Simple-Flashlight/app/src/main/java/flashlight/simplemobiletools/com/MyWidgetProvider.java

package flashlight.simplemobiletools.com;

import android.app.PendingIntent;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.widget.RemoteViews;

public class MyWidgetProvider extends AppWidgetProvider implements MyCamera {
    private static MyCameraImpl cameraImpl;
    private static RemoteViews remoteViews;
    private static int[] widgetIds;
    private static AppWidgetManager widgetManager;
    private static final String TOGGLE = "toggle";

    @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
        initVariables(context);
        appWidgetManager.updateAppWidget(appWidgetIds, remoteViews);
    }

    private void initVariables(Context context) {
        final ComponentName component = new ComponentName(context, MyWidgetProvider.class);
        widgetManager = AppWidgetManager.getInstance(context);
        widgetIds = widgetManager.getAppWidgetIds(component);

        final Intent intent = new Intent(context, MyWidgetProvider.class);
        intent.setAction(TOGGLE);

        final PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, intent, 0);
        remoteViews = new RemoteViews(context.getPackageName(), R.layout.widget);
        remoteViews.setOnClickPendingIntent(R.id.toggle_btn, pendingIntent);
        cameraImpl = new MyCameraImpl(this);
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        final String action = intent.getAction();
        if (action.equals(TOGGLE)) {
            if (cameraImpl == null) {
                initVariables(context);
            }

            cameraImpl.toggleFlashlight();
        } else
            super.onReceive(context, intent);
    }

    @Override
    public void enableFlashlight() {
        remoteViews.setImageViewResource(R.id.toggle_btn, R.mipmap.flashlight_big_on);
        widgetManager.updateAppWidget(widgetIds, remoteViews);
    }

    @Override
    public void disableFlashlight() {
        remoteViews.setImageViewResource(R.id.toggle_btn, R.mipmap.flashlight_big_off);
        widgetManager.updateAppWidget(widgetIds, remoteViews);
        cameraImpl.releaseCamera();
    }

    @Override
    public void cameraUnavailable() {
    }

    @Override
    public void onDeleted(Context context, int[] appWidgetIds) {
        super.onDeleted(context, appWidgetIds);
        releaseCamera(context);
    }

    private void releaseCamera(Context context) {
        if (cameraImpl == null)
            initVariables(context);

        disableFlashlight();
        cameraImpl.releaseCamera();
    }
}