ZoomTransaction.java

/***
  Copyright (c) 2013 CommonsWare, LLC
  
  Licensed under the Apache License, Version 2.0 (the "License"); you may
  not use this file except in compliance with the License. You may obtain
  a copy of the License at
    http://www.apache.org/licenses/LICENSE-2.0
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
 */

package com.commonsware.cwac.camera;

import android.hardware.Camera;
import android.hardware.Camera.OnZoomChangeListener;

/**
 * Class for processing a zoom request. Create an instance
 * of this by calling zoomTo() on a CameraFragment or
 * CameraView.
 */
final public class ZoomTransaction implements OnZoomChangeListener {
  private Camera camera;
  private int level;
  private Runnable onComplete=null;
  private OnZoomChangeListener onChange=null;

  /**
   * Local-only constructor. Please use zoomTo() on a
   * CameraFragment or CameraView to create your own
   * ZoomTransaction instances
   * 
   * @param camera
   * @param level
   */
  ZoomTransaction(Camera camera, int level) {
    this.camera=camera;
    this.level=level;
  }

  /**
   * Call this to specify a Runnable to be executed when the
   * zoom operation is complete.
   * 
   * @param onComplete
   *          a Runnable
   * @return the ZoomTransaction itself
   */
  public ZoomTransaction onComplete(Runnable onComplete) {
    this.onComplete=onComplete;

    return(this);
  }

  /**
   * Call this to specify an OnZoomChangeListener to be
   * notified of changes in the zoom level. For a smooth
   * zoom, this will be called for each change in the zoom
   * level. For a non-smooth zoom, this will be called once,
   * at the end.
   * 
   * @param onChange
   *          the listener for zoom change events
   * @return the ZoomTransaction itself
   */
  public ZoomTransaction onChange(OnZoomChangeListener onChange) {
    this.onChange=onChange;

    return(this);
  }

  /**
   * Actually performs the zoom. If smooth zooming is
   * supported, the zoom begins but happens asynchronously.
   * If smoooth zooming is not supported, the zoom happens
   * immediately, and your callback objects
   * (OnZoomChangedListener, Runnable) are immediately
   * invoked.
   */
  public void go() {
    Camera.Parameters params=camera.getParameters();

    if (params.isSmoothZoomSupported()) {
      camera.setZoomChangeListener(this);
      camera.startSmoothZoom(level);
    }
    else {
      params.setZoom(level);
      camera.setParameters(params);
      onZoomChange(level, true, camera);
    }
  }

  /**
   * Cancels an outstanding smooth zoom request. Call this
   * after go() and before your onCompleted Runnable is
   * invoked.
   */
  public void cancel() {
    camera.stopSmoothZoom();
  }

  /*
   * (non-Javadoc)
   * 
   * @see
   * android.hardware.Camera.OnZoomChangeListener#onZoomChange
   * (int, boolean, android.hardware.Camera)
   */
  @Override
  public void onZoomChange(int zoomValue, boolean stopped, Camera camera) {
    if (onChange != null) {
      onChange.onZoomChange(zoomValue, stopped, camera);
    }

    if (stopped && onComplete != null) {
      onComplete.run();
    }
  }
}