internal static void Focus(ModelItem itemToFocus, int maxExpandLevel, bool shouldGetKeyboardFocus, Rect rectToBringIntoView)
{
// Check if this model item exist in the model tree
IModelTreeItem modelTreeItem = itemToFocus as IModelTreeItem;
if (modelTreeItem != null)
{
// If this model item doesn't exist in the tree, don't do anything,
// chances are it's an activity that has been deleted.
if (!IsRootedAt(itemToFocus, modelTreeItem.ModelTreeManager.Root) && !(itemToFocus is FakeModelItemImpl))
{
return;
}
}
//if there is another focus operation in progress, mark it so it would abort itself on next OnContextIdle processing -
//we don't want to multiple elements racing for keyboard focus
if (null != focusTicket)
{
focusTicket.shouldAbort = true;
}
//create new focus ticket
focusTicket = new ModelItemFocusHelper(itemToFocus, maxExpandLevel, shouldGetKeyboardFocus, rectToBringIntoView);
//and start its processing as soon as application gets idle
Dispatcher.CurrentDispatcher.BeginInvoke(new Action <ModelItemFocusHelper>((p) => { p.Focus(); }), DispatcherPriority.ContextIdle, focusTicket);
}
public static void Focus(this ModelItem item, int level)
{
if (null == item)
{
throw FxTrace.Exception.ArgumentNull("item");
}
if (level < 1)
{
throw FxTrace.Exception.AsError(new ArgumentOutOfRangeException("level"));
}
ModelItemFocusHelper.Focus(item, level);
}
//Expand method is executed repeatadly until maximum expand level is reached. it iterates through the model item tree
//(from child up to MaximumExpandLevel parents) and tries to find first visible designer and populate it with content
//If one elemnt is visited twice (denoted by currentItem argument) it means that expansion failed - (i.e. element is collapsed),
//so i try to set that element as root designer and restart algoritm with that designer beeing new root
void Expand(ModelItem currentItem)
{
//can i continue?
if (this.shouldAbort)
{
return;
}
//stop condition - prevents infinite loop (the method is delegated into dispatcher, so it would never cause stack overflow
if (0 > this.currentLevel)
{
ModelItemFocusHelper.focusTicket = null;
return;
}
//browse direct parents, and Populate the fist one which is visible
for (int index = 0; null != this.itemsToExpand && index < this.itemsToExpand.Length; ++index)
{
//is given parent visible? (it would return container for given model item)
var container = this.ContainerService.QueryContainerForItem(this.itemsToExpand[index]);
if (null != container)
{
//check if container we are trying to expand is not the same as the one in previous iteration
//if it isn't --> populate its content
if (!ModelItem.Equals(currentItem, this.itemsToExpand[index]))
{
this.Populate(container);
return;
}
//if it is --> it means it is collapsed and further expand doesn't make sense.
else if (null != currentItem)
{
int j = 0;
//get index of item which we've tried to expand recently
for (; j < this.itemsToExpand.Length; ++j)
{
if (ModelItem.Equals(this.itemsToExpand[j], currentItem))
{
break;
}
}
//starting at that point, see if given item can be a breadcrumb root
for (int skipLevel = 0; j >= 0; --j)
{
currentItem = this.itemsToExpand[j];
//if it can - make it a new breadcrumb root and restart
if (this.viewService.ShouldAppearOnBreadCrumb(currentItem, true))
{
//make that designer a new root (don't set selection)
this.DesignerView.MakeRootDesigner(currentItem, false);
//and try to set focus with less maximum expand level, assuming that current designer is now expanded
ModelItemFocusHelper.Focus(this.itemToFocus, this.currentLevel - skipLevel, this.shouldGetKeyboardFocus);
return;
}
++skipLevel;
}
//nothing in parent list can be made a breadcrumb, try set item which is supposed to get focus as a root
if (this.viewService.ShouldAppearOnBreadCrumb(this.itemToFocus, true))
{
this.DesignerView.MakeRootDesigner(this.itemToFocus, false);
ModelItemFocusHelper.Focus(this.itemToFocus, 1, this.shouldGetKeyboardFocus);
return;
}
//the item we want to set focus to, also cannot be displayed as root;
//at this point - simply set selection to the current item, check if visibility has changed due to selection change
this.Context.Items.SetValue(new Selection(currentItem));
Dispatcher.CurrentDispatcher.BeginInvoke(this.onElementFocusingDelegate, DispatcherPriority.ContextIdle, currentItem);
//the final check - if item is still not visible, force it to be
Dispatcher.CurrentDispatcher.BeginInvoke(this.onForceElementFocusDelegate, DispatcherPriority.ContextIdle);
return;
}
}
}
ModelItemFocusHelper.focusTicket = null;
//if we end up here and itemsToExpand is not null - something is wrong...
//it is possible that algorithm stops here and itemsToExpand is null - this would be scenario when user tries to set focus to model item which cannot be
//visualized and doesn't have any visual parent - i.e. Service or ActivityBuilder (they have a child property Body which can be visualized, but themselves - are not)
if (null != this.itemsToExpand)
{
var displayProperty = this.itemToFocus.Properties["DisplayName"];
var displayName = displayProperty == null ? "(unknown)" : displayProperty.ComputedValue.ToString();
Fx.Assert("Expand is in invalid state - we should never end up here. Item to focus: " + displayName + " (" + this.itemToFocus.ItemType.Name + ")");
}
}
internal static void Highlight(this ModelItem item, Rect rectToBringIntoView)
{
ModelItemFocusHelper.Focus(item, MaxExpandLevel, false, rectToBringIntoView);
}
internal static void Highlight(this ModelItem item)
{
ModelItemFocusHelper.Focus(item, MaxExpandLevel, false, Rect.Empty);
}
