/* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

package org.mozilla.gecko.gfx;

import android.os.Handler;
import android.os.Looper;
import android.view.Choreographer;
import org.mozilla.gecko.annotation.WrapForJNI;
import org.mozilla.gecko.mozglue.JNIObject;

/** This class receives HW vsync events through a {@link Choreographer}. */
@WrapForJNI
/* package */ final class AndroidVsync extends JNIObject implements Choreographer.FrameCallback {
  @WrapForJNI
  @Override // JNIObject
  protected native void disposeNative();

  private static final String LOGTAG = "AndroidVsync";

  /* package */ Choreographer mChoreographer;
  private volatile boolean mObservingVsync;

  public AndroidVsync() {
    final Handler mainHandler = new Handler(Looper.getMainLooper());
    mainHandler.post(
        new Runnable() {
          @Override
          public void run() {
            mChoreographer = Choreographer.getInstance();
            if (mObservingVsync) {
              mChoreographer.postFrameCallback(AndroidVsync.this);
            }
          }
        });
  }

  @WrapForJNI(stubName = "NotifyVsync")
  private native void nativeNotifyVsync(final long frameTimeNanos);

  // Choreographer callback implementation.
  public void doFrame(final long frameTimeNanos) {
    if (mObservingVsync) {
      mChoreographer.postFrameCallback(this);
      nativeNotifyVsync(frameTimeNanos);
    }
  }

  /**
   * Start/stop observing Vsync event.
   *
   * @param enable true to start observing; false to stop.
   * @return true if observing and false if not.
   */
  @WrapForJNI
  public synchronized boolean observeVsync(final boolean enable) {
    if (mObservingVsync != enable) {
      mObservingVsync = enable;

      if (mChoreographer != null) {
        if (enable) {
          mChoreographer.postFrameCallback(this);
        } else {
          mChoreographer.removeFrameCallback(this);
        }
      }
    }
    return mObservingVsync;
  }
}