/// <summary>
/// Performs navigation against current ModernFrame.
/// </summary>
/// <param name="oldValue">Navigate From Uri</param>
/// <param name="newValue">Navigate To Uri</param>
/// <param name="navigationType">Type of Navigation</param>
/// <param name="passingParameter">Parameter for passing.</param>
/// <remarks>
/// Can be used to fire Navigated events.
/// </remarks>
public void Navigate <TK>(Uri oldValue, Uri newValue, NavigationType navigationType, TK passingParameter)
{
Debug.WriteLine("Navigating from '{0}' to '{1}'", oldValue, newValue);
// set IsLoadingContent state
Frame.SetValue(ModernFrame.IsLoadingContentPropertyKey, true);
// cancel previous load content task (if any)
// note: no need for thread synchronization, this code always executes on the UI thread
if (Frame.TokenSource != null)
{
Frame.TokenSource.Cancel();
Frame.TokenSource = null;
}
// push previous source onto the history stack (only for new navigation types)
if (oldValue != null && navigationType == NavigationType.New)
{
_history.Push(oldValue);
}
object newContent = null;
if (newValue != null)
{
// content is cached on uri without fragment
var newValueNoFragment = NavigationHelper.RemoveFragment(newValue);
if (navigationType == NavigationType.Refresh || !this._contentCache.TryGetValue(newValueNoFragment, out newContent))
{
var localTokenSource = new CancellationTokenSource();
Frame.TokenSource = localTokenSource;
// load the content (asynchronous!)
var scheduler = TaskScheduler.FromCurrentSynchronizationContext();
var task = Frame.ContentLoader.LoadContentAsync(newValue, Frame.TokenSource.Token);
task.ContinueWith(t => {
try
{
if (t.IsCanceled || localTokenSource.IsCancellationRequested)
{
Debug.WriteLine("Cancelled navigation to '{0}'", newValue);
}
else if (t.IsFaulted && t.Exception != null)
{
var failedArgs = new NavigationFailedEventArgs
{
Frame = Frame,
Source = newValue,
Error = t.Exception.InnerException,
Handled = false
};
OnNavigationFailed(failedArgs);
// if not handled, show error as content
newContent = failedArgs.Handled ? null : failedArgs.Error;
SetContent(newValue, navigationType, newContent, true, passingParameter);
}
else
{
newContent = t.Result;
if (ShouldKeepContentAlive(newContent))
{
// keep the new content in memory
_contentCache[newValueNoFragment] = newContent;
}
SetContent(newValue, navigationType, newContent, false, passingParameter);
}
}
finally
{
// clear global tokenSource to avoid a Cancel on a disposed object
if (Frame.TokenSource == localTokenSource)
{
Frame.TokenSource = null;
}
// and dispose of the local tokensource
localTokenSource.Dispose();
}
}, scheduler);
return;
}
}
// newValue is null or newContent was found in the cache
SetContent(newValue, navigationType, newContent, false, passingParameter);
}
/// <summary>
/// Performs navigation to specified link.
/// </summary>
/// <param name="uri">The uri to navigate to.</param>
/// <param name="source">The source element that triggers the navigation. Required for frame navigation.</param>
/// <param name="parameter">An optional command parameter or navigation target.</param>
public virtual void Navigate(Uri uri, FrameworkElement source = null, string parameter = null)
{
if (uri == null)
{
throw new ArgumentNullException(nameof(uri));
}
if (uri.OriginalString.StartsWith(@"www."))
{
uri = new Uri("http://" + uri.OriginalString);
}
var args = new NavigateEventArgs(uri);
PreviewNavigate?.Invoke(this, args);
if (args.Cancel)
{
return;
}
// first check if uri refers to a command
if (Commands != null)
{
if (Commands.TryGetValue(uri, out var command))
{
// note: not executed within BbCodeBlock context, Hyperlink instance has Command and CommandParameter set
if (command.CanExecute(parameter))
{
command.Execute(parameter);
}
return;
}
if (uri.IsAbsoluteUri)
{
var original = uri.AbsoluteUri;
var index = original.IndexOf('?');
if (index != -1)
{
var subUri = new Uri(original.Substring(0, index), UriKind.Absolute);
if (Commands.TryGetValue(subUri, out command))
{
parameter = uri.GetQueryParam("param");
if (command.CanExecute(parameter))
{
command.Execute(parameter);
}
return;
}
}
}
}
if (uri.IsAbsoluteUri && ExternalSchemes != null && ExternalSchemes.Any(s => uri.Scheme.Equals(s, StringComparison.OrdinalIgnoreCase)))
{
// uri is external, load in default browser
Process.Start(uri.AbsoluteUri);
}
else
{
// perform frame navigation
if (source == null) // source required
{
throw new ArgumentException(string.Format(CultureInfo.CurrentUICulture, UiStrings.NavigationFailedSourceNotSpecified, uri));
}
// use optional parameter as navigation target to identify target frame (_self, _parent, _top or named target frame)
var frame = NavigationHelper.FindFrame(parameter, source);
if (frame == null)
{
throw new ArgumentException(string.Format(CultureInfo.CurrentUICulture, UiStrings.NavigationFailedFrameNotFound, uri, parameter));
}
if (!(Window.GetWindow(frame) is INavigateUriHandler window) || frame.GetParent <ModernFrame>() != null || window.NavigateTo(uri) != true)
{
// delegate navigation to the frame
frame.Source = uri;
}
}
}
