Show the number of apps to update in the bottom nav.

Shows a red badge over the "Updates" menu item.

The updates badge is a bit hacky. There are indeed libraries which
implement a bottom nav which have support for badges built into
them. However they target API 14. There are also other badge
libraries which just deal with rendering, but for the cost of
another dependency, it is not particularly difficult to create a
`TextView` with a background and position it ourselves.

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

@@ -1,16 +1,27 @@
 package org.fdroid.fdroid.views.main;
 
 import android.app.SearchManager;
+import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
+import android.content.IntentFilter;
+import android.database.Cursor;
 import android.net.Uri;
 import android.os.Bundle;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
+import android.support.design.internal.BottomNavigationItemView;
+import android.support.v4.app.LoaderManager;
+import android.support.v4.content.CursorLoader;
+import android.support.v4.content.Loader;
+import android.support.v4.content.LocalBroadcastManager;
 import android.support.v7.app.AppCompatActivity;
 import android.support.v7.widget.LinearLayoutManager;
 import android.text.TextUtils;
 import android.view.MenuItem;
+import android.view.View;
+import android.widget.RelativeLayout;
+import android.widget.TextView;
 import android.widget.Toast;
 import android.support.v7.widget.RecyclerView;
 
@@ -18,6 +29,7 @@ import com.ittianyu.bottomnavigationviewex.BottomNavigationViewEx;
 
 import org.fdroid.fdroid.AppDetails;
 import org.fdroid.fdroid.AppDetails2;
+import org.fdroid.fdroid.AppUpdateStatusManager;
 import org.fdroid.fdroid.FDroidApp;
 import org.fdroid.fdroid.NfcHelper;
 import org.fdroid.fdroid.Preferences;
@@ -25,7 +37,9 @@ import org.fdroid.fdroid.R;
 import org.fdroid.fdroid.UpdateService;
 import org.fdroid.fdroid.Utils;
 import org.fdroid.fdroid.compat.UriCompat;
+import org.fdroid.fdroid.data.AppProvider;
 import org.fdroid.fdroid.data.NewRepoConfig;
+import org.fdroid.fdroid.data.Schema;
 import org.fdroid.fdroid.views.ManageReposActivity;
 import org.fdroid.fdroid.views.apps.AppListActivity;
 import org.fdroid.fdroid.views.swap.SwapWorkflowActivity;
@@ -44,7 +58,8 @@ import org.fdroid.fdroid.views.swap.SwapWorkflowActivity;
  *  When switching from one screen to the next, we stay within this activity. The new screen will
  *  get inflated (if required)
  */
-public class MainActivity extends AppCompatActivity implements BottomNavigationViewEx.OnNavigationItemSelectedListener {
+public class MainActivity extends AppCompatActivity implements BottomNavigationViewEx.OnNavigationItemSelectedListener,
+        LoaderManager.LoaderCallbacks<Cursor> {
 
     private static final String TAG = "MainActivity";
 
@@ -56,11 +71,14 @@ public class MainActivity extends AppCompatActivity implements BottomNavigationV
 
     private static final String STATE_SELECTED_MENU_ID = "selectedMenuId";
 
+    private static final int LOADER_NUM_UPDATES = 1;
+
     private static final int REQUEST_SWAP = 3;
 
     private RecyclerView pager;
     private MainViewAdapter adapter;
     private BottomNavigationViewEx bottomNavigation;
+    private TextView updatesBadge;
     private int selectedMenuId = R.id.whats_new;
 
     @Override
@@ -81,6 +99,11 @@ public class MainActivity extends AppCompatActivity implements BottomNavigationV
         bottomNavigation.enableShiftingMode(false);
         bottomNavigation.enableItemShiftingMode(false);
 
+        updatesBadge = (TextView) findViewById(R.id.updates_badge);
+        IntentFilter updateableAppsFilter = new IntentFilter(AppUpdateStatusManager.BROADCAST_APPSTATUS_LIST_CHANGED);
+        LocalBroadcastManager.getInstance(this).registerReceiver(onUpdateableAppsChanged, updateableAppsFilter);
+        getSupportLoaderManager().initLoader(LOADER_NUM_UPDATES, null, this);
+
         if (savedInstanceState != null) {
             selectedMenuId = savedInstanceState.getInt(STATE_SELECTED_MENU_ID, R.id.whats_new);
         }
@@ -283,6 +306,56 @@ public class MainActivity extends AppCompatActivity implements BottomNavigationV
         }
     }
 
+    @Override
+    public Loader<Cursor> onCreateLoader(int id, Bundle args) {
+        Uri uri = AppProvider.getCanUpdateUri();
+        String[] projection = new String[]{Schema.AppMetadataTable.Cols._COUNT};
+
+        return new CursorLoader(this, uri, projection, null, null, null);
+    }
+
+    @Override
+    public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
+        cursor.moveToFirst();
+        int canUpdateCount = cursor.getInt(cursor.getColumnIndex(Schema.AppMetadataTable.Cols._COUNT));
+        cursor.close();
+        refreshUpdatesBadge(canUpdateCount);
+    }
+
+    /**
+     * The updates badge is a bit hacky. There are indeed libraries which implement a bottom nav
+     * which have support for badges built into them. However they target API 14. There are also
+     * other badge libraries which just deal with rendering, but for the cost of another dependency,
+     * it is not particularly difficult to create a {@link TextView} with a background and position
+     * it ourselves.
+     */
+    private void refreshUpdatesBadge(int canUpdateCount) {
+        if (canUpdateCount == 0) {
+            updatesBadge.setVisibility(View.GONE);
+        } else {
+            String text = Integer.toString(canUpdateCount);
+            updatesBadge.setVisibility(View.VISIBLE);
+            updatesBadge.setText(text);
+
+            BottomNavigationItemView updatesNavItem = bottomNavigation.getBottomNavigationItemView(adapter.adapterPositionFromItemId(R.id.updates));
+            int[] locationInWindow = new int[2];
+            updatesNavItem.getLocationInWindow(locationInWindow);
+
+            int height = (int) getResources().getDimension(R.dimen.badge_size);
+            int width = text.length() < 3 ? height : height * 2;
+            RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(width, height);
+            layoutParams.leftMargin = locationInWindow[0] + updatesNavItem.getWidth() - width;
+            layoutParams.topMargin = locationInWindow[1] - updatesNavItem.getHeight() + (height * 2);
+
+            updatesBadge.setLayoutParams(layoutParams);
+        }
+    }
+
+    @Override
+    public void onLoaderReset(Loader<Cursor> loader) {
+
+    }
+
     private static class NonScrollingHorizontalLayoutManager extends LinearLayoutManager {
         NonScrollingHorizontalLayoutManager(Context context) {
             super(context, LinearLayoutManager.HORIZONTAL, false);
@@ -299,4 +372,13 @@ public class MainActivity extends AppCompatActivity implements BottomNavigationV
         }
     }
 
+    private final BroadcastReceiver onUpdateableAppsChanged = new BroadcastReceiver() {
+        @Override
+        public void onReceive(Context context, Intent intent) {
+            if (AppUpdateStatusManager.REASON_UPDATES_AVAILABLE.equals(intent.getStringExtra(AppUpdateStatusManager.EXTRA_REASON_FOR_CHANGE))) {
+                getSupportLoaderManager().restartLoader(LOADER_NUM_UPDATES, null, MainActivity.this);
+            }
+        }
+    };
+
 }

app/src/main/res/drawable/badge_background.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <item>
+        <shape android:shape="rectangle">
+            <corners android:radius="@dimen/badge_size" />
+            <solid android:color="#ffdd0000" />
+        </shape>
+    </item>
+</selector>

app/src/main/res/layout/activity_main.xml

@@ -22,6 +22,21 @@
         android:layout_alignParentTop="true"
         android:layout_above="@+id/bottom_navigation"
         android:layout_width="match_parent"
-        android:layout_height="match_parent" />
+        android:layout_height="match_parent"
+        tools:listitem="@layout/main_tab_whats_new" />
+
+    <TextView
+        android:id="@+id/updates_badge"
+        android:layout_width="@dimen/badge_size"
+        android:layout_height="@dimen/badge_size"
+        tools:text="12"
+        android:visibility="gone"
+        tools:visibility="visible"
+        android:textSize="12sp"
+        android:textAlignment="center"
+        android:elevation="10dp"
+        android:lines="1"
+        android:textColor="@android:color/white"
+        android:background="@drawable/badge_background" />
 
 </RelativeLayout>

app/src/main/res/values/dimens.xml

@@ -29,4 +29,6 @@
     <dimen name="category_preview__padding__recycler_view__top">12dp</dimen>
     <dimen name="category_preview__padding__app_card__horizontal">3dp</dimen>
     <dimen name="category_preview__padding__app_card__vertical">4dp</dimen>
+
+    <dimen name="badge_size">18dp</dimen>
 </resources>