VelocityTrackerCompat

public static void addMovement(@NonNull VelocityTracker tracker, @NonNull MotionEvent event)

Add a user's movement to the tracker.

For pointer events, you should call this for the initial ACTION_DOWN, the following ACTION_MOVE events that you receive, and the final ACTION_UP. You can, however, call this for whichever events you desire.

public static void clear(@NonNull VelocityTracker tracker)

Reset the velocity tracker back to its initial state.

public static void computeCurrentVelocity(@NonNull VelocityTracker tracker, int units)

Equivalent to invoking computeCurrentVelocity with a maximum velocity of Float.MAX_VALUE.

public static void computeCurrentVelocity(
    @NonNull VelocityTracker tracker,
    int units,
    float maxVelocity
)

Compute the current velocity based on the points that have been collected. Only call this when you actually want to retrieve velocity information, as it is relatively expensive. You can then retrieve the velocity with getAxisVelocity ()}.

public static float getAxisVelocity(@NonNull VelocityTracker tracker, int axis)

Equivalent to calling getAxisVelocity for axis and the active pointer.

public static float getAxisVelocity(@NonNull VelocityTracker tracker, int axis, int pointerId)

Retrieve the last computed velocity for a given motion axis. You must first call computeCurrentVelocity or computeCurrentVelocity before calling this function.

In addition to AXIS_X and AXIS_Y which have been supported since the introduction of this class, the following axes can be candidates for this method:

• AXIS_SCROLL: supported via the platform starting UPSIDE_DOWN_CAKE. Supported via a fallback logic at all platform levels for the active pointer only.

Before accessing velocities of an axis using this method, check that your VelocityTracker instance supports the axis by using isAxisSupported.

@ReplaceWith(expression = "tracker.getXVelocity(pointerId)")
public static float getXVelocity(VelocityTracker tracker, int pointerId)

Call getXVelocity. If running on a pre-HONEYCOMB device, returns getXVelocity.

@ReplaceWith(expression = "tracker.getYVelocity(pointerId)")
public static float getYVelocity(VelocityTracker tracker, int pointerId)

Call getYVelocity. If running on a pre-HONEYCOMB device, returns getYVelocity.

public static boolean isAxisSupported(@NonNull VelocityTracker tracker, int axis)

Checks whether a given velocity-trackable MotionEvent axis is supported for velocity tracking by this VelocityTracker instance (refer to getAxisVelocity for a list of potentially velocity-trackable axes).

Note that the value returned from this method will stay the same for a given instance, so a single check for axis support is enough per a VelocityTracker instance.

public static void recycle(@NonNull VelocityTracker tracker)

Return a VelocityTracker object back to be re-used by others.

Call this method for your VelocityTracker when you have finished tracking velocity for the use-case you created this tracker for and decided that you no longer need it. This allows it to be returned back to the pool of trackers to be re-used by others.

You must not touch the object after calling this function. That is, don't call any methods on it, or pass it as an input to any of this class' compat APIs, as the instance is no longer valid for velocity tracking.