/// <summary>
/// Make sure a <see cref="Link"/> exists for the link relationship between the given
/// pair of node data, added to the <see cref="LinkLayer"/>
/// specified by its <see cref="Part.LayerName"/>.
/// </summary>
/// <param name="fromnodedata">the data from which the link relationship comes</param>
/// <param name="tonodedata">the data to which the link relationship goes</param>
/// <param name="model">the model that the node data are in, not an <see cref="Northwoods.GoXam.Model.ILinksModel"/></param>
/// <returns>
/// the <see cref="Link"/> for the connecting the two node data,
/// either an existing one or a newly created one,
/// or null if <see cref="FilterLinkForData(Object, Object, IDiagramModel)"/> returns false or if the diagram is uninitialized
/// </returns>
/// <remarks>
/// <para>
/// If the diagram already has a <see cref="Link"/> for the pair of node data,
/// as determined by <see cref="FindLinkForData(Object, Object, IDiagramModel)"/>,
/// or if <see cref="FilterLinkForData(Object, Object, IDiagramModel)"/> is false,
/// this method will do nothing.
/// </para>
/// <para>
/// The implementation of this method should not modify the model.
/// </para>
/// </remarks>
public Link AddLinkForData(Object fromnodedata, Object tonodedata, IDiagramModel model) {
if (fromnodedata == null || tonodedata == null) return null;
VerifyAccess();
Diagram diagram = this.Diagram;
if (diagram == null) return null;
DiagramPanel panel = diagram.Panel;
if (panel == null) return null;
if (model is ILinksModel) Diagram.Error("Diagram.AddLinkForData(Object, Object) cannot be used with an ILinksModel");
Link oldlink = FindLinkForData(fromnodedata, tonodedata, model);
if (oldlink != null) {
UpdateCachedMembership(model, oldlink);
return oldlink;
}
if (!FilterLinkForData(fromnodedata, tonodedata, model)) return null;
// the "data" for this link is artificial, a VirtualLinkData
Object linkdata = new VirtualLinkData(fromnodedata, tonodedata);
String category = FindCategoryForLink(linkdata, model);
DataTemplate template = FindTemplateForLink(linkdata, model, category);
Link newlink = MakeLinkForData(linkdata, model, template, category);
VerifyTransaction(linkdata, model);
if (newlink != null) {
newlink.Model = model;
// add to collection of Links
_LinksDictionary[linkdata] = newlink;
_Links.Add(newlink);
// add to a temporary layer so that ApplyTemplate will be successful
// so that any attached properties become available on the Part's VisualElement
LinkLayer templayer = panel.GetLayer<LinkLayer>(DiagramPanel.ToolLayerName);
if (templayer != null) {
templayer.IsAddingLink = true;
templayer.Add(newlink);
}
newlink.ApplyTemplate(); //?? virtualization
//?? LayerName might not be correct value until after ApplyTemplate
if (templayer != null) templayer.IsAddingLink = false;
String layername = newlink.LayerName;
LinkLayer layer = (this.TemporaryParts ? templayer : panel.GetLayer<LinkLayer>(layername));
if (layer != null) {
layer.Add(newlink);
UpdateCachedMembership(model, newlink);
UpdatePortKnots(newlink);
//?? AddLogicalChild
OnLinkAdded(newlink);
}
}
return newlink;
}
// links for IConnectedModel and ITreeModel -- no link data exists, so we use the VirtualLinkData class
/// <summary>
/// Given a pair of node data for which there is a link relationship,
/// find the corresponding <see cref="Link"/> in this diagram.
/// </summary>
/// <param name="fromnodedata">the data from which the link relationship comes</param>
/// <param name="tonodedata">the data to which the link relationship goes</param>
/// <param name="model">the model that the node data are in, not an <see cref="Northwoods.GoXam.Model.ILinksModel"/></param>
/// <returns>a <see cref="Link"/>, or null if such a link has not been created for that pair of node data</returns>
/// <remarks>
/// <para>
/// The implementation of this method should not modify the model.
/// </para>
/// </remarks>
public Link FindLinkForData(Object fromnodedata, Object tonodedata, IDiagramModel model) {
if (fromnodedata == null && tonodedata == null) return null;
VerifyAccess();
ILinksModel lmodel = model as ILinksModel;
if (lmodel != null) {
foreach (Object linkdata in lmodel.GetFromLinksForNode(tonodedata)) {
if (lmodel.GetFromNodeForLink(linkdata) == fromnodedata) return FindLinkForData(linkdata, model);
}
return null;
} else {
Object linkdata = new VirtualLinkData(fromnodedata, tonodedata);
return FindLinkForData(linkdata, model);
}
}
