foo") {
            propagate = false;
            var target = this.target;
            target.triggerEvent("foostart");
            window.setTimeout(function() {
                target.triggerEvent("fooend");
            }, 1000);
        }
        return propagate;
    }
});
// only required if extension provides more than one event type
ALKMaps.Events.fooend = ALKMaps.Events.foostart;

extensionCount

{Object} Keys are event types (like in listeners), values are the number of extension listeners for each event type.

Functions

clearMouseListener

A version of clearMouseCache that is bound to this instance so that it can be used with ALKMaps.Event.observe and ALKMaps.Event.stopObserving.

Constructor

ALKMaps.Events

Construct an ALKMaps.Events object.

Parameters

object	{Object} The js object to which this Events object is being added
element	{DOMElement} A dom element to respond to browser events
eventTypes	{Array(String)} Deprecated. Array of custom application events. A listener may be registered for any named event, regardless of the values provided here.
fallThrough	{Boolean} Allow events to fall through after these have been handled?
options	{Object} Options for the events object.

Functions

destroy

destroy: function ()

addEventType

addEventType: function( eventName )

Deprecated. Any event can be triggered without adding it first.

Parameters

eventName

{String}

attachToElement

attachToElement: function ( element )

Parameters

element

{HTMLDOMElement} a DOM element to attach browser events to

on

on: function( object )

Convenience method for registering listeners with a common scope. Internally, this method calls register as shown in the examples below.

Example use

// register a single listener for the "loadstart" event
events.on({"loadstart": loadStartListener});

// this is equivalent to the following
events.register("loadstart", undefined, loadStartListener);

// register multiple listeners to be called with the same `this` object
events.on({
    "loadstart": loadStartListener,
    "loadend": loadEndListener,
    scope: object
});

// this is equivalent to the following
events.register("loadstart", object, loadStartListener);
events.register("loadend", object, loadEndListener);

Parameters

object

{Object}

register

register: function ( type,
obj,
func,
priority )

When the event is triggered, the ‘func’ function will be called, in the context of ‘obj’. Imagine we were to register an event, specifying an ALKMaps.Bounds Object as ‘obj’. When the event is triggered, the context in the callback function will be our Bounds object. This means that within our callback function, we can access the properties and methods of the Bounds object through the “this” variable. So our callback could execute something like:

leftStr = "Left: " + this.left;

centerStr = "Center: " + this.getCenterLonLat();

Parameters

type	{String} Name of the event to register
obj	{Object} The object to bind the context to for the callback#. If no object is specified, default is the Events’s ‘object’ property.
func	{Function} The callback function. If no callback is specified, this function does nothing.
priority	{Boolean\|Object} If true, adds the new listener to the front of the events queue instead of to the end.

Valid options for priority

extension	{Boolean} If true, then the event will be registered as extension event. Extension events are handled before all other events.
always	{Boolean} If true, event listener will always be triggered even if event propagation is stopped for a particular event.

registerPriority

registerPriority: function ( type,
obj,
func )

Same as register() but adds the new listener to the front of the events queue instead of to the end.

Parameters

type	{String} Name of the event to register
obj	{Object} The object to bind the context to for the callback#. If no object is specified, default is the Events’s ‘object’ property.
func	{Function} The callback function. If no callback is specified, this function does nothing.

un

un: function( object )

Convenience method for unregistering listeners with a common scope. Internally, this method calls unregister as shown in the examples below.

Example use

// unregister a single listener for the "loadstart" event
events.un({"loadstart": loadStartListener});

// this is equivalent to the following
events.unregister("loadstart", undefined, loadStartListener);

// unregister multiple listeners with the same `this` object
events.un({
    "loadstart": loadStartListener,
    "loadend": loadEndListener,
    scope: object
});

// this is equivalent to the following
events.unregister("loadstart", object, loadStartListener);
events.unregister("loadend", object, loadEndListener);

unregister

unregister: function ( type,
obj,
func )

Parameters

type	{String}
obj	{Object} If none specified, defaults to this.object
func	{Function}

remove

remove: function( type )

Remove all listeners for a given event type. If type is not registered, does nothing.

Parameters

type

{String}

triggerEvent

triggerEvent: function ( type,
evt )

Trigger a specified registered event.

Parameters

type	{String}
evt	{Event}

Returns

{Boolean} The last listener return. If a listener returns false, the chain of listeners will stop getting called.

handleBrowserEvent

handleBrowserEvent: function ( evt )

Basically just a wrapper to the triggerEvent() function, but takes care to set a property ‘xy’ on the event with the current mouse position.

Parameters

evt

{Event}

clearMouseCache

clearMouseCache: function()

Clear cached data about the mouse position. This should be called any time the element that events are registered on changes position within the page.

getMousePosition

getMousePosition: function ( evt )

Parameters

evt

{Event}

Returns

{ALKMaps.Pixel} The current xy coordinate of the mouse, adjusted for offsets