Thursday, March 6, 2008

First Silverlight 2 impressions

After the first few days I wanted to share some of my first Silverlight 2 experiences.

Nice controls!

To be honest, I was very impressed with the set of controls that are supplied. They look great and in the demo app I've downloaded they seem to work well too.

On the downside, after the first day I've had a few dissapointments as well:

No inheritance in UserControls

According to someone on the forum, it's a "limitation", but I think it's a bug:

It it not possible to use inheritance in a UserControl even if the Base class inherits the UserControl class. When building you get the error:
"Partial declarations of 'CLASSNAME' must not specify different base classes" in the file CLASSNAME.g.cs (g = generated).

When you open the .g.cs file and remove the base class from it, the project compiles fine and also seems to work fine. Looks like a bug in the implementation of Silverlight in Visual Studio.

**************************** UPDATE ****************************
I've posted my problem on the forum (like some more people) and got some nice responses. Some even seem to work almost right :):

Check out this forum thread:

So it is possible but has some peculiarities. For instance, when opening a file in Blend it gives an error. When you have no need for that, it's no problem, but I would like my designers to still have the ability to change things in the design after I used inheritance on the control.
Not quite sure what to think of this...


XAP project shortcoming?

This could be my lack of experience in SL2, but again, it's my first impression. If I find a way this does work, I'll post it as well :)

When having multiple Silverlight pages (or applications as they are called now) in a single Silverlight Project it seems impossible to load any other than the default Page.xaml:

- When using the "html" <object> method: it expects a parameter with a xap file, xaml files are not allowed.
- asp:Silverlight control also needs a xap file. asp:xaml doesn't work.

I also posted this at the forum so if I get any solution I'll let you know.

**************************** UPDATE ****************************
There is an option by setting an initParam with the name of the startup control you want to use. I'm not sure if I like this option, but it's a workaround.

WebClient instead of Downloader, improvement?

Okay, probably a better control I assume. Hmmm, dunno about that after implementing it. For a simple thing as loading an image from a zip file (thanks Marnix)....

Old school (1.1 alpha) code:


New school (2 beta) code:


Seems like more lines of code. Doesn't necessarily mean that it's a worse solution than the SL1.1 one, but it definitely makes it easier to make an error.

I think that they (MS), maybe in a later version, want to support bitmap effects like Flash does (blurring, etc). Maybe that's the reason they chose for the addition of a bitmap object.
Time will tell.

Uri inconsistency

As Imran Shaik posted on his blog, Silverlight 2 beta 1 is inconsistent when it comes to relative Uri.
The relative path should be the path from the root of the website, as it is in SL1.0 and as it was in SL1.1.

In SL2 beta 1, the path in design is relative to the root of the site, but when running the app, it is relative to the location of the XAP file. So when downloading "" using the WebClient it looks for in the ClientBin folder instead of in the root of your website.

Setting the WebClient.BaseAddress to the root of the site doesn't seem to work either.

That's what I've encountered up until now. So far, I'm not very positive about this release. I was much happier with SL1.1 alpha, but it's only the first few days.

I'll keep you informed....

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