Sharovatov’s Weblog

Pomodoro Windows 7 gadget

Posted in widgets, windows 7 by sharovatov on 3 December 2009

I was really inspired by http://tomatoi.st/ web service which provides an easy to use web interface for Pomodoro time management technique.

But unfortunately, tomatoi.st is down due to overload too often, so I spent 20 minutes and prepared a simple Windows 7 pomodoro gadget. It does just what’s needed – showing timers:

image

Click on “Work” button to start 25 minutes work interval, “short br” – to get 5 minutes short break timeout, “long br” for a 15 minutes long break.

It’s dead easy to download and install – just click here. Or you can inspect the code if you want to – gadget is just a zip file with html, css and js inside.

Ah, and I have to warn you – when a period of time is over, it starts playing Alert.wav every second until you set a new period.

For more information about Windows 7 gadgets you read the following posts on my blog:

  1. introduction to the gadgets platform
  2. Exploring Windows Desktop Gadgets 
  3. Exploring Windows Desktop Gadgets #2 – security and limitations
  4. Exploring Windows Desktop Gadgets #3 – settings storage
  5. Exploring Windows Desktop Gadgets #4 – flyouts

Or read MSDN.

P.S. this gadget doesn’t have any settings or flyout or anything else – it’s very simple.


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Exploring Windows Desktop Gadgets #3 – settings storage

Posted in IE8, javascript, widgets, windows 7 by sharovatov on 29 May 2009

This is the third post in Exploring Windows Desktop Gadgets series and it will be devoted to improving our comments feed reader gadget by adding settings storage functionality.

Settings storage theory

Any desktop program has its own settings storage (ini files, xml files, etc.) or uses a global OS storage (registry).

But in web-applications everything’s different – part of the functionality is provided by client (browser) and another part – by the server. Although it’s dead easy to store data on the server, on the client-side you can’t get access neither to file system nor to registry. (You actually can in IE, but this will require ActiveX scripting and therefore will ask user for an explicit permission.)

Until very recent DOM Storage specification draft, in most browsers you could only use cookies for storing some data on client side. However, IE5 introduced support for true client-side only storage – DOM Storage predecessor – userData. So it took almost eight years for the whole browsers industry to define and support similar client-side storage approach. And right at the time as DOM Storage is being drafted by W3C, it gets support in IE8.

The reason I’m telling you about DOM Storage in IE8 is that I have a strong feeling that this DOM Storage is used by Gadgets Platform to allow storing settings data for each gadget.

Settings storage practice

Settings dialog is a modal window which opens on top of your gadget. As it’s modal, the only way you can close it is to press OK or CANCEL button in its UI. Similarly to the gadget itself, settings dialog is a HTML page displayed by MSHTML.

As it would be useful to have comments feed URL and refresh frequency configurable, this is what I’ll add to my gadget:

image

In the settings dialog only area outlined in red is actually a HTML file, title and OK/CANCEL buttons are provided by Gadgets Platform:

image

To add the settings dialog to our gadget we’ll have to create a HTML file, let’s call it “settings.html”. To save comments feed URL and refresh frequency, we only need two fields and couple of labels. This is what I came up with.

If  you look at the JS code, you’ll see that it does two things:

  1. calls System.Gadget.Settings.read function to retrieve data from the Gadget settings storage
  2. defines a handler for System.Gadget.onSettingsClosing event

There’s a complete reference of Gadget platform events and properties on MSDN, but for our simple case it’s enough to say that System.Gadget.Settings.read reads object from the storage by its name, System.Gadget.Settings.write writes object to the storage with its name and System.Gadget.onSettingsClosing event fires when the settings dialog is closing. Settings store is separate for each gadget so don’t be afraid that your settings names can be accessed from other gadgets.

So in the window.onload handler of settings.html I try to get the data from the storage and set inputs values accordingly, and when the gadget is closing, I check if OK was pressed (e.closeAction == e.Action.commit) and if so, save inputs values into the storage. Dead easy.

Now we have to attach settings.html page to our gadget. This is done by adding the following javascript code to main.html file:

System.Gadget.settingsUI = "settings.html";

Now our Gadget will show this button in the control area:

image

And if you click on it, you’ll see your settings.html page rendered in a nice UI:

image

So now we have a settings dialog that reads and writes data from the Gadget settings store.  What we also need to do is to make our main.html read comments feed URL and refresh frequency from settings store as well. If you look at this javascript, you’ll see how it’s changed from the previous version. Basically, I just did the following:

  1. rss.js now doens’t have blog comments feed URL and refresh frequency hardcoded, instead, it reads these values from settings store:
    window.onload = function(){
    
      //read data from storage
      var data = getDataFromStorage();
    
      if ("" != data.url && 
          "" != data.frequency && 
          /^(\d*)(\.?)(\d*)$/.match(data.frequency)) startLoop(data);
      else document.body.innerHTML = "<b>Please make sure you"+
                                    "configured everything properly</b>";
    
    };

  2. System.Gadget.onSettingsClosed event handler is used to restart main loop with new settings:

    System.Gadget.onSettingsClosed = function(){
      var data = getDataFromStorage();
      startLoop(data);
    };

  3. And startLoop function has been rewritten to allow only one main loop (but that’s pretty irrelevant to Gadgets platform):

    var startLoop = function(data){
       //clear existing interval (if present)
       if ("undefined" != typeof arguments.callee.intervalHandler)
         window.clearInterval(arguments.callee.intervalHandler);
     
       //retrieve feed again
       getRSS(data.url);
     
       //set new main loop
       arguments.callee.intervalHandler = window.setInterval(
         function(){ getRSS(data.url); }, data.frequency * 1000
       );
    };

And here we go – gadget’s ready :)

Save it as rss-comments.gadget to your computer and install it – you will be able to set comments feed URL (so you can start using it to watch comments on your own blog) and refresh frequency in seconds.

In the next posts of this series I will cover flyouts, make the gadget look really slick with UI enhancements Gadget platform provides, show how debugging gadgets can be really effective and dive into more details of the Gadgets platform. Stay tuned for more interesting stuff!

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Exploring Windows Desktop Gadgets #2 – security and limitations

Posted in IE8, javascript, widgets, windows 7 by sharovatov on 28 May 2009

In this post (second in Exploring Windows Desktop Gadgets series) I’m going to dive deeper into Windows Desktop Gadgets platform and cover its security model and some limitations.

First of all, let me repeat that gadget is a client-side web-application running in chromeless mode on your desktop. It’s similar to HTA but provides a whole new set of functionality and also has some restrictions compared to HTA.

Gadgets security model

IE has always been the de-facto-standard platform for building powerful applications that require access to file system, Cryptographic Service Provider, WMI and other OS functionality. This functionality is achieved by using ActiveX controls. But ActiveX can’t run without a user permission! So by default javascript in web-applications has quite strong security limitations. This security model can only be weaken by users choice – by allowing ActiveX controls to run or by adding a website to a trusted zone.

But as gadgets are installed by user, so it’s his choice to run them, all functionality that MSHTML can provide is enabled (*). MSDN says:

The MSHTML runtime is configured with the set of permissions given to HTAs or the Local Machine Zone security configuration.

This rises a very important point – don’t install gadgets from non trusted sources. Or if you do, please inspect the code before you install the gadget. As Gadget runs under current user account, it won’t be able to delete system32 directory or do any other critical damage to the system. But it will surely succeed in deleting your documents or photos.

And of course, as any other Microsoft technology, Gadgets can be fully controlled by Group Policy.

For more information on Gadgets security please read this and this MSDN article.

Gadgets limitations

The main limitation to me is that there’re no modal dialogs. No alerts, no window.confirm, nothing. So if you want to do a quick debug, you have to dump data to the document itself or use a script debugger.

In one of the next posts on this topic I will cover debugging gadgets.


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Exploring Windows Desktop Gadgets

Posted in IE8, javascript, widgets, windows 7 by sharovatov on 27 May 2009

With this post I’m starting a series of posts about one great Microsoft technology – Windows 7 Gadgets. I’ve already created an introduction post earlier and I recommend you to read it to find out the history of desktop gadgets. But now I will describe the technology, its theory and practice in more detail.

First of all, let’s get our hands dirty and create a simple gadget.

Creating a simple gadget

One of the things that was always bothering me was checking comments to my blog entries. There’re usually two ways to check for new comments on your blog – either by subscribing to comments RSS feed or by going to admin web-interface of the blog and checking for comments there. I don’t like first option because I’m subscribed to more than a hundred feeds in my Outlook so I only read them at the weekends when I’ve got enough free time. And I don’t particularly fancy logging to my blog every three-four hours to check for new comments. So Windows 7 Desktop Gadget with my blog comments feed would perfectly suit my needs.

Although this might not sound as a killer app to you, but it does its job and also perfectly shows how simple it is to build a gadget.

First of all, as I’ve already said, Windows 7 Gadget is nothing more than just a HTML page with Javascript and CSS. So I use the same approach as if I had to parse my blog comments on a website – a simple HTML, a bit of CSS and a bit of AJAX. So gadget building comes down to building a client-side web-app and packing it.

Creating a web-app

I created a simple page with a pretty straight-forward javascript. If you take a look at window.onload js code, you’ll see the following:

window.setInterval( function(){ getRSS(url); }, 5*60*1000);

meaning that every five minutes getRSS function is called.

This is the “main loop” of our program. As our gadget is a desktop program written in javascript and since  Javascript blocks UI when being executed, setInterval/setTimeout is the only one way to set the “main loop”.

That’s how the javascript in this web-app works:

  1. getRSS function creates XMLHTTPRequest object and sends HTTP GET request to https://sharovatov.wordpress.com/comments/feed/.
  2. wordpress responds with XML file containing last ten comments from my blog
  3. parseRSS function parses the XML and passes the resulting object to displayRSS which just dumps it to document.body

It takes 15-20 minutes to write such a tiny piece of code. So now we’ve got a small web-application which is a very basic version of RSS reader.

As you may notice, the script doesn’t work on sharovatov.ru. Cross-domain security restrictions is a reason for that – the script is located on one domain (sharovatov.ru) and it tries to request data from another domain (sharovatov.wordpress.com). However, if you save main.html page and rss.js file to your machine, run main.html from IE8 and confirm JS execution, you will see the comments feed displayed.

As we’re done with functionality, it’s time to convert our small client-side web-app to a gadget.

Converting to a gadget

All we need to do now is to add a special manifest file. It’s just an XML file with your gadget description. Here’s mine.

That’s all. Now we pack these three files into a zip archive and rename its extension to .gadget. Here’s a link to what I came up with. Save it as test.gadget and double-click on it. If you then confirm gadget installation prompt, it will appear on the screen and the feed is downloaded and displayed.

That’s the basics of creating a gadget, if you feel interested, read MSDN or follow my posts – I will keep on writing about gadgets and in the next post I’ll show what my comments reader gadget will look like eventually :)

This is the screenshot of a 20-minutes job:

image image

Every five minutes the gadget is updated so I can clearly see whose comment is the last one and reply if needed. Very handy :)

Stay tuned and we’ll proceed.


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Windows 7 Desktop Gadgets

Posted in browsers, IE8, javascript, widgets by sharovatov on 14 May 2009

I’ve been playing with Windows 7 Desktop Gadget technology and I must tell you – I just love it! And I’ll tell you why :)

History

The approach of putting web-application right on a desktop was invented by Microsoft in 1994-95 (in Windows Nashville which was intended to be released in 1996) and was a part of Windows Desktop Update for Windows 95 and a core of Windows 98 Active Desktop. You could set an HTML page (plus JS, of course) as your desktop background and it would be run in IE. Microsoft even had a gallery of Active Desktop widgets. So web-widgets-like functionality was around almost twelve years ago. As with many other Microsoft inventions, it was way too ahead of time.

Another technology that played a role in inventing desktop gadgets is HTA – short HTML applications that run in a standalone way. You had to put your scripts (VBScript or JScript) and styles in a single HTML file, add a special description and rename the file extension to .hta. Here’s a sample code:

<html>
<head>
<title>HTA Test</title>
<HTA:APPLICATION
ID="objTest"
APPLICATIONNAME="HTA Test"
SCROLL="yes"
SINGLEINSTANCE="yes"
>
</head>

<SCRIPT type="text/javascript">
//some javascript code
</SCRIPT>

<body>

<!-- some html -->

</body>

You could access all ActiveX objects that your system provided – Scripting.FileSystemObject, UserAccounts, WMI etc. – basically everything that was supported in WSH and Script Runtime. If you were using classic ASP on the server, you could switch to writing HTAs with zero effort – language and all the objects would be the same. While any web-development IDEs could be used, there even was a special IDE for building HTAs – HTAEDIT.

So Microsoft had two nice technologies that weren’t actively used – Active Desktop as a way to integrate web-application with desktop and HTA as a core for writing standalone client-side web applications. Both technologies combined both to create Microsoft Desktop Gadgets – small standalone client-side web applications that run as dockable widgets on your desktop – pure HTML,CSS and JS packed with manifest file in an archive.

Usage

If you double-click on this archive, gadget will get installed and can be moved to any place of your desktop. IE8 core is used to run them, so you get full support for CSS2.1, great level of javascript and other IE8 goodness.

The gadgets concept was introduced In Windows Vista – but gadgets had to be positioned inside a special sidebar area – which is not very flexible. In Windows 7 you can put your gadgets wherever you want them to be.

Here’s a screenshot how gadgets look like on my desktop:

gadgets-screenshot[1]

Gadgets are especially useful when you have a widescreen monitor or two monitors configuration so that you’ve got much horizontal space, but even if you’ve got a normal monitor as gadgets can be freely positioned, you will find them useful.

I use Twitter, weather (standard), network traffic and cpu meter gadgets.

Awesome technology! I’m planning to build couple of my own gadgets and will definitely prepare a blog post on this :)

Update: It looks like Windows Mobile 6.5 will have support for similar gadgets functionality!


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HTML+CSS+JS Widgets – future cross-platform environment

Posted in web-development, widgets by sharovatov on 13 May 2009

Yesterday I installed Windows 7 on both my laptop (MSI Wind U100) and work PC (Core2Duo with 2Gb RAM). Both machines had XP – Home on laptop and Pro on work PC. One of the first things I’ve noticed right after installation was Gadgets technology that Windows 7 supports (actually, support for Sidebar Gadgets appeared in Vista, but as I didn’t have Vista installed, I couldn’t check it out). The technology is very simple – you create a manifest file with your gadget settings and HTML file with your gadget code, styles and scripting (of course, you’d better put styles and js in separate files); then zip everything in one archive and rename its extension to .gadget. That’s it, then you can install it on your sidebar in Vista or Windows 7.

Technical details of how gadgets work are for one of next blog posts, but I feel the tendency that all small applications soon will be written in HTML/JS/CSS (especially those that use web-services!).

Look, Opera has proposed a draft to W3C called Widgets – the same concept of small HTML/CSS/JS application but running inside a browser. Vodafone hired PPK to spec Mobile Widgets technology and test thoroughly (and Peter-Paul is famous for his great tests and compatibility tables!). Nokia already supports Web Widgets on S60 phones.

So instead of multiple environments we have one common environment for building applications for almost any platform – be it a browser, a mobile phone or Windows desktop. Yes, there’re API and DOM differences, for example, Windows Gadgets allow access to WMI so that you can build an application leveraging all the system functionality provided by WMI, on the phones and in Opera you will be limited to web-service based development and some pretty basic DOM, but even so it’s great that html/js/css is becoming a standard for writing cross-platform applications.

Front-end developers – our skills will become even more valuable :)


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