delphi – TListView SelCount报告虚拟列表中错误的项目数

以下是重现此问题的代码.使用OnData事件填充列表,它允许选择多行.

我以为我可以使用OnSelectItem来检测用户何时更改选择,然后使用TListView SelCount函数来检测所选行的数量.

问题是当用户选择多行时,SelCount返回0.如果手动填充列表(即不通过OnData事件),这可以正常工作.

有任何想法吗？

谢谢

更新：使用OnChange事件似乎可以解决问题.仍然有趣的是,当选择多行时(从SelectItem事件中),SelCount为什么返回0.

另一个更新：我发布了一个测试项目：https://dl.dropboxusercontent.com/u/35370420/TestListView2.zip以及截图：

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要重现此问题,请运行应用程序,选择Item1,然后按SHIFT单击Item2.该按钮被禁用.我的目的是只要在列表中选择了至少一个项目,就动态启用按钮.如果没有选定项目,则禁用该按钮.

PAS文件：

unit MainUnit;

interface

uses
  Winapi.Windows,Winapi.Messages,System.SysUtils,System.Variants,System.Classes,Vcl.Graphics,Vcl.Controls,Vcl.Forms,Vcl.Dialogs,Vcl.ComCtrls,Vcl.StdCtrls;

type
  TForm3 = class(TForm)
    ListView1: TListView;
    Button1: TButton;
    procedure FormCreate(Sender: TObject);
    procedure ListView1Data(Sender: TObject; Item: TListItem);
    procedure ListView1SelectItem(Sender: TObject; Item: TListItem; Selected: Boolean);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form3: TForm3;

implementation

{$R *.dfm}

procedure TForm3.FormCreate(Sender: TObject);
begin
 ListView1.Items.Count := 5;
end;

procedure TForm3.ListView1Data(Sender: TObject; Item: TListItem);
begin
  Item.Caption := String.Format('Item%d',[Item.Index]);
end;

procedure TForm3.ListView1SelectItem(Sender: TObject; Item: TListItem; Selected: Boolean);
begin
 Button1.Enabled := ListView1.SelCount > 0;
 OutputDebugString(pchar(String.Format('SelCount = %d',[ListView1.SelCount])));
end;

end.

形成：

object Form3: TForm3
  Left = 0
  Top = 0
  Caption = 'Form3'
  ClientHeight = 600
  ClientWidth = 952
  Color = clBtnFace
  DoubleBuffered = True
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  OnCreate = FormCreate
  PixelsPerInch = 96
  TextHeight = 13
  object ListView1: TListView
    Left = 168
    Top = 160
    Width = 250
    Height = 150
    Columns = <
      item
        AutoSize = True
        Caption = 'Test'
      end>
    HideSelection = False
    MultiSelect = True
    OwnerData = True
    TabOrder = 0
    ViewStyle = vsReport
    OnData = ListView1Data
    OnSelectItem = ListView1SelectItem
  end
  object Button1: TButton
    Left = 168
    Top = 120
    Width = 75
    Height = 25
    Caption = 'Some Action'
    Enabled = False
    TabOrder = 1
  end
end