Generate a QR bitmap using RxJava instead of AsyncTask.

app/src/full/java/org/fdroid/fdroid/nearby/SwapWorkflowActivity.java

@@ -34,7 +34,18 @@ import android.widget.ProgressBar;
 import android.widget.TextView;
 import android.widget.Toast;
 
+import androidx.annotation.LayoutRes;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.StringRes;
+import androidx.appcompat.app.AlertDialog;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.appcompat.widget.SearchView;
+import androidx.core.content.ContextCompat;
+import androidx.localbroadcastmanager.content.LocalBroadcastManager;
+
 import com.google.android.material.appbar.MaterialToolbar;
+import com.google.android.material.switchmaterial.SwitchMaterial;
 import com.google.zxing.integration.android.IntentIntegrator;
 import com.google.zxing.integration.android.IntentResult;
 
@@ -54,7 +65,6 @@ import org.fdroid.fdroid.net.BluetoothDownloader;
 import org.fdroid.fdroid.net.Downloader;
 import org.fdroid.fdroid.net.HttpDownloader;
 import org.fdroid.fdroid.qr.CameraCharacteristicsChecker;
-import org.fdroid.fdroid.qr.QrGenAsyncTask;
 import org.fdroid.fdroid.views.main.MainActivity;
 
 import java.util.Date;
@@ -65,17 +75,8 @@ import java.util.Set;
 import java.util.Timer;
 import java.util.TimerTask;
 
-import androidx.annotation.LayoutRes;
-import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
-import androidx.annotation.StringRes;
-import androidx.appcompat.app.AlertDialog;
-import androidx.appcompat.app.AppCompatActivity;
-import androidx.appcompat.widget.SearchView;
-import com.google.android.material.switchmaterial.SwitchMaterial;
-import androidx.core.content.ContextCompat;
-import androidx.localbroadcastmanager.content.LocalBroadcastManager;
 import cc.mvdan.accesspoint.WifiApControl;
+import io.reactivex.rxjava3.disposables.CompositeDisposable;
 
 import static org.fdroid.fdroid.views.main.MainActivity.ACTION_REQUEST_SWAP;
 
@@ -118,6 +119,8 @@ public class SwapWorkflowActivity extends AppCompatActivity {
     @LayoutRes
     private int currentSwapViewLayoutRes = STEP_INTRO;
 
+    private final CompositeDisposable compositeDisposable = new CompositeDisposable();
+
     public static void requestSwap(Context context, String repo) {
         requestSwap(context, Uri.parse(repo));
     }
@@ -235,6 +238,7 @@ public class SwapWorkflowActivity extends AppCompatActivity {
 
     @Override
     protected void onDestroy() {
+        compositeDisposable.dispose();
         localBroadcastManager.unregisterReceiver(downloaderInterruptedReceiver);
         unbindService(serviceConnection);
         super.onDestroy();
@@ -929,18 +933,23 @@ public class SwapWorkflowActivity extends AppCompatActivity {
         ImageView qrImage = container.findViewById(R.id.wifi_qr_code);
         if (qrUriString != null && qrImage != null) {
             Utils.debugLog(TAG, "Encoded swap URI in QR Code: " + qrUriString);
-            new QrGenAsyncTask(SwapWorkflowActivity.this, R.id.wifi_qr_code).execute(qrUriString);
 
-            // Replace all blacks with the background blue.
+            compositeDisposable.add(Utils.generateQrBitmap(this, qrUriString)
-            qrImage.setColorFilter(new LightingColorFilter(0xffffffff, ContextCompat.getColor(this,
+                    .subscribe(qrBitmap -> {
-                    R.color.swap_blue)));
+                        qrImage.setImageBitmap(qrBitmap);
 
-            final View qrWarningMessage = container.findViewById(R.id.warning_qr_scanner);
+                        // Replace all blacks with the background blue.
-            if (CameraCharacteristicsChecker.getInstance(this).hasAutofocus()) {
+                        qrImage.setColorFilter(new LightingColorFilter(0xffffffff,
-                qrWarningMessage.setVisibility(View.GONE);
+                                ContextCompat.getColor(this, R.color.swap_blue)));
-            } else {
+
-                qrWarningMessage.setVisibility(View.VISIBLE);
+                        final View qrWarningMessage = container.findViewById(R.id.warning_qr_scanner);
-            }
+                        if (CameraCharacteristicsChecker.getInstance(this).hasAutofocus()) {
+                            qrWarningMessage.setVisibility(View.GONE);
+                        } else {
+                            qrWarningMessage.setVisibility(View.VISIBLE);
+                        }
+                    })
+            );
         }
     }
 

app/src/main/java/org/fdroid/fdroid/Utils.java

@@ -27,6 +27,7 @@ import android.content.pm.Signature;
 import android.content.res.Resources;
 import android.database.Cursor;
 import android.graphics.Bitmap;
+import android.graphics.Point;
 import android.graphics.Rect;
 import android.net.Uri;
 import android.os.Build;
@@ -44,11 +45,21 @@ import android.text.style.TypefaceSpan;
 import android.util.DisplayMetrics;
 import android.util.Log;
 import android.util.TypedValue;
+import android.view.Display;
 import android.view.View;
 import android.view.ViewTreeObserver;
 import android.widget.ImageView;
 import android.widget.Toast;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.RequiresApi;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;
+
+import com.google.zxing.BarcodeFormat;
+import com.google.zxing.encode.Contents;
+import com.google.zxing.encode.QRCodeEncoder;
 import com.nostra13.universalimageloader.core.DisplayImageOptions;
 import com.nostra13.universalimageloader.core.ImageLoader;
 import com.nostra13.universalimageloader.core.assist.ImageScaleType;
@@ -92,10 +103,9 @@ import java.util.TimeZone;
 import java.util.concurrent.TimeUnit;
 import java.util.regex.Pattern;
 
-import androidx.annotation.NonNull;
+import io.reactivex.rxjava3.android.schedulers.AndroidSchedulers;
-import androidx.annotation.Nullable;
+import io.reactivex.rxjava3.core.Single;
-import androidx.annotation.RequiresApi;
+import io.reactivex.rxjava3.schedulers.Schedulers;
-import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;
 
 public final class Utils {
 
@@ -986,6 +996,27 @@ public final class Utils {
         }
     }
 
+    @NonNull
+    public static Single<Bitmap> generateQrBitmap(@NonNull final AppCompatActivity activity,
+                                                  @NonNull final String qrData) {
+        return Single.fromCallable(() -> {
+            Display display = activity.getWindowManager().getDefaultDisplay();
+            Point outSize = new Point();
+            display.getSize(outSize);
+            final int x = outSize.x;
+            final int y = outSize.y;
+            final int qrCodeDimension = Math.min(x, y);
+            debugLog(TAG, "generating QRCode Bitmap of " + qrCodeDimension + "x" + qrCodeDimension);
+            QRCodeEncoder qrCodeEncoder = new QRCodeEncoder(qrData, null,
+                    Contents.Type.TEXT, BarcodeFormat.QR_CODE.toString(), qrCodeDimension);
+
+            return qrCodeEncoder.encodeAsBitmap();
+        })
+                .subscribeOn(Schedulers.computation())
+                .observeOn(AndroidSchedulers.mainThread())
+                .doOnError(throwable -> Log.e(TAG, "Could not encode QR as bitmap", throwable));
+    }
+
     /**
      * Keep an instance of this class as an field in an AppCompatActivity for figuring out whether the on
      * screen keyboard is currently visible or not.

app/src/main/java/org/fdroid/fdroid/qr/QrGenAsyncTask.java

@@ -1,74 +0,0 @@
-package org.fdroid.fdroid.qr;
-
-import android.annotation.TargetApi;
-import android.graphics.Bitmap;
-import android.graphics.Point;
-import android.os.AsyncTask;
-import android.util.Log;
-import android.view.Display;
-import android.widget.ImageView;
-
-import com.google.zxing.BarcodeFormat;
-import com.google.zxing.WriterException;
-import com.google.zxing.encode.Contents;
-import com.google.zxing.encode.QRCodeEncoder;
-
-import org.fdroid.fdroid.Utils;
-
-import androidx.appcompat.app.AppCompatActivity;
-
-public class QrGenAsyncTask extends AsyncTask<String, Void, Void> {
-    private static final String TAG = "QrGenAsyncTask";
-
-    private final AppCompatActivity activity;
-    private final int viewId;
-    private Bitmap qrBitmap;
-
-    public QrGenAsyncTask(AppCompatActivity activity, int viewId) {
-        this.activity = activity;
-        this.viewId = viewId;
-    }
-
-    /*
-     * The method for getting screen dimens changed, so this uses both the
-     * deprecated one and the 13+ one, and supports all Android versions.
-     */
-    @SuppressWarnings("deprecation")
-    @TargetApi(13)
-    @Override
-    protected Void doInBackground(String... s) {
-        String qrData = s[0];
-        Display display = activity.getWindowManager().getDefaultDisplay();
-        Point outSize = new Point();
-        int x, y, qrCodeDimension;
-        display.getSize(outSize);
-        x = outSize.x;
-        y = outSize.y;
-        if (x < y) {
-            qrCodeDimension = x;
-        } else {
-            qrCodeDimension = y;
-        }
-        Utils.debugLog(TAG, "generating QRCode Bitmap of " + qrCodeDimension + "x" + qrCodeDimension);
-        QRCodeEncoder qrCodeEncoder = new QRCodeEncoder(qrData, null,
-                Contents.Type.TEXT, BarcodeFormat.QR_CODE.toString(), qrCodeDimension);
-
-        try {
-            qrBitmap = qrCodeEncoder.encodeAsBitmap();
-        } catch (WriterException e) {
-            Log.e(TAG, "Could not encode QR as bitmap", e);
-        }
-        return null;
-    }
-
-    @Override
-    protected void onPostExecute(Void v) {
-        ImageView qrCodeImageView = (ImageView) activity.findViewById(viewId);
-
-        // If the generation takes too long for whatever reason, then this view, and indeed the entire
-        // activity may not be around any more.
-        if (qrCodeImageView != null) {
-            qrCodeImageView.setImageBitmap(qrBitmap);
-        }
-    }
-}

app/src/main/java/org/fdroid/fdroid/views/RepoDetailsActivity.java

@@ -23,9 +23,19 @@ import android.view.ViewGroup;
 import android.widget.Button;
 import android.widget.CompoundButton;
 import android.widget.EditText;
+import android.widget.ImageView;
 import android.widget.TextView;
 import android.widget.Toast;
 
+import androidx.annotation.NonNull;
+import androidx.appcompat.app.AlertDialog;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.core.app.NavUtils;
+import androidx.core.content.ContextCompat;
+import androidx.localbroadcastmanager.content.LocalBroadcastManager;
+import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.recyclerview.widget.RecyclerView;
+
 import com.google.android.material.appbar.MaterialToolbar;
 import com.google.android.material.textfield.TextInputLayout;
 
@@ -38,20 +48,12 @@ import org.fdroid.fdroid.Utils;
 import org.fdroid.fdroid.data.Repo;
 import org.fdroid.fdroid.data.RepoProvider;
 import org.fdroid.fdroid.data.Schema.RepoTable;
-import org.fdroid.fdroid.qr.QrGenAsyncTask;
 
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.Locale;
 
-import androidx.annotation.NonNull;
+import io.reactivex.rxjava3.disposables.Disposable;
-import androidx.appcompat.app.AlertDialog;
-import androidx.appcompat.app.AppCompatActivity;
-import androidx.core.app.NavUtils;
-import androidx.core.content.ContextCompat;
-import androidx.localbroadcastmanager.content.LocalBroadcastManager;
-import androidx.recyclerview.widget.LinearLayoutManager;
-import androidx.recyclerview.widget.RecyclerView;
 
 public class RepoDetailsActivity extends AppCompatActivity {
     private static final String TAG = "RepoDetailsActivity";
@@ -91,6 +93,8 @@ public class RepoDetailsActivity extends AppCompatActivity {
 
     private MirrorAdapter adapterToNotify;
 
+    private Disposable disposable;
+
     /**
      * Help function to make switching between two view states easier.
      * Perhaps there is a better way to do this. I recall that using Adobe
@@ -141,7 +145,19 @@ public class RepoDetailsActivity extends AppCompatActivity {
         Uri uri = Uri.parse(repo.address);
         uri = uri.buildUpon().appendQueryParameter("fingerprint", repo.fingerprint).build();
         String qrUriString = uri.toString();
-        new QrGenAsyncTask(this, R.id.qr_code).execute(qrUriString);
+        disposable = Utils.generateQrBitmap(this, qrUriString)
+                .subscribe(bitmap -> {
+                    final ImageView qrCode = findViewById(R.id.qr_code);
+                    if (qrCode != null) {
+                        qrCode.setImageBitmap(bitmap);
+                    }
+                });
+    }
+
+    @Override
+    protected void onDestroy() {
+        disposable.dispose();
+        super.onDestroy();
     }
 
     @TargetApi(14)