OpenCV应用-Android摄像头持续显示黑屏 [英] OpenCV app - Android camera keeps showing black screen
问题描述
背景
我已经在Android Studio上开始了这个项目，目的是创建一个OpenCV应用程序，该应用程序可以使用我的OnePlus android设备上的相机处理帧.运行该应用程序后，我很高兴看到它最终在我的设备上启动.但是，该应用程序将以黑屏显示应在相机预览的位置.这是我的MainActivity，activity_main和AndroidManifest文件的代码:
I had started out this project on Android Studio with the intent of creating a OpenCV application that could process frames using the camera on my OnePlus android device. After running the application, I was gratified to see it finally launch on my device. However, the application shows up with a black screen where the camera preview should be. Here is my code for my MainActivity, activity_main, and AndroidManifest files:
在我的设备上启动该应用程序时，我确实授予了该应用程序使用相机的权限
While the application launched on my device, I did give the application permission to use camera
MainActivity.java
package com.example.cv;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.SurfaceView;
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;
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);
javaCameraView.setVisibility(SurfaceView.VISIBLE);
javaCameraView.setCvCameraViewListener(MainActivity.this);
}
@Override
public void onCameraViewStarted(int width, int height)
{
mRGBA = new Mat(height, width, CvType.CV_8UC4);
}
@Override
public void onCameraViewStopped()
{
mRGBA.release();
}
@Override
public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame)
{
mRGBA = inputFrame.rgba();
mRGBAT = mRGBA.t();
Core.flip(mRGBA.t(), mRGBAT, 1);
Imgproc.resize(mRGBAT, mRGBAT, mRGBA.size());
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);
}
}
}
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">
<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/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
推荐答案
Ciao，
您面临的问题实际上是摄像头权限检查
the issue you are facing is actually with the camera permission check
从Android Marshmallow开始， CAMERA 权限被认为是危险的权限，用户必须在运行时单击系统对话框，明确同意其使用方式
Starting from Android Marshmallow, the CAMERA permission is considered a dangerous one and the user must explicitly agree on its usage at runtime, clicking on the system dialog
正常权限"不会发生这种情况.[例如. INTERNET ]是默认授予的.如果您对哪些危险和哪些危险不感兴趣，可以直接在 Android文档
This wouldn't happen for "normal permissions" [e.g. INTERNET] that are granted by default. If you are interested in which ones are dangerous and which not you can check for the one of interest directly in the Android documentation
您的初始代码所发生的情况是，您提到您将需要清单文件中的摄像头权限，然后从Android设置[切换摄像头滑块]中启用它.但是，当您启动应用程序时，代码中没有任何内容可以检查切换.然后，您会看到黑屏，因为Android假定用户未明确同意
What's happening with your initial code is that you are mentioning you will require the camera permission in your manifest file and then you are enabling it from the Android Settings [toggling the Camera slider]. But then, when you start the app there is nothing in the code that goes and checks that toggle. Then you get a black screen because Android assumes that the user has not given explicit consent
此链接应该可以帮助您了解更多.这是使您的代码正常工作的代码段.简而言之，您可以使用 onCreate()来检查用户是否已授予许可，如果没有，您将询问它.在 onRequestPermissionResult()中，有我们之前提到的检查.如果用户同意，相机将启动，否则不会启动
This link from the Android documentation should help you understand more. Here the snippet that will make your code work. In a nutshell, with onCreate() you go and check if the user has already granted the permission and if not you will ask it. In onRequestPermissionResult() there is the check we were talking about before. If the user agreed the camera will start, otherwise it won't
private static final int MY_CAMERA_REQUEST_CODE = 100;
int activeCamera = CameraBridgeViewBase.CAMERA_ID_FRONT;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
javaCameraView = (JavaCameraView) findViewById(R.id.my_camera_view);
// checking if the permission has already been granted
if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA)
== PackageManager.PERMISSION_GRANTED) {
Log.d(TAG, "Permissions granted");
initializeCamera(javaCameraView, activeCamera);
} else {
// prompt system dialog
Log.d(TAG, "Permission prompt");
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, MY_CAMERA_REQUEST_CODE);
}
}
// callback to be executed after the user has givenapproval or rejection via system prompt
@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) {
// camera can be turned on
Toast.makeText(this, "camera permission granted", Toast.LENGTH_LONG).show();
initializeCamera(javaCameraView, activeCamera);
} else {
// camera will stay off
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);
}
今天过得好，
安东尼诺
Have a good day,
Antonino
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