booleanavailable 

True if Image Tracking is available. This property will be false if no images were provided for the AR session or there was an error processing the provided images.

XrTrackedImage[]images 

List of XrTrackedImage that contain tracking information.

booleansupported 

True if Image Tracking is supported.

add(image, width) 

Add an image for image tracking. A width can also be provided to help the underlying system estimate the appropriate transformation. Modifying the tracked images list is only possible before an AR session is started.

// image with width of 20cm (0.2m)
app.xr.imageTracking.add(bookCoverImg, 0.2);

Parameters

image	HTMLCanvasElement, HTMLImageElement, SVGImageElement, HTMLVideoElement, Blob, ImageData, ImageBitmap	Image that is matching real world image as close as possible. Resolution of images should be at least 300x300. High resolution does NOT improve tracking performance. Color of image is irrelevant, so grayscale images can be used. Images with too many geometric features or repeating patterns will reduce tracking stability.
width	number	Width (in meters) of image in the real world. Providing this value as close to the real value will improve tracking quality.

Returns

XrTrackedImage, null

Tracked image object that will contain tracking information. Returns null if image tracking is not supported or if the XR manager is not active.

remove(trackedImage) 

Remove an image from image tracking.

Parameters

trackedImage

XrTrackedImage

Tracked image to be removed. Modifying the tracked images list is only possible before an AR session is started.

error 

Fired when the XR session is started, but image tracking failed to process the provided images.

Parameters

error

Error

Error object related to a failure of image tracking.

fire(name, [arg1], [arg2], [arg3], [arg4], [arg5], [arg6], [arg7], [arg8]) 

Fire an event, all additional arguments are passed on to the event listener.

obj.fire('test', 'This is the message');

Parameters

name	string	Name of event to fire.
arg1	*	First argument that is passed to the event handler.
arg2	*	Second argument that is passed to the event handler.
arg3	*	Third argument that is passed to the event handler.
arg4	*	Fourth argument that is passed to the event handler.
arg5	*	Fifth argument that is passed to the event handler.
arg6	*	Sixth argument that is passed to the event handler.
arg7	*	Seventh argument that is passed to the event handler.
arg8	*	Eighth argument that is passed to the event handler.

Returns

EventHandler

Self for chaining.

hasEvent(name) 

Test if there are any handlers bound to an event name.

obj.on('test', function () { }); // bind an event to 'test'
obj.hasEvent('test'); // returns true
obj.hasEvent('hello'); // returns false

Parameters

name

string

The name of the event to test.

Returns

boolean

True if the object has handlers bound to the specified event name.

off([name], [callback], [scope]) 

Detach an event handler from an event. If callback is not provided then all callbacks are unbound from the event, if scope is not provided then all events with the callback will be unbound.

const handler = function () {
};
obj.on('test', handler);

obj.off(); // Removes all events
obj.off('test'); // Removes all events called 'test'
obj.off('test', handler); // Removes all handler functions, called 'test'
obj.off('test', handler, this); // Removes all handler functions, called 'test' with scope this

Parameters

name	string	Name of the event to unbind.
callback	HandleEventCallback	Function to be unbound.
scope	object	Scope that was used as the this when the event is fired.

Returns

EventHandler

Self for chaining.

on(name, callback, [scope]) 

Attach an event handler to an event.

obj.on('test', function (a, b) {
    console.log(a + b);
});
obj.fire('test', 1, 2); // prints 3 to the console

const evt = obj.on('test', function (a, b) {
    console.log(a + b);
});
// some time later
evt.off();

Parameters

name	string	Name of the event to bind the callback to.
callback	HandleEventCallback	Function that is called when event is fired. Note the callback is limited to 8 arguments.
scope	object	Object to use as 'this' when the event is fired, defaults to current this.

Returns

EventHandle

Can be used for removing event in the future.

once(name, callback, [scope]) 

Attach an event handler to an event. This handler will be removed after being fired once.

obj.once('test', function (a, b) {
    console.log(a + b);
});
obj.fire('test', 1, 2); // prints 3 to the console
obj.fire('test', 1, 2); // not going to get handled

Parameters

name	string	Name of the event to bind the callback to.
callback	HandleEventCallback	Function that is called when event is fired. Note the callback is limited to 8 arguments.
scope	object	Object to use as 'this' when the event is fired, defaults to current this.

Returns

EventHandle

• can be used for removing event in the future.