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AutoFocusManager.java
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AutoFocusManager.java
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/*
* Copyright (C) 2012 ZXing authors
*
* 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 android.content.Context;
import android.content.SharedPreferences;
import android.hardware.Camera;
import android.os.AsyncTask;
import android.preference.PreferenceManager;
import android.util.Log;
import java.util.ArrayList;
import java.util.Collection;
import java.util.concurrent.RejectedExecutionException;
import com.google.zxing.client.android.PreferencesActivity;
@SuppressWarnings("deprecation") // camera APIs
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<>(2);
FOCUS_MODES_CALLING_AF.add(Camera.Parameters.FOCUS_MODE_AUTO);
FOCUS_MODES_CALLING_AF.add(Camera.Parameters.FOCUS_MODE_MACRO);
}
private boolean stopped;
private boolean focusing;
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) {
focusing = false;
autoFocusAgainLater();
}
private synchronized void autoFocusAgainLater() {
if (!stopped && outstandingTask == null) {
AutoFocusTask newTask = new AutoFocusTask();
try {
newTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
outstandingTask = newTask;
} catch (RejectedExecutionException ree) {
Log.w(TAG, "Could not request auto focus", ree);
}
}
}
synchronized void start() {
if (useAutoFocus) {
outstandingTask = null;
if (!stopped && !focusing) {
try {
camera.autoFocus(this);
focusing = true;
} catch (RuntimeException re) {
// Have heard RuntimeException reported in Android 4.0.x+; continue?
Log.w(TAG, "Unexpected exception while focusing", re);
// Try again later to keep cycle going
autoFocusAgainLater();
}
}
}
}
private synchronized void cancelOutstandingTask() {
if (outstandingTask != null) {
if (outstandingTask.getStatus() != AsyncTask.Status.FINISHED) {
outstandingTask.cancel(true);
}
outstandingTask = null;
}
}
synchronized void stop() {
stopped = true;
if (useAutoFocus) {
cancelOutstandingTask();
// Doesn't hurt to call this even if not focusing
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);
}
}
}
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
}
start();
return null;
}
}
}