Rants
This weekend I will be at the Atlanta Code Camp this Saturday. I have four talks and they follow the predictable Silverlight and Data topics. Here are the talks:
- Using Blend 2.0 for Silverlight
- Consuming Data with Silverlight 2
- Digging into Deep Zoom
- Using C# 3.0 Features for Clean Code
In addition, we giving away a seat at the upcoming Atlanta stop of the Silverlight Tour (on May 12-14th, 2008). Com early and state late to be there for the drawing. The code camp is giving away a number of prizes, this is just one of them.
Hopefully, i'll see you there!
If you havent voted, please feel free to vote for what data access strategy here:
http://wildermuth.com/2008/03/21/Data_Access_Strategies.aspx
For those who were interested in the results:
One thing that I took away from this is that some strategies did not get any votes (and I expected them to) like CSLA. I think that's a product more of the fact that Rocky's readers probably don't read my blog...so the poll is very unscientific. I was surprised by the sheer number of LINQ for SQL respondents and the big Entity Framework numbers. Both being new technologies, I didn't expect there to be much usage yet. Go figure.
If you are interested in attending the upcoming Silverlight Tour stop in Seattle on April 9-11th, there are only a handful of seats left. Be sure and sign up soon. We only accomodate sixteen students per class to make sure everyone can get the attention they deserve.
In my weekend attempt to upgrade some of my older examples, the Silverlight SeeqPod Player is now all Silverlight 2.
Converting the Silverligth 1.1 application to a 2.0 was remarkably harder than the Silverlight 1.0 to 2.0. It may be because of use of user controls versus real controls (I changed from using two nested user controls to using a ListBox with Control Templates). In addition, switching the format of the web service usage from consuming XML directly to using DataContracts confused it a bit but overall it wasn't difficult. Lastly, I was using a layered HTML input control for a TextBox, and changing it over to a built-in one, took a little time too. Some code just simply disappeared (as I was moving some text around to make it appear like it was centered, but now its just a matter of marking it as TextAlignment = Center.
I was also able to polish some features I wanted to add:
- The Play Panel how slides in and out like I originally wanted.
- When the URL from SeeqPod is a dead link, I now change the UI to show its a bad song so you don't continue to click on the song.
- I also added Tooltips to help make sense of some of the non-text buttons.
Here's the source if you want to play with it: Source Code
UPDATE: I've updated the code (and the app) as I found some odd behavior with random or shuffle play. One of the things I noticed was that the selected item was not getting updated all the time. I realized that during some operations (MediaElement specific events and callbacks in Web Service Proxy's), you're not actually running on the main UI thread. This is not a big surprise but since it fails silently it can cause odd issues. To get around it I used the Dispatcher to fire an event on the UI thread:
Dispatcher.BeginInvoke(() => { songList.SelectedIndex = someValue; } );
You could use an anonymous delegate, but I prefer this shorthand Lambda function. It fixed the issue with the wierdness of showing hte selected index.
Hope this helps some of you struggling with issues.
Its not a dramatic change, but I've ported my Silverlight 1.0 Silverlight page to use Silverlight 2. There were some interesting lessons learned:
- If I want to use the ASP.NET Silverlight control, I have to upgrade to ASP.NET AJAX 3.5. Not a big deal but annoying.
- If you used class-style JavaScript, it came over to C# pretty easily. (Can't same the same for VB though).
- I was able to switch from Dynamic XAML to Data Templates (with a ListBox) very easily.
- There are some font rendering changes as the old XAML that used to fit on the template now overlaps. Had to do some editorial changes to accomodate the change.
- There is a bug in ListBox that does not reset the position of the ListBox's Scrollbar if the number of items changes (e.g. changed the ItemsSource). Doing hacks like ScrollIntoView() doesn't seem to fix it. If you move it with the mouse it heals itself.
I've decided to release the code this time. You can download it here: Source Code
Overall it was a fun little task. Tomorrow I am going to port my SeeqPod player from Silverlight 1.1 to Silverlight 2 to see what can be learned there.
Quick fix for a problem that was haunting me today:
If you upgrade an ASP.NET 2.0 app to 3.5 and have .xaml files in your project that are part of a Silverlight 1.0 or 1.1 project, the conversion wizard converters them to Build-type: "Page" and adds a custom build for building the WPF files. If this happens you'll get a cryptic error:
"error MC6000: Project file must include the .NET Framework assembly 'WindowsBase, PresentationCore, PresentationFramework' in the reference list."
Go through your xaml files and mark them as "Content" and remove any custom tools and it will fix it.
Jon Galloway has a new blog entry where he discussed and dissects DeepZoom. He explains it better than most and is really worth a read. Of particular interest is the comparison with other technologies (e.g. Google Maps, Zoomorama, etc.). He really makes some key points to explain why this is important to the Silverlight platform. If you care about Silverlight, read it now.
I've been teaching my students to be careful not to create Silverlight projects that alienate users and break the basic working of the web. One of the things I've explained is that you need to make it so that the back button and links work (where applicable) in your applications. I haven't had a good example to show them until now.
I've created a quick and dirty example of how to change the address bar (and respond to this change when you return). The trick to getting this to work is to use the HtmlWindow's CurrentBookmark and NavigateToBookmark members. For example, in the example I have a ListBox that changes some state in my app. When the SelectedIndex changes, I use NavigateToBookmark to change the Url:
theList.SelectionChanged += (s, e) =>
{
if (theList.SelectedItems.Count > 0)
{
siteInfo.Visibility = Visibility.Visible;
siteInfo.DataContext = theList.SelectedItem;
Site site = (Site) theList.SelectedItem;
HtmlPage.Window.NavigateToBookmark(string.Concat("id=", site.Id));
// HACK to fix non-binding of NaviateUri
theLink.NavigateUri = new Uri(site.Url);
}
else
{
siteInfo.Visibility = Visibility.Collapsed;
}
};
Then in my app, on Load I look at the CurrentBookmark so that if I've returned to my application with the Bookmark specified, I can change the state of my app back:
this.Loaded += (s, x) =>
{
// Show current item if included in bookmark
if (!string.IsNullOrEmpty(HtmlPage.Window.CurrentBookmark))
{
string[] parts = HtmlPage.Window.CurrentBookmark.Split('=');
if (parts.Length == 2)
{
int id;
if (int.TryParse(parts[1], out id))
{
Site selected = sites.FirstOrDefault(e => e.Id == id);
theList.SelectedItem = selected;
}
}
}
};
This is enabling both the Back button as well as Linking to my app. You can download the source here:
http://wildermuth.com/downloads/backenabledsilverlight.zip
Or see a live version of it here:
http://www.silverlightdata.com/backenabledsilverlight.aspx
One caveats on the example:
-
When you return to the page with a bookmark, the ListBox selection isn't showing. This is a ListBox bug that has been communicated to Microsoft. It has nothing to do with this code.
I had interesting conversations with a number of people about different data access/ORM strategies at MIX recently and was trying to understand where people are spending their efforts in consuming data. The conversation was essentially a discussion of who is using what to access data in .NET applications. I had assumed that certain solutions were widely used and others were not but I didn't have a good idea of what the market was really like. To help me with this I am asking you (my readers) to share with me where you are investing time in data access by taking the following poll:
This is an excellent looking Silverlight 1 ad that I found on Microsoft's site today. Clear, consise and a bit sexy.
Made me think about more Silverlight based ads for non-Microsoft sites. Too bad SL isn't ubiquitous yet...but it feels like its coming...
