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Developing simple Windows 7 Gadget – Part 1

February 24th, 2010 Anuraj P Leave a comment Go to comments

Gadgets are simple and lightweight applications, which can be developed using HTML, Javascript and CSS. Gadgets can also include Image files. In Windows Vista, we can create Gadgets by zipping the files, and rename the it with .Gadget extension. In Windows 7 we can create Gadget by creating the .Gadget folder in C:\Program Files\Windows Sidebar\Gadgets\ folder. This folder contains all the default gadgets from Microsoft.

Creating Simple RegEx Tester Gadget

Regular Expressions are complex but efficient technique for processing text. And the RegEx functions are available in Javascript. So I am to creating simple regex tester gadget using Javascript. You can find a simple RegEx Tester using Javascript here : http://www.regular-expressions.info/javascriptexample.html.

For creating a Gadget we require a XML Definition file, which contains the details about the Gadget File, Links to Icons, and Copyright information. Here is skeleton a XML Definition file.

<?xml version="1.0" encoding="utf-8" ?>
<gadget>
<name>RegExTester</name>
<namespace>dotnetthoughts</namespace>
<version>1.0.0.0</version>
<author name="dotnetthoughts">
<info url="http://dotnetthoughts.net" text="www.dotnetthoughts.net" />
<logo src="logo.png" />
</author>
<copyright>&#0169; 2010</copyright>
<description>For Testing Regular Expressions</description>
<icons>
<icon width="64" height="64" src="icon.png" />
</icons>
<hosts>
<host name="sidebar">
<base type="HTML" apiVersion="1.0.0" src="RegExTester.html" />
<permissions>full</permissions>
<platform minPlatformVersion="0.3" />
</host>
</hosts>
</gadget>

And the Tags details are

name: Title of your gadget.
version: Version number of your gadget.
author: Your name or your company’s name.
info url: Web site address.
info text: Friendly name for your Web site.
logo src: Name of company’s logo image file.
copyright: Copyright notice.
description: Description of the gadget.
icon src: Name of icon image file for the gadget.
base src: Name of gadget’s main HTML file.

Gadget Details.

Save this file as Gadget.xml. Next we need to create the RegExTester.html, which is the main file, nothing but simple HTML file with some UI components.


<html>
<head>
<link rel="stylesheet" type="text/css" href="style.css" />
<script type="text/vbscript" src="message.vbs"></script>
<script type="text/javascript" src="regexcheck.js"></script>
<title>RegEx Tester</title>
</head>
<body>
<form>
<table border="1" cellpadding="1" cellspacing="5" bordercolor="red">
<tr><td><b><u>RegEx Tester</u></b></td></tr>
<tr><td><label>Regular Expression</label></td></tr>
<tr><td><textarea id="txtRegExp" cols="25" rows="4"></textarea></td></tr>
<tr><td><label>Subject String</label></td></tr>
<tr><td><textarea id="txtSubject" cols="25" rows="4"></textarea></td></tr>
<tr><td><button onclick="javascript:demoMatchClick();">Test Match</button>&nbsp;&nbsp;
<button onclick="javascript:demoShowMatchClick();">Show Match</button></td></tr> </table>
</form>
</body>
</html>

You may noticed that I have included a message.vbs file, it helps to display alert() boxes from Javascript. I don’t know why alert and prompt functions are not available in Gadgets. Also we don’t need to worry about cross platform compatibility issues in Gadgets, we can write anything supported by Microsoft Internet Explorer.

Here is the code of Message.vbs file.

sub alert(prompt)
MsgBox prompt, 48 , "RegEx Tester"
end sub

And here is the contents of regexcheck.js file.

function demoMatchClick() {
var regExCtrl = document.getElementById("txtRegExp");
var subjectCtrl = document.getElementById("txtSubject");
var re = new RegExp(regExCtrl.value);
if (subjectCtrl.value.match(re)) {
	alert("Successful match");
} else {
	alert("No match");
}
}
function demoShowMatchClick() {
var regExCtrl = document.getElementById("txtRegExp");
var subjectCtrl = document.getElementById("txtSubject");
var re = new RegExp(regExCtrl.value);
var m = re.exec(subjectCtrl.value);
if (m == null) {
	alert("No match");
} else {
	var s = "Match at position " + m.index + ":\n";
	for (i = 0; i < m.length; i++) {
		s = s + m[i] + "\n";
	}
	alert(s);
}
}

Also I added a CSS file for styling the components. Also to specify the Height and Width of the Gadget. In Windows Vista, we need to limit the size of the Gadget, because the Gadget can only place in the Sidebar, but in Windows 7 we can place the Gadget anywhere in the desktop. Also I have added icon.png and logo.png files, as specified in the XML definition file.
The current folder structure is like this.

Folder Structure

Now using any compression tool, compress the files, and Rename it as RegExTester.Gadget. Double click on the Gadget file, Windows will ask for a confirmation.