/// <summary>
/// Checks that moving down the selected tree node is possible.
/// </summary>
public static bool MoveDownIsEnabled(TreeNode selectedNode, TreeNodeBehavior moveBehavior)
{
if (selectedNode == null)
{
return(false);
}
else if (selectedNode.NextNode != null)
{
return(true);
}
else if (moveBehavior == TreeNodeBehavior.ThroughSimilarParents)
{
TreeNode parentNode = selectedNode.Parent;
TreeNode parentNodeNext = parentNode?.NextNode;
return(parentNode != null && parentNodeNext != null &&
(parentNode.Tag is ITreeNode && parentNodeNext.Tag is ITreeNode &&
parentNode.Tag.GetType() == parentNodeNext.Tag.GetType() ||
parentNode.Tag is TreeNodeTag tag1 && parentNodeNext.Tag is TreeNodeTag tag2 &&
tag1.NodeType == tag2.NodeType));
}
else
{
return(false);
}
}
/// <summary>
/// Checks that moving up the selected tree node is possible.
/// </summary>
public static bool MoveUpSelectedNodeIsEnabled(this TreeView treeView, TreeNodeBehavior moveBehavior)
{
TreeNode selectedNode = treeView.SelectedNode;
if (selectedNode == null)
{
return(false);
}
else if (selectedNode.PrevNode != null)
{
return(true);
}
else if (moveBehavior == TreeNodeBehavior.ThroughSimilarParents)
{
TreeNode parentNode = selectedNode.Parent;
TreeNode parentNodePrev = parentNode?.PrevNode;
return(parentNode != null && parentNodePrev != null &&
(parentNode.Tag is ITreeNode && parentNodePrev.Tag is ITreeNode &&
parentNode.Tag.GetType() == parentNodePrev.Tag.GetType() ||
parentNode.Tag is TreeNodeTag tag1 && parentNodePrev.Tag is TreeNodeTag tag2 &&
tag1.NodeType == tag2.NodeType));
}
else
{
return(false);
}
}
/// <summary>
/// Moves down the selected tree node and the associated list item.
/// </summary>
/// <remarks>Use this method if the underlying list items implement ITreeNode.</remarks>
public static void MoveDownSelectedNode(this TreeView treeView, TreeNodeBehavior moveBehavior)
{
TreeNode selectedNode = treeView.SelectedNode;
if (GetRelatedObject(selectedNode) is not ITreeNode selectedObj || selectedObj.Parent == null)
{
return;
}
try
{
treeView.BeginUpdate();
TreeNodeCollection siblings = treeView.GetChildNodes(selectedNode.Parent);
IList list = selectedObj.Parent.Children;
int index = selectedNode.Index;
int newIndex = index + 1;
if (newIndex < siblings.Count)
{
siblings.RemoveAt(index);
siblings.Insert(newIndex, selectedNode);
list.RemoveAt(index);
list.Insert(newIndex, selectedObj);
treeView.SelectedNode = selectedNode;
}
else if (moveBehavior == TreeNodeBehavior.ThroughSimilarParents)
{
TreeNode parentNode = selectedNode.Parent;
TreeNode parentNodeNext = parentNode?.NextNode;
if (parentNode?.Tag is ITreeNode &&
parentNodeNext?.Tag is ITreeNode nextParentObj &&
parentNode.Tag.GetType() == parentNodeNext.Tag.GetType())
{
// the node being moved gets a new parent
siblings.RemoveAt(index);
parentNodeNext.Nodes.Insert(0, selectedNode);
list.RemoveAt(index);
nextParentObj.Children.Insert(0, selectedObj);
selectedObj.Parent = nextParentObj;
treeView.SelectedNode = selectedNode;
}
}
}
finally
{
treeView.EndUpdate();
}
}
/// <summary>
/// Checks that moving down the selected tree node is possible.
/// </summary>
public static bool MoveDownSelectedNodeIsEnabled(this TreeView treeView, TreeNodeBehavior moveBehavior)
{
return(MoveDownIsEnabled(treeView.SelectedNode, moveBehavior));
}
