Delphi - 拖放 + MouseDown + MouseUp

Question

我正在开发一个拖放应用程序，当拖放项目时，我对默认 DragCursor 感到困扰，如下默认 DragCursors 列表>:

所以我正在尝试开发一种新的方式让用户看到像 GMAIL 一样的拖放 Action :

我的问题是:Delphi 7 中是否可以将拖放事件与鼠标事件一起使用？

如果我将 dmAutomatic 放入 DragMode 中，MouseDown 事件将不起作用，如果我将 dmManual 放入 DragMode MouseDown 工作正常，但 DragDrop 事件不起作用。

下面是我的代码:

type
  TForm1 = class(TForm)
    pnlInformacaoDragDrop: TPanel;
    pnl1: TPanel;
    pnl2: TPanel;
    procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
    procedure FormMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
    procedure FormMouseUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
    procedure pnl1DragDrop(Sender, Source: TObject; X, Y: Integer);
    procedure pnl2DragDrop(Sender, Source: TObject; X, Y: Integer);
    procedure pnl2DragOver(Sender, Source: TObject; X, Y: Integer;
      State: TDragState; var Accept: Boolean);
    procedure pnl1DragOver(Sender, Source: TObject; X, Y: Integer;
      State: TDragState; var Accept: Boolean);
    procedure pnl1MouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure pnl1MouseUp(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
  private
    { Private declarations }
  public
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{ TForm1 }

procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
begin
  if Assigned(Self) then
  begin
    if pnlInformacaoDragDrop.Visible then
    begin
      pnlInformacaoDragDrop.Left :=X + 10;
      pnlInformacaoDragDrop.Top := Y + 10;
    end;
  end;
end;

procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
begin
  if Assigned(Self) then
  begin
    if not pnlInformacaoDragDrop.Visible then
      pnlInformacaoDragDrop.Visible := True;

//    img1.BeginDrag(True);
  end;
end;

procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
begin
  if Assigned(Self) then
  begin
    if pnlInformacaoDragDrop.Visible then
      pnlInformacaoDragDrop.Visible := False;
  end;
end;

procedure TForm1.pnl1DragDrop(Sender, Source: TObject; X, Y: Integer);
begin
  TPanel(Sender).Caption := TPanel(Sender).Caption + ' - ' + TPanel(Source).Caption;
end;

procedure TForm1.pnl2DragDrop(Sender, Source: TObject; X, Y: Integer);
begin
  TPanel(Sender).Caption := TPanel(Sender).Caption + ' - ' + TPanel(Source).Caption;
end;

procedure TForm1.pnl2DragOver(Sender, Source: TObject; X, Y: Integer;
  State: TDragState; var Accept: Boolean);
begin
  Accept := true;
end;

procedure TForm1.pnl1DragOver(Sender, Source: TObject; X, Y: Integer;
  State: TDragState; var Accept: Boolean);
begin
  Accept := true;
end;

抱歉我的问题很简单，但我不知道该怎么做......

非常感谢!

Answer 1

您可以使用dmAutomatic并为OnStartDrag事件编写处理程序，而不是您尝试使用的鼠标事件。

来自 D7 文档:

Description

Use the OnStartDrag event handler to implement special processing when the user starts to drag the control or an object it contains. OnStartDrag only occurs if DragKind is dkDrag.

...

The OnStartDrag event handler can create a TDragControlObjectEx instance for the DragObject parameter to specify the drag cursor, or, optionally, a drag image list.