Choreographer

public final class Choreographer
extends Object

Coordinates the timing of animations, input and drawing.

The choreographer receives timing pulses (such as vertical synchronization) from the display subsystem then schedules work to occur as part of rendering the next display frame.

Applications typically interact with the choreographer indirectly using higher level abstractions in the animation framework or the view hierarchy. Here are some examples of things you can do using the higher-level APIs.

• To post an animation to be processed on a regular time basis synchronized with display frame rendering, use start().
• To post a Runnable to be invoked once at the beginning of the next display frame, use postOnAnimation(Runnable).
• To post a Runnable to be invoked once at the beginning of the next display frame after a delay, use postOnAnimationDelayed(Runnable, long).
• To post a call to invalidate() to occur once at the beginning of the next display frame, use postInvalidateOnAnimation() or postInvalidateOnAnimation(int, int, int, int).
• To ensure that the contents of a View scroll smoothly and are drawn in sync with display frame rendering, do nothing. This already happens automatically. onDraw(Canvas) will be called at the appropriate time.

However, there are a few cases where you might want to use the functions of the choreographer directly in your application. Here are some examples.

• If your application does its rendering in a different thread, possibly using GL, or does not use the animation framework or view hierarchy at all and you want to ensure that it is appropriately synchronized with the display, then use postFrameCallback(Choreographer.FrameCallback).
• ... and that's about it.

Each Looper thread has its own choreographer. Other threads can post callbacks to run on the choreographer but they will run on the Looper to which the choreographer belongs.

Summary

Inherited methods

From class java.lang.Object Object clone() Creates and returns a copy of this object. boolean equals(Object obj) Indicates whether some other object is "equal to" this one. void finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. final Class<?> getClass() Returns the runtime class of this Object. int hashCode() Returns a hash code value for the object. final void notify() Wakes up a single thread that is waiting on this object's monitor. final void notifyAll() Wakes up all threads that are waiting on this object's monitor. String toString() Returns a string representation of the object. final void wait(long millis, int nanos) Causes the current thread to wait until another thread invokes the notify() method or the notifyAll() method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed. final void wait(long millis) Causes the current thread to wait until either another thread invokes the notify() method or the notifyAll() method for this object, or a specified amount of time has elapsed. final void wait() Causes the current thread to wait until another thread invokes the notify() method or the notifyAll() method for this object.

Public methods

Choreographer getInstance ()

void postFrameCallback (Choreographer.FrameCallback callback)

void postFrameCallbackDelayed (Choreographer.FrameCallback callback, 
                long delayMillis)

void removeFrameCallback (Choreographer.FrameCallback callback)