Android camerax 预览

引入依赖

    def camerax_version = "1.2.0-alpha04"
    implementation "androidx.camera:camera-core:${camerax_version}"
    implementation "androidx.camera:camera-camera2:${camerax_version}"
    implementation "androidx.camera:camera-lifecycle:${camerax_version}"
    implementation "androidx.camera:camera-view:${camerax_version}"

页面添加预览的视图 PreviewView

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ui.SimpleCaneraActivity">

    <androidx.camera.view.PreviewView
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:id="@+id/previewView"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"/>

</androidx.constraintlayout.widget.ConstraintLayout>

 开启相机预览代码

PreviewView previewView = findViewById(R.id.previewView);
previewView.setImplementationMode(PreviewView.ImplementationMode.PERFORMANCE);

ListenableFuture<ProcessCameraProvider> cameraProviderFuture = ProcessCameraProvider.getInstance(this);
cameraProviderFuture.addListener(() -> {
    try {
        ProcessCameraProvider cameraProvider = cameraProviderFuture.get();
        Preview preview = new Preview.Builder()
            .build();

        CameraSelector cameraSelector = new CameraSelector.Builder()
            // 设置后置摄像头
            .requireLensFacing(CameraSelector.LENS_FACING_BACK)
            .build();
        
        // previewView 页面的显示视图
        preview.setSurfaceProvider(previewView.getSurfaceProvider());

        // 下面的方法Activity没有实现 LifecycleOwner 不能直接在 Activity 中使用
        // 需要在androidx.activity.ComponentActivity及其子类中使用 (AppCompatActivity, FragmentActivity)
        Camera camera = cameraProvider.bindToLifecycle((LifecycleOwner) this, cameraSelector, preview);
    } catch (Exception e) {
        e.printStackTrace();
    }

}, ContextCompat.getMainExecutor(this));