goog.net.ImageLoader
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Image loader utility class. Raises a goog.events.EventType.LOAD
event for each image loaded, with an Image object as the target of
the event, normalized to have naturalHeight and naturalWidth
attributes.
To use this class, run:
const imageLoader = new goog.net.ImageLoader();
goog.events.listen(imageLoader, goog.net.EventType.COMPLETE,
function(e) { ... });
imageLoader.addImage("image_id", "http://path/to/image.gif");
imageLoader.start();
The start() method must be called to start image loading. Images can be added and removed after loading has started, but only those images added before start() was called will be loaded until start() is called again. A goog.net.EventType.COMPLETE event will be dispatched only once all outstanding images have completed uploading.
new ImageLoader( opt_parent )
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Instance Methods
this.addEventListener( type, handler, opt_capture, opt_handlerScope ) → void
voidAdds an event listener to the event target. The same handler can only be added once per the type. Even if you add the same handler multiple times using the same type then it will only be called once when the event is dispatched.
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this.addImage( id, image, opt_corsRequestType ) → void
voidAdds an image to the image loader, and associates it with the given ID
string. If an image with that ID already exists, it is silently replaced.
When the image in question is loaded, the target of the LOAD event will be
an Image object with id and src attributes based on
these arguments.
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this.addOnDisposeCallback<T>( callback, opt_scope ) → void
voidInvokes a callback function when this object is disposed. Callbacks are invoked in the order in which they were added. If a callback is added to an already disposed Disposable, it will be called immediately.
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this.dispatchEvent( e ) → boolean
booleanDispatches an event (or event like object) and calls all listeners listening for events of this type. The type of the event is decided by the type property on the event object.
If any of the listeners returns false OR calls preventDefault then this function will return false. If one of the capture listeners calls stopPropagation, then the bubble listeners won't fire.
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this.dispose() → ?
?Disposes of the object and its resources.
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this.disposeInternal() → void
voidRemoves listeners from this object. Classes that extend EventTarget may need to override this method in order to remove references to DOM Elements and additional listeners.
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this.fireListeners<EVENTOBJ>( type, capture, eventObject ) → boolean
booleanFires all registered listeners in this listenable for the given type and capture mode, passing them the given eventObject. This does not perform actual capture/bubble. Only implementors of the interface should be using this.
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this.getDisposed() → boolean
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this.getListener<SCOPE, EVENTOBJ>( type, listener, capture, opt_listenerScope ) → (goog.events.ListenableKey|null)
(goog.events.ListenableKey|null)Gets the goog.events.ListenableKey for the event or null if no such listener is in use.
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this.getListeners<EVENTOBJ>( type, capture ) → Array<goog.events.ListenableKey>
Array<goog.events.ListenableKey>Gets all listeners in this listenable for the given type and capture mode.
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this.getParentEventTarget() → (goog.events.Listenable|null)
(goog.events.Listenable|null)Returns the parent of this event target to use for capture/bubble mechanism.
NOTE(chrishenry): The name reflects the original implementation of
custom event target (goog.events.EventTarget). We decided
that changing the name is not worth it.
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this.hasListener<EVENTOBJ>( opt_type, opt_capture ) → boolean
booleanWhether there is any active listeners matching the specified signature. If either the type or capture parameters are unspecified, the function will match on the remaining criteria.
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this.isDisposed() → boolean
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this.listen<SCOPE, EVENTOBJ>( type, listener, opt_useCapture, opt_listenerScope ) → goog.events.ListenableKey
goog.events.ListenableKeyAdds an event listener. A listener can only be added once to an object and if it is added again the key for the listener is returned. Note that if the existing listener is a one-off listener (registered via listenOnce), it will no longer be a one-off listener after a call to listen().
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this.listenOnce<SCOPE, EVENTOBJ>( type, listener, opt_useCapture, opt_listenerScope ) → goog.events.ListenableKey
goog.events.ListenableKeyAdds an event listener that is removed automatically after the listener fired once.
If an existing listener already exists, listenOnce will do nothing. In particular, if the listener was previously registered via listen(), listenOnce() will not turn the listener into a one-off listener. Similarly, if there is already an existing one-off listener, listenOnce does not modify the listeners (it is still a once listener).
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this.registerDisposable( disposable ) → void
voidAssociates a disposable object with this object so that they will be disposed together.
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this.removeAllListeners( opt_type ) → number
numberRemoves all listeners from this listenable. If type is specified, it will only remove listeners of the particular type. otherwise all registered listeners will be removed.
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this.removeEventListener( type, handler, opt_capture, opt_handlerScope ) → void
voidRemoves an event listener from the event target. The handler must be the same object as the one added. If the handler has not been added then nothing is done.
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this.removeImage( id ) → void
voidRemoves the image associated with the given ID string from the image loader. If the image was previously loading, removes any listeners for its events.
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this.setParentEventTarget( parent ) → void
voidSets the parent of this event target to use for capture/bubble mechanism.
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this.setTargetForTesting( target ) → void
voidSets the target to be used for event.target when firing
event. Mainly used for testing. For example, see
goog.testing.events.mixinListenable.
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this.start() → void
voidStarts loading all images in the image loader in parallel. Raises a LOAD event each time an image finishes loading, and a COMPLETE event after all images have finished loading.
this.unlisten<SCOPE, EVENTOBJ>( type, listener, opt_useCapture, opt_listenerScope ) → boolean
booleanRemoves an event listener which was added with listen() or listenOnce().
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this.unlistenByKey( key ) → boolean
booleanRemoves an event listener which was added with listen() by the key returned by listen().
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Instance Properties
this.creationStack → (string|undefined)
(string|undefined)If monitoring the goog.Disposable instances is enabled, stores the creation stack trace of the Disposable instance.