VST Node mit Child Nodes hinzufügen (InitChildren)

[SvB]

Guten Morgen Community,

ich habe einige Zeit nichts mit VirtualTreeView gemacht und hab nach genau so einem Beispiel gesucht, um eine neue Anforderung bei einem Projekt umsetzen zu können.
Da ich mit Generics arbeite, habe ich den Beispielcode zum besseren Verständnis angepasst und stelle ihn hier für euch bereit.
Ich habe hier mit Delphi 10.4 gearbeitet.

Code:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, System.Generics.Collections,
  Dialogs, ContNrs, VirtualTrees;

type
  TNamedItem = class
  private
    fName: string;
    fItems: TObjectList<TNamedItem>;
  public
    constructor Create(const name: string);
    property Items: TObjectList<TNamedItem> read fItems;
    property Name: string read fName write fName;
  end;

  TForm1 = class(TForm)
    VirtualStringTree1: TVirtualStringTree;
    procedure FormCreate(Sender: TObject);
    procedure VirtualStringTree1InitNode(Sender: TBaseVirtualTree; ParentNode, Node: PVirtualNode; var InitialStates: TVirtualNodeInitStates);
    procedure VirtualStringTree1InitChildren(Sender: TBaseVirtualTree; Node: PVirtualNode; var ChildCount: Cardinal);
    procedure VirtualStringTree1GetText(Sender: TBaseVirtualTree; Node: PVirtualNode; Column: TColumnIndex; TextType: TVSTTextType; var CellText: string);
  private
    { Private-Deklarationen }
    FVstRootItemList: TObjectList<TNamedItem>;
  public
    { Public-Deklarationen }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
var
  folder1: TNamedItem;
  folder1_1, folder1_2, folder1_3: TNamedItem;
  folder1_1_1: TNamedItem;
begin
  FVstRootItemList := TObjectList<TNamedItem>.Create;
  folder1 := TNamedItem.Create('Folder 1');
  folder1_1 := TNamedItem.Create('Folder 1.1');
  folder1_1_1 := TNamedItem.Create('Folder 1.1.1');
  folder1_1.Items.Add(folder1_1_1);
  folder1.Items.Add(folder1_1);
  FVstRootItemList.Add(folder1);

  folder1 := TNamedItem.Create('node');
  folder1_1 := TNamedItem.Create('subnode');
  folder1_2 := TNamedItem.Create('subnode');
  folder1_3 := TNamedItem.Create('subnode');
  folder1.Items.Add(folder1_1);
  folder1.Items.Add(folder1_2);
  folder1.Items.Add(folder1_3);
  FVstRootItemList.Add(folder1);

  folder1 := TNamedItem.Create('node');
  folder1_1 := TNamedItem.Create('subnode');
  folder1_2 := TNamedItem.Create('subnode');
  folder1_3 := TNamedItem.Create('subnode');
  folder1.Items.Add(folder1_1);
  folder1.Items.Add(folder1_2);
  folder1.Items.Add(folder1_3);
  FVstRootItemList.Add(folder1);

  VirtualStringTree1.NodeDataSize := SizeOf(TNamedItem);
  VirtualStringTree1.RootNodeCount := FVstRootItemList.Count;
end;

procedure TForm1.VirtualStringTree1GetText(Sender: TBaseVirtualTree; Node: PVirtualNode; Column: TColumnIndex; TextType: TVSTTextType; var CellText: string);
var
  NamedItem: TNamedItem;
begin
  NamedItem := Sender.GetNodeData<TNamedItem>(Node);
  if not assigned(NamedItem) then
    exit;
  case Column of
    0:
      CellText := NamedItem.name;
  end;
end;

procedure TForm1.VirtualStringTree1InitChildren(Sender: TBaseVirtualTree; Node: PVirtualNode; var ChildCount: Cardinal);
var
  NamedItem: TNamedItem;
begin
  NamedItem := Sender.GetNodeData<TNamedItem>(Node);
  ChildCount := NamedItem.Items.Count;
end;

procedure TForm1.VirtualStringTree1InitNode(Sender: TBaseVirtualTree; ParentNode, Node: PVirtualNode; var InitialStates: TVirtualNodeInitStates);
var
  NamedItem: TNamedItem;
begin
  if VirtualStringTree1.GetNodeLevel(Node) = 0 then begin
    NamedItem := FVstRootItemList[Node.Index];
    Node.SetData<TNamedItem>(NamedItem)
  end
  else
  begin
    NamedItem := Sender.GetNodeData<TNamedItem>(ParentNode).Items[Node.Index];
    Node.SetData<TNamedItem>(NamedItem);
  end;
  if NamedItem.Items.Count > 0 then
    InitialStates := InitialStates + [ivsHasChildren, ivsExpanded];
end;

{ TNamedItem }
constructor TNamedItem.Create(const name: string);
begin
  fName := name;
  fItems := TObjectList<TNamedItem>.Create;
end;

end.