public ViewBackstackEntry ToBackstack()
{
ViewBackstackEntry newEntry = null;
if (data.ShouldGoToBackStack)
{
newEntry = new ViewBackstackEntry();
newEntry.ViewID = ViewID;
newEntry.ApplicationID = ApplicationID;
newEntry.URI = URI;
newEntry.CacheID = CacheID;
newEntry.Transition = data.Transition;
newEntry.IsPopup = data.IsPopup;
newEntry.WasCached = data.WasCached;
newEntry.ShouldGoToBackStack = data.ShouldGoToBackStack;
newEntry.DefinitionID = (data.Root != null) ? data.Root.DefinitionID : -1;
newEntry.SignpostNames = data.SignpostNames;
newEntry.LiveEntity = this;
}
return(newEntry);
}
private bool ShowPreviousNode()
{
// save current node
Node currentNode = CurrentNode;
// search for backstack entry
ViewBackstackEntry entry = null;
if (backstack.Count > 0)
{
entry = backstack.Pop();
}
if (entry != null)
{
// have old node - restore it
Node prevNode = entry.LiveEntity;
if (prevNode == null)
{
prevNode = CreateNewNode(entry.ToNodeData());
if (prevNode != null)
{
Children.Add(prevNode);
}
}
if (prevNode != null)
{
// deactivate current node (if any)
if (currentNode != null)
{
currentNode.SignalHide();
}
// show restored node and activate it
prevNode.Visibility = Visibility.Visible;
prevNode.SignalShow();
// launch transition
TransitionHelper.Hide(
currentNode,
currentNode.Transition,
() =>
{
if (currentNode != null)
{
// hide
currentNode.Visibility = Visibility.Collapsed;
// destroy
Children.Remove(currentNode);
currentNode.SignalDestroy();
currentNode = null;
}
});
return(true);
}
}
else
{
// backstack is empty - just deactivate current node
if (currentNode != null)
{
currentNode.SignalHide();
currentNode.SignalDestroy();
currentNode = null;
}
}
return(false);
}
private void ShowNewNode(Node newNode)
{
if (newNode != null)
{
Node currentNode = CurrentNode;
bool hideOldNode = true, destroyOldNode = false;
// handle current node
if (currentNode != null)
{
ViewBackstackEntry newEntry = null;
if (isBackstackEnabled)
{
newEntry = currentNode.ToBackstack();
}
// method ToBackstack() returns null if the current node should not be added to backstack
if (newEntry != null)
{
// save current node to backstack
backstack.Push(newEntry);
// clean backstack (if needed)
if (backstack.Count > BackstackLiveEntitiesLimit)
{
var backstackEntries = backstack.ToArray();
for (int i = BackstackLiveEntitiesLimit; i < backstackEntries.Length; i++)
{
if (backstackEntries[i].LiveEntity != null)
{
backstackEntries[i].LiveEntity.Visibility = Visibility.Collapsed;
Children.Remove(backstackEntries[i].LiveEntity);
backstackEntries[i].LiveEntity = null;
}
}
}
// set actions
hideOldNode = !newNode.IsPopup;
destroyOldNode = false;
}
else
{
// must hide and destroy old node
hideOldNode = true;
destroyOldNode = true;
}
}
// handle new node
Children.Add(newNode);
// launch transition
TransitionHelper.Show(
newNode,
newNode.Transition,
() =>
{
if (currentNode != null)
{
// deactivate
currentNode.SignalHide();
// hide
if (hideOldNode)
{
currentNode.Visibility = Visibility.Collapsed;
}
// if needed - destroy
if (destroyOldNode)
{
Children.Remove(currentNode);
currentNode.SignalDestroy();
currentNode = null;
}
}
newNode.Visibility = Visibility.Visible;
newNode.SignalShow();
});
}
}