HelloWebView.java

package com.novoda;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.webkit.WebView;

import com.novoda.utils.PinchZoomDetector;

public class HelloWebView extends Activity{

	private static final int DIALOG_CHOOSE_VIEW_ID = 0;
	private WebView webView;
	private int fontSize;
	private PinchZoomDetector zoomDetector;

	@Override
	public void onCreate(Bundle savedInstanceState) {
	    super.onCreate(savedInstanceState);
	    setContentView(R.layout.webview_main);
	    webView = (WebView) findViewById(R.id.webview_main);
	    webView.loadUrl("file:///android_asset/two_columns.html");
	    fontSize = webView.getSettings().getDefaultFontSize();
	    
		if (getPackageManager().hasSystemFeature(PackageManager.FEATURE_TOUCHSCREEN_MULTITOUCH)) {
			webView.setOnTouchListener(touchListener);
			zoomDetector = new PinchZoomDetector();
		}
	}
	
	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
	    MenuInflater inflater = getMenuInflater();
	    inflater.inflate(R.menu.webview_main_menu, menu);
	    return true;
	}
	
	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
		boolean result;
		switch (item.getItemId()) {
			case R.id.menu_action_zoom_in:
				fontSizePlus();
				result = true;
				break;
			case R.id.menu_action_choose_view:
				showDialog(DIALOG_CHOOSE_VIEW_ID);
				result = true;
				break;
			case R.id.menu_action_zoom_out:
				fontSizeMinus();
				result = true;
				break;
			default:
				result = super.onOptionsItemSelected(item);
		}
		return result;
	}
	
	private void fontSizePlus() {
		if (fontSize < 72) {
			webView.getSettings().setDefaultFontSize(++fontSize);
		}
	}

	private void fontSizeMinus() {
		int minimumFont = webView.getSettings().getMinimumFontSize();
		if (fontSize > minimumFont) {
			webView.getSettings().setDefaultFontSize(--fontSize);
		}
	}
	
	@Override
	protected Dialog onCreateDialog(int id) {
		Dialog dialog = null;
		
		switch (id) {
			case DIALOG_CHOOSE_VIEW_ID:
				dialog = getChooseViewDialog();
				break;
			default:
				dialog = super.onCreateDialog(id);
		}
		
		return dialog;
	}
	
	private Dialog getChooseViewDialog() {
		final String[] fileNames = {"Two columns", "Three columns", "Two columns and photo"};
		final String[] filePaths = {"file:///android_asset/two_columns.html",
									"file:///android_asset/three_columns.html",
									"file:///android_asset/two_columns_and_photo.html"};

		AlertDialog.Builder builder = new AlertDialog.Builder(this);
		builder.setTitle("Choose a View");
		builder.setItems(fileNames, new DialogInterface.OnClickListener() {
		    public void onClick(DialogInterface dialog, int item) {
		    	webView.loadUrl(filePaths[item]);
		    }
		});
		
		return builder.create();
	}

	private OnTouchListener touchListener = new OnTouchListener() {
		@Override
		public boolean onTouch(View v, MotionEvent event) {
			int result = zoomDetector.detectZoom(event);
			
			switch(result){
				case PinchZoomDetector.ZOOMING_IN:
					fontSizePlus();
					break;
				case PinchZoomDetector.ZOOMING_OUT:
					fontSizeMinus();
					break;
			}

			return true;
		}
	};
	
}