Android Open Source - final_app Auto Focus Manager

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The source code is released under:

CC0 1.0 Universal Statement of Purpose The laws of most jurisdictions throughout the world automatically confer exclusive Copyright and Related Rights (defined below) upon the creator and subsequent...

Java Source Code

/*
 * Copyright (C) 2012 ZXing authors/*from   w  w  w . j ava  2s.  c  o  m*/
 *
 * 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.google.zxing.client.android.camera;

import java.util.ArrayList;
import java.util.Collection;

import android.content.Context;
import android.content.SharedPreferences;
import android.hardware.Camera;
import android.os.AsyncTask;
import android.preference.PreferenceManager;
import android.util.Log;

import com.google.zxing.client.android.PreferencesActivity;

final class AutoFocusManager implements Camera.AutoFocusCallback {

  private static final String TAG = AutoFocusManager.class.getSimpleName();

  private static final long AUTO_FOCUS_INTERVAL_MS = 2000L;
  private static final Collection<String> FOCUS_MODES_CALLING_AF;
  static {
    FOCUS_MODES_CALLING_AF = new ArrayList<String>(2);
    FOCUS_MODES_CALLING_AF.add(Camera.Parameters.FOCUS_MODE_AUTO);
    FOCUS_MODES_CALLING_AF.add(Camera.Parameters.FOCUS_MODE_MACRO);
  }

  private boolean active;
  private final boolean useAutoFocus;
  private final Camera camera;
  private AsyncTask<?, ?, ?> outstandingTask;

  AutoFocusManager(Context context, Camera camera) {
    this.camera = camera;
    SharedPreferences sharedPrefs = PreferenceManager.getDefaultSharedPreferences(context);
    String currentFocusMode = camera.getParameters().getFocusMode();
    useAutoFocus = sharedPrefs.getBoolean(PreferencesActivity.KEY_AUTO_FOCUS, true) && FOCUS_MODES_CALLING_AF.contains(currentFocusMode);
    Log.i(TAG, "Current focus mode '" + currentFocusMode + "'; use auto focus? " + useAutoFocus);
    start();
  }

  @Override
  public synchronized void onAutoFocus(boolean success, Camera theCamera) {
    if (active) {
      outstandingTask = new AutoFocusTask();
      outstandingTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
    }
  }

  synchronized void start() {
    if (useAutoFocus) {
      active = true;
      try {
        camera.autoFocus(this);
      } catch (RuntimeException re) {
        // Have heard RuntimeException reported in Android 4.0.x+; continue?
        Log.w(TAG, "Unexpected exception while focusing", re);
      }
    }
  }

  synchronized void stop() {
    if (useAutoFocus) {
      try {
        camera.cancelAutoFocus();
      } catch (RuntimeException re) {
        // Have heard RuntimeException reported in Android 4.0.x+; continue?
        Log.w(TAG, "Unexpected exception while cancelling focusing", re);
      }
    }
    if (outstandingTask != null) {
      outstandingTask.cancel(true);
      outstandingTask = null;
    }
    active = false;
  }

  private final class AutoFocusTask extends AsyncTask<Object, Object, Object> {
    @Override
    protected Object doInBackground(Object... voids) {
      try {
        Thread.sleep(AUTO_FOCUS_INTERVAL_MS);
      } catch (InterruptedException e) {
        // continue
      }
      synchronized (AutoFocusManager.this) {
        if (active) {
          start();
        }
      }
      return null;
    }
  }

}

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