// This event is fired when a navigation or loading of a resource, has failed.
// This event will also be fired for navigations blocked by the NavigationInterceptor
// or an IResourceInterceptor, and the error code in this case will be: ABORTED.
private void webControl_LoadingFrameFailed(object sender, LoadingFrameFailedEventArgs e)
{
if (!webControl.IsLive)
{
return;
}
if (e.IsMainFrame && (e.ErrorCode == NetError.ABORTED))
{
// This condition usually indicates a navigation blocked by the INavigationInterceptor
// or an IResourceInterceptor. For this example, we add an additional check, to be sure.
// Get the NavigationInterceptor service.
INavigationInterceptor navigationInterceptor = webControl.GetService(typeof(INavigationInterceptor)) as INavigationInterceptor;
// Check if this URL is actually blocked by the NavigationInterceptor service.
if ((navigationInterceptor != null) && (navigationInterceptor.GetRule(e.Url.AbsoluteUri) == NavigationRule.Deny))
{
// You can display your error message anyway you want, here.
Debug.Print(String.Format("Navigation to {0} was blocked.", e.Url));
}
else
{
// You can display your error message anyway you want, here.
Debug.Print(String.Format("Navigation to {0} was aborted.", e.Url));
}
}
}
// This event is fired right when IsLive is set to true.
private void webControl_NativeViewInitialized(object sender, WebViewEventArgs e)
{
if (!webControl.IsLive)
{
return;
}
// Acquire the NavigationInterceptor service. Navigation events (available through this interceptor)
// are fired on the I/O thread.
INavigationInterceptor navigationInterceptor = webControl.GetService(typeof(INavigationInterceptor)) as INavigationInterceptor;
if (navigationInterceptor == null)
{
return;
}
// Add a handler for the BeginNavigation event. This will allow us
// to explicitly cancel navigations.
navigationInterceptor.BeginNavigation += OnBeginNavigation;
// Declare a filtering rule. This accepts wildcards. In this example,
// we deny navigations to any Google site. Note that this will not
// prevent the initial loading of the WebControl; the value defined
// to Source at design-time, will always be loaded. After the program
// starts, try to navigate to any of the other Google services (Images, Mail etc.).
navigationInterceptor.AddRule(@"http?://*.google.com/*", NavigationRule.Deny);
}
public JavascriptCallbackState(INavigationInterceptor navigationInterceptor, JSObject callback, object data, int timeout)
{
this.callback = callback;
this.data = data;
cts = new CancellationTokenSource();
cts.Token.Register(OnCanceled);
this.navigationInterceptor = navigationInterceptor;
navigationInterceptor.BeginNavigation += OnNavigation;
timer = new Timer(OnTimeout, null, timeout, Timeout.Infinite);
}
protected virtual void OnDispose(bool disposing)
{
lock ( SyncRoot )
{
// To avoid race conditions, the first to
// be disposed must be the timer...
if (timer != null)
{
timer.Dispose();
}
timer = null;
// .. and then remove the event handler
// for the same reason.
if (disposing)
{
GC.SuppressFinalize(this);
if (navigationInterceptor != null)
{
navigationInterceptor.BeginNavigation -= OnNavigation;
}
navigationInterceptor = null;
if (cts != null)
{
cts.Dispose();
}
cts = null;
if (callback != null)
{
callback.Dispose();
}
callback = null;
}
}
}
// Handler of the external.app.performHeavyWork method.
private void OnWork(object sender, JavascriptMethodEventArgs e)
{
// Must have 2 arguments passed.
if (e.Arguments.Length != 3)
{
return;
}
// Must be a function object.
if (!e.Arguments[0].IsFunctionObject)
{
return;
}
// Must be a timeout value.
if (!e.Arguments[1].IsNumber)
{
return;
}
// Must be the image id.
if (!e.Arguments[2].IsNumber)
{
return;
}
// Get the NavigationInterceptor. This will allow us to cancel the operation
// if the user navigates away.
INavigationInterceptor navigationInterceptor = webControl.GetService(typeof(INavigationInterceptor)) as INavigationInterceptor;
// Without this, do not proceed.
if (navigationInterceptor == null)
{
return;
}
// You can cache the callback and call it only when your application
// has performed all work necessary and has a result ready to send.
// Note that this callback object is valid for as long as the current
// page is loaded; a navigation will invalidate it. This is why we
// need the NavigationInterceptor service acquired above.
JSFunction callbackArg = e.Arguments[0];
// Get the image id.
int id = (int)e.Arguments[1];
// Get the timeout specified.
int timeout = (int)e.Arguments[2];
// Make sure it's a function object.
if (!callbackArg)
{
return;
}
// See it!
Debug.Print(callbackArg.ToString());
// You need to copy the object if you intend to cache it. The original
// object argument passed to the handler is destroyed by default when
// the handler returns. A copy will keep it alive. Note that the clone
// of a JSFunction, will definitely be a JSFunction as well.
JSFunction callback = (JSFunction)callbackArg.Clone();
// Create a state object. This holds the callback and controls
// cancellation. It is passed to both the background operation procedure
// and the response procedure.
JavascriptCallbackState state = new JavascriptCallbackState(navigationInterceptor, callback, id, timeout);
// Perform your heavy work.
Task.Factory.StartNew(
/* The function that will perform the work. */
(Func <Object, String>)PerformWork,
/* Pass the state object. */
state,
/* The CancellationToken that will let us know if we
* should cancel passing back the result. */
state.Token).ContinueWith(
/* Send the result when complete. */
SendResponse,
/* Make sure the result is sent on the
* initial thread. */
TaskScheduler.FromCurrentSynchronizationContext());
}
