Merge pull request #24692 from savuor:doc_android_tutorial_camera

Android camera tutorial update #24692

This PR extends the OpenCV 4 Android tutorial by a simple camera app based on existing code.
This part was accidentally removed during the #24653 preparation, this PR restores it and aligns it to the latest Android Studio.

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake

samples/android/tutorial-1-camerapreview/gradle/AndroidManifest.xml

@@ -27,11 +27,13 @@
                       android:largeScreens="true"
                       android:anyDensity="true" />
 
+    //! [camera_permissions]
     <uses-permission android:name="android.permission.CAMERA"/>
 
     <uses-feature android:name="android.hardware.camera" android:required="false"/>
     <uses-feature android:name="android.hardware.camera.autofocus" android:required="false"/>
     <uses-feature android:name="android.hardware.camera.front" android:required="false"/>
     <uses-feature android:name="android.hardware.camera.front.autofocus" android:required="false"/>
+    //! [camera_permissions]
 
 </manifest>

samples/android/tutorial-1-camerapreview/res/layout/tutorial1_surface_view.xml

@@ -4,6 +4,7 @@
     android:layout_width="match_parent"
     android:layout_height="match_parent" >
 
+    <!-- [camera_view] -->
     <org.opencv.android.JavaCameraView
         android:layout_width="fill_parent"
         android:layout_height="fill_parent"
@@ -11,5 +12,6 @@
         android:id="@+id/tutorial1_activity_java_surface_view"
         opencv:show_fps="true"
         opencv:camera_id="any" />
+    <!-- [camera_view] -->
 
 </FrameLayout>

samples/android/tutorial-1-camerapreview/src/org/opencv/samples/tutorial1/Tutorial1Activity.java

@@ -9,7 +9,6 @@ import org.opencv.android.CameraBridgeViewBase.CvCameraViewListener2;
 
 import android.os.Bundle;
 import android.util.Log;
-import android.view.MenuItem;
 import android.view.SurfaceView;
 import android.view.WindowManager;
 import android.widget.Toast;
@@ -21,8 +20,6 @@ public class Tutorial1Activity extends CameraActivity implements CvCameraViewLis
     private static final String TAG = "OCVSample::Activity";
 
     private CameraBridgeViewBase mOpenCvCameraView;
-    private boolean              mIsJavaCamera = true;
-    private MenuItem             mItemSwitchCamera = null;
 
     public Tutorial1Activity() {
         Log.i(TAG, "Instantiated new " + this.getClass());
@@ -44,7 +41,9 @@ public class Tutorial1Activity extends CameraActivity implements CvCameraViewLis
         }
         //! [ocv_loader_init]
 
+        //! [keep_screen]
         getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
+        //! [keep_screen]
 
         setContentView(R.layout.tutorial1_surface_view);
 
@@ -76,18 +75,22 @@ public class Tutorial1Activity extends CameraActivity implements CvCameraViewLis
         return Collections.singletonList(mOpenCvCameraView);
     }
 
+    @Override
     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(CvCameraViewFrame inputFrame) {
         return inputFrame.rgba();
     }