背景
我在 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。运行应用程序后，我很高兴看到它终于在我的设备上启动了。但是，该应用程序在相机预览应位于的位置显示为黑屏。这是我的 MainActivity、activity_main 和 AndroidManifest 文件的代码:
编辑:当应用程序在我的设备上启动时，我确实授予了应用程序使用相机的权限
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);
}
}
}
<?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>
<?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>
最佳答案
再见，
您面临的问题实际上是相机权限检查
从 Android Marshmallow 开始，CAMERA权限被认为是危险的，用户必须在运行时明确同意其使用，点击系统对话框
“正常权限”不会发生这种情况[例如INTERNET ] 默认授予。如果您对哪些是危险的，哪些不是危险的感兴趣，可以直接在 Android documentation 中查看感兴趣的。
您的初始代码发生的情况是您提到您将需要 list 文件中的相机权限，然后您从 Android 设置 [切换相机 slider ] 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该切换。然后你会得到一个黑屏，因为 Android 假定用户没有明确同意
This link来自Android文档应该可以帮助您了解更多。这是将使您的代码工作的代码段。简而言之，与 onCreate()你去检查用户是否已经授予权限，如果没有，你会问它。在 onRequestPermissionResult()有我们之前讨论过的支票。如果用户同意相机将启动，否则它不会
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);
}
安东尼诺
关于java - OpenCV 应用程序 - Android 相机一直显示黑屏，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/64417874/