Part 4 – Collection Views

[embedyt] https://www.youtube.com/watch?v=MMiuy9jK6X8[/embedyt]

In part 4 of the app widget tutorial, we will learn how to implement adapter-based views into our home screen widget.
For this we can use a ListView, GridView, AdapterViewFlipper or a StackView.
Since the app widget is in another process, we have to use a RemoteViewsService that returns RemoteViewsFactory objects in it’s onGetViewFactory method as a replacement for a normal adapter. In this class we have to implement onCreate, onDestroy, onDataSetChanged, getCount, getViewAt, getLoadingView, getViewTypeCount, getItemId and hasStableIds, which are similar to the methods of the normal adapter interface.
We set this adapter on our widget with setRemoteAdapter and can additionaly define an empty view that will be displayed if our data set is empty with setEmptyView.
In our manifest file we register our RemoteViewsService with the BIND_REMOTEVIEWS permission that can only be held by the Android system.
With autoAdvanceViewId we can flip through our StackView automatically and with loopViews we can make it restart at card 1 after reaching the last card in the stack.

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gradient.xmlexample_widget_item.xmlExampleWidgetService.javaactivity_example_app_widget_config.xmlExampleAppWidgetConfig.javaexample_widget.xmlExampleAppWidgetProvider.javaexample_appwidget_info.xmlAndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <gradient
        android:angle="90"
        android:endColor="#044fab"
        android:startColor="#9cefee" />
</shape>

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/example_widget_item_text"
    android:layout_width="200dp"
    android:layout_height="200dp"
    android:background="@drawable/gradient"
    android:gravity="center"
    android:text="Item"
    android:textColor="@android:color/white"
    android:textSize="20sp"
    android:textStyle="bold" />

package com.codinginflow.widgetexample;

import android.appwidget.AppWidgetManager;
import android.content.Context;
import android.content.Intent;
import android.os.SystemClock;
import android.widget.RemoteViews;
import android.widget.RemoteViewsService;

public class ExampleWidgetService extends RemoteViewsService {
    @Override
    public RemoteViewsFactory onGetViewFactory(Intent intent) {
        return new ExampleWidgetItemFactory(getApplicationContext(), intent);
    }

    class ExampleWidgetItemFactory implements RemoteViewsFactory {
        private Context context;
        private int appWidgetId;
        private String[] exampleData = {"one", "two", "three", "four",
                "five", "six", "seven", "eight", "nine", "ten"};

        ExampleWidgetItemFactory(Context context, Intent intent) {
            this.context = context;
            this.appWidgetId = intent.getIntExtra(AppWidgetManager.EXTRA_APPWIDGET_ID,
                    AppWidgetManager.INVALID_APPWIDGET_ID);
        }

        @Override
        public void onCreate() {
            //connect to data source
            SystemClock.sleep(3000);
        }

        @Override
        public void onDataSetChanged() {

        }

        @Override
        public void onDestroy() {
            //close data source
        }

        @Override
        public int getCount() {
            return exampleData.length;
        }

        @Override
        public RemoteViews getViewAt(int position) {
            RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.example_widget_item);
            views.setTextViewText(R.id.example_widget_item_text, exampleData[position]);
            SystemClock.sleep(500);
            return views;
        }

        @Override
        public RemoteViews getLoadingView() {
            return null;
        }

        @Override
        public int getViewTypeCount() {
            return 1;
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

        @Override
        public boolean hasStableIds() {
            return true;
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center_horizontal"
    android:orientation="vertical"
    tools:context="com.codinginflow.widgetexample.ExampleAppWidgetConfig">

    <EditText
        android:id="@+id/edit_text_button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:hint="Button text" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="confirmConfiguration"
        android:text="Confirm" />

</LinearLayout>

package com.codinginflow.widgetexample;

import android.app.PendingIntent;
import android.appwidget.AppWidgetManager;
import android.content.Intent;
import android.content.SharedPreferences;
import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.RemoteViews;

public class ExampleAppWidgetConfig extends AppCompatActivity {
    public static final String SHARED_PREFS = "prefs";
    public static final String KEY_BUTTON_TEXT = "keyButtonText";

    private int appWidgetId = AppWidgetManager.INVALID_APPWIDGET_ID;
    private EditText editTextButton;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_example_app_widget_config);

        Intent configIntent = getIntent();
        Bundle extras = configIntent.getExtras();
        if (extras != null) {
            appWidgetId = extras.getInt(AppWidgetManager.EXTRA_APPWIDGET_ID,
                    AppWidgetManager.INVALID_APPWIDGET_ID);
        }

        Intent resultValue = new Intent();
        resultValue.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId);
        setResult(RESULT_CANCELED, resultValue);

        if (appWidgetId == AppWidgetManager.INVALID_APPWIDGET_ID) {
            finish();
        }

        editTextButton = findViewById(R.id.edit_text_button);
    }

    public void confirmConfiguration(View v) {
        AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(this);

        Intent intent = new Intent(this, MainActivity.class);
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent, 0);

        String buttonText = editTextButton.getText().toString();

        Intent serviceIntent = new Intent(this, ExampleWidgetService.class);
        serviceIntent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId);
        serviceIntent.setData(Uri.parse(serviceIntent.toUri(Intent.URI_INTENT_SCHEME)));

        RemoteViews views = new RemoteViews(this.getPackageName(), R.layout.example_widget);
        views.setOnClickPendingIntent(R.id.example_widget_button, pendingIntent);
        views.setCharSequence(R.id.example_widget_button, "setText", buttonText);
        views.setRemoteAdapter(R.id.example_widget_stack_view, serviceIntent);
        views.setEmptyView(R.id.example_widget_stack_view, R.id.example_widget_empty_view);

        appWidgetManager.updateAppWidget(appWidgetId, views);

        SharedPreferences prefs = getSharedPreferences(SHARED_PREFS, MODE_PRIVATE);
        SharedPreferences.Editor editor = prefs.edit();
        editor.putString(KEY_BUTTON_TEXT + appWidgetId, buttonText);
        editor.apply();

        Intent resultValue = new Intent();
        resultValue.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId);
        setResult(RESULT_OK, resultValue);
        finish();
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center_horizontal"
    android:orientation="vertical">

    <TextView
        android:id="@+id/example_widget_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="#FFF"
        android:text="My Widget"
        android:textAppearance="@style/TextAppearance.AppCompat.Large" />

    <Button
        android:id="@+id/example_widget_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Press me" />

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <StackView
            android:id="@+id/example_widget_stack_view"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:loopViews="true" />

        <TextView
            android:id="@+id/example_widget_empty_view"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@android:color/darker_gray"
            android:gravity="center"
            android:text="Empty"
            android:textColor="@android:color/white"
            android:textSize="20sp"
            android:textStyle="bold" />

    </FrameLayout>

</LinearLayout>

package com.codinginflow.widgetexample;

import android.app.PendingIntent;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.RemoteViews;
import android.widget.Toast;

import static com.codinginflow.widgetexample.ExampleAppWidgetConfig.KEY_BUTTON_TEXT;
import static com.codinginflow.widgetexample.ExampleAppWidgetConfig.SHARED_PREFS;


public class ExampleAppWidgetProvider extends AppWidgetProvider {

    @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
        for (int appWidgetId : appWidgetIds) {
            Intent intent = new Intent(context, MainActivity.class);
            PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, intent, 0);

            SharedPreferences prefs = context.getSharedPreferences(SHARED_PREFS, Context.MODE_PRIVATE);
            String buttonText = prefs.getString(KEY_BUTTON_TEXT + appWidgetId, "Press me");

            Intent serviceIntent = new Intent(context, ExampleWidgetService.class);
            serviceIntent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId);
            serviceIntent.setData(Uri.parse(serviceIntent.toUri(Intent.URI_INTENT_SCHEME)));

            RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.example_widget);
            views.setOnClickPendingIntent(R.id.example_widget_button, pendingIntent);
            views.setCharSequence(R.id.example_widget_button, "setText", buttonText);
            views.setRemoteAdapter(R.id.example_widget_stack_view, serviceIntent);
            views.setEmptyView(R.id.example_widget_stack_view, R.id.example_widget_empty_view);

            Bundle appWidgetOptions = appWidgetManager.getAppWidgetOptions(appWidgetId);
            resizeWidget(appWidgetOptions, views);

            appWidgetManager.updateAppWidget(appWidgetId, views);
        }
    }

    @Override
    public void onAppWidgetOptionsChanged(Context context, AppWidgetManager appWidgetManager, int appWidgetId, Bundle newOptions) {
        RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.example_widget);

        resizeWidget(newOptions, views);

        appWidgetManager.updateAppWidget(appWidgetId, views);
    }

    private void resizeWidget(Bundle appWidgetOptions, RemoteViews views) {
        int minWidth = appWidgetOptions.getInt(AppWidgetManager.OPTION_APPWIDGET_MIN_WIDTH);
        int maxWidth = appWidgetOptions.getInt(AppWidgetManager.OPTION_APPWIDGET_MAX_WIDTH);
        int minHeight = appWidgetOptions.getInt(AppWidgetManager.OPTION_APPWIDGET_MIN_HEIGHT);
        int maxHeight = appWidgetOptions.getInt(AppWidgetManager.OPTION_APPWIDGET_MAX_HEIGHT);

        if (maxHeight > 100) {
            views.setViewVisibility(R.id.example_widget_text, View.VISIBLE);
            views.setViewVisibility(R.id.example_widget_button, View.VISIBLE);
        } else {
            views.setViewVisibility(R.id.example_widget_text, View.GONE);
            views.setViewVisibility(R.id.example_widget_button, View.GONE);
        }
    }

    @Override
    public void onDeleted(Context context, int[] appWidgetIds) {
        Toast.makeText(context, "onDeleted", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onEnabled(Context context) {
        Toast.makeText(context, "onEnabled", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onDisabled(Context context) {
        Toast.makeText(context, "onDisabled", Toast.LENGTH_SHORT).show();
    }
}

<?xml version="1.0" encoding="utf-8"?>
<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
    android:autoAdvanceViewId="@id/example_widget_stack_view"
    android:configure="com.codinginflow.widgetexample.ExampleAppWidgetConfig"
    android:initialLayout="@layout/example_widget"
    android:minHeight="110dp"
    android:minResizeHeight="40dp"
    android:minWidth="110dp"
    android:previewImage="@drawable/widget_preview"
    android:resizeMode="vertical|horizontal"
    android:updatePeriodMillis="3600000"
    android:widgetCategory="home_screen" />

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.codinginflow.widgetexample">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity
            android:name=".MainActivity"
            android:launchMode="singleTop">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <receiver android:name=".ExampleAppWidgetProvider">
            <intent-filter>
                <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
            </intent-filter>

            <meta-data
                android:name="android.appwidget.provider"
                android:resource="@xml/example_appwidget_info" />
        </receiver>

        <activity android:name=".ExampleAppWidgetConfig">
            <intent-filter>
                <action android:name="android.appwidget.action.APPWIDGET_CONFIGURE" />
            </intent-filter>
        </activity>

        <service
            android:name=".ExampleWidgetService"
            android:permission="android.permission.BIND_REMOTEVIEWS" />
    </application>

</manifest>