Android 人臉識別

和你一起終身學習，這裏是程序員 Android

經典好文推薦，通過閱讀本文，您將收穫以下知識點:

一、實現思路與步驟
二、創建佈局文件
三、獲取相機信息
四、申請Camera 權限
五、獲取相機參數
六、開始相機配流
七、創建Capture 請求
八、實現預覽回調
九、Demo 所有代碼

一、實現思路與步驟

最近項目需求是統計當前攝像頭中的人臉個數，安卓有提供現成的Api，最終實現效果如下圖。

1.1 分析思路和步奏：

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

1.通過SurfaceView展示預覽區。
2.在SurfaceView創建成功後通過CameraManager獲取當前設備可用的攝像頭。
3.檢測攝像頭權限。
4.通過CameraManager打開攝像頭。
5.在打開成功的回調中通過CameraDevice創建會話。
6.在會話創建成功的回調方法中創建預覽請求。
7.在預覽請求的回調方法onCaptureCompleted()方法中獲取預覽界面中返回的人臉數。

以下是實現步奏：

二、創建佈局文件

<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、獲取相機信息

 //獲取可用的相機列表
                    String[] cameraIdList = cameraManager.getCameraIdList();

四、申請Camera 權限

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、獲取相機參數

//獲取開啓相機的相關參數
                    CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics(cameraIdList[1]);
                    //可用於判斷是否支持人臉檢測，以及支持到哪種程度
                    faceDetectModes = characteristics.get(CameraCharacteristics.STATISTICS_INFO_AVAILABLE_FACE_DETECT_MODES);//支持的人臉檢測模式
                    cameraManager.openCamera(cameraIdList[1], mStateCallback, null);

六、開始相機配流

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、創建Capture 請求

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、實現預覽回調

 /**
     * 預覽回調
     */
    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 + "張臉");
            }
        }

        @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 所有代碼

MainActivity.java

package com.zg.lcddemo;

import android.Manifest;
import android.content.ContentValues;
import android.content.Context;
import android.content.pm.PackageManager;
import android.content.res.Configuration;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.ImageFormat;
import android.graphics.Rect;
import android.graphics.SurfaceTexture;
import android.hardware.Camera;
import android.hardware.camera2.CameraAccessException;
import android.hardware.camera2.CameraCaptureSession;
import android.hardware.camera2.CameraCharacteristics;
import android.hardware.camera2.CameraDevice;
import android.hardware.camera2.CameraManager;
import android.hardware.camera2.CameraMetadata;
import android.hardware.camera2.CaptureFailure;
import android.hardware.camera2.CaptureRequest;
import android.hardware.camera2.CaptureResult;
import android.hardware.camera2.TotalCaptureResult;
import android.hardware.camera2.params.Face;
import android.hardware.camera2.params.SessionConfiguration;
import android.hardware.camera2.params.StreamConfigurationMap;
import android.media.FaceDetector;
import android.media.ImageReader;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.HandlerThread;
import android.os.Message;
import android.provider.MediaStore;
import android.util.Log;
import android.util.Size;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.annotation.RequiresApi;
import androidx.appcompat.app.AppCompatActivity;

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.Semaphore;

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<>();

    /**
     * 獲取支持的最高人臉檢測級別
     *
     * @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 {
                    //獲取可用的相機列表
                    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;
                    }
                    //獲取開啓相機的相關參數
                    CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics(cameraIdList[1]);
                    //可用於判斷是否支持人臉檢測，以及支持到哪種程度
                    faceDetectModes = characteristics.get(CameraCharacteristics.STATISTICS_INFO_AVAILABLE_FACE_DETECT_MODES);//支持的人臉檢測模式
                    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) {

            }
        });

    }

    /**
     * 相機狀態回調
     */
    private CameraDevice.StateCallback mStateCallback = new CameraDevice.StateCallback() {
        @Override
        public void onOpened(@NonNull final CameraDevice camera) {
            //打開成功，可以獲取CameraDevice對象
            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) {
            //斷開連接
            Toast.makeText(MainActivity.this, "onDisconnected", Toast.LENGTH_SHORT).show();
        }

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


    /**
     * 預覽回調
     */
    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 + "張臉");
                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>

以上就能實現統計當前攝像頭下有多少個人臉。

原文鏈接：https://blog.csdn.net/qq77485042/article/details/109176683

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