App widget on Android. test by benznest

activity_main.xml

<?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:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.benzneststudios.mywidgetapp.MainActivity">

    <TextView
        android:id="@+id/tv_title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Title"
        android:textSize="40sp"/>

    <!--<Button-->
        <!--android:id="@+id/btn_save"-->
        <!--android:layout_width="wrap_content"-->
        <!--android:layout_height="wrap_content"-->
        <!--android:text="Save"/>-->
</LinearLayout>

AndroidManifest.xml

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

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

        <receiver
            android:name=".MyWidgetProvider"
            android:label="My Widget">
            <intent-filter>
                <action android:name="android.appwidget.action.APPWIDGET_UPDATE"/>
            </intent-filter>
            <meta-data
                android:name="android.appwidget.provider"
                android:resource="@xml/app_widget_info"/>
        </receiver>

        <receiver
            android:name=".MyWidgetListViewProvider"
            android:label="My WidgetListView">
            <intent-filter>
                <action android:name="android.appwidget.action.APPWIDGET_UPDATE"/>
            </intent-filter>
            <meta-data
                android:name="android.appwidget.provider"
                android:resource="@xml/app_widget_listview"/>
        </receiver>

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

    </application>
</manifest>

app_widget_default.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:orientation="vertical"
              android:padding="16dp"
    android:background="@drawable/dialog_rounded_corner_bg">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Are you ready for sending your phone to the moon?"
        android:textSize="28sp"
        android:id="@+id/textView"
        android:textColor="#FFFFFF"
        android:textStyle="bold"/>

    <Button
        android:id="@+id/btn_start"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Start now !!"
        android:textSize="20sp"
        android:padding="30dp"
        android:textColor="@color/colorAccent"/>
</LinearLayout>

app_widget_default_2_coulmns.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:orientation="vertical"
              android:padding="16dp"
    android:background="@drawable/dialog_rounded_corner_bg">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="This is 2 column. "
        android:textSize="24sp"
        android:id="@+id/textView"
        android:textColor="#FFFFFF"
        android:textStyle="bold"/>
</LinearLayout>

app_widget_info.xml

<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
                    android:minWidth="50dp"
                    android:minHeight="50dp"
                    android:updatePeriodMillis="86400000"
                    android:previewImage="@mipmap/ic_launcher"
                    android:initialLayout="@layout/app_widget_default"
                    android:resizeMode="horizontal|vertical"
                    android:widgetCategory="home_screen">
</appwidget-provider>

app_widget_listview.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:background="@drawable/dialog_rounded_corner_bg"
              android:orientation="vertical"
              android:padding="16dp">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="My favorite food"
        android:textColor="#FFFFFF"
        android:textSize="24sp"/>

    <ListView
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

    <TextView xmlns:android="http://schemas.android.com/apk/res/android"
              android:id="@+id/empty_view"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:gravity="center"
              android:text="No data"
              android:textColor="#ffffff"
              android:textSize="28sp"
              android:textStyle="bold"/>
</LinearLayout>

MainActivity.java

package com.benzneststudios.mywidgetapp;

import android.appwidget.AppWidgetManager;
import android.content.ComponentName;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.TextView;


public class MainActivity extends AppCompatActivity {

//    Button btnSave;

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

        Bundle bundle = getIntent().getExtras();
        if (bundle != null) {
            String str = bundle.getString("MY_KEY");
            TextView tv = (TextView) findViewById(R.id.tv_title);
            tv.setText(str);
        }

//        btnSave = (Button) findViewById(R.id.btn_save);
//        btnSave.setOnClickListener(new View.OnClickListener() {
//            @Override
//            public void onClick(View v) {
//                updateWidget();
//            }
//        });
    }

    private void updateWidget() {
        Intent intent = new Intent(this, MyWidgetProvider.class);
        intent.setAction(AppWidgetManager.ACTION_APPWIDGET_UPDATE);

        int[] ids = AppWidgetManager.getInstance(getApplication())
                .getAppWidgetIds(new ComponentName(getApplication(), MyWidgetProvider.class));
        intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS, ids);
        sendBroadcast(intent);
    }
}

MyRemoteViewFactory.java

package com.benzneststudios.mywidgetapp;

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

import java.util.ArrayList;
import java.util.List;

/**
 * Created by benznest on 02-Oct-16.
 */

public class MyRemoteViewFactory implements RemoteViewsService.RemoteViewsFactory {

    private static final int mCount = 20;
    private List<String> mFoodName = new ArrayList<String>();
    private Context mContext;
    private int mAppWidgetId;

    public MyRemoteViewFactory(Context context, Intent intent) {
        mContext = context;
        mAppWidgetId = intent.getIntExtra(AppWidgetManager.EXTRA_APPWIDGET_ID,
                AppWidgetManager.INVALID_APPWIDGET_ID);
    }

    @Override
    public void onCreate() {
        for (int i = 0; i < mCount; i++) {
            mFoodName.add("Padthai "+i);
        }
    }

    public RemoteViews getViewAt(int position) {

        RemoteViews rv = new RemoteViews(mContext.getPackageName(), R.layout.row_food);
        rv.setTextViewText(R.id.tv_food_name, mFoodName.get(position));

        // add onclick.
        Bundle extras = new Bundle();
        extras.putString("MY_KEY", mFoodName.get(position));
        Intent fillInIntent = new Intent();
        fillInIntent.putExtras(extras);
        rv.setOnClickFillInIntent(R.id.my_row, fillInIntent);

        return rv;
    }

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

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

    @Override
    public long getItemId(int position) {
        return 0;
    }

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

    @Override
    public void onDataSetChanged() {

    }

    @Override
    public void onDestroy() {

    }

    @Override
    public int getCount() {
        return mCount;
    }

}

MyWidgetListViewProvider.java

package com.benzneststudios.mywidgetapp;

import android.app.PendingIntent;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.widget.RemoteViews;
import android.widget.Toast;

/**
 * Created by benznest on 02-Oct-16.
 */

public class MyWidgetListViewProvider extends AppWidgetProvider {

    @Override
    public void onReceive(Context context, Intent intent) {
        int viewIndex = intent.getIntExtra("MY_KEY", 0);
        Toast.makeText(context, "Touched view " + viewIndex, Toast.LENGTH_SHORT).show();
        super.onReceive(context, intent);
    }


    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {

        for (int i = 0; i < appWidgetIds.length; ++i) {

            Intent intent = new Intent(context, MyWidgetListViewService.class);
            intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetIds[i]);
            intent.setData(Uri.parse(intent.toUri(Intent.URI_INTENT_SCHEME)));
            RemoteViews rv = new RemoteViews(context.getPackageName(), R.layout.app_widget_listview);

            rv.setRemoteAdapter(R.id.listView, intent);
            rv.setEmptyView(R.id.listView, R.id.empty_view);

            Intent startActivityIntent = new Intent(context, MainActivity.class);
            PendingIntent startActivityPendingIntent = PendingIntent.getActivity(context, 0, startActivityIntent, PendingIntent.FLAG_UPDATE_CURRENT);
            rv.setPendingIntentTemplate(R.id.listView, startActivityPendingIntent);

            appWidgetManager.updateAppWidget(appWidgetIds[i], rv);
        }
        super.onUpdate(context, appWidgetManager, appWidgetIds);
    }
}

MyWidgetListViewService.java

package com.benzneststudios.mywidgetapp;

import android.content.Intent;
import android.widget.RemoteViewsService;

/**
 * Created by benznest on 02-Oct-16.
 */

public class MyWidgetListViewService extends RemoteViewsService {
    @Override
    public RemoteViewsFactory onGetViewFactory(Intent intent) {
        return new MyRemoteViewFactory(this.getApplicationContext(), intent);
    }
}

MyWidgetProvider.java

package com.benzneststudios.mywidgetapp;

import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.Context;
import android.os.Bundle;
import android.widget.RemoteViews;
import android.widget.Toast;

/**
 * Created by benznest on 02-Oct-16.
 */

public class MyWidgetProvider extends AppWidgetProvider {

    @Override
    public void onAppWidgetOptionsChanged(Context context, AppWidgetManager appWidgetManager, int appWidgetId, Bundle newOptions) {

        int[] appWidgetIds = {appWidgetId};
        onUpdate(context,appWidgetManager, appWidgetIds);

        super.onAppWidgetOptionsChanged(context, appWidgetManager, appWidgetId, newOptions);
    }

    private RemoteViews getRemoteViews(Context context, int minWidth, int minHeight) {
        // First find out rows and columns based on width provided.
        int rows = getCellsForSize(minHeight);
        int columns = getCellsForSize(minWidth);
        // Now you changing layout base on you column count
        // In this code from 1 column to 4
        // you can make code for more columns on your own.
        switch (columns) {
            case 2:
                return new RemoteViews(context.getPackageName(), R.layout.app_widget_default_2_columns);
            case 3:
                return new RemoteViews(context.getPackageName(), R.layout.app_widget_default_3_columns);
            default:
                return new RemoteViews(context.getPackageName(), R.layout.app_widget_default_4_columns);
        }
    }

    private static int getCellsForSize(int size) {
        int n = 2;
        while (70 * n - 30 < size) {
            n++;
        }
        return n - 1;
    }

    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {

        // loop each App Widget.
        for (int i = 0; i < appWidgetIds.length; i++) {
            Bundle options = null;
            if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.JELLY_BEAN) {
                options = appWidgetManager.getAppWidgetOptions(appWidgetIds[i]);

                // Get min width and height.
                int minWidth = options.getInt(AppWidgetManager.OPTION_APPWIDGET_MIN_WIDTH);
                int minHeight = options.getInt(AppWidgetManager.OPTION_APPWIDGET_MIN_HEIGHT);

                // Obtain appropriate widget and update it.
                RemoteViews remoteViews = getRemoteViews(context, minWidth, minHeight);
                appWidgetManager.updateAppWidget(appWidgetIds[i], remoteViews);
            }
            Toast.makeText(context, "Update appWidgetId = " + appWidgetIds[i], Toast.LENGTH_SHORT).show();
        }
    }
}

row_food.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:id="@+id/my_row"
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:orientation="horizontal"
    android:padding="16dp">

    <ImageView
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:src="@mipmap/ic_launcher"/>

    <TextView
        android:id="@+id/tv_food_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Food name"
        android:textSize="20sp"
        android:layout_gravity="center_vertical"
        android:layout_marginLeft="16dp"
        android:textColor="#FFFFFF"/>
</LinearLayout>

xml_app_widget_listview.xml

<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
                                         android:minWidth="250dp"
                                         android:minHeight="200dp"
                                         android:updatePeriodMillis="86400000"
                                         android:previewImage="@mipmap/ic_launcher"
                                         android:initialLayout="@layout/app_widget_listview"
                                         android:resizeMode="horizontal|vertical"
                                         android:widgetCategory="home_screen">
</appwidget-provider>