So far we've seen a lot of "basic" controls
built-in to Silverlight's UI control toolbox. Buttons, textboxes, hyperlinks,
images, and the like are all relatively basic controls that form the foundation
of any application UI. What we haven't seen are more
advanced or complex controls like a treeview, tabstrip, panelbar, scheduler, or
the ever popular carousel. As of Silverlight 2 beta 1, these controls simply
aren't present and time will reveal which get included by Microsoft and which
will depend on the 3rd party UI market to supply. For now, the only complex
control in Silverlight is the DataGrid, so let's take a look at how it works.
DataGrids are fundamental UI controls for almost all line of
business (LOB) applications. They radically simplify the task of displaying
structured data to users by automatically handling the rendering of rows,
columns, headers, and data navigation. Silverlight's data grid is no exception.
While it is far from being a complete or "advanced" grid control by
today's WinForms and ASP.NET standards, it does provide basic grid
To use the DataGrid control, you must simply bind the Grid
to a list of items (that implement IEnumerable) via the ItemSource property. In
the simplest approach, the Grid will automatically generate columns based on
the data you supply and even render "special" column types- like
checkbox columns- based on your data types. You can, of course, take more
control and manually define the columns that will be rendered in your grid by
setting the AutoGenerateColumns property to false.
Listing 24 shows a simple Silverlight DataGrid that is bound
to data supplied by a WCF web service. The Grid is bound in the XAML page's
code-behind by simply supplying the list of items returned by the WCF web
service to the Grid's ItemSource property. Things to notice in listing 24 are
the checkbox column automatically generated for Boolean data and that the Grid
has the built-in ability to allow users to resize columns.
Listing 24 - Silverlight DataGrid
<my:DataGrid x:Name="dataGrid1" AutoGenerateColumns="true">
void proxy_GetPeopleCompleted(object sender,
this.dataGrid1.ItemsSource = e.Result;
Unlike all of the other UI controls you've seen so far, the
DataGrid UI tag is prefixed by the odd "my" name. That's because the
DataGrid does not exist in the default Silverlight namespace. You need to add
the namespace in Listing 25 to your XAML document in order to use the
Silverlight DataGrid control. The "standard" name you'll find
assigned to this namespace in most Silverlight demos is "my," but you
could name this namespace whatever you like (producing
Listing 25 - DataGrid namespace
The DataGrid already exposes a number of properties that
enable you to customize its appearance and behavior. Among the most significant
are AlternatingRowBackground, CanUserResizeColumns,
RowBackground, and SelectionMode.
That last property, SelectionMode, allows you to control how rows can be
selected. Setting the value to SingleFullRow will only allow one row to be
selected at a time; setting it to ExtendedFullRow allows users to select
multiple rows by using the shift and control keys.
While the DataGrid in Sivlerligth 2 beta 1 is a great
addition to the framework, it is still a far, far cry from providing the level
of functionality we as developers have come to expect from datagrid controls.
For example, the current DataGrid provides no out of the box support for sorting,
grouping, filtering, or hierarchal data display. Paging isn't even a supported
concept as all data is currently rendered and then scrolled (as is usually done
in WinForms). Since Silverlight is going to attract web developers, I expect
many will view this approach to paging as a shortcoming, too.
Data editing is another soft spot. The Grid does support
basic inline editing, but advanced modes like form editing and pop-up window
data editing are absent. For Windows developers, this probably isn't a problem;
for web developers, this is another road block. That is a repeating theme in
Silverlight that could pose problems for both Microsoft and UI component
vendors that build for Silverlight. What type of developer do you try to please:
traditional web developers migrating towards richer web experiences or
traditional WinForms developers trying to build apps that can be distributed
via the browser? Each group has vastly different expectations of how UI
controls should behave, so it will be interesting to see which UI concepts win-out