private void OnSelectedSourceChanged(Uri oldValue, Uri newValue)
{
// Uri "Page1.xaml#111" and "Page1#222" points to the same page, but with a different fragment
// Must remove the fragment to avoid believing we are on different pages.
Uri oldValueNoFragment = NavigationHelper.RemoveFragment(oldValue);
Uri newValueNoFragment = NavigationHelper.RemoveFragment(newValue);
if (!this.isSelecting)
{
// if old and new are equal, don't do anything
if (newValueNoFragment != null && newValueNoFragment.Equals(oldValueNoFragment))
{
return;
}
UpdateSelection();
}
// raise SelectedSourceChanged event
var handler = this.SelectedSourceChanged;
if (handler != null)
{
handler(this, new SourceEventArgs(newValue));
}
}
private void OnSourceChanged(Uri oldValue, Uri newValue)
{
// if resetting source or old source equals new, don't do anything
if (this.isResetSource || newValue != null && newValue.Equals(oldValue))
{
return;
}
// handle fragment navigation
string newFragment = null;
var oldValueNoFragment = NavigationHelper.RemoveFragment(oldValue);
var newValueNoFragment = NavigationHelper.RemoveFragment(newValue, out newFragment);
if (newValueNoFragment != null && newValueNoFragment.Equals(oldValueNoFragment))
{
// fragment navigation
var args = new FragmentNavigationEventArgs {
Fragment = newFragment
};
OnFragmentNavigation(this.Content as IContent, args);
}
else
{
var navType = this.isNavigatingHistory ? NavigationType.Back : NavigationType.New;
// only invoke CanNavigate for new navigation
if (!this.isNavigatingHistory && !CanNavigate(oldValue, newValue, navType))
{
return;
}
Navigate(oldValue, newValue, navType);
}
}
private void UpdateSelection()
{
LinkGroup selectedGroup = null;
Link selectedLink = null;
Uri sourceNoFragment = NavigationHelper.RemoveFragment(this.SelectedSource);
if (this.LinkGroups != null)
{
// find the current select group and link based on the selected source
var linkInfo = (from g in this.LinkGroups
from l in g.Links
where l.Source == sourceNoFragment
select new {
Group = g,
Link = l
}).FirstOrDefault();
if (linkInfo != null)
{
selectedGroup = linkInfo.Group;
selectedLink = linkInfo.Link;
}
else
{
// could not find link and group based on selected source, fall back to selected link group
selectedGroup = this.SelectedLinkGroup;
// if selected group doesn't exist in available groups, select first group
if (!this.LinkGroups.Any(g => g == selectedGroup))
{
selectedGroup = this.LinkGroups.FirstOrDefault();
}
}
}
ReadOnlyLinkGroupCollection groups = null;
if (selectedGroup != null)
{
// ensure group itself maintains the selected link
selectedGroup.SelectedLink = selectedLink;
// find the collection this group belongs to
var groupKey = GetGroupKey(selectedGroup);
this.groupMap.TryGetValue(groupKey, out groups);
}
this.isSelecting = true;
// update selection
SetValue(VisibleLinkGroupsPropertyKey, groups);
SetCurrentValue(SelectedLinkGroupProperty, selectedGroup);
SetCurrentValue(SelectedLinkProperty, selectedLink);
this.isSelecting = false;
}
private void SetContent(Uri newSource, NavigationType navigationType, object newContent, bool contentIsError)
{
var oldContent = this.Content as IContent;
// assign content
this.Content = newContent;
// do not raise navigated event when error
if (!contentIsError)
{
var args = new NavigationEventArgs {
Frame = this,
Source = newSource,
Content = newContent,
NavigationType = navigationType
};
OnNavigated(oldContent, newContent as IContent, args);
}
// set IsLoadingContent to false
SetValue(IsLoadingContentPropertyKey, false);
if (!contentIsError)
{
// and raise optional fragment navigation events
string fragment;
NavigationHelper.RemoveFragment(newSource, out fragment);
if (fragment != null)
{
// fragment navigation
var fragmentArgs = new FragmentNavigationEventArgs {
Fragment = fragment
};
OnFragmentNavigation(newContent as IContent, fragmentArgs);
}
}
}
private void Navigate(Uri oldValue, Uri newValue, NavigationType navigationType)
{
Debug.WriteLine("Navigating from '{0}' to '{1}'", oldValue, newValue);
// set IsLoadingContent state
SetValue(IsLoadingContentPropertyKey, true);
// cancel previous load content task (if any)
// note: no need for thread synchronization, this code always executes on the UI thread
if (this.tokenSource != null)
{
this.tokenSource.Cancel();
this.tokenSource = null;
}
// push previous source onto the history stack (only for new navigation types)
if (oldValue != null && navigationType == NavigationType.New)
{
this.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();
this.tokenSource = localTokenSource;
// load the content (asynchronous!)
var scheduler = TaskScheduler.FromCurrentSynchronizationContext();
var task = this.ContentLoader.LoadContentAsync(newValue, this.tokenSource.Token);
task.ContinueWith(t => {
try {
if (t.IsCanceled || localTokenSource.IsCancellationRequested)
{
Debug.WriteLine("Cancelled navigation to '{0}'", newValue);
}
else if (t.IsFaulted)
{
// raise failed event
var failedArgs = new NavigationFailedEventArgs {
Frame = this,
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);
}
else
{
newContent = t.Result;
if (ShouldKeepContentAlive(newContent))
{
// keep the new content in memory
this.contentCache[newValueNoFragment] = newContent;
}
SetContent(newValue, navigationType, newContent, false);
}
}
finally {
// clear global tokenSource to avoid a Cancel on a disposed object
if (this.tokenSource == localTokenSource)
{
this.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);
}