Silverlight - Mike Taulty's Blog

In my head, I see Silverlight 4 applications as either running; In Browser Out of Browser Out of Browser and Trusted Out of Browser and Trusted and in the presence of COM interop ( i.e. on Windows ) and you might write functionality that only works in certain of those contexts – e.g.; HTML display only works out of browser. You can only read the contents of “My Documents” when out of browser and elevated You can only run any COM interop code when in the presence of COM interop and I thought that it might be a good use of MEF as a way of only bringing in the functionality that is going to work in a particular context. So, I defined an enum; [Flags] public enum AppContextStatus { InBrowser = 1, OutOfBrowser = 2, InOrOutOfBrowser = 3, OutOfBrowserTrusted = 4, OutOfBrowserCOMInterop = 8, All = 15 } and then I wanted to be able to figure out which of these particular states my code might be running in. So, a little class; public static class AppContext { public static AppContextStatus CurrentStatus { get { AppContextStatus...

Just a quick advert for something that I thought I’d already publicised but now I’m “not so sure” as I can’t find it on my site :-) I’ll be giving a talk about the Managed Extensibility Framework (MEF) in Silverlight down at the Silverlight User Group in London on Wednesday evening this week. This happens in the Microsoft office and you can find the details & registration by clicking the image below to jump over toe Mark’s blog which details the agenda including a session on Bing Maps from Johannes .   Hope to see you there :-)

I was reading Tim’s post over here on “Silverlight 4 with COM can do anything – on Windows” which referenced Justin’s amazingly detailed post with a bunch of COM interop examples from Silverlight 4 . A Silverlight 4 beta application that has been explicitly installed as trusted by the user can create COM objects if they have a registered ProgId and if they implement IDispatch. As anyone who’s been around Windows for a while and especially anyone who wrote scripting code like ASP pages will know, that opens up quite a lot of code to those applications. I think that was made pretty clear at the PDC when the feature was first announced. My personal view is that the COM interop feature is something that you'd use sparingly to add additional functionality that becomes available when and where COM interop is turned on rather than writing a tonne of code that takes the COM interop route. Why’s that? Firstly, you might find your application goes into an environment where the users aren't allowed to run trusted...

I was looking for an example of how Silverlight content is drawn with vectors that I could use in a slide-deck and it occurred to me to look at Bing Maps . I think the Bing Maps beta is pretty stunning and I was searching my blog for where I’d made reference to the beta and I realised that I don’t think that I have made reference to it; I must have just dreamt it. Or, more likely, dropped it onto Twitter. Anyway, if you haven’t seen the Bing Maps beta with Silverlight & PhotoSynth and all that goodness then read this post from Chris and then go and check it out although I warn you that it can eat quite a bit of time once you get playing with it. Anyway, back to vectors. It’s easy to see the “vector effect” on Bing Maps by just zooming the browser up to 200% or 400% where you can see the quality of the fonts and UI elements such as;   and you can very quickly see where bitmaps are used in the UI like in this weather symbol ( and the maps :-) );

One of the things I often find when publishing blog posts is that I want to display a bunch of files. For instance – in talking about WPF or Silverlight you might be trying to show something that involves a XAML file and a couple of code files and it can be a bit painful if you have to do that with 3 separate lumps of embedded text inside of a blog post. I was thinking about that problem a bit more generally and I wondered how I could do something such that I’d have a control that I could just drop into a blog post in order to display a number of files. Almost like a mini-explorer view across a set of files. I figured that I could use Silverlight for this and then I pondered a little on how I’d want to file-set packaged in order that it’d be as little trouble as possible to create one of these plug-ins. I decided on Zip. There are a few zip libraries out there for .NET but I settled on using the DotNetZip   project from CodePlex which I brought down in source form and hacked to work with Silverlight. When...

Just a little plug for a video I made just before Xmas with the guys from iMeta , a UK company that’s built a scrum tool called iMeta Agility with Silverlight. The picture’s hyperlinked to their video on Channel 9 – click to take a look and, also, try the latest version of the application .

One of the interesting things about Silverlight 4 is the inclusion of the Managed Extensibility Framework (MEF) and I think it really helps to build the case for Silverlight 4 as a great platform for business applications. Silverlight applications are rich internet applications – the deployment model is strongly angled towards web deployment as the only way to install a Silverlight application is to start on a web page and run the application - the deployment is intended to be simple, quick and secure. As developers build more and increasingly complex applications with Silverlight they can hit a tension between preserving the ethos of Silverlight deployment ( i.e. simple, quick and secure ) and building an application with the rich set of functionality that they need. They also have to contend with the usual “abilities” of software development like making sure that the application is correct, performant, available, secure, scalable, maintainable and possibly extensible whilst being productive with the code they...

Ok, ok – this will be the last post about webcams and capturing video. I’ve got to stop :-) BUT…I thought I’d modify the code from the last post a little in order to try and capture audio along with the video. This opened up some “interesting questions” in that in Silverlight you derive from an AudioSink to capture audio and from a VideoSink to capture video. Now, those 2 base classes look awfully similar and if you want to capture both audio and video and try to synchronise the two then it feels a bit painful that you can’t implement some capturing interfaces rather than have to derive from base classes. Also, even though you feed both sinks into a CaptureSource, I noticed that I was getting audio samples a little before I was getting any video samples and so it looks like there a job involved to try and synchronize the two together. Silverlight does tell you where in the time sequence these various samples come from and it tells you how long they last but it could be expensive to try and analyse that information...