Android Jetpack

CameraX简单使用

Posted by alonealice on 2020-05-20

CameraX实际上还是用的Camera2的代码，但是它对调用API进行了很好的封装，使用起来对比直接Camera2更加的方便。同时使用需要绑定lifecircle，能够自动管理生命周期。

添加依赖

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implementation "androidx.camera:camera-core:1.0.0-rc01"
implementation "androidx.camera:camera-camera2:1.0.0-rc01"
implementation 'androidx.camera:camera-view:1.0.0-alpha20'
implementation "androidx.camera:camera-lifecycle:1.0.0-rc01"

申请权限

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<uses-permission android:name="android.permission.CAMERA" />
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int checkCallPhonePermission = ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA);
if (checkCallPhonePermission != PackageManager.PERMISSION_GRANTED) {
    ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, 222);
}

预览

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<androidx.camera.view.PreviewView
    android:id="@+id/tv_camera"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

cameraX显示布局需要PreviewView，直接在xml中添加。

启动相机，需要先获取到ProcessCameraProvider：

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previewView.post(new Runnable() {
    @Override
    public void run() {
        setupCamera();
    }
});
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private void setupCamera() {
    ListenableFuture<ProcessCameraProvider> instance = ProcessCameraProvider.getInstance(this);
    instance.addListener(new Runnable() {
        @Override
        public void run() {
            try {
                cameraProvider = instance.get();
            } catch (ExecutionException e) {
                e.printStackTrace();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            if (cameraProvider != null) {
                startCamera();
            }
        }
    }, ContextCompat.getMainExecutor(this));
}

添加预览的参数preview：

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private void startCamera() {
  //预览
    Preview preview = new Preview.Builder()
            .setTargetAspectRatio(AspectRatio.RATIO_16_9)
            .setTargetRotation(Surface.ROTATION_90)
            .build();
  //拍照
    ImageCapture imageCapture = new ImageCapture.Builder()
            .setCaptureMode(ImageCapture.CAPTURE_MODE_MAXIMIZE_QUALITY)
            .setTargetAspectRatio(AspectRatio.RATIO_16_9)
            .setTargetRotation(Surface.ROTATION_90)
            .build();
		//图像数据
		ImageAnalysis imageAnalysis = new 					ImageAnalysis.Builder().setTargetAspectRatio(AspectRatio.RATIO_16_9).setTargetRotation(Surface.ROTATION_90).build();
    imageAnalysis.setAnalyzer(cameraExecutor, new ImageAnalysis.Analyzer() {
        @Override
        public void analyze(@NonNull ImageProxy image) {
            Log.e("画面", image.getWidth() + "**" + image.getHeight());
        }
    });

		//选择后置摄像头
		CameraSelector selector = new C		ameraSelector.Builder().requireLensFacing(CameraSelector.LENS_FACING_BACK).build();
  	//绑定参数
		cameraProvider.unbindAll();
		cameraProvider.bindToLifecycle(this, selector, preview, imageCapture, imageAnalysis);

  	//绑定previewView 并开始预览
    preview.setSurfaceProvider(previewView.getSurfaceProvider());
}

bindToLifecycle方法中的preview、imageCapture和imageAnalysis并不是每次都需要，如果只是预览的话就只传preview即可。

图像分析

ImageAnalysis 可以帮助我们做一些图像质量的分析，需要我们去实现 ImageAnalysis.Analyzer 接口的 analyze 方法。

拍照

拍照需要在预览的基础上，调用ImageCapture拍照，同时需要创建OutputFileOptions用以存储文件信息。在onImageSaved方法回调时，照片会自动存储到对应的文件。

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public void takePicture(View v) {
    imageCapture.setFlashMode(ImageCapture.FLASH_MODE_AUTO);
    File file = new File(getCacheDir()+"/"+System.currentTimeMillis()+".png");
    if(!file.exists()){
        try {
            file.createNewFile();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    ImageCapture.OutputFileOptions outputFileOptions = new ImageCapture.OutputFileOptions.Builder(file).build();
    imageCapture.takePicture(outputFileOptions, cameraExecutor, new ImageCapture.OnImageSavedCallback() {
        @Override
        public void onImageSaved(@NonNull ImageCapture.OutputFileResults outputFileResults) {
            if (outputFileResults.getSavedUri() != null) {
                    //保存成功
            }
        }
        @Override
        public void onError(@NonNull ImageCaptureException exception) {

        }
    });
}
录像

录像是需要创建VideoCapture，同时在bind方法中不能和imageAnalysis一起使用。

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videoCapture = new VideoCapture.Builder()
        .setTargetRotation(Surface.ROTATION_0)
        //设置宽高比
        .setTargetAspectRatio(AspectRatio.RATIO_16_9)
        .setAudioBitRate(44100)
        .setAudioRecordSource(MediaRecorder.AudioSource.MIC)
        //视频帧率  越高视频体积越大
        .setVideoFrameRate(25)
        //bit率  越大视频体积越大
        .setBitRate(3 * 1024 * 1024)
        .build();
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if (start) {
    videoCapture.stopRecording();
    start = false;
} else {
    File file = new File(Environment.getExternalStorageDirectory() + "/" + System.currentTimeMillis() + ".mp4");
    if (!file.exists()) {
        try {
            file.createNewFile();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    VideoCapture.OutputFileOptions outputFileOptions = new VideoCapture.OutputFileOptions.Builder(file).build();
    videoCapture.startRecording(outputFileOptions, cameraExecutor, new VideoCapture.OnVideoSavedCallback() {
        @Override
        public void onVideoSaved(@NonNull VideoCapture.OutputFileResults outputFileResults) {
            Log.e("画面", "视频保存成功");
        }

        @Override
        public void onError(int videoCaptureError, @NonNull String message, @Nullable Throwable cause) {

        }
    });
    start = true;
}

CameraView

如果觉得上面的代码还是比较多，官方提供了一个极简拍摄的组件CameraView。

在xml中添加依赖：

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<androidx.camera.view.CameraView
    android:id="@+id/view_finder"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    />

同时通过绑定开始预览，并调用对应的takePicture和startRecording，完成拍照和摄影，这两个方法的参数与上面相同。

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cameraView = findViewById(R.id.view_finder);
cameraView.bindToLifecycle(this);
cameraView.takePicture(...);
cameraView.startRecording(...);

CameraX官方还未出正式版本，这部分的代码各个版本改动较大，建议直接参考官方demo：https://github.com/android/camera-samples/tree/main/CameraXBasic




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