LifecycleCameraController.java
/*
* Copyright 2020 The Android Open Source Project
*
* 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 androidx.camera.view;
import static androidx.annotation.RestrictTo.Scope.TESTS;
import android.Manifest;
import android.annotation.SuppressLint;
import android.content.Context;
import android.util.Log;
import androidx.annotation.MainThread;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.RequiresPermission;
import androidx.annotation.RestrictTo;
import androidx.annotation.experimental.UseExperimental;
import androidx.camera.core.Camera;
import androidx.camera.core.UseCase;
import androidx.camera.core.UseCaseGroup;
import androidx.camera.core.impl.utils.Threads;
import androidx.camera.lifecycle.ExperimentalUseCaseGroupLifecycle;
import androidx.camera.lifecycle.ProcessCameraProvider;
import androidx.lifecycle.LifecycleOwner;
/**
* A controller that provides most of the CameraX features.
*
* <p> This a high level controller that provides most of the CameraX core features
* in a single class. It handles camera initialization, creates and configures {@link UseCase}s,
* and bind them to a {@link LifecycleOwner} when ready. It also listens to device motion sensor
* and set the target rotation for the use cases.
*
* <p> Code sample:
* <pre><code>
* // Setup.
* CameraController controller = new LifecycleCameraController(context);
* controller.bindToLifecycle(lifecycleOwner);
* PreviewView previewView = findViewById(R.id.preview_view);
* previewView.setController(controller);
*
* // Use case features
* controller.takePicture(...);
*
* // Camera control features
* controller.setZoomRatio(.5F);
* </code></pre>
*/
public final class LifecycleCameraController extends CameraController {
private static final String TAG = "CamLifecycleController";
@Nullable
private LifecycleOwner mLifecycleOwner;
public LifecycleCameraController(@NonNull Context context) {
super(context);
}
/**
* Sets the {@link LifecycleOwner} to be bound with the controller.
*
* <p> The state of the lifecycle will determine when the cameras are open, started, stopped
* and closed. When the {@link LifecycleOwner}'s state is start or greater, the controller
* receives camera data. It stops once the {@link LifecycleOwner} is destroyed.
*
* @throws IllegalStateException If the provided camera selector is unable to resolve a
* camera to be used for the given use cases.
* @see ProcessCameraProvider#bindToLifecycle
*/
@SuppressLint("MissingPermission")
@MainThread
public void bindToLifecycle(@NonNull LifecycleOwner lifecycleOwner) {
Threads.checkMainThread();
mLifecycleOwner = lifecycleOwner;
startCameraAndTrackStates();
}
/**
* Clears the previously set {@link LifecycleOwner} and stops the camera.
*
* @see ProcessCameraProvider#unbindAll
*/
@MainThread
public void unbind() {
Threads.checkMainThread();
mLifecycleOwner = null;
mCamera = null;
if (mCameraProvider != null) {
mCameraProvider.unbindAll();
}
}
/**
* Unbind and rebind all use cases to {@link LifecycleOwner}.
*
* @return null if failed to start camera.
*/
@UseExperimental(markerClass = ExperimentalUseCaseGroupLifecycle.class)
@RequiresPermission(Manifest.permission.CAMERA)
@Override
@Nullable
Camera startCamera() {
if (mLifecycleOwner == null) {
Log.d(TAG, "Lifecycle is not set.");
return null;
}
if (mCameraProvider == null) {
Log.d(TAG, "CameraProvider is not ready.");
return null;
}
UseCaseGroup useCaseGroup = createUseCaseGroup();
if (useCaseGroup == null) {
// Use cases can't be created.
return null;
}
return mCameraProvider.bindToLifecycle(mLifecycleOwner, mCameraSelector, useCaseGroup);
}
/**
* @hide
*/
@RestrictTo(TESTS)
@SuppressWarnings("FutureReturnValueIgnored")
void shutDownForTests() {
if (mCameraProvider != null) {
mCameraProvider.unbindAll();
mCameraProvider.shutdown();
}
}
}