Accepting keyboard input in Silverlight

I thought I’d tackle one of the most obvious problems with Silverlight today, the lack of a text edit control. So I thought I’d share my first "toe wetting" in this.
 
First off I created simple Silverlight 1.1 project with a canvas and a TextBlock…
<Canvas x:Name="parentCanvas"
        xmlns="
http://schemas.microsoft.com/client/2007"
        xmlns:x="
http://schemas.microsoft.com/winfx/2006/xaml"
        Loaded="Page_Loaded"
        x:Class="SilverlightProjectKeyEcho.Page;assembly=ClientBin/SilverlightProjectKeyEcho.dll"
        Width="640"
        Height="480"
        Background="White"
        >
  <TextBlock x:Name="TextBlockEcho" Text="Hello there"></TextBlock>
</Canvas>
I find it useful to always create something I can see by default.
 
Q1. How to accept keyboard input at all?
Well there is a trick to this. First off I used Intellisense in both the XAML and the code behind to create an event for KeyDown on the TextBlock, but I kept getting a (hidden) exception when running the code. After a quick look around the web I discovered that keyboard event can only be attached to the root canvas. I created a quick handler…
 public void EchoKeyDown(object sender, KeyboardEventArgs e)
        {
            int keyCode = (char)e.PlatformKeyCode;
            if (!e.Shift)
            {
                keyCode = keyCode + 32;
            }
            TextBlockEcho.Text += (char)keyCode;
        }
 and I’ve got a very simple text echo. Now to tackle CTRL,SHIFT, Delete, arrow keys, etc, etc…
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2 Responses to Accepting keyboard input in Silverlight

  1. Unknown says:

    public partial class Page : Canvas
    {
    UserControl1 s;
    public void Page_Loaded(object o, EventArgs e)
    {
    // Required to initialize variables
    InitializeComponent();
    s = new UserControl1();
    Children.Add(s); —– Not works
    }
     
    public class UserControl1 : Control
    {
    public UserControl1()
    {
    System.IO.Stream s = this.GetType().Assembly.GetManifestResourceStream("SilverlightProject5.UserControl1.xaml");
    FrameworkElement fe = this.InitializeFromXaml(new System.IO.StreamReader(s).ReadToEnd());
    Canvas cv = fe.FindName("canvas");
    cv.KeyDown += new KeyboardEventHandler(cv_KeyDown);
    }
    void cv_KeyDown(object sender, KeyboardEventArgs e)
    {

    }
    }
     
    if keydown event handler is added in usercontrol , chodren.add not works

  2. Paulio says:

    What error do you get?

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