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Android 获取人脸个数Demo

程序员Android

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2021-08-25 01:41

和你一起终身学习，这里是程序员Android

经典好文推荐，通过阅读本文，您将收获以下知识点:

一、实现思路与步骤
二、创建布局文件
三、获取相机信息
四、申请Camera 权限
五、获取相机参数
六、开始相机配流
七、创建Capture 请求
八、实现预览回调
九、Demo 所有代码

一、实现思路与步骤

最近项目需求是统计当前摄像头中的人脸个数，安卓有提供现成的Api，最终实现效果如下图。

1.1 分析思路和步奏：

主要使用到的类：SurfaceView、CameraManager、CameraDevice.StateCallback、CameraCaptureSession.StateCallback。

1.通过SurfaceView展示预览区。
2.在SurfaceView创建成功后通过CameraManager获取当前设备可用的摄像头。
3.检测摄像头权限。
4.通过CameraManager打开摄像头。
5.在打开成功的回调中通过CameraDevice创建会话。
6.在会话创建成功的回调方法中创建预览请求。
7.在预览请求的回调方法onCaptureCompleted()方法中获取预览界面中返回的人脸数。

以下是实现步奏：

二、创建布局文件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical">

    <SurfaceView
        android:id="@+id/sv"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />
</LinearLayout>


java

cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
        surfaceHolder = sv.getHolder();
        surface = surfaceHolder.getSurface();

三、获取相机信息

 //获取可用的相机列表
                    String[] cameraIdList = cameraManager.getCameraIdList();

四、申请Camera 权限

if (checkSelfPermission(Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
                        // TODO: Consider calling
                        //    Activity#requestPermissions
                        // here to request the missing permissions, and then overriding
                        //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                        //                                          int[] grantResults)
                        // to handle the case where the user grants the permission. See the documentation
                        // for Activity#requestPermissions for more details.
                        return;
                    }

五、获取相机参数

//获取开启相机的相关参数
                    CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics(cameraIdList[1]);
                    //可用于判断是否支持人脸检测，以及支持到哪种程度
                    faceDetectModes = characteristics.get(CameraCharacteristics.STATISTICS_INFO_AVAILABLE_FACE_DETECT_MODES);//支持的人脸检测模式
                    cameraManager.openCamera(cameraIdList[1], mStateCallback, null);

六、开始相机配流

camera.createCaptureSession(Arrays.asList(surface), new CameraCaptureSession.StateCallback() {
                    @Override
                    public void onConfigured(@NonNull CameraCaptureSession session) {
                     
                    }

                    @Override
                    public void onConfigureFailed(@NonNull CameraCaptureSession session) {

                    }
                }, new Handler());

七、创建Capture 请求

CaptureRequest.Builder captureRequest = camera.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
                            captureRequest.addTarget(surface);
                            captureRequest.set(CaptureRequest.CONTROL_MODE, CameraMetadata.CONTROL_MODE_AUTO);
                            captureRequest.set(CaptureRequest.STATISTICS_FACE_DETECT_MODE, getFaceDetectMode());
                            session.setRepeatingRequest(captureRequest.build(),captureCallback,new Handler());

八、实现预览回调

 /**
     * 预览回调
     */
    private CameraCaptureSession.CaptureCallback captureCallback = new CameraCaptureSession.CaptureCallback() {
        @Override
        public void onCaptureStarted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, long timestamp, long frameNumber) {
            super.onCaptureStarted(session, request, timestamp, frameNumber);
        }

        @Override
        public void onCaptureProgressed(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull CaptureResult partialResult) {
            super.onCaptureProgressed(session, request, partialResult);
        }

        @Override
        public void onCaptureCompleted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull TotalCaptureResult result) {
            super.onCaptureCompleted(session, request, result);
            Face faces[] = result.get(CaptureResult.STATISTICS_FACES);
            if (faces.length != face) {
                Log.e("lee", faces.length + "张脸");
            }
        }

        @Override
        public void onCaptureFailed(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull CaptureFailure failure) {
            super.onCaptureFailed(session, request, failure);
        }

        @Override
        public void onCaptureSequenceCompleted(@NonNull CameraCaptureSession session, int sequenceId, long frameNumber) {
            super.onCaptureSequenceCompleted(session, sequenceId, frameNumber);
        }

        @Override
        public void onCaptureSequenceAborted(@NonNull CameraCaptureSession session, int sequenceId) {
            super.onCaptureSequenceAborted(session, sequenceId);
        }

        @Override
        public void onCaptureBufferLost(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull Surface target, long frameNumber) {
            super.onCaptureBufferLost(session, request, target, frameNumber);
        }
    };

九、Demo 所有代码

MainActivity.java

public class MainActivity extends AppCompatActivity {
    private SurfaceView sv;
    private SurfaceHolder surfaceHolder;
    private CameraManager cameraManager;
    private Surface surface;
    int[] faceDetectModes;
    int face;
    List<Bitmap> bitmaps = new ArrayList<>();

    /**
     * 获取支持的最高人脸检测级别
     *
     * @return
     */
    private int getFaceDetectMode() {
        if (faceDetectModes == null) {
            return CaptureRequest.STATISTICS_FACE_DETECT_MODE_FULL;
        } else {
            return faceDetectModes[faceDetectModes.length - 1];
        }
    }

    @RequiresApi(api = Build.VERSION_CODES.M)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        sv = findViewById(R.id.sv);
        cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
        surfaceHolder = sv.getHolder();
        surface = surfaceHolder.getSurface();
        surfaceHolder.addCallback(new SurfaceHolder.Callback() {
            @RequiresApi(api = Build.VERSION_CODES.M)
            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                try {
                    //获取可用的相机列表
                    String[] cameraIdList = cameraManager.getCameraIdList();
                    if (checkSelfPermission(Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
                        // TODO: Consider calling
                        //    Activity#requestPermissions
                        // here to request the missing permissions, and then overriding
                        //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                        //                                          int[] grantResults)
                        // to handle the case where the user grants the permission. See the documentation
                        // for Activity#requestPermissions for more details.
                        return;
                    }
                    //获取开启相机的相关参数
                    CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics(cameraIdList[1]);
                    //可用于判断是否支持人脸检测，以及支持到哪种程度
                    faceDetectModes = characteristics.get(CameraCharacteristics.STATISTICS_INFO_AVAILABLE_FACE_DETECT_MODES);//支持的人脸检测模式
                    cameraManager.openCamera(cameraIdList[1], mStateCallback, null);
                } catch (CameraAccessException e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

            }

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {

            }
        });

    }

    /**
     * 相机状态回调
     */
    private CameraDevice.StateCallback mStateCallback = new CameraDevice.StateCallback() {
        @Override
        public void onOpened(@NonNull final CameraDevice camera) {
            //打开成功，可以获取CameraDevice对象
            try {
                camera.createCaptureSession(Arrays.asList(surface), new CameraCaptureSession.StateCallback() {
                    @Override
                    public void onConfigured(@NonNull CameraCaptureSession session) {
                        try {
                            CaptureRequest.Builder captureRequest = camera.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
                            captureRequest.addTarget(surface);
                            captureRequest.set(CaptureRequest.CONTROL_MODE, CameraMetadata.CONTROL_MODE_AUTO);
                            captureRequest.set(CaptureRequest.STATISTICS_FACE_DETECT_MODE, getFaceDetectMode());
                            session.setRepeatingRequest(captureRequest.build(),captureCallback,new Handler());
                        } catch (CameraAccessException e) {
                            e.printStackTrace();
                        }
                    }

                    @Override
                    public void onConfigureFailed(@NonNull CameraCaptureSession session) {

                    }
                }, new Handler());
            } catch (CameraAccessException e) {
                e.printStackTrace();
            }

        }

        @Override
        public void onDisconnected(@NonNull CameraDevice camera) {
            //断开连接
            Toast.makeText(MainActivity.this, "onDisconnected", Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onError(@NonNull CameraDevice camera, final int error) {
            //发生异常
            Toast.makeText(MainActivity.this, "onError", Toast.LENGTH_SHORT).show();
        }
    };


    /**
     * 预览回调
     */
    private CameraCaptureSession.CaptureCallback captureCallback = new CameraCaptureSession.CaptureCallback() {
        @Override
        public void onCaptureStarted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, long timestamp, long frameNumber) {
            super.onCaptureStarted(session, request, timestamp, frameNumber);
        }

        @Override
        public void onCaptureProgressed(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull CaptureResult partialResult) {
            super.onCaptureProgressed(session, request, partialResult);
        }

        @Override
        public void onCaptureCompleted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull TotalCaptureResult result) {
            super.onCaptureCompleted(session, request, result);
            Face faces[] = result.get(CaptureResult.STATISTICS_FACES);
            if (faces.length != face) {
                Log.e("lee", faces.length + "张脸");
                face = faces.length;        
            }
        }

        @Override
        public void onCaptureFailed(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull CaptureFailure failure) {
            super.onCaptureFailed(session, request, failure);
        }

        @Override
        public void onCaptureSequenceCompleted(@NonNull CameraCaptureSession session, int sequenceId, long frameNumber) {
            super.onCaptureSequenceCompleted(session, sequenceId, frameNumber);
        }

        @Override
        public void onCaptureSequenceAborted(@NonNull CameraCaptureSession session, int sequenceId) {
            super.onCaptureSequenceAborted(session, sequenceId);
        }

        @Override
        public void onCaptureBufferLost(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull Surface target, long frameNumber) {
            super.onCaptureBufferLost(session, request, target, frameNumber);
        }
    };
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical">

    <SurfaceView
        android:id="@+id/sv"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />
</LinearLayout>

以上就能实现统计当前摄像头下有多少个人脸。

原文链接：https://blog.csdn.net/qq77485042/article/details/109176683

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