OpenCV

Question

背景

作为软件新手，我目前的目标是将我的相机预览格式化为全屏，这与 Snapchat 上的相机预览相同。现在，我可以按照 this tutorial 设置的 1:1 框格式展示我的相机预览。我在其他问题中遇到的其他潜在解决方案要么 stretched/distorted 预览图像，要么完全不启动应用程序。我怎样才能在保持肖像模式的同时做到这一点？下面提供的代码

其他设备规格包括我打算在其上启动应用程序的设备是 OnePlus Six，其纵横比为 19:9。这是我的应用程序上的相机目前的样子。

.

我想消除预览上方和下方的黑边，让相机占据整个屏幕。

MainActivity.java

package com.example.cv;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import android.Manifest;
import android.content.pm.PackageManager;
import android.opengl.Matrix;
import android.os.Bundle;
import android.util.Log;
import android.view.SurfaceView;
import android.view.WindowManager;
import android.widget.Toast;

import org.opencv.android.BaseLoaderCallback;
import org.opencv.android.CameraBridgeViewBase;
import org.opencv.android.JavaCameraView;
import org.opencv.android.OpenCVLoader;
import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.imgproc.Imgproc;

public class MainActivity extends AppCompatActivity implements CameraBridgeViewBase.CvCameraViewListener2
{
    private static String TAG = "MainActivity";
    JavaCameraView javaCameraView;
    Mat mRGBA, mRGBAT, dst;

    private static final int MY_CAMERA_REQUEST_CODE = 100;


    BaseLoaderCallback baseLoaderCallback = new BaseLoaderCallback(MainActivity.this) {
        @Override
        public void onManagerConnected(int status)
        {
            if (status == BaseLoaderCallback.SUCCESS) {
                javaCameraView.enableView();
            } else {
                super.onManagerConnected(status);
            }
        }
    };

    static
    {
        if (OpenCVLoader.initDebug())
        {
            Log.d(TAG, "OpenCV is Configured or Connected successfully.");
        }
        else
        {
            Log.d(TAG, "OpenCV not Working or Loaded.");
        }
    }

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        javaCameraView = (JavaCameraView) findViewById(R.id.my_camera_view);



        if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA)
                == PackageManager.PERMISSION_GRANTED)  {
            Log.d(TAG, "Permissions granted");
            javaCameraView.setCameraPermissionGranted();
            javaCameraView.setCameraIndex(CameraBridgeViewBase.CAMERA_ID_BACK);
            javaCameraView.setVisibility(CameraBridgeViewBase.VISIBLE);
            javaCameraView.setCvCameraViewListener(this);
        } else {
            Log.d(TAG, "Permission prompt");
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, MY_CAMERA_REQUEST_CODE);
        }



    }

    @Override
    public void onCameraViewStarted(int width, int height)
    {
        mRGBAT = new Mat();
        dst = new Mat();
    }

    @Override
    public void onCameraViewStopped()
    {
        mRGBA.release();
    }

    @Override
    public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame)
    {
        mRGBA = inputFrame.rgba();
        Core.transpose(mRGBA, mRGBAT);
        Core.flip(mRGBAT, mRGBAT, 1);
        Imgproc.resize(mRGBAT, dst, mRGBA.size());
        mRGBA.release();
        mRGBAT.release();
        return dst;
    }

    @Override
    public void onPointerCaptureChanged(boolean hasCapture) {

    }


    @Override
    protected void onDestroy() {
        super.onDestroy();

        if (javaCameraView != null)
        {
            javaCameraView.disableView();
        }
    }

    @Override
    protected void onPause() {
        super.onPause();

        if (javaCameraView != null)
        {
            javaCameraView.disableView();
        }
    }


    @Override
    protected void onResume() {
        super.onResume();

        if (OpenCVLoader.initDebug())
        {
            Log.d(TAG, "OpenCV is Configured or Connected successfully.");
            baseLoaderCallback.onManagerConnected(BaseLoaderCallback.SUCCESS);
        }
        else
        {
            Log.d(TAG, "OpenCV not Working or Loaded.");
            OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION, this, baseLoaderCallback);
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == MY_CAMERA_REQUEST_CODE) {
            // camera can be turned on
            Toast.makeText(this, "camera permission granted", Toast.LENGTH_LONG).show();
            javaCameraView.setCameraPermissionGranted();
            javaCameraView.setCameraIndex(CameraBridgeViewBase.CAMERA_ID_FRONT);
            javaCameraView.setVisibility(CameraBridgeViewBase.VISIBLE);
            javaCameraView.setCvCameraViewListener(this);
        } else {
            //camera will stay off
            Toast.makeText(this, "camera permission denied", Toast.LENGTH_LONG).show();
        }
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    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=".MainActivity">


    <org.opencv.android.JavaCameraView
        android:id="@+id/my_camera_view"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        />

</RelativeLayout>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.cv">

    <supports-screens android:resizeable="true"
        android:smallScreens="true"
        android:normalScreens="true"
        android:largeScreens="true"
        android:anyDensity="true" />


    <uses-permission android:name="android.permission.CAMERA"/>
    <uses-feature android:name="android.hardware.camera"/>
    <uses-feature android:name="android.hardware.camera.autofocus"/>
    <uses-feature android:name="android.hardware.camera.front"/>
    <uses-feature android:name="android.hardware.camera.front.autofocus"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.AppCompat.Light.NoActionBar">
        <activity android:name=".MainActivity"
            android:screenOrientation="portrait"
            android:configChanges="keyboardHidden|orientation">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

更新：我遇到过旨在改变方向的解决方案 and/or 消除操作栏。除了拉伸 CameraPreview 的分辨率外，应用 setMaxFrameSize() 不起作用。我看到的另一个答案是 getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);，它不再有效，因为 FLAG_KEEP_SCREEN_ON 已被弃用。如果有人能就我如何解决这个问题提供一点点解决方案，我将永远感激不已。

更新 2：我试图在我的 activity_main.xml 文件中修改 layout_height，只是让它将预览推到屏幕下方，同时它仍然保留它的 1:1 框格式。此外，我还考虑过在我的 MainActivity 中实现 javaCameraView.getLayoutParams().height= 只是让它 distort/stretch 相机预览而没有实现我的预期愿望。

Answer 1

尝试将此添加到您的 MainActivity.java

@Override
    public void onPreviewFrame(byte[] data, Camera camera) {
        try {
            Data = data;
            if(flag == true) {
                fheight = camera.getParameters().getPreviewSize().height;
                fwidth = camera.getParameters().getPreviewSize().width;
                flag = false;
            }
        } catch (Exception e) {
        }
    }

Answer 2

再见，

简答

我最后留下 MainActivity class 的完整解决方案 - 后置和前置摄像头 - 在代码解释后

详细信息

我加入了本站的几个答案并修改了onCameraFrame()。现在我可以在纵向模式下打开应用程序，作为原生 Android 相机或 Snapchat 视图

这个解决方案真的很轻量级，我没有像本网站上的其他答案那样更改任何 OpenCV 文件 [例如this one]。根据您要使用的 activeCamera [即back or front one]里面需要稍微修改一下onCameraFrame()，我会在下面列出

同基

所以我首先遵循 this answer 中的 4 个步骤，完全按照那里介绍的那样进行，它们确实让我走上了正确的轨道。值得注意的是，通过这些更改，您将立即获得漂亮的横向视图，但是一旦您将 phone 置于纵向位置，上下黑带就会恢复。将步骤 3 中的行更改为：

android:screenOrientation="portrait"

没有为我解决。另外，如果你想全屏显示，你需要删除标题栏，为了这样做，我也加入了 this answer。这意味着您还需要修改上一步 2

中 AndroidManifest.xml 中的这一行

android:theme="@style/Theme.AppCompat.Light.NoActionBar.FullScreen"

由于您在两个地方初始化了摄像头并且需要更改它[当前代码片段适用于前置摄像头，您需要后置摄像头]您可以clean-up代码并开始定义摄像头感兴趣的可以修改输入源只需一点：

public class MainActivity extends AppCompatActivity implements
        CameraBridgeViewBase.CvCameraViewListener2
{
    ...
    // back camera
    int activeCamera = CameraBridgeViewBase.CAMERA_ID_BACK;
    // front camera
    // int activeCamera = CameraBridgeViewBase.CAMERA_ID_FRONT;

然后将其传递给新的 initializeCamera() 方法

private void initializeCamera(JavaCameraView javaCameraView, int activeCamera){
    javaCameraView.setCameraPermissionGranted();
    javaCameraView.setCameraIndex(activeCamera);
    javaCameraView.setVisibility(CameraBridgeViewBase.VISIBLE);
    javaCameraView.setCvCameraViewListener(this);
}

一旦 Android 检测到用户已授予 CAMERA 权限，您必须立即调用它：

    if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA)
            == PackageManager.PERMISSION_GRANTED) {
        Log.d(TAG, "Permissions granted");
        initializeCamera(javaCameraView, activeCamera);

和：

    if (requestCode == MY_CAMERA_REQUEST_CODE) {
        if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            Toast.makeText(this, "Camera Permission granted", Toast.LENGTH_LONG).show();
            initializeCamera(javaCameraView, activeCamera);

现在是时候区分前后摄像头了

后置摄像头

在这种情况下，您根本不需要操作帧，代码如下：

@Override
public void onCameraViewStarted(int width, int height){
}

@Override
public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame)
{
    mRGBA = inputFrame.rgba();
    return mRGBA;
}

前置摄像头

在这种情况下，您需要稍微操纵框架翻转它们，否则您的人像模式将显示颠倒

@Override
public void onCameraViewStarted(int width, int height)
{
    mRGBAT = new Mat();
} 

@Override
public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame)
{
    mRGBA = inputFrame.rgba();
    // flipping to show portrait mode properly
    Core.flip(mRGBA, mRGBAT, 1);
    // releasing what's not anymore needed
    mRGBA.release();
    return mRGBAT;
}

最后，确保您添加到代码中的帧操作确实是必需的。它们的处理时间会降低性能，甚至会让您遇到不必要的麻烦。我没有准确检查，但我很确定你 onCameraFrame() 中的矩阵转置是失真

的根本原因

后置摄像头的 MainActivity

package com.change.package.name;

import android.Manifest;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.util.Log;
import android.view.WindowManager;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import org.opencv.android.BaseLoaderCallback;
import org.opencv.android.CameraBridgeViewBase;
import org.opencv.android.JavaCameraView;
import org.opencv.android.OpenCVLoader;
import org.opencv.core.Core;
import org.opencv.core.Mat;

public class MainActivity extends AppCompatActivity implements
        CameraBridgeViewBase.CvCameraViewListener2
{
    private static String TAG = "MainActivity";
    JavaCameraView javaCameraView;
    Mat mRGBA;
    private static final int MY_CAMERA_REQUEST_CODE = 100;
    int activeCamera = CameraBridgeViewBase.CAMERA_ID_BACK;


    BaseLoaderCallback baseLoaderCallback = new BaseLoaderCallback(MainActivity.this) {
        @Override
        public void onManagerConnected(int status)
        {
            if (status == BaseLoaderCallback.SUCCESS) {
                javaCameraView.enableView();
            } else {
                super.onManagerConnected(status);
            }
        }
    };

    static
    {
        if (OpenCVLoader.initDebug())
        {
            Log.d(TAG, "OpenCV is Configured or Connected successfully.");
        }
        else
        {
            Log.d(TAG, "OpenCV not Working or Loaded.");
        }
    }

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        javaCameraView = (JavaCameraView) findViewById(R.id.my_camera_view);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

        if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA)
                == PackageManager.PERMISSION_GRANTED) {
            Log.d(TAG, "Permissions granted");
            initializeCamera(javaCameraView, activeCamera);
        } else {
            Log.d(TAG, "Troubles");
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, MY_CAMERA_REQUEST_CODE);
            }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == MY_CAMERA_REQUEST_CODE) {
            if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                Toast.makeText(this, "Camera Permission granted", Toast.LENGTH_LONG).show();  
                initializeCamera(javaCameraView, activeCamera);
            } else {
                Toast.makeText(this, "Camera Permission denied", Toast.LENGTH_LONG).show();
            }
        }
    }

    private void initializeCamera(JavaCameraView javaCameraView, int activeCamera){
        javaCameraView.setCameraPermissionGranted();
        javaCameraView.setCameraIndex(activeCamera);

        javaCameraView.setVisibility(CameraBridgeViewBase.VISIBLE);
        javaCameraView.setCvCameraViewListener(this);
    }

    @Override
    public void onCameraViewStarted(int width, int height)
    {
    
    }

    @Override
    public void onCameraViewStopped()
    {
        mRGBA.release();
    }

    @Override
    public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame)
    {
        // code for the back camera
        mRGBA = inputFrame.rgba();
        return mRGBA;
    }

    @Override
    public void onPointerCaptureChanged(boolean hasCapture) {

    }    

    @Override
    protected void onDestroy() {
        super.onDestroy();

        if (javaCameraView != null)
        {
            javaCameraView.disableView();
        }
    }

    @Override
    protected void onPause() {
        super.onPause();

        if (javaCameraView != null)
        {
            javaCameraView.disableView();
        }
    }    

    @Override
    protected void onResume() {
        super.onResume();

        if (OpenCVLoader.initDebug())
        {
            Log.d(TAG, "OpenCV is Configured or Connected successfully.");
            baseLoaderCallback.onManagerConnected(BaseLoaderCallback.SUCCESS);
        }
        else
        {
            Log.d(TAG, "OpenCV not Working or Loaded.");
            OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION, this, baseLoaderCallback);
        }
    }
}

前置摄像头的MainActivity

package com.change.package.name;

import android.Manifest;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.util.Log;
import android.view.WindowManager;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import org.opencv.android.BaseLoaderCallback;
import org.opencv.android.CameraBridgeViewBase;
import org.opencv.android.JavaCameraView;
import org.opencv.android.OpenCVLoader;
import org.opencv.core.Core;
import org.opencv.core.Mat;

public class MainActivity extends AppCompatActivity implements
        CameraBridgeViewBase.CvCameraViewListener2
{
    private static String TAG = "MainActivity";
    JavaCameraView javaCameraView;
    Mat mRGBA, mRGBAT;
    private static final int MY_CAMERA_REQUEST_CODE = 100;
    int activeCamera = CameraBridgeViewBase.CAMERA_ID_FRONT;


    BaseLoaderCallback baseLoaderCallback = new BaseLoaderCallback(MainActivity.this) {
        @Override
        public void onManagerConnected(int status)
        {
            if (status == BaseLoaderCallback.SUCCESS) {
                javaCameraView.enableView();
            } else {
                super.onManagerConnected(status);
            }
        }
    };

    static
    {
        if (OpenCVLoader.initDebug())
        {
            Log.d(TAG, "OpenCV is Configured or Connected successfully.");
        }
        else
        {
            Log.d(TAG, "OpenCV not Working or Loaded.");
        }
    }

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        javaCameraView = (JavaCameraView) findViewById(R.id.my_camera_view);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

        if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA)
                == PackageManager.PERMISSION_GRANTED) {
            Log.d(TAG, "Permissions granted");
            initializeCamera(javaCameraView, activeCamera);
        } else {
            Log.d(TAG, "Troubles");
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, MY_CAMERA_REQUEST_CODE);
            }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == MY_CAMERA_REQUEST_CODE) {
            if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                Toast.makeText(this, "Camera Permission granted", Toast.LENGTH_LONG).show();
                initializeCamera(javaCameraView, activeCamera);
            } else {
                Toast.makeText(this, "Camera Permission denied", Toast.LENGTH_LONG).show();
            }
        }
    }

    private void initializeCamera(JavaCameraView javaCameraView, int activeCamera){
        javaCameraView.setCameraPermissionGranted();
        javaCameraView.setCameraIndex(activeCamera);   
        javaCameraView.setVisibility(CameraBridgeViewBase.VISIBLE);
        javaCameraView.setCvCameraViewListener(this);
    }

    @Override
    public void onCameraViewStarted(int width, int height)
    {
        mRGBAT = new Mat();
    }

    @Override
    public void onCameraViewStopped()
    {
        mRGBA.release();
    }

    @Override
    public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame)
    {
        // code for the front camera
        mRGBA = inputFrame.rgba();
        // flipping to show portrait mode properly
        Core.flip(mRGBA, mRGBAT, 1);
        mRGBA.release();
        return mRGBAT;
    }

    @Override
    public void onPointerCaptureChanged(boolean hasCapture) {

    }    

    @Override
    protected void onDestroy() {
        super.onDestroy();

        if (javaCameraView != null)
        {
            javaCameraView.disableView();
        }
    }

    @Override
    protected void onPause() {
        super.onPause();

        if (javaCameraView != null)
        {
            javaCameraView.disableView();
        }
    }    

    @Override
    protected void onResume() {
        super.onResume();

        if (OpenCVLoader.initDebug())
        {
            Log.d(TAG, "OpenCV is Configured or Connected successfully.");
            baseLoaderCallback.onManagerConnected(BaseLoaderCallback.SUCCESS);
        }
        else
        {
            Log.d(TAG, "OpenCV not Working or Loaded.");
            OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION, this, baseLoaderCallback);
        }
    }
}

祝你有美好的一天，
安东尼奥

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