【Delphi】接收windows文件夹中文件拖拽

本文根据EmailX45的视频文件，进行了优化改进，原文参见：Delphi: Drag and Drop Files from Explorer into TPanel / TMemo - YouTube

在Windows中，如果将选择的文件拖动到Delphi程序的控件上，有很多实现方法，特别是三方的成熟控件，但是这个方法最简单，无需使用第三方资源，简单使用windows API即可。

直接上代码入如下：

主窗体：

unit uDragFile_Form;

interface

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

  uMyPanelWithDropFileEvents,
  uMyMemoWithDropFileEvents;



type
  TForm4 = class(TForm)
    Panel1: TPanel;
    Memo1: TMemo;
    Label1: TLabel;
    GestureManager1: TGestureManager;
    procedure FormCreate(Sender: TObject);
  private
    procedure OnDraopFileToPanel(Sender : TObject; FileName : string);     //重点，必须是这个类型 TOnDropFile
    procedure OnDraopFileToMemo(Sender : TObject; FileName : string);

  public
    { Public declarations }
  end;

var
  Form4: TForm4;

implementation

uses
  Winapi.ShellAPI;

{$R *.dfm}

{ TForm4 }

procedure TForm4.FormCreate(Sender: TObject);
begin

  Panel1.EnableFileDrop(OnDraopFileToPanel);
  Memo1.EnableFileDrop(OnDraopFileToMemo);

end;

procedure TForm4.OnDraopFileToMemo(Sender: TObject; FileName: string);
begin
  Memo1.Lines.Add(FileName);
end;

procedure TForm4.OnDraopFileToPanel(Sender: TObject; FileName: string);
begin
 Label1.Caption := Label1.Caption + sLineBreak + Filename;

end;

end.

以下两段代码分别是Panel和Memo的实现代码，需要在主窗体中引用。

{sensor 参考：https://www.youtube.com/watch?v=XaO0YWRcxMw
使用说明：
1. 主程序中引用这个单元
2. 主程序中必须定义 TOnDropFile 事件   ，例如：   procedure OnDraopFileToPanel(Sender : TObject; FileName : string);
3. 主程序CreateForm中：Panel1.EnableFileDrop(OnDraopFileToPanel);

4. 如果不需要拖动文件： DisableFileDrop

2025-06-02
}
unit uMyPanelWithDropFileEvents;

interface
uses
  Winapi.Messages,
  VCL.ExtCtrls;

type
  TOnDropFile = procedure(Sender : TObject; FileName : string) of Object;

  TPanel = class(VCL.ExtCtrls.TPanel)
    private
      FOnDropFile : TOnDropFile;
      procedure DropFileEvent(var MSG : TWMDropFiles); message WM_DROPFILES;
    public
      procedure EnableFileDrop(FOnDrop: TOnDropFile);
      procedure DisableFileDrop;
      property OnDropFile : TOnDropFile read FOnDropFile write FOnDropFile;
  end;

implementation

uses
  Winapi.Windows,
  Winapi.ShellAPI;

const
  MY_FILE_COUNTING = $FFFFFFFF;



{ TPanel }

procedure TPanel.DisableFileDrop;
begin
  DragAcceptFiles(Self.Handle,False);
  FOnDropFile := nil;
end;

procedure TPanel.DropFileEvent(var MSG: TWMDropFiles);
var
  LFileCounting : Cardinal;
  LFileName     : array[0..MAX_Path] of char;
begin
  LFileCounting := DragQueryFile(MSG.Drop,MY_FILE_COUNTING,LFileName, MAX_Path);
  if Assigned(FOnDropFile) then
    begin
      for var i := 0 to LFileCounting - 1 do
        begin
          DragQueryFile(MSG.Drop,i,LFileName, MAX_Path);
          FOnDropFile(Self, String(LFileName));
        end;

    end;
  DragFinish(MSG.Drop);
end;

procedure TPanel.EnableFileDrop(FOnDrop: TOnDropFile);
begin
  DragAcceptFiles(Self.Handle,True);
  FOnDropFile := FOnDrop;
end;

end.

Memo代码

unit uMyMemoWithDropFileEvents;

interface
uses
  Winapi.Messages,
  VCL.StdCtrls;

type
  TOnDropFile = procedure(Sender : TObject; FileName : string) of Object;

  TMemo = class(VCL.StdCtrls.TMemo)
    private
      FOnDropFile : TOnDropFile;
      procedure DropFileEvent(var MSG : TWMDropFiles); message WM_DROPFILES;
    public
      procedure EnableFileDrop(FOnDrop: TOnDropFile);
      procedure DisableFileDrop;
      property OnDropFile : TOnDropFile read FOnDropFile write FOnDropFile;
  end;

implementation

uses
  Winapi.Windows,
  Winapi.ShellAPI;

const
  MY_FILE_COUNTING = $FFFFFFFF;



{ TMemo }

procedure TMemo.DisableFileDrop;
begin
  DragAcceptFiles(Self.Handle,False);
  FOnDropFile := nil;
end;

procedure TMemo.DropFileEvent(var MSG: TWMDropFiles);
var
  LFileCounting : Cardinal;
  LFileName     : array[0..MAX_Path] of char;
begin
  LFileCounting := DragQueryFile(MSG.Drop,MY_FILE_COUNTING,LFileName, MAX_Path);
  if Assigned(FOnDropFile) then
    begin
      for var i := 0 to LFileCounting - 1 do
        begin
          DragQueryFile(MSG.Drop,i,LFileName, MAX_Path);
          FOnDropFile(Self, String(LFileName));
        end;

    end;
  DragFinish(MSG.Drop);
end;

procedure TMemo.EnableFileDrop(FOnDrop: TOnDropFile);
begin
  DragAcceptFiles(Self.Handle,True);
  FOnDropFile := FOnDrop;
end;

end.