Package com.google.ar.sceneform

Class TouchEventSystem

java.lang.Object

com.google.ar.sceneform.TouchEventSystem

public class TouchEventSystem
extends java.lang.Object

Manages propagation of touch events to node's within a scene.

The way that touch events are propagated mirrors the way touches are propagated to Android Views.

When an ACTION_DOWN event occurs, that represents that start of a gesture. ACTION_UP or ACTION_CANCEL represents when a gesture ends. When a gesture starts, the following is done:

• Call Node.dispatchTouchEvent(HitTestResult, MotionEvent) on the node that was touched as detected by scene.hitTest.
• If Node.dispatchTouchEvent(HitTestResult, MotionEvent) returns false, recurse upwards through the node's parents and call Node.dispatchTouchEvent(HitTestResult, MotionEvent) until one of the node's returns true.
• If every node returns false, the gesture is ignored and subsequent events that are part of the gesture will not be passed to any nodes.
• If one of the node's returns true, then that node will receive all future touch events for the gesture.

Constructor Summary

Constructors

Constructor	Description
TouchEventSystem()

Method Summary

Modifier and Type	Method	Description
void	addOnPeekTouchListener(Scene.OnPeekTouchListener onPeekTouchListener)	Adds a listener that will be called before the Scene.OnTouchListener is invoked.
Scene.OnTouchListener	getOnTouchListener()	Get the currently registered callback for touch events.
void	onTouchEvent(HitTestResult hitTestResult, android.view.MotionEvent motionEvent)
void	removeOnPeekTouchListener(Scene.OnPeekTouchListener onPeekTouchListener)	Removes a listener that will be called before the Scene.OnTouchListener is invoked.
void	setOnTouchListener(Scene.OnTouchListener onTouchListener)	Register a callback to be invoked when the scene is touched.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

TouchEventSystem

public TouchEventSystem()

Method Detail

getOnTouchListener

@Nullable
public Scene.OnTouchListener getOnTouchListener()

Get the currently registered callback for touch events.

Returns:

the attached touch listener

See Also:

setOnTouchListener(Scene.OnTouchListener)

setOnTouchListener

public void setOnTouchListener(@Nullable
                               Scene.OnTouchListener onTouchListener)

Register a callback to be invoked when the scene is touched. The callback is invoked before any node receives the event. If the callback handles the event, then the gesture is never received by the nodes.

Parameters:

onTouchListener - the touch listener to attach

addOnPeekTouchListener

public void addOnPeekTouchListener(Scene.OnPeekTouchListener onPeekTouchListener)

Adds a listener that will be called before the Scene.OnTouchListener is invoked. This is invoked even if the gesture was consumed, making it possible to observe all motion events dispatched to the scene. This is called even if the touch is not over a node, in which case HitTestResult.getNode() will be null. The listeners will be called in the order in which they were added.

Parameters:

onPeekTouchListener - the peek touch listener to add

removeOnPeekTouchListener

public void removeOnPeekTouchListener(Scene.OnPeekTouchListener onPeekTouchListener)

Removes a listener that will be called before the Scene.OnTouchListener is invoked. This is invoked even if the gesture was consumed, making it possible to observe all motion events dispatched to the scene. This is called even if the touch is not over a node, in which case HitTestResult.getNode() will be null.

Parameters:

onPeekTouchListener - the peek touch listener to remove

onTouchEvent

public void onTouchEvent(HitTestResult hitTestResult,
                         android.view.MotionEvent motionEvent)