如何编写一个支持拖放操作的ListBox,就是把文件拖放入ListBox时，ListBox显示这些文件的全路径+文件名

Question

处理一个windows消息就行了,对不起,我忘了...

Answer 1

//componet pasunit DropFiles;
//E-Mail: [email protected]
  Messages, Windows, SysUtils, Controls, Forms, Classes, Menus, Graphics,
  StdCtrls, ShellApi, ComCtrls;type
  TDropFilesEvent = procedure(Sender: TObject; X, Y: Integer; FileNames: TStrings) of object;type
  TDropFilesMemo = class(TCustomMemo)
  private
    FCanDropFiles: Boolean;
    FOnDropFiles: TDropFilesEvent;
    procedure WMDropFiles(var Msg: TMessage); message WM_DROPFILES;
    procedure SetCanDropFiles(const Value: Boolean);
  published
    property Align;
    property Alignment;
    property Anchors;
    property BevelEdges;
    property BevelInner;
    property BevelKind default bkNone;
    property BevelOuter;
    property BiDiMode;
    property BorderStyle;
    property Color;
    property Constraints;
    property Ctl3D;
    property DragCursor;
    property DragKind;
    property DragMode;
    property Enabled;
    property Font;
    property HideSelection;
    property ImeMode;
    property ImeName;
    property Lines;
    property MaxLength;
    property OEMConvert;
    property ParentBiDiMode;
    property ParentColor;
    property ParentCtl3D;
    property ParentFont;
    property ParentShowHint;
    property PopupMenu;
    property ReadOnly;
    property ScrollBars;
    property ShowHint;
    property TabOrder;
    property TabStop;
    property Visible;
    property WantReturns;
    property WantTabs;
    property WordWrap;
    property OnChange;
    property OnClick;
    property OnContextPopup;
    property OnDblClick;
    property OnDragDrop;
    property OnDragOver;
    property OnEndDock;
    property OnEndDrag;
    property OnEnter;
    property OnExit;
    property OnKeyDown;
    property OnKeyPress;
    property OnKeyUp;
    property OnMouseDown;
    property OnMouseMove;
    property OnMouseUp;
    property OnStartDock;
    property OnStartDrag;
    property CanDropFiles: Boolean read FCanDropFiles write SetCanDropFiles;
    property OnDropFiles: TDropFilesEvent read FOnDropFiles write FOnDropFiles;
  end;  TDropFilesEdit = class(TCustomEdit)
  private
    FCanDropFiles: Boolean;
    FOnDropFiles: TDropFilesEvent;
    procedure WMDropFiles(var Msg: TMessage); message WM_DROPFILES;
    procedure SetCanDropFiles(const Value: Boolean);
  published
    property Anchors;
    property AutoSelect;
    property AutoSize;
    property BevelEdges;
    property BevelInner;
    property BevelKind default bkNone;
    property BevelOuter;
    property BiDiMode;
    property BorderStyle;
    property CharCase;
    property Color;
    property Constraints;
    property Ctl3D;
    property DragCursor;
    property DragKind;
    property DragMode;
    property Enabled;
    property Font;
    property HideSelection;
    property ImeMode;
    property ImeName;
    property MaxLength;
    property OEMConvert;
    property ParentBiDiMode;
    property ParentColor;
    property ParentCtl3D;
    property ParentFont;
    property ParentShowHint;
    property PasswordChar;
    property PopupMenu;
    property ReadOnly;
    property ShowHint;
    property TabOrder;
    property TabStop;
    property Text;
    property Visible;
    property OnChange;
    property OnClick;
    property OnContextPopup;
    property OnDblClick;
    property OnDragDrop;
    property OnDragOver;
    property OnEndDock;
    property OnEndDrag;
    property OnEnter;
    property OnExit;
    property OnKeyDown;
    property OnKeyPress;
    property OnKeyUp;
    property OnMouseDown;
    property OnMouseMove;
    property OnMouseUp;
    property OnStartDock;
    property OnStartDrag;
    property CanDropFiles: Boolean read FCanDropFiles write SetCanDropFiles;
    property OnDropFiles: TDropFilesEvent read FOnDropFiles write FOnDropFiles;
  end;  TDropFilesRichEdit = class(TCustomRichEdit)
  private
    FCanDropFiles: Boolean;
    FOnDropFiles: TDropFilesEvent;
    procedure WMDropFiles(var Msg: TMessage); message WM_DROPFILES;
    procedure SetCanDropFiles(const Value: Boolean);
  published
    property Align;
    property Alignment;
    property Anchors;
    property BevelEdges;
    property BevelInner;
    property BevelOuter;
    property BevelKind default bkNone;
    property BevelWidth;
    property BiDiMode;
    property BorderStyle;
    property BorderWidth;
    property Color;
    property Ctl3D;
    property DragCursor;
    property DragKind;
    property DragMode;
    property Enabled;
    property Font;
    property HideSelection;
    property HideScrollBars;
    property ImeMode;
    property ImeName;
    property Constraints;
    property Lines;
    property MaxLength;
    property ParentBiDiMode;
    property ParentColor;
    property ParentCtl3D;
    property ParentFont;
    property ParentShowHint;
    property PlainText;
    property PopupMenu;
    property ReadOnly;
    property ScrollBars;
    property ShowHint;
    property TabOrder;
    property TabStop default True;
    property Visible;
    property WantTabs;
    property WantReturns;
    property WordWrap;
    property OnChange;
    property OnContextPopup;
    property OnDragDrop;
    property OnDragOver;
    property OnEndDock;
    property OnEndDrag;
    property OnEnter;
    property OnExit;
    property OnKeyDown;
    property OnKeyPress;
    property OnKeyUp;
    property OnMouseDown;
    property OnMouseMove;
    property OnMouseUp;
    property OnMouseWheel;
    property OnMouseWheelDown;
    property OnMouseWheelUp;
    property OnProtectChange;
    property OnResizeRequest;
    property OnSaveClipboard;
    property OnSelectionChange;
    property OnStartDock;
    property OnStartDrag;
    property CanDropFiles: Boolean read FCanDropFiles write SetCanDropFiles;
    property OnDropFiles: TDropFilesEvent read FOnDropFiles write FOnDropFiles;
  end;  TDropFilesListBox = class(TCustomListBox)
    procedure WMDropFiles(var Msg: TMessage); message WM_DROPFILES;
    procedure SetCanDropFiles(const Value: Boolean);
  private
    FCanDropFiles: Boolean;
    FOnDropFiles: TDropFilesEvent;
  published
    property Style;
    property AutoComplete;
    property Align;
    property Anchors;
    property BevelEdges;
    property BevelInner;
    property BevelKind default bkNone;
    property BevelOuter;
    property BiDiMode;
    property BorderStyle;
    property Color;
    property Columns;
    property Constraints;
    property Ctl3D;
    property DragCursor;
    property DragKind;
    property DragMode;
    property Enabled;
    property ExtendedSelect;
    property Font;
    property ImeMode;
    property ImeName;
    property IntegralHeight;
    property ItemHeight;
    property Items;
    property MultiSelect;
    property ParentBiDiMode;
    property ParentColor;
    property ParentCtl3D;
    property ParentFont;
    property ParentShowHint;
    property PopupMenu;
    property ScrollWidth;
    property ShowHint;
    property Sorted;
    property TabOrder;
    property TabStop;
    property TabWidth;
    property Visible;
    property OnClick;
    property OnContextPopup;
    property OnData;
    property OnDataFind;
    property OnDataObject;
    property OnDblClick;
    property OnDragDrop;
    property OnDragOver;
    property OnDrawItem;
    property OnEndDock;
    property OnEndDrag;
    property OnEnter;
    property OnExit;
    property OnKeyDown;
    property OnKeyPress;
    property OnKeyUp;
    property OnMeasureItem;
    property OnMouseDown;
    property OnMouseMove;
    property OnMouseUp;
    property OnStartDock;
    property OnStartDrag;
    property CanDropFiles: Boolean read FCanDropFiles write SetCanDropFiles;
    property OnDropFiles: TDropFilesEvent read FOnDropFiles write FOnDropFiles;
  end;procedure Register;implementationprocedure Register;
begin
  RegisterComponents('Zsoft', [TDropFilesMemo, TDropFilesEdit, TDropFilesRichEdit]);
end;{ TDropFilesMemo }procedure TDropFilesMemo.SetCanDropFiles(const Value: Boolean);
begin
  FCanDropFiles := Value;
  DragAcceptFiles(Handle, FCanDropFiles);
end;procedure TDropFilesMemo.WMDropFiles(var Msg: TMessage);
var
  I, FilesCount: Integer;
  FileName: array[0..MAX_PATH] of Char;
  Point: TPoint;
  FilesNames: TStringList;
begin
  if Assigned(FOnDropFiles) then begin
    FilesNames := TStringList.Create;
    try
      FilesCount := DragQueryFile(THandle(Msg.wParam), Cardinal(-1), nil, 0);
      DragQueryPoint(THandle(Msg.wParam), Point);
      for I := 0 to FilesCount - 1 do begin
        DragQueryFile(THandle(Msg.wParam), I, FileName,
          SizeOf(FileName));
        FilesNames.Add(FileName);
      end;
      FOnDropFiles(Self, Point.X, Point.Y, FilesNames);
    finally
      FilesNames.Free;
    end;
  end;
  Msg.Result := 0;
  DragFinish(THandle(Msg.wParam));
end;{ TDropFilesEdit }procedure TDropFilesEdit.SetCanDropFiles(const Value: Boolean);
begin
  FCanDropFiles := Value;
  DragAcceptFiles(Handle, FCanDropFiles);
end;procedure TDropFilesEdit.WMDropFiles(var Msg: TMessage);
var
  I, FilesCount: Integer;
  FileName: array[0..MAX_PATH] of Char;
  Point: TPoint;
  FilesNames: TStringList;
begin
  if Assigned(FOnDropFiles) then begin
    FilesNames := TStringList.Create;
    try
      FilesCount := DragQueryFile(THandle(Msg.wParam), Cardinal(-1), nil, 0);
      DragQueryPoint(THandle(Msg.wParam), Point);
      for I := 0 to FilesCount - 1 do begin
        DragQueryFile(THandle(Msg.wParam), I, FileName,
          SizeOf(FileName));
        FilesNames.Add(FileName);
      end;
      FOnDropFiles(Self, Point.X, Point.Y, FilesNames);
    finally
      FilesNames.Free;
    end;
  end;
  Msg.Result := 0;
  DragFinish(THandle(Msg.wParam));
end;{ TDropFilesRichEdit }procedure TDropFilesRichEdit.SetCanDropFiles(const Value: Boolean);
begin
  FCanDropFiles := Value;
  DragAcceptFiles(Handle, FCanDropFiles);
end;procedure TDropFilesRichEdit.WMDropFiles(var Msg: TMessage);
var
  I, FilesCount: Integer;
  FileName: array[0..MAX_PATH] of Char;
  Point: TPoint;
  FilesNames: TStringList;
begin
  if Assigned(FOnDropFiles) then begin
    FilesNames := TStringList.Create;
    try
      FilesCount := DragQueryFile(THandle(Msg.wParam), Cardinal(-1), nil, 0);
      DragQueryPoint(THandle(Msg.wParam), Point);
      for I := 0 to FilesCount - 1 do begin
        DragQueryFile(THandle(Msg.wParam), I, FileName,
          SizeOf(FileName));
        FilesNames.Add(FileName);
      end;
      FOnDropFiles(Self, Point.X, Point.Y, FilesNames);
    finally
      FilesNames.Free;
    end;
  end;
  Msg.Result := 0;
  DragFinish(THandle(Msg.wParam));
end;{ TDropFilesListBox }procedure TDropFilesListBox.SetCanDropFiles(const Value: Boolean);
begin
  FCanDropFiles := Value;
  DragAcceptFiles(Handle, FCanDropFiles);
end;procedure TDropFilesListBox.WMDropFiles(var Msg: TMessage);
var
  I, FilesCount: Integer;
  FileName: array[0..MAX_PATH] of Char;
  Point: TPoint;
  FilesNames: TStringList;
begin
  if Assigned(FOnDropFiles) then begin
    FilesNames := TStringList.Create;
    try
      FilesCount := DragQueryFile(THandle(Msg.wParam), Cardinal(-1), nil, 0);
      DragQueryPoint(THandle(Msg.wParam), Point);
      for I := 0 to FilesCount - 1 do begin
        DragQueryFile(THandle(Msg.wParam), I, FileName,
          SizeOf(FileName));
        FilesNames.Add(FileName);
      end;
      FOnDropFiles(Self, Point.X, Point.Y, FilesNames);
    finally
      FilesNames.Free;
    end;
  end;
  Msg.Result := 0;
  DragFinish(THandle(Msg.wParam));
end;end.
//demo pas
unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, DropFiles;type
  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
  private
    { Private declarations }
    FDropFilesListBox: TDropFilesListBox;
    procedure DropFilesListBoxDropFiles(Sender: TObject; X, Y: Integer; FileNames: TStrings);
  public
    { Public declarations }
  end;var
  Form1: TForm1;implementation{$R *.dfm}procedure TForm1.DropFilesListBoxDropFiles(Sender: TObject; X, Y: Integer;
  FileNames: TStrings);
begin
  TListBox(Sender).Items.Assign(FileNames);
end;procedure TForm1.FormCreate(Sender: TObject);
begin
  FDropFilesListBox := TDropFilesListBox.Create(Self);
  FDropFilesListBox.Parent := Self;
  FDropFilesListBox.Width := 200;
  FDropFilesListBox.Height := 100;
  FDropFilesListBox.CanDropFiles := True;
  FDropFilesListBox.OnDropFiles := DropFilesListBoxDropFiles;
end;procedure TForm1.FormDestroy(Sender: TObject);
begin
  FDropFilesListBox.Free;
end;end.

Answer 2

unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Classes, Controls, Forms, Dialogs, StdCtrls;type
  TForm1 = class(TForm)
    ListBox1: TListBox;
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
    procedure WMDropFiles(var Message: TMessage); message WM_DropFiles;
  end;var
  Form1: TForm1;implementation{$R *.dfm}
uses ShellApi;procedure TForm1.WMDropFiles(var Message: TMessage);
var
  sFileName: array [0..255] of char;
  iIndex, iCount: integer;
begin
  iIndex := -1;
  iCount := DragQueryFile(Message.WParam, iIndex, sFileName, 255);
  for iIndex := 0 to iCount - 1 do
  begin
    DragQueryFile(Message.WParam, iIndex, sFileName, 255);
    ListBox1.Items.Add(sFileName);
  end;
  DragFinish(Message.WParam);
end;procedure TForm1.FormCreate(Sender: TObject);
begin
  DragAcceptFiles(Handle, true);
end;end.