A few weeks ago, we released the Silverlight control toolkit. There are some nice controls in there, including the expander.
In this post I will take a look at the expander and alter is so it’s content transitions in/out. Yes, my peeps: we are extending the expander!

In a simple scenario, the expander is used as follows:

I have used a border to show off its content. When you run this program, and click on the expander, this is what you will see:

Now, when you click the expander button (helpfully pointed out by my big red arrow!), the expander will immediately remove our content. There is no nice effect or transition going on.
This is consistent with WPF behavior.

But it is not cool, is it?

So, let’s take a better look, and open up the expander.xaml inside of our toolkit source. The relevant part is here:

and in the visual states:

So, the ‘ExpandSite’ is an element that has a visibility of Collapsed. When the control is ‘expanded’ the expandsite will be set to visible. Effective, but no fun.

We will manually transition the height of the content. I will leave it up to you to create a switch on the expanddirection and animate the width instead.

In order to hook everything up, I will create a new class, called: SmoothExpander.

The code should point you to the next change: I have added a scrollviewer inside the new template. So, I copied the expander template and put it inside themes\generic.xaml. The relevant parts are:

and

First off, I removed the Storyboard in the VisualState, since I will be creating on in code. Also, I have put a scrollviewer around my contentcontrol. Let’s take a look at that in more detail:

• The scrollviewer will host the contentcontrol
• Its height is set to 0, so it will not show up
• The visibility of the contentcontrol is set to Visible

This gives us the option of using the extentHeight property of the Scrollviewer to figure out how large our contentcontrol wants to be!

So, lets implement our behavior:

I have been wanting to show how to use a storyboard in code for some time.
In both cases a storyboard is created with a DoubleAnimation that animates from the current Height to either 0 or the intended height. We couple this animation to our scrollViewer and off we go.

Since we do not collapse or expand straight away, we should change our code to run those methods on the storyboard finish:

Running sample is below. The second expander is of type ‘SmoothExpander’.

Source for this sample

I kept the sample as straightforward as possible. Extra work that should be done though:

1. Create a templatepart attribute so that Blend knows about this scrollviewer
2. Do not rely on the existence of the scrollviewer.
3. Use expanddirection to toggle behavior.
4. Possibly allow for a maximum to be set on the scrollviewer.

[update: source included
I have included the source. The source code works with the asp.net developer webserver instead of IIS. That will make it easier for you to run the sample!]

The autocomplete box is a control that will popup a combobox based on what the user is typing. You see a lot of these on the web, and for good reason: they really help make your enduser more productive!
In this post I will walk you through building a (WCF) webservice and connecting it up to the box. As you will see, it's really easy.

If you are unable to visualize it, this picture from our codeplex pages demonstrates a simple example:

Step 1: create the webservice

We start of by creating a new project and choosing to create a new asp.net project for us. It will hold our webservice. Let's add one by choosing the 'Silverlight enabled WCF Service' template that should be when you add a new item.

So, add a service called 'NamesService.svc'.
After you have made a list of your friends, return them in a similar fashion as I do:

(Actually, after watching the PDC keynotes, don't you really want to use livemesh to do this kinds of stuff?? Or could we get this from Bluehoo? )

Step 2: connecting from silverlight

In your silverlight application, add a service reference. Because you are working from one big happy solution, you will be able to press the discover button and get your service. Add it and give it a nice name.

This will add a proxy to your Silverlight client.

Step 2.1: test it out, man!

Let's just quickly see if we can get our service to work! Add these lines of code in your page.xaml.cs file and run.

This should print out the number 7 in your output.

We are first setting up a callback that will be called when the webservice returns with information. The args.Result property is a strongly typed property which holds your result.
We kick of the call to the webservice with our proxy.GetFriendsAsync() call.

Step 3: bring in the autocomplete textbox

It is time to add the autocomplete textbox in the mix.

Add a reference to the silverlight toolkit to your project, and (do) use the 'controls' prefix as the xmlns namespace. Then, just add it to the page xaml.

I have added the box and have added an eventhandler to the Populating event. This will allow me intercept and call our webservice. Dropping back to code, we'll hook everything up:

On line 33, I'm cancelling the population. Populating should really be done synchronously and fast. Since we can't do it fast, we will be doing the populating ourselves.
On line 50, we make the call to our webservice. When it is finished, it will execute the anonymous delegate on lines 39 to 46.
Our args.Result is a string[] with friends from the server. I will combine that with a list of friends we might keep in a different source.

The result:

Check out the LiveSearch scenario sample that comes with the toolkit. It connects to livesearch and fetches search suggestions on the fly.

When you are browsing the charting samples here, you will notice a scenario that is currently called 'Zoom'.

I think it's pretty clear that you are supposed to drag the zoom slider :)

When you do, the chart is resized and to look like this:

Charts do not have this capability built-in at the moment, so this gives us the opportunity to dig into the charts a bit.

All charts are of the same type (Chart) and you can create a line series by adding an instance of LineSeries to the chart. This is quite flexible, because you can add as many as you want. It our case, two are added. Let's take a look at the different controls that make up this sample:

As you can see, two LineSeries have been added, their ItemsSource pointing to a static resource defined somewhere else.

The slider is hooked up to a method in my codebehind which executes this one line of code:

            ChartArea.Width = ScrollArea.ViewportWidth + (ScrollArea.ViewportWidth * zoom / 100.0);

I am not setting the width of the complete chart. If I were to do that, the legend and title would scroll away as well, which is not what I want. Besides, there is no ScrollViewer around to handle the scrolling. Lets take a look at the custom template that does have a ScrollViewer in it:

I have retemplated the chart to include a ScrollViewer.

You can clearly see that the legend is not in the ChartArea. So, setting the width of the ChartArea will give you the zoom you are aiming for. The axis get notified of the change and (if set to 'Auto'), will update to show more or less information.

Since Chart is a sealed class, I had to walk the visual tree to get to both the ChartArea component and the ScrollViewer.

Today, Scott Guthrie announced our teams product: the Silverlight Toolkit. My boss, Shawn Burke just posted a blog that lists all the different controls that are included and gives out information about the quality levels of the controls. It's a must-read.

The components included in this release are:

Components in the Preview Quality Band

• AutoCompleteBox
• NumericUpDown
• Viewbox
• Expander
• ImplicitStyleManager
• Charting

Components in the Stable Quality Band

• TreeView
• DockPanel
• WrapPanel
• Label
• HeaderedContentControl
• HeaderedItemsControl

I joined only a few weeks ago and have been looking at the controls. What is most impressive, is the incredible amount of unittests that are included with this release. On the team is Jeff Wilcox who heads the Silverlight Unit Test Framework.

I have been playing around with the controls and will probably be blogging some short blobs about my findings. I've spend quite some time with charting.

David Anson (Delay) heads up the charting control, which is the biggest feature that we are including. He has just announced it with a very detailed introduction post. He is also announcing the ChartBuilder application, that will make it easy for you to play around with the settings.

Go download and play, let us know what you think!