Notes

package com.example.shaperecognitiongame;

import android.Manifest;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.Snackbar;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

import com.example.shaperecognitiongame.shapes.Shape;
import com.example.shaperecognitiongame.shapes.ShapeHelper;

public class MainActivity extends AppCompatActivity {
private static final int PERMISSION_REQUEST_CAMERA = 0;
public static final String VERTICES_EXTRA = "vertices_extra";
public static final int NEW_GAME_REQUEST = 100;
public static final String FOUND_REQUEST = "found_request";

private View mMainLayout;
private ImageView mImageView;
private TextView mScoreText;
private int mVertices;

private int mScore;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_main);

mMainLayout = findViewById(R.id.main_layout);
mImageView = findViewById(R.id.imageView);
mScoreText = findViewById(R.id.textView2);
mScore = 0;

chooseNewShape();

final Button button = findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
verifyCameraPermission();
}
});
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == NEW_GAME_REQUEST) {
chooseNewShape();

if (resultCode == RESULT_OK) {
mScore++;
mScoreText.setText(String.valueOf(mScore));
}
}
}

private void chooseNewShape() {
Shape shape = ShapeHelper.getRandomShape();
mVertices = shape.numberOfVertices();

int imageResource = shape.imageResource();
mImageView.setImageResource(imageResource);
}

private void startCamera() {
Intent intent = new Intent(getApplicationContext(), CvCameraActivity.class);
intent.putExtra(VERTICES_EXTRA, mVertices);
startActivityForResult(intent, NEW_GAME_REQUEST);
}

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
if (requestCode == PERMISSION_REQUEST_CAMERA) {
// Request for camera permission.
if (grantResults.length == 1 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
startCamera();
} else {
// Permission request was denied.
Snackbar.make(mMainLayout, R.string.camera_access_required,
Snackbar.LENGTH_SHORT)
.show();
}
}
}

private void verifyCameraPermission() {
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA)
== PackageManager.PERMISSION_GRANTED) {
// Permission is already available, start camera preview
startCamera();
} else {
// Permission is missing and must be requested.
requestCameraPermission();
}
}

/**
* Requests the {@link android.Manifest.permission#CAMERA} permission.
* If an additional rationale should be displayed, the user has to launch the request from
* a SnackBar that includes additional information.
*/
private void requestCameraPermission() {
// Permission has not been granted and must be requested.
if (ActivityCompat.shouldShowRequestPermissionRationale(this,
Manifest.permission.CAMERA)) {
// Provide an additional rationale to the user if the permission was not granted
// and the user would benefit from additional context for the use of the permission.
// Display a SnackBar with cda button to request the missing permission.
Snackbar.make(mMainLayout, R.string.camera_access_required,
Snackbar.LENGTH_INDEFINITE).setAction(R.string.ok, new View.OnClickListener() {
@Override
public void onClick(View view) {
// Request the permission
ActivityCompat.requestPermissions(MainActivity.this,
new String[]{Manifest.permission.CAMERA},
PERMISSION_REQUEST_CAMERA);
}
}).show();

} else {
// Request the permission. The result will be received in onRequestPermissionResult().
ActivityCompat.requestPermissions(this,
new String[]{Manifest.permission.CAMERA}, PERMISSION_REQUEST_CAMERA);
}
}
}