delphi vcl 的 TPageControl 控件，实现对页签的拖动

我们在TPageControl 控件里 放了几个页签，但很多时候我们的需求是把某个页签放前面 和 另一个旁边的方便切换做对比。这个可以有更好的体验，类似Delphi IDE编辑器一样切换页签。

分别 在 DragDrop 、DragOver 、MouseDown 事件写上对应代码

unit Unit1;

interface

uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, StdCtrls, ComCtrls;

type

  TForm1 = class(TForm)

    PageControl1: TPageControl;

    TabSheet1: TTabSheet;

    TabSheet2: TTabSheet;

    Label1: TLabel;

    TabSheet3: TTabSheet;

    Label2: TLabel;

    procedure PageControl1MouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);

    procedure PageControl1DragDrop(Sender, Source: TObject; X, Y: Integer);

    procedure PageControl1DragOver(Sender, Source: TObject; X, Y: Integer; State: TDragState; var Accept: Boolean);

  private

    { Private declarations }

  public

    { Public declarations }

  end;

var

  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.PageControl1MouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);

begin

  //拖动标签

  if (Sender is TPageControl) then

  if ssLeft in Shift then begin

    TPageControl(Sender).BeginDrag(False);

  end;

end;

procedure TForm1.PageControl1DragDrop(Sender, Source: TObject; X, Y: Integer);

const

  TCM_GETITEMRECT = $130A;

var

  TabRect: TRect;

  Idx: Integer;

begin

  //拖动标签

  if (Sender is TPageControl) then

  for Idx := TPageControl(Sender).PageCount - 1 downto 0 do

  begin

    TPageControl(Sender).Perform(TCM_GETITEMRECT, Idx, LParam(@TabRect));

    if PtInRect(TabRect, Point(X, Y)) then // 搜索 每个Tab的区域并判断鼠标区域

    begin

      if TPageControl(Sender).ActivePage.PageIndex <> Idx then begin

        TPageControl(Sender).ActivePage.PageIndex := Idx;

      end;

      Exit;

    end;

  end;

end;

procedure TForm1.PageControl1DragOver(Sender, Source: TObject; X, Y: Integer; State: TDragState; var Accept: Boolean);

begin

  // 判断调用者为 TPageControl 类型可以拖动标签

  Accept := (Sender is TPageControl);

end;

end.

运行效果如下

来源：http://www.delphifmx.com/node/69