学习 TTreeView [2] - Items.Item[i]、Items[i]、.Text、SetFocus(设置焦点)、Select(选择)

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, ComCtrls, StdCtrls;

type
TForm1 = class(TForm)
TreeView1: TTreeView;
Button1: TButton;
Button2: TButton;
Button3: TButton;
Button4: TButton;
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
procedure Button3Click(Sender: TObject);
procedure Button4Click(Sender: TObject);
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

var
i: Integer;

{这四个按钮的功能是一模一样的}
procedure TForm1.Button1Click(Sender: TObject);
begin
Self.Text := TreeView1.Items.Item[i].Text;
if i < TreeView1.Items.Count-1 then Inc(i) else i := 0;

TreeView1.SetFocus;
TreeView1.Select(TreeView1.Items.Item[i]);
end;

{TreeView1.Items.Item[i] 是默认属性, 可以简写为: TreeView1.Items[i]}
procedure TForm1.Button2Click(Sender: TObject);
begin
Text := TreeView1.Items[i].Text;
if i < TreeView1.Items.Count-1 then Inc(i) else i := 0;

TreeView1.SetFocus;
TreeView1.Select(TreeView1.Items[i]);
end;

{每个元素都是 TTreeNode 类型的}
procedure TForm1.Button3Click(Sender: TObject);
var
node: TTreeNode;
begin
node := TreeView1.Items[i];
Text := node.Text;
if i < TreeView1.Items.Count-1 then Inc(i) else i := 0;

TreeView1.SetFocus;
TreeView1.Select(node);
end;

{尽量使用 TTreeNodes 与 TTreeNode}
procedure TForm1.Button4Click(Sender: TObject);
var
Nodes: TTreeNodes;
node: TTreeNode;
begin
Nodes := TreeView1.Items;
node := Nodes[i];
Text := node.Text;
if i < Nodes.Count-1 then Inc(i) else i := 0;

TreeView1.SetFocus;
TreeView1.Select(node);
end;

end.