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unit TV_Add_Remove_U1;
{
This demo was written by Andre .v.d. Merwe and marked public domain.
Quickly converted to Lazarus and FPC by Tom Lisjac <vlx@users.sourceforge.net>
The original source and an *excellent* tutorial on the TTreeview
component can be found here:
http://users.iafrica.com/d/da/dart/Delphi/TTreeView/TreeView.html
}
interface
{$mode objfpc} {$H+}
uses
SysUtils, LResources, Classes, LCLProc, Graphics, Controls, Forms, Dialogs,
StdCtrls, ComCtrls, Buttons;
type
TForm1 = class(TForm)
tv_eg1: TTreeView;
but_Add: TButton;
but_Remove: TButton;
procedure but_AddClick(Sender: TObject);
procedure but_RemoveClick(Sender: TObject);
private
public
constructor Create(TheOwner: TComponent); override;
end;
var
Form1: TForm1;
implementation
procedure TForm1.but_AddClick(Sender: TObject);
var
sText : ansistring;
begin
{If nothing is selected}
if( tv_eg1.Selected = nil ) then
begin
{Does a root node already exist?}
if( tv_eg1.Items.Count = 0 ) then
begin
{Add the root node}
with tv_eg1.Items.AddFirst( nil, 'Root' ) do
begin
Selected := true;
debugln('tv_eg1.Selected=',DbgS(tv_eg1.Selected));
end;
end
else begin
{There is a root, so user must first select a node}
//MessageBeep( -1 );
ShowMessage( 'Select a parent node' );
Exit;
end;
end
else begin
{Get a name for the new node}
sText := 'New node';
InputQuery( 'New Node', 'Caption ?', sText );
{Add the node as a child of the selected node}
with tv_eg1.Items.AddChild( tv_eg1.Selected, sText ) do
begin
MakeVisible;
end;
end;
end;
procedure TForm1.but_RemoveClick(Sender: TObject);
begin
{Make sure somthing is selected, before trying to
delete it}
if( tv_eg1.Selected = nil ) then
begin
//MessageBeep( -1 );
ShowMessage( 'Nothing selected' );
Exit;
end;
{Dont allow user to delete the root node}
if( tv_eg1.Selected.Level = 0 ) then
begin
//MessageBeep( -1 );
ShowMessage( 'Cant delete the root node' );
Exit;
end;
{Delete the node}
tv_eg1.Selected.Delete;
end;
constructor TForm1.Create(TheOwner: TComponent);
var
RootNode: TTreeNode;
begin
inherited Create(TheOwner);
RootNode:=tv_eg1.Items.AddFirst(nil,'Root');
tv_eg1.Items.AddChild(RootNode,'Node1');
tv_eg1.Items.AddChild(RootNode,'Node2');
tv_eg1.Items.AddChild(RootNode,'Node3');
RootNode.Expanded:=true;
end;
{$R *.lfm}
end.
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