/// <summary>
/// Creates a new editing context layer. Editing context layers can be used to
/// create editing modes. For example, you may create a layer before starting a
/// drag operation on the designer. Any new context items you add to the layer
/// hide context items underneath it. When the layer is removed, all context
/// items under the layer are re-surfaced. This allows you to create a layer
/// and set overrides for context items during operations such as drag and drop.
/// </summary>
internal override ContextLayer CreateLayer()
{
_currentLayer = new DefaultContextLayer(this, _currentLayer);
return(_currentLayer);
}
internal DefaultContextLayer(DefaultContextItemCollection collection, DefaultContextLayer parentLayer)
{
_collection = collection;
_parentLayer = parentLayer; // can be null
}
internal override void Remove()
{
// Only remove the layer if we have a parent layer.
// Also, once we remove the layer make sure we don't
// try to remove it if someone else calls Remove.
if (_parentLayer != null)
{
_collection.OnLayerRemoved(this);
_parentLayer = null;
}
}
internal DefaultContextItemCollection(EditingContext context)
{
_context = context;
_currentLayer = new DefaultContextLayer(this, null);
}
/// <summary>
/// Called when the user removes a layer.
/// </summary>
private void OnLayerRemoved(DefaultContextLayer layer)
{
if (_currentLayer == layer)
{
_currentLayer = layer.ParentLayer;
}
else
{
var childLayer = FindChildLayer(layer);
childLayer.ParentLayer = layer.ParentLayer;
}
Debug.Assert(_currentLayer != null, "DefaultContextLayer should not call OnLayerRemoved for top most layer");
// For each item that was in the layer, raise a changed event for it
if (_subscriptions != null)
{
foreach (var oldItem in layer.Items.Values)
{
OnItemChanged(GetValue(oldItem.ItemType));
}
}
}
internal DefaultContextLayer(DefaultContextItemCollection collection, DefaultContextLayer parentLayer)
{
_collection = collection;
_parentLayer = parentLayer; // can be null
}
/// <summary>
/// This helper function returns the childLayer for the layer that is passed in.
/// This function is used in the OnLayerRemoved to link the layers when
/// a layer (in the middle) is removed.
/// </summary>
/// <param name="layer"></param>
/// <returns></returns>
private DefaultContextLayer FindChildLayer(DefaultContextLayer layer)
{
var startLayer = _currentLayer;
while (startLayer.ParentLayer != layer)
{
startLayer = startLayer.ParentLayer;
}
return startLayer;
}
/// <summary>
/// Creates a new editing context layer. Editing context layers can be used to
/// create editing modes. For example, you may create a layer before starting a
/// drag operation on the designer. Any new context items you add to the layer
/// hide context items underneath it. When the layer is removed, all context
/// items under the layer are re-surfaced. This allows you to create a layer
/// and set overrides for context items during operations such as drag and drop.
/// </summary>
internal override ContextLayer CreateLayer()
{
_currentLayer = new DefaultContextLayer(this, _currentLayer);
return _currentLayer;
}
internal DefaultContextLayer(DefaultContextLayer parentLayer)
{
_parentLayer = parentLayer; // can be null
}
internal DefaultContextItemCollection(EditingContext context)
{
_context = context;
_currentLayer = new DefaultContextLayer(this, null);
}
internal DefaultContextItemManager(EditingContext context)
{
_context = context;
_currentLayer = new DefaultContextLayer(null);
}
public override void Remove(bool disposing = false)
{
// Only remove the layer if we have a parent layer or if being disposed.
// Also, once we remove the layer make sure we don't
// try to remove it if someone else calls Remove.
if (_parentLayer != null || disposing)
{
foreach (var item in _items.Values)
{
var d = item as IDisposable;
if (d != null)
{
d.Dispose();
}
}
_items.Clear();
_collection.OnLayerRemoved(this);
_parentLayer = null;
}
}
/// <summary>
/// Called when the user removes a layer.
/// </summary>
/// <param name="layer"></param>
private void OnLayerRemoved(DefaultContextLayer layer)
{
if (_currentLayer == layer)
{
_currentLayer = layer.ParentLayer;
}
else
{
var childLayer = FindChildLayer(layer);
if (childLayer != null)
{
childLayer.ParentLayer = layer.ParentLayer;
}
}
}
internal DefaultContextLayer(DefaultContextLayer parentLayer)
{
_parentLayer = parentLayer; // can be null
}
internal DefaultContextItemManager(EditingContext context)
{
_context = context;
_currentLayer = new DefaultContextLayer(null);
}
