dotUpdate()

I needed a timer control for a Silverlight 1.1 application but it is not supported in the Alpha release.  My solution was to use the timer in Javascript and have it send events to the C# code.

Event sending from Javascript to C# is described in the Silverlight QuickStart document.

Here is the initialization of the timer in Javascript:

//initialize silverlight event hookup and start timer
var control;
function init(sender){
control = sender;
control.Content.basic.AgEvents = agEventHandler;
setInterval(jtimer,10);
}

In this routine, the timer is set to execute the jtimer function every 10 ms.  (The agEvents statement is used for sending information to the Javascript.  I will describe this later.)

The init function is called by the CreateSilverlight function in the page.js file:

// JScript source code 

//contains calls to silverlight.js, example below loads Page.xaml
function createSilverlight()
{
    Silverlight.createObjectEx({
        source: "Page.xaml",
        parentElement: document.getElementById("SilverlightControlHost"),
        id: "SilverlightControl",
        properties: {
            width: "100%",
            height: "100%",
            version: "1.1",
            enableHtmlAccess: "true",
            isWindowless: "True"
        },
        events: {
        onLoad: init
        }
    }); 

    // Give the keyboard focus to the Silverlight control by default
    document.body.onload = function() {
      var silverlightControl = document.getElementById('SilverlightControl');
      if (silverlightControl)
      silverlightControl.focus();
    }
}

Here is the jtimer function:

//Send position of player to silverlight based on a timer
function jtimer(){
control.Content.basic.timer(playerGetPosition());
}

In this function, a function timer is called in the C# code with a value that is passed as an argument.

On the C# side, the timer function looks like this:

        //This receives the timer event from Javascript
        [Scriptable]
        public void timer(double arg)
        {
            tnow = arg;

…

Note the ‘[Scriptable]‘ tag which makes the timer function usable from Javascript.

Finally, the page load event needs some boilerplate to hook the Javascript to C# communications:

        public void Page_Loaded(object o, EventArgs e)
        {
            // Required to initialize variables
            InitializeComponent();
            //Register the scriptable endpoints
            WebApplication.Current.RegisterScriptableObject("basic", this);