windows – 如何在Delphi中允许拖动特定控件的文件

unit Unit5;

interface

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

type
  TMemo = class(StdCtrls.TMemo)
  protected
    procedure WMDropFiles(var Message: TWMDropFiles); message WM_DROPFILES;
    procedure CreateWnd; override;
    procedure DestroyWnd; override;
  end;

  TForm5 = class(TForm)
    Memo1: TMemo;
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form5: TForm5;

implementation

{$R *.dfm}

procedure TForm5.FormCreate(Sender: TObject);
begin
end;

{ TMemo }

procedure TMemo.CreateWnd;
begin
  inherited;
  DragAcceptFiles(Handle,true);
end;

procedure TMemo.DestroyWnd;
begin
  DragAcceptFiles(Handle,false);
  inherited;
end;

procedure TMemo.WMDropFiles(var Message: TWMDropFiles);
var
  c: integer;
  fn: array[0..MAX_PATH-1] of char;
begin

  c := DragQueryFile(Message.Drop,$FFFFFFFF,fn,MAX_PATH);

  if c <> 1 then
  begin
    MessageBox(Handle,'Too many files.','Drag and drop error',MB_ICONERROR);
    Exit;
  end;

  if DragQueryFile(Message.Drop,MAX_PATH) = 0 then Exit;

  Text := fn;

end;


end.

上面的示例只接受丢弃的单个文件.文件名将放在备忘录控件中.但您也可以删除多项选择：

VAR
??c：整数;
??fn：char的数组[0..MAX_PATH-1];
??我：整数;
开始

c := DragQueryFile(Message.Drop,MAX_PATH);

Clear;
for i := 0 to c - 1 do
begin
  if DragQueryFile(Message.Drop,i,MAX_PATH) = 0 then Exit;
  Lines.Add(fn);
end;