When I originally created marker support I had given this some thought and was just waiting for the opportunity to add this feature.  I am excited someone really wants it.  Back in July I created a post called Communicating between two Silverlight objects on a single page. In this post I demonstrate how one can use a [ScriptableMember] to expose a method to JavaScript. To add this feature to the Video Player I can use this technique.

The first step was to create a method in my mediaControls control, which would allow a time (TimeSpan) to be passed during playback.  This call will jump the slider to that position in time and begin or continue playback.

Once we have a method in mediaControl we can expose a scriptable method in Page.xaml. This method can be called from any page hosting out Silverlight XAP.

To demonstrate how to use this method I created a sample html page that presents a list of bookmarks that target the video player.  Each link calls a JavaScript method, that in turn calls my [ScritableMember]

This got me thinking about how I might duplicate that technique in Silverlight 2. I figured that the first step was to figure out a simple way communicate between two distinct Silverlight object which exists on the same page.  For this example I am going to have one SL object contain a series of Buttons, while the other SL object contains a single TextBlock.

In the image above the red box I refer to as slObject1, where the blue box I refer to as slObject2.  Both of these <objects> have unique id’s and point to their own respective Silverlight Project and both have been placed in a single html file. 

In this example my slObject1 will be executing a Javascript function, which in turn will be calling an internal function inside of slObject2.  To do this I simply add a reference to the “System.Windows.Browser” namespace and call the Invoke method of the Window object.  here is what my button click handler looks like. 

Once I have this defined I can now go back into my default.html file and define this Javascript function.  The function finds the appropriate html object and calls the internal function in slObject2. 

To create my “UpdateTextBlock function I need to add a few things to the slObject2 project.  First I have to go into my App.xaml.cs file and enter the following in my Application_Startup handler.  “HtmlPage.RegisterScriptableObject("Page", page);”  This registers a managed object for scriptable access by JavaScript code.  Once registered I can create my methods as follows.

That is all there is to it.  Now that I have the ability to communicate between the two SL object I can go after a more complicated implementation.

Code: SLObjects.zip