OpenCV 调用 Android智能手机摄像头

ゞ浴缸里的玫瑰 2022-03-12 10:10 449阅读 0赞

**目录**

环境配置

示例效果

关键代码

源代码文件

JavaCameraView

CvCameraViewListener2

--------------------

## 环境配置 ##

Android Studio 配置OpenCV，参考下面的链接：

[https://blog.csdn.net/qq\_24118527/article/details/87923390][https_blog.csdn.net_qq_24118527_article_details_87923390]

--------------------

## 示例效果 ##

![20190305184107788.gif][]

注意：本例程没有使用自定义View的方式实现

使用自定义View方式实现的例程有空了更新

--------------------

## 关键代码 ##

RealtimeActivity.java

package cn.edu.zju.myopencv;
    
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.util.Log;
    import android.view.MenuItem;
    import android.view.Surface;
    import android.view.SurfaceView;
    import android.view.WindowManager;
    
    import org.opencv.android.BaseLoaderCallback;
    import org.opencv.android.CameraBridgeViewBase;
    import org.opencv.android.LoaderCallbackInterface;
    import org.opencv.android.OpenCVLoader;
    import org.opencv.core.Mat;
    import org.opencv.imgproc.Imgproc;
    
    public class RealtimeActivity extends AppCompatActivity implements CameraBridgeViewBase.CvCameraViewListener2 {
    
        private CameraBridgeViewBase mOpenCvCameraView;
        private static final String TAG = "nikolajohn";
        private boolean mIsJavaCamera = true;
        private MenuItem mItemSwitchCamera = null;
        private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) {
            @Override
            public void onManagerConnected(int status) {
                switch (status){
                    case LoaderCallbackInterface.SUCCESS:
                    {
                        Log.i(TAG,"OpenCV loaded successfully");
                        mOpenCvCameraView.enableView();
                    }break;
                    default:
                    {
                        super.onManagerConnected(status);
                    }break;
                }
            }
        };
        public RealtimeActivity() {
            // Instantiate
            Log.i(TAG, "Instantiated new " + this.getClass());
        }
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            Log.i(TAG,"Called on Create");
            super.onCreate(savedInstanceState);
            // 屏幕常亮
            getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
            setContentView(R.layout.activity_realtime);
            mOpenCvCameraView = findViewById(R.id.tutorial1_activity_java_surface_view);
            mOpenCvCameraView.setVisibility(SurfaceView.VISIBLE);
            mOpenCvCameraView.setCvCameraViewListener(this);
        }
    
        @Override
        public void onPause()
        {
            super.onPause();
            if (mOpenCvCameraView != null)
                mOpenCvCameraView.disableView();
        }
    
        @Override
        public void onResume()
        {
            super.onResume();
            if(!OpenCVLoader.initDebug()){
    
                Log.d(TAG,"Internal OpenCV library not found , Using OpenCV Manager for initialization");
                OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_3_4_0,this,mLoaderCallback);
    
            }else{
    
                Log.d(TAG,"OpenCV library found inside package , Using it");
                mLoaderCallback.onManagerConnected(LoaderCallbackInterface.SUCCESS);
    
            }
        }
    
        public void onDestroy() {
            super.onDestroy();
            if (mOpenCvCameraView != null)
                mOpenCvCameraView.disableView();
        }
    
        @Override
        public void onCameraViewStarted(int width, int height) {
    
        }
    
        @Override
        public void onCameraViewStopped() {
    
        }
    
        @Override
        public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame) {
            Mat src = inputFrame.rgba();
            Mat temp = new Mat();
            Mat dst = new Mat();
            Imgproc.cvtColor(src, temp, Imgproc.COLOR_RGBA2BGR);
            Imgproc.cvtColor(temp, dst, Imgproc.COLOR_BGR2HLS);
            return src;
        }
    }

activity\_realtime.xml

<?xml version="1.0" encoding="utf-8"?>
    <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:opencv="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=".RealtimeActivity">
    
        <org.opencv.android.JavaCameraView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:visibility="visible"
            android:id="@+id/tutorial1_activity_java_surface_view"
            opencv:show_fps="true"
            opencv:camera_id="any" />
    
    </FrameLayout>

--------------------

## 源代码文件 ##

链接: https://pan.baidu.com/s/1uFvg\_KvB7IIBaqgSANuAtg

提取码: qeh8

--------------------

## JavaCameraView ##

先看一下类的派生关系

![20190305185135892.png][]

显然，其父类是CameraBridgeViewBase

JavaCameraView类是View的子类，可以认为是用于OpenCV和Java Camera之间衔接的一种Bridge View

这个类继承了基类中可用的功能，并实现一些必要的方法：

*  connectCamera

打开java camera 并设置需要被传递的变量PreviewCallback

*  disconnectCamera

关闭摄像头并停止预览

当一帧一帧的图像数据通过callback从摄像头传递过来时，图像数据将会通过OpenCV转换为RGBA32格式

--------------------

## CvCameraViewListener2 ##

这个是Activity需要实现的接口类

implement这个接口类后，我们需要实现以下几个方法：

*  onCameraFrame

当图像的数据需要被传递时调用此方法，返回值是被修改过的帧数据

*  onCameraViewStarted

当摄像头的预览开启时，此方法被调用。当这个方法被调用后，图像数据才能通过onCameraFrame函数返回给屏幕

*  onCameraViewStopped

当摄像头的预览由于某些原因而被终止时该方法将会被调用，当该方法被调用后，图像无法再通过onCameraFrame显示到屏幕

--------------------

## BaseLoaderCallback ##

用法如下图：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI0MTE4NTI3_size_16_color_FFFFFF_t_70][]

--------------------

## 参考 ##

可以看一下这些文章：

[https://jayrambhia.com/blog/beginning-android-opencv][https_jayrambhia.com_blog_beginning-android-opencv]

[https://docs.opencv.org/3.0-beta/platforms/android/service/doc/BaseLoaderCallback.html][https_docs.opencv.org_3.0-beta_platforms_android_service_doc_BaseLoaderCallback.html]

[https_blog.csdn.net_qq_24118527_article_details_87923390]: https://blog.csdn.net/qq_24118527/article/details/87923390
[20190305184107788.gif]: /images/20220312/697e72add847452996d4d1479120754e.png
[20190305185135892.png]: /images/20220312/d11856ff505a40f4bad6e05145da1193.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI0MTE4NTI3_size_16_color_FFFFFF_t_70]: /images/20220312/59a79bae484e4d04a958e28ff95d7e2a.png
[https_jayrambhia.com_blog_beginning-android-opencv]: https://jayrambhia.com/blog/beginning-android-opencv
[https_docs.opencv.org_3.0-beta_platforms_android_service_doc_BaseLoaderCallback.html]: https://docs.opencv.org/3.0-beta/platforms/android/service/doc/BaseLoaderCallback.html