private void CollapseExpandButton_Click(object sender, RoutedEventArgs e)
{
// the Button is in the visual tree of a Node
Button button = (Button)sender;
Node n = Part.FindAncestor <Node>(button);
if (n != null)
{
SimpleData parentdata = (SimpleData)n.Data;
// always make changes within a transaction
myDiagram.StartTransaction("CollapseExpand");
// if needed, create the child data for this node
if (!parentdata.EverExpanded)
{
parentdata.EverExpanded = true; // only create children once per node!
int numchildren = CreateSubTree(parentdata);
if (numchildren == 0) // now known no children: don't need Button!
{
button.Visibility = Visibility.Collapsed;
}
}
// toggle whether this node is expanded or collapsed
n.IsExpandedTree = !n.IsExpandedTree;
if (n.IsExpandedTree)
{
myDiagram.Panel.CenterPart(n);
}
else
{
myDiagram.Panel.CenterPart(n.NodesInto.FirstOrDefault());
}
myDiagram.CommitTransaction("CollapseExpand");
}
}
private int CreateSubTree(SimpleData parentdata)
{
int numchildren = rand.Next(10);
if (myDiagram.PartManager.NodesCount <= 1)
{
numchildren += 1; // make sure the root node has at least one child
}
// create several SimpleData objects and add them to the model
for (int i = 0; i < numchildren; i++)
{
SimpleData childdata = new SimpleData();
childdata.Color = String.Format("#{0:X}{1:X}{2:X}",
120 + rand.Next(100), 120 + rand.Next(100), 120 + rand.Next(100));
childdata.Key = parentdata.Key + "/" + childdata.Color;
childdata.ParentKey = parentdata.Key;
myDiagram.Model.AddNode(childdata);
}
return(numchildren);
}