WidgetView.java

import android.app.Activity;
import android.appwidget.AppWidgetHost;
import android.appwidget.AppWidgetHostView;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProviderInfo;
import android.content.Intent;
import android.view.Gravity;
import android.view.ViewGroup;
import android.widget.FrameLayout;

public class WidgetView {

    private static final int HOST_ID = 128;
    private static final int REQUEST_PICK_CODE = 256;
    private static final int REQUEST_CREATE_CODE = 512;

    private AppWidgetHost widgetHost;
    private AppWidgetManager widgetManager;
    private Activity activity;
    private ViewGroup container;
    private int widgetId = -1;

    /**
     * Constructor
     * @param activity activity que iniciara los Intents
     * @param container contenedor para el Widget
     */
    public WidgetView(Activity activity, ViewGroup container) {
        this.activity = activity;
        this.container = container;

        widgetManager = AppWidgetManager.getInstance(activity);
        widgetHost = new AppWidgetHost(activity, HOST_ID);
    }

    /**
     * El {@link AppWidgetHost} debe escuchar los cambios en el widget
     * @see AppWidgetHost#startListening() 
     */
    public void startListening() {
        if (widgetHost != null)
            widgetHost.startListening();
    }

    /**
     * El {@link AppWidgetHost} debe dejar de escuchar los cambios en el widget
     * @see AppWidgetHost#stopListening() ()
     */
    public void stopListening() {
        if (widgetHost != null)
            widgetHost.stopListening();
    }

    /**
     * Inicia el {@link Intent} que crea el widget
     */
    public void createWidget() {
        widgetId = widgetHost.allocateAppWidgetId();
        Intent pickIntent = new Intent(AppWidgetManager.ACTION_APPWIDGET_PICK);
        pickIntent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, widgetId);
        activity.startActivityForResult(pickIntent, REQUEST_PICK_CODE);
    }

    /**
     * Elimina el widget de la layout y libera la ID
     */
    public void destroyWidget() {
        container.removeAllViews();
        if (widgetId != -1) {
            widgetHost.deleteAppWidgetId(widgetId);
        }
    }

    /**
     * Capturar el resultado de los Intents
     * @see Activity#onActivityResult(int, int, Intent) ¡
     */
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (resultCode == Activity.RESULT_CANCELED) {
            int appWidgetId = data.getIntExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, -1);
            if (appWidgetId != -1) {
                widgetHost.deleteAppWidgetId(appWidgetId);
            }
        } else if (resultCode == Activity.RESULT_OK) {
            if (requestCode == REQUEST_PICK_CODE) {
                configureWidget(data);
            } else if (requestCode == REQUEST_CREATE_CODE) {
                addWidget(data);
            }
        }
    }

    /**
     * Agrega el widget a la layout
     * @param data resultado con la información del widget
     */
    private void addWidget(Intent data) {
        int appWidgetId = data.getIntExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, -1);
        AppWidgetProviderInfo appWidgetInfo = widgetManager.getAppWidgetInfo(appWidgetId);
        if (appWidgetInfo == null) {
            container.removeAllViews();
            return;
        }
        AppWidgetHostView hostView = widgetHost.createView(activity, appWidgetId, appWidgetInfo);
        hostView.setMinimumHeight(appWidgetInfo.minHeight);
        hostView.setAppWidget(appWidgetId, appWidgetInfo);
        hostView.updateAppWidgetSize(null, appWidgetInfo.minWidth, appWidgetInfo.minHeight, appWidgetInfo.minWidth, appWidgetInfo.minHeight);
        container.addView(hostView, getLayoutParams(appWidgetInfo.minWidth, appWidgetInfo.minHeight));
    }

    /**
     * Configura el widget si es necesario
     * @param data informacion del widget
     */
    private void configureWidget(Intent data) {
        int appWidgetId = data.getIntExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, -1);
        AppWidgetProviderInfo appWidget = widgetManager.getAppWidgetInfo(appWidgetId);
        if (appWidget.configure != null) {
            Intent intent = new Intent(AppWidgetManager.ACTION_APPWIDGET_CONFIGURE);
            intent.setComponent(appWidget.configure);
            intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId);
            activity.startActivityForResult(intent, REQUEST_CREATE_CODE);
        } else {
            onActivityResult(REQUEST_CREATE_CODE, Activity.RESULT_OK, data);
        }
    }

    private ViewGroup.LayoutParams getLayoutParams(int w, int h) {
        if (container instanceof FrameLayout) {
            FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(w, h);
            params.gravity = Gravity.CENTER;
            return params;
        }
        return new ViewGroup.LayoutParams(w, h);
    }

}