Delphi: show assigned Frame to Node of Tree View

问题:

I have no experience with frames.

How to use a Tree View with frames? I need to switch among nods of the Tree View and show assigned Frame to the selected node.

Big big thank for help!!!

回答1:

It doesn't really make any difference if the Data of nodes hold a pointer to a frame or any other kind of object, typecast the pointer to the type of object it holds.

Below code adds two frames ('Frame2' and 'Frame3', created by the IDE - much like a new form), as nodes of a TreeView, and sets the visibility of the selected node's frame to true and the deselected one's to false.

type
  TForm1 = class(TForm)
    TreeView1: TTreeView;
    procedure FormCreate(Sender: TObject);
    procedure TreeView1Change(Sender: TObject; Node: TTreeNode);
    procedure TreeView1Changing(Sender: TObject; Node: TTreeNode;
      var AllowChange: Boolean);
    procedure FormDestroy(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

uses Unit2, Unit3;

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
  TreeView1.Align := alLeft;

  with TFrame(TreeView1.Items.AddObject(nil, 'Frame2', TFrame2.Create(nil)).Data) do begin
    Visible := False;
    Parent := Self;
    Align := alClient;
  end;

  with TFrame(TreeView1.Items.AddObject(nil, 'Frame3', TFrame3.Create(nil)).Data) do begin
    Visible := False;
    Parent := Self;
    Align := alClient;
  end;
end;

procedure TForm1.FormDestroy(Sender: TObject);
var
  i: Integer;
begin
  for i := 0 to TreeView1.Items.Count - 1 do
    TFrame(TreeView1.Items[i].Data).Free;
end;


procedure TForm1.TreeView1Change(Sender: TObject; Node: TTreeNode);
begin
  TFrame(Node.Data).Visible := True;
end;

procedure TForm1.TreeView1Changing(Sender: TObject; Node: TTreeNode;
  var AllowChange: Boolean);
begin
  if Assigned((Sender as TTreeView).Selected) then
    TFrame(TTreeView(Sender).Selected.Data).Visible := False;
end;