Mega Code Archive
Copy subnodes of a TreeView to a second Treeview
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Title: Copy subnodes of a TreeView to a second Treeview?
type
{: Callback to use to copy the data of a treenode when the
node itself is copied by CopySubtree.
@param oldnode is the old node
@param newnode is the new node
@Desc Use a callback of this type to implement your own algorithm
for a node copy. The default just uses the Assign method, which
produces a shallow copy of the nodes Data property. }
TCopyDataProc = procedure(oldnode, newnode : TTreenode);
{: The default operation is to do a shallow copy of the node, via
Assign. }
procedure DefaultCopyDataProc(oldnode, newnode : TTreenode);
begin
newnode.Assign(oldnode);
end;
{-- CopySubtree
-------------------------------------------------------}
{: Copies the source node with all child nodes to the target treeview.
@Param sourcenode is the node to copy
@Param target is the treeview to insert the copied nodes into
@Param targetnode is the node to insert the copy under, can be nil to
make the copy a top-level node.
@Param CopyProc is the (optional) callback to use to copy a node.
If Nil is passed for this parameter theDefaultCopyDataProc will be
used.
@Precondition sourcenode nil, target nil, targetnode is either
nil or a node of target
@Raises Exception if targetnode happens to be in the subtree rooted in
sourcenode. Handling that special case is rather complicated, so we
simply refuse to do it at the moment.
}{ Created 2003-04-09 by P. Below -----------------------------------------------------------------------
}
procedure CopySubtree(sourcenode : TTreenode; target : TTreeview;
targetnode : TTreenode; CopyProc : TCopyDataProc = nil);
var
anchor : TTreenode;
child : TTreenode;
begin { CopySubtree }
Assert(Assigned(sourcenode),
'CopySubtree:sourcenode cannot be nil');
Assert(Assigned(target),
'CopySubtree: target treeview cannot be nil');
Assert((targetnode = nil) or (targetnode.TreeView = target),
'CopySubtree: targetnode has to be a node in the target
treeview.');
if (sourcenode.TreeView = target) and
(targetnode.HasAsParent(sourcenode) or (sourcenode =
targetnode)) then
raise Exception.Create('CopySubtree cannot copy a subtree to one of the ' +
'subtrees nodes.');
if not Assigned(CopyProc) then
CopyProc := DefaultCopyDataProc;
anchor := target.Items.AddChild(targetnode, sourcenode.Text);
CopyProc(sourcenode, anchor);
child := sourcenode.GetFirstChild;
while Assigned(child) do
begin
CopySubtree(child, target, anchor, CopyProc);
child := child.getNextSibling;
end; { While }
end; { CopySubtree }
procedure TForm1.Button1Click(Sender : TObject);
begin
if assigned(treeview1.selected) then
CopySubtree(treeview1.selected, treeview2, nil);
end;
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