Scott Hanselman

The Weekly Source Code 57 -Controlling an Eagletron TrackerPod with C# 4, ASP.NET MVC and jQuery

November 22, '10 Comments [12] Posted in Channel9 | Hardware | Open Source | Remote Work | Source Code | VS2010
Sponsored By

LifeCam mounted to an Eagletron TrackerPod I have a 42" HDTV in Seattle that's hooked up all the time as an "Embodied Social Proxy." It's a portal between the Microsoft Redmond campus and my house here in Oregon. I've blogged about Embodied Social Proxies before as well as shot video of one for Channel 9. It's called the "HanselCart" around work, although recently it's stopped being a cart and now it's a whole office that folks in Building 42 can drop by and see me, er, the Virtual Me.

One of the things that hasn't been 100% smooth is that while the LifeCam Cinema HD 720p is a nice camera, I can't MOVE it. I have to ask folks to move it for me, which is a slight irritant.

I'm getting ready to head up to Seattle for a meeting. While I was packing I found this TrackerPod motorized WebCam pan/tilt/zoom in my junk closet. I must have purchased it a long time ago and forgotten. I drilled a hole into the metal base of the LifeCam Cinema HD and superglued it while half-threading it on the TrackerPod's standard tripod-style male screw.

It's late, but I figured it I was going up to Seattle tomorrow, maybe I could hack something together quickly with this device and take it with me. There's a Custom Programming API page on the TrackerPod site with a TrackerPod COM Client.

This is what I built in action:

Here's how I did it in 40 minutes. First, I made a new ASP.NET MVC 3 web project, keeping the default template. This is quick and dirty, right?

Yes, I used a <TABLE>, sue me.

image

Here's the complete Razor View. I knew that I'd want a bunch of buttons to move the camera, and I assumed I would use jQuery to make an AJAX to the server side running ASP.NET MVC. I'm using the latest jQuery 1.4.4 and I'm getting it from the updated Microsoft cookieless CDN (Content Delivery Network.)

Rather than making a complex switch statement for the different buttons or different event handlers, I decided to use arbitrary HTML5 data attributes. Each INPUT Button has attributes like data-xvalue and data-yvalue.

There's one Click() handler hooked up to all Buttons. It gets the values of those data attributes, then POSTs the data to the Move method of the Home Controller.

@{
View.Title = "Home Page";
}
<script src="•http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.4.4.min.js"
type="text/javascript"></script>
<table border="0">
<tr>
<td></td><td>
<input type="button" value=" up " name="up"
data-xvalue="0" data-yvalue="-10" data-method="0" />
</td><td></td>
</tr>
<tr>
<td>
<input type="button" value="left" name="left"
data-xvalue="10" data-yvalue="0" data-method="0" />
</td>
<td>
<input type="button" value="home" name="home"
data-xvalue="0" data-yvalue="0" data-method="1" />
</td>
<td>
<input type="button" value="right" name="right"
data-xvalue="-10" data-yvalue="0"
data-method="0" />
</td>
</tr>
<tr>
<td>
</td>
<td>
<input type="button" value="down" name="down"
data-xvalue="0" data-yvalue="10" data-method="0" />
</td>
<td>
</td>
</tr>
</table>
<script type="text/javascript">
//<![CDATA[
$(document).ready(function () {
$('input').click(function (event) {
var target = event.target;
x = $(target).data('xvalue');
y = $(target).data('yvalue');
m = $(target).data('method');
$.post("/Home/Move", { x: x, y: y, method: m });
}
);
});
//]]>
</script>

In the Home Controller, there's a method called Move(int x, int y, int method) where method is the way to move the camera - relative is 0 or absolute is 1. That's part of the camera's calling convention.

using TRACKERPOD_DUAL_COMLib;

namespace TrackerPodWeb.Controllers
{
public class HomeController : Controller
{
private dynamic cam = MvcApplication.myCameraInstance;

[HttpPost]
public void Move(int x, int y, int method)
{
cam.x = x;
cam.y = y;
cam.move_method = method;
cam.move();
}

public ActionResult Index()
{
return View();
}
}
}

See that dynamic object? That was the part that blew me away. I'm so used to COM Interop being a freaking nightmare from .NET that I spent most of the time messing with COM Interfaces and Type Libraries and exceptions when I realized that C# 4 was supposed to fix all that.

Like I've been saying about Razor - "stop thinking about syntax and just use it." - the same applies to COM interop in .NET 4 (Remember that the Visual Basic guys have have this nice experience for years...that's why VB is such a popular business automation language.)

Just use the dynamic keyword and start calling COM methods. Seriously, it just worked. I was copy/pasting code from the TrackerCam's VB6 (yes Visual Basic 6) samples into C#4 and other than a few semicolons, it was working directly!

Here's my Web Application's startup code:

public static dynamic myCameraInstance { get; set; }

protected void Application_Start()
{
//snip the MVC init stuff...
myCameraInstance = new TrackerPod();
myCameraInstance.app_name = "hanselcam";
myCameraInstance.initialize();
}

Here I hang on to the COM object for the camera as a poor man's singleton for use elsewhere. I should probably put guard-code around this to make sure it doesn't disappear or something but it's working so far. It should be a proper singleton I think.

Then I use that instance in my HomeController and call the COM methods in Move(). ASP.NET MVC takes care of the binding from jQuery to the Action Method, and .NET 4, C# and the DLR take care of the call into the COM TrackerCam stuff.

HTML5+jQuery -> ASP.NET MVC -> C# 4 dynamic keyword -> DLR COM Binder -> COM Library = It just works.

There's some HTML5 attributes, five lines of JS here and basically four lines of COM interop on my Move() method.

Now I'll be able to control my Seattle WebCam from Oregon. I may make it so I can control it from the Office Communicator Lync chat client or something. It'd also be nice if someone wrapped up the TrackerPod as a nice C# library and put it on CodePlex.

I'll add that to my ToDo list, or perhaps you will, Dear Reader. ;)

Related Links

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

facebook twitter subscribe
About   Newsletter
Sponsored By
Hosting By
Dedicated Windows Server Hosting by SherWeb

This Developer's Life 1.0.8 - Motivation

November 19, '10 Comments [11] Posted in Podcast
Sponsored By

imageIn this episode of This Developer's Life 1.0.8, Rob and I talk to 2 people with fairly different stories, about what motivates them:

  • I talk to Brad Wilson, Senior Developer on the Microsoft ASP.NET MVC team about what motivates him to get out of bed and come to work every day at a high-intensity company, surrounded by brilliant people.
  • Rob talks to Rob Sullivan, a database administrator at a large company, about what motivates him to make developer’s lives miserable in order to keep his job.

You can download the MP3 here (58 minutes) and visit our site at http://thisdeveloperslife.com.

Please consider subscribing with iTunes, or Zune. Or if you have a BitTorrent client and would like to help save us bandwidth money, as well as the bragging rights of downloading legal torrents via RSS, get our Torrent Feed at ClearBits.

The bandwidth and other costs for this week's show were picked up by Twilio:

Need SMS or Voice call capabilities for your application? Check out Twilio.

… and Umbraco

“Priceless CMS at the cost of virtually nothing”

See you next time!

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

facebook twitter subscribe
About   Newsletter
Sponsored By
Hosting By
Dedicated Windows Server Hosting by SherWeb

Hanselminutes Podcast 241 - The MVVM Pattern with Laurent Bugnion

November 19, '10 Comments [2] Posted in Open Source | Podcast | Silverlight | WPF
Sponsored By

Scott talks to Laurent Bugnion about the often misunderstood Model-View-ViewModel (MVVM) pattern. What's the different between this pattern and MVC? Can I use this pattern for Silverlight, WPF and Windows Phone 7, and what Open Source projects can support this pattern?

Links from the Show

NOTE: If you want to download our complete archives as a feed - that's all 241 shows, subscribe to the Complete MP3 Feed here.

Also, please do take a moment and review the show on iTunes.

Subscribe: Subscribe to Hanselminutes Subscribe to my Podcast in iTunes

Download: MP3 Full Show

Do also remember the complete archives are always up and they have PDF Transcripts, a little known feature that show up a few weeks after each show.

Telerik is our sponsor for this show.

Building quality software is never easy. It requires skills and imagination. We cannot promise to improve your skills, but when it comes to User Interface and developer tools, we can provide the building blocks to take your application a step closer to your imagination. Explore the leading UI suites for ASP.NET AJAX,MVC,Silverlight,Windows Forms and WPF. Enjoy developer tools like .NET Reporting, ORM, Automated Testing Tools, Agile Project Management Tools, and Content Management Solution. And now you can increase your productivity with JustCode, Telerik’s new productivity tool for code analysis and refactoring. Visit www.telerik.com.

As I've said before this show comes to you with the audio expertise and stewardship of Carl Franklin. The name comes from Travis Illig, but the goal of the show is simple. Avoid wasting the listener's time. (and make the commute less boring)

Enjoy. Who knows what'll happen in the next show?

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

facebook twitter subscribe
About   Newsletter
Sponsored By
Hosting By
Dedicated Windows Server Hosting by SherWeb

Hanselminutes Podcast 240 - Developing Indie Games for Xbox 360 and XNA with George Clingerman

November 19, '10 Comments [2] Posted in Gaming | Learning .NET | Podcast
Sponsored By

Kissy Poo Xbox Live Indie Game for Kids This week Scott talks to George Clingerman, a member of the Independent Xbox Game Development Community (Indie Games) who also runs http://www.xnadevelopment.com. George is a business developer by day and a game developer by night, using C# and managed code in both instances. How does this all work and how can you develop and sell your own games?

Links from the Show

NOTE: If you want to download our complete archives as a feed - that's all 240 shows, subscribe to the Complete MP3 Feed here.

Also, please do take a moment and review the show on iTunes.

Subscribe: Subscribe to Hanselminutes Subscribe to my Podcast in iTunes

Download: MP3 Full Show

Do also remember the complete archives are always up and they have PDF Transcripts, a little known feature that show up a few weeks after each show.

Telerik is our sponsor for this show.

Building quality software is never easy. It requires skills and imagination. We cannot promise to improve your skills, but when it comes to User Interface and developer tools, we can provide the building blocks to take your application a step closer to your imagination. Explore the leading UI suites for ASP.NET AJAX,MVC,Silverlight,Windows Forms and WPF. Enjoy developer tools like .NET Reporting, ORM, Automated Testing Tools, Agile Project Management Tools, and Content Management Solution. And now you can increase your productivity with JustCode, Telerik’s new productivity tool for code analysis and refactoring. Visit www.telerik.com.

As I've said before this show comes to you with the audio expertise and stewardship of Carl Franklin. The name comes from Travis Illig, but the goal of the show is simple. Avoid wasting the listener's time. (and make the commute less boring)

Enjoy. Who knows what'll happen in the next show?

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

facebook twitter subscribe
About   Newsletter
Sponsored By
Hosting By
Dedicated Windows Server Hosting by SherWeb

Hanselminutes Podcast 239 - Creative Outlets with Rob Conery

November 19, '10 Comments [0] Posted in Podcast
Sponsored By

devlifeglassesRob Conery joins Scott this week as the they talk about their new (and very different) podcast "This Developer's Life." Why does Rob feel the need to create? What's the process? How does one create their own podcast and what are some tips for not just success, but feeling good after!

NOTE: If you want to download our complete archives as a feed - that's all 239 shows, subscribe to the Complete MP3 Feed here.

Also, please do take a moment and review the show on iTunes.

Subscribe: Subscribe to Hanselminutes Subscribe to my Podcast in iTunes

Download: MP3 Full Show

Do also remember the complete archives are always up and they have PDF Transcripts, a little known feature that show up a few weeks after each show.

Telerik is our sponsor for this show.

Building quality software is never easy. It requires skills and imagination. We cannot promise to improve your skills, but when it comes to User Interface and developer tools, we can provide the building blocks to take your application a step closer to your imagination. Explore the leading UI suites for ASP.NET AJAX,MVC,Silverlight,Windows Forms and WPF. Enjoy developer tools like .NET Reporting, ORM, Automated Testing Tools, Agile Project Management Tools, and Content Management Solution. And now you can increase your productivity with JustCode, Telerik’s new productivity tool for code analysis and refactoring. Visit www.telerik.com.

As I've said before this show comes to you with the audio expertise and stewardship of Carl Franklin. The name comes from Travis Illig, but the goal of the show is simple. Avoid wasting the listener's time. (and make the commute less boring)

Enjoy. Who knows what'll happen in the next show?

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

facebook twitter subscribe
About   Newsletter
Sponsored By
Hosting By
Dedicated Windows Server Hosting by SherWeb

Disclaimer: The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.