refactor onBackPressed to use the callback dispatcher (#937)

app/src/main/java/com/m2049r/xmrwallet/BaseActivity.java

@@ -17,11 +17,14 @@
 package com.m2049r.xmrwallet;
 
 import android.content.Context;
+import android.os.Bundle;
 import android.os.Handler;
 import android.os.Looper;
 import android.os.PowerManager;
 
+import androidx.activity.OnBackPressedCallback;
 import androidx.annotation.CallSuper;
+import androidx.fragment.app.FragmentActivity;
 
 import com.m2049r.xmrwallet.data.BarcodeData;
 import com.m2049r.xmrwallet.dialog.ProgressDialog;
@@ -35,18 +38,13 @@ public class BaseActivity extends SecureActivity
 
     ProgressDialog progressDialog = null;
 
-    private class SimpleProgressDialog extends ProgressDialog {
+    private static class SimpleProgressDialog extends ProgressDialog {
 
         SimpleProgressDialog(Context context, int msgId) {
             super(context);
             setCancelable(false);
             setMessage(context.getString(msgId));
         }
-
-        @Override
-        public void onBackPressed() {
-            // prevent back button
-        }
     }
 
     @Override
@@ -59,13 +57,15 @@ public class BaseActivity extends SecureActivity
         progressDialog = new SimpleProgressDialog(BaseActivity.this, msgId);
         if (delayMillis > 0) {
             Handler handler = new Handler();
-            handler.postDelayed(new Runnable() {
+            handler.postDelayed(() -> {
-                public void run() {
+                if (progressDialog != null) {
-                    if (progressDialog != null) progressDialog.show();
+                    progressDialog.show();
+                    disableBackPressed();
                 }
             }, delayMillis);
         } else {
             progressDialog.show();
+            disableBackPressed();
         }
     }
 
@@ -75,6 +75,7 @@ public class BaseActivity extends SecureActivity
         progressDialog = new LedgerProgressDialog(BaseActivity.this, mode);
         Ledger.setListener((Ledger.Listener) progressDialog);
         progressDialog.show();
+        disableBackPressed();
     }
 
     @Override
@@ -87,6 +88,28 @@ public class BaseActivity extends SecureActivity
             progressDialog.dismiss();
         }
         progressDialog = null;
+        enableBackPressed();
+    }
+
+    OnBackPressedCallback backPressedCallback = new OnBackPressedCallback(false) {
+        @Override
+        public void handleOnBackPressed() {
+            // no going back
+        }
+    };
+
+    public void disableBackPressed() {
+        backPressedCallback.setEnabled(true);
+    }
+
+    public void enableBackPressed() {
+        backPressedCallback.setEnabled(false);
+    }
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        getOnBackPressedDispatcher().addCallback(this, backPressedCallback);
     }
 
     static final int RELEASE_WAKE_LOCK_DELAY = 5000; // millisconds

app/src/main/java/com/m2049r/xmrwallet/GenerateReviewFragment.java

@@ -40,6 +40,7 @@ import android.widget.ScrollView;
 import android.widget.TextView;
 import android.widget.Toast;
 
+import androidx.activity.OnBackPressedCallback;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.appcompat.app.AlertDialog;
@@ -98,6 +99,13 @@ public class GenerateReviewFragment extends Fragment {
     private String walletPath;
     private String walletName;
 
+    private OnBackPressedCallback backPressedCallback = new OnBackPressedCallback(false) {
+        @Override
+        public void handleOnBackPressed() {
+            // nothing
+        }
+    };
+
     @Override
     public View onCreateView(LayoutInflater inflater, ViewGroup container,
                              Bundle savedInstanceState) {
@@ -160,6 +168,9 @@ public class GenerateReviewFragment extends Fragment {
         walletPath = args.getString(REQUEST_PATH);
         localPassword = args.getString(REQUEST_PASSWORD);
         showDetails();
+        if (type.equals(GenerateReviewFragment.VIEW_TYPE_ACCEPT)) {
+            backPressedCallback.setEnabled(true);
+        }
         return view;
     }
 
@@ -420,14 +431,11 @@ public class GenerateReviewFragment extends Fragment {
         pbProgress.setVisibility(View.INVISIBLE);
     }
 
-    boolean backOk() {
-        return !type.equals(GenerateReviewFragment.VIEW_TYPE_ACCEPT);
-    }
-
     @Override
     public void onCreate(@Nullable Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setHasOptionsMenu(true);
+        requireActivity().getOnBackPressedDispatcher().addCallback(this, backPressedCallback);
     }
 
     @Override

app/src/main/java/com/m2049r/xmrwallet/LoginActivity.java

@@ -295,7 +295,7 @@ public class LoginActivity extends BaseActivity
         toolbar.setOnButtonListener(type -> {
             switch (type) {
                 case Toolbar.BUTTON_BACK:
-                    onBackPressed();
+                    getOnBackPressedDispatcher().onBackPressed();
                     break;
                 case Toolbar.BUTTON_CLOSE:
                     finish();
@@ -1086,30 +1086,6 @@ public class LoginActivity extends BaseActivity
         }
     }
 
-    @Override
-    public void onBackPressed() {
-        Fragment f = getSupportFragmentManager().findFragmentById(R.id.fragment_container);
-        if (f instanceof GenerateReviewFragment) {
-            if (((GenerateReviewFragment) f).backOk()) {
-                super.onBackPressed();
-            }
-        } else if (f instanceof NodeFragment) {
-            if (!((NodeFragment) f).isRefreshing()) {
-                super.onBackPressed();
-            } else {
-                Toast.makeText(LoginActivity.this, getString(R.string.node_refresh_wait), Toast.LENGTH_LONG).show();
-            }
-        } else if (f instanceof LoginFragment) {
-            if (((LoginFragment) f).isFabOpen()) {
-                ((LoginFragment) f).animateFAB();
-            } else {
-                super.onBackPressed();
-            }
-        } else {
-            super.onBackPressed();
-        }
-    }
-
     @Override
     public boolean onOptionsItemSelected(MenuItem item) {
         final int id = item.getItemId();
@@ -1294,21 +1270,21 @@ public class LoginActivity extends BaseActivity
                 if (!Ledger.check()) {
                     Ledger.disconnect();
                     runOnUiThread(() -> Toast.makeText(LoginActivity.this,
-                            getString(R.string.toast_ledger_start_app, usbDevice.getProductName()),
+                                    getString(R.string.toast_ledger_start_app, usbDevice.getProductName()),
-                            Toast.LENGTH_SHORT)
+                                    Toast.LENGTH_SHORT)
                             .show());
                 } else {
                     registerDetachReceiver();
                     onLedgerAction();
                     runOnUiThread(() -> Toast.makeText(LoginActivity.this,
-                            getString(R.string.toast_ledger_attached, usbDevice.getProductName()),
+                                    getString(R.string.toast_ledger_attached, usbDevice.getProductName()),
-                            Toast.LENGTH_SHORT)
+                                    Toast.LENGTH_SHORT)
                             .show());
                 }
             } catch (IOException ex) {
                 runOnUiThread(() -> Toast.makeText(LoginActivity.this,
-                        getString(R.string.open_wallet_ledger_missing),
+                                getString(R.string.open_wallet_ledger_missing),
-                        Toast.LENGTH_SHORT)
+                                Toast.LENGTH_SHORT)
                         .show());
             }
     }
@@ -1368,8 +1344,8 @@ public class LoginActivity extends BaseActivity
                     Timber.i("Ledger detached!");
                     if (device != null)
                         runOnUiThread(() -> Toast.makeText(LoginActivity.this,
-                                getString(R.string.toast_ledger_detached, device.getProductName()),
+                                        getString(R.string.toast_ledger_detached, device.getProductName()),
-                                Toast.LENGTH_SHORT)
+                                        Toast.LENGTH_SHORT)
                                 .show());
                     Ledger.disconnect();
                     onLedgerAction();
@@ -1383,7 +1359,7 @@ public class LoginActivity extends BaseActivity
     public void onLedgerAction() {
         Fragment f = getSupportFragmentManager().findFragmentById(R.id.fragment_container);
         if (f instanceof GenerateFragment) {
-            onBackPressed();
+            getOnBackPressedDispatcher().onBackPressed();
         } else if (f instanceof LoginFragment) {
             if (((LoginFragment) f).isFabOpen()) {
                 ((LoginFragment) f).animateFAB();

app/src/main/java/com/m2049r/xmrwallet/LoginFragment.java

@@ -35,6 +35,7 @@ import android.widget.RelativeLayout;
 import android.widget.TextView;
 import android.widget.Toast;
 
+import androidx.activity.OnBackPressedCallback;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.fragment.app.Fragment;
@@ -148,6 +149,13 @@ public class LoginFragment extends Fragment implements WalletInfoAdapter.OnInter
         //activityCallback.runOnNetCipher(this::pingSelectedNode);
     }
 
+    private OnBackPressedCallback onBackPressedCallback = new OnBackPressedCallback(false) {
+        @Override
+        public void handleOnBackPressed() {
+            animateFAB();
+        }
+    };
+
     @Override
     public View onCreateView(LayoutInflater inflater, ViewGroup container,
                              Bundle savedInstanceState) {
@@ -287,6 +295,7 @@ public class LoginFragment extends Fragment implements WalletInfoAdapter.OnInter
     public void onCreate(@Nullable Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setHasOptionsMenu(true);
+        requireActivity().getOnBackPressedDispatcher().addCallback(this, onBackPressedCallback);
     }
 
     @Override
@@ -295,7 +304,7 @@ public class LoginFragment extends Fragment implements WalletInfoAdapter.OnInter
         super.onCreateOptionsMenu(menu, inflater);
     }
 
-    private boolean isFabOpen = false;
+    private boolean fabOpen = false;
     private FloatingActionButton fab, fabNew, fabView, fabKey, fabSeed, fabImport, fabLedger;
     private RelativeLayout fabScreen;
     private RelativeLayout fabNewL, fabViewL, fabKeyL, fabSeedL, fabImportL, fabLedgerL;
@@ -303,11 +312,16 @@ public class LoginFragment extends Fragment implements WalletInfoAdapter.OnInter
     private Animation fab_pulse;
 
     public boolean isFabOpen() {
-        return isFabOpen;
+        return fabOpen;
+    }
+
+    private void setFabOpen(boolean value) {
+        fabOpen = value;
+        onBackPressedCallback.setEnabled(value);
     }
 
     public void animateFAB() {
-        if (isFabOpen) { // close the fab
+        if (isFabOpen()) { // close the fab
             fabScreen.setClickable(false);
             fabScreen.startAnimation(fab_close_screen);
             fab.startAnimation(rotate_backward);
@@ -326,7 +340,7 @@ public class LoginFragment extends Fragment implements WalletInfoAdapter.OnInter
                 fabImportL.startAnimation(fab_close);
                 fabImport.setClickable(false);
             }
-            isFabOpen = false;
+            setFabOpen(false);
         } else { // open the fab
             fabScreen.setClickable(true);
             fabScreen.startAnimation(fab_open_screen);
@@ -360,7 +374,7 @@ public class LoginFragment extends Fragment implements WalletInfoAdapter.OnInter
                 fabImportL.startAnimation(fab_open);
                 fabImport.setClickable(true);
             }
-            isFabOpen = true;
+            setFabOpen(true);
         }
     }
 
@@ -372,7 +386,7 @@ public class LoginFragment extends Fragment implements WalletInfoAdapter.OnInter
             animateFAB();
         } else if (id == R.id.fabNew) {
             fabScreen.setVisibility(View.INVISIBLE);
-            isFabOpen = false;
+            setFabOpen(false);
             activityCallback.onAddWallet(GenerateFragment.TYPE_NEW);
         } else if (id == R.id.fabView) {
             animateFAB();

app/src/main/java/com/m2049r/xmrwallet/NodeFragment.java

@@ -31,6 +31,7 @@ import android.widget.Button;
 import android.widget.TextView;
 import android.widget.Toast;
 
+import androidx.activity.OnBackPressedCallback;
 import androidx.annotation.Nullable;
 import androidx.appcompat.app.AlertDialog;
 import androidx.fragment.app.Fragment;
@@ -145,6 +146,13 @@ public class NodeFragment extends Fragment
         }
     }
 
+    private OnBackPressedCallback onBackPressedCallback = new OnBackPressedCallback(false) {
+        @Override
+        public void handleOnBackPressed() {
+            Toast.makeText(requireActivity(), getString(R.string.node_refresh_wait), Toast.LENGTH_LONG).show();
+        }
+    };
+
     @Override
     public View onCreateView(LayoutInflater inflater, ViewGroup container,
                              Bundle savedInstanceState) {
@@ -187,6 +195,7 @@ public class NodeFragment extends Fragment
 
     private boolean refresh(int type) {
         if (asyncFindNodes != null) return false; // ignore refresh request as one is ongoing
+        onBackPressedCallback.setEnabled(true);
         asyncFindNodes = new AsyncFindNodes();
         updateRefreshElements();
         asyncFindNodes.execute(type);
@@ -197,6 +206,7 @@ public class NodeFragment extends Fragment
     public void onCreate(@Nullable Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setHasOptionsMenu(true);
+        requireActivity().getOnBackPressedDispatcher().addCallback(this, onBackPressedCallback);
     }
 
     @Override
@@ -342,6 +352,7 @@ public class NodeFragment extends Fragment
 
         private void complete() {
             asyncFindNodes = null;
+            onBackPressedCallback.setEnabled(false);
             if (!isAdded()) return;
             //if (isCancelled()) return;
             tvPull.setText(getString(R.string.node_pull_hint));
@@ -575,6 +586,7 @@ public class NodeFragment extends Fragment
                 }
             }
         }
+
     }
 
     void restoreDefaultNodes() {

app/src/main/java/com/m2049r/xmrwallet/OnBackPressedListener.java

@@ -1,21 +0,0 @@
-/*
- * Copyright (c) 2017 m2049r
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.m2049r.xmrwallet;
-
-public interface OnBackPressedListener {
-    boolean onBackPressed();
-}

app/src/main/java/com/m2049r/xmrwallet/WalletActivity.java

@@ -377,12 +377,12 @@ public class WalletActivity extends BaseActivity implements WalletFragment.Liste
                 switch (type) {
                     case Toolbar.BUTTON_BACK:
                         onDisposeRequest();
-                        onBackPressed();
+                        getOnBackPressedDispatcher().onBackPressed();
                         break;
                     case Toolbar.BUTTON_CANCEL:
                         onDisposeRequest();
                         Helper.hideKeyboard(WalletActivity.this);
-                        WalletActivity.super.onBackPressed();
+                        getOnBackPressedDispatcher().onBackPressed();
                         break;
                     case Toolbar.BUTTON_CLOSE:
                         finish();
@@ -964,23 +964,6 @@ public class WalletActivity extends BaseActivity implements WalletFragment.Liste
         return getWallet().getUnlockedBalance();
     }
 
-    @Override
-    public void onBackPressed() {
-        if (drawer.isDrawerOpen(GravityCompat.START)) {
-            drawer.closeDrawer(GravityCompat.START);
-            return;
-        }
-        final Fragment fragment = getCurrentFragment();
-        if (fragment instanceof OnBackPressedListener) {
-            if (!((OnBackPressedListener) fragment).onBackPressed()) {
-                super.onBackPressed();
-            }
-        } else {
-            super.onBackPressed();
-        }
-        Helper.hideKeyboard(this);
-    }
-
     @Override
     public void onFragmentDone() {
         popFragmentStack(null);
@@ -1201,7 +1184,7 @@ public class WalletActivity extends BaseActivity implements WalletFragment.Liste
     @Override
     public void onSubaddressSelected(@Nullable final Subaddress subaddress) {
         selectedSubaddressIndex = subaddress.getAddressIndex();
-        onBackPressed();
+        getOnBackPressedDispatcher().onBackPressed();
     }
 
     @Override

app/src/main/java/com/m2049r/xmrwallet/fragment/send/SendFragment.java

@@ -29,6 +29,7 @@ import android.view.ViewGroup;
 import android.widget.Button;
 import android.widget.EditText;
 
+import androidx.activity.OnBackPressedCallback;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.fragment.app.Fragment;
@@ -37,7 +38,6 @@ import androidx.fragment.app.FragmentStatePagerAdapter;
 import androidx.viewpager.widget.ViewPager;
 
 import com.google.android.material.transition.MaterialContainerTransform;
-import com.m2049r.xmrwallet.OnBackPressedListener;
 import com.m2049r.xmrwallet.OnUriScannedListener;
 import com.m2049r.xmrwallet.R;
 import com.m2049r.xmrwallet.WalletActivity;
@@ -63,7 +63,7 @@ public class SendFragment extends Fragment
         SendAmountWizardFragment.Listener,
         SendConfirmWizardFragment.Listener,
         SendSuccessWizardFragment.Listener,
-        OnBackPressedListener, OnUriScannedListener {
+        OnUriScannedListener {
 
     final static public int MIXIN = 0;
 
@@ -248,16 +248,18 @@ public class SendFragment extends Fragment
     private SpendViewPager spendViewPager;
     private SpendPagerAdapter pagerAdapter;
 
-    @Override
+    OnBackPressedCallback backPressedCallback = new OnBackPressedCallback(true) {
-    public boolean onBackPressed() {
+        @Override
-        if (isComitted()) return true; // no going back
+        public void handleOnBackPressed() {
-        if (spendViewPager.getCurrentItem() == 0) {
+            if (isComitted()) return; // no going back
-            return false;
+            if (spendViewPager.getCurrentItem() == 0) {
-        } else {
+                setEnabled(false);
-            spendViewPager.previous();
+                requireActivity().getOnBackPressedDispatcher().onBackPressed();
-            return true;
+            } else {
+                spendViewPager.previous();
+            }
         }
-    }
+    };
 
     @Override
     public boolean onUriScanned(BarcodeData barcodeData) {
@@ -546,8 +548,9 @@ public class SendFragment extends Fragment
         final MaterialContainerTransform transform = new MaterialContainerTransform();
         transform.setDrawingViewId(R.id.fragment_container);
         transform.setDuration(getResources().getInteger(R.integer.tx_item_transition_duration));
-        transform.setAllContainerColors(ThemeHelper.getThemedColor(getContext(), android.R.attr.colorBackground));
+        transform.setAllContainerColors(ThemeHelper.getThemedColor(requireContext(), android.R.attr.colorBackground));
         setSharedElementEnterTransition(transform);
+        requireActivity().getOnBackPressedDispatcher().addCallback(this, backPressedCallback);
     }
 
     @Override

app/src/main/java/com/m2049r/xmrwallet/ledger/LedgerProgressDialog.java

@@ -46,11 +46,6 @@ public class LedgerProgressDialog extends ProgressDialog implements Ledger.Liste
             setMessage(context.getString(R.string.progress_ledger_progress));
     }
 
-    @Override
-    public void onBackPressed() {
-        // prevent back button
-    }
-
     private int firstSubaddress = Integer.MAX_VALUE;
 
     private boolean validate = false;