Delphi中将ShowMessage,MessageDlg, MessageBox,InputBox,InputQuery及任意模态窗口相对主窗口(父窗口、母窗口）居中

procedure NextModalFormMoveToMyCenter(Owner: TForm);
begin
  //From HeZiHang@cnBlogs
  TThread.ForceQueue(nil,
    procedure
    var
      R: TRect;
      X, Y: Integer;
    begin
      GetWindowRect(Application.ActiveFormHandle, R);
      X := Owner.Left + (Owner.Width - R.Width) div 2;
      Y := Owner.Top + (Owner.Height - R.Height) div 2; // 将InputBox或MessageBox在Owner Form居中
      SetWindowPos(Application.ActiveFormHandle, HWND_TOP, X,Y, 0, 0, SWP_NOSIZE or SWP_SHOWWINDOW or SWP_NOOWNERZORDER);
    end);
end;


//Demo1：MessageBox自动居中
procedure TForm1.btnResetClick(Sender: TObject);
begin
  NextModalFormMoveToMyCenter(Self);
  if Application.MessageBox('是否复位重启？', '重启', MB_YESNOCANCEL or MB_ICONQUESTION or MB_DEFBUTTON2) <> mrYes then
    。。。。。。。。。//此时MessageBox对Form1居中
end;

//Demo2：InputBox自动居中 

procedure TForm1.btnCommandClick(Sender: TObject);

var
  S: String;
begin
  NextModalFormMoveToMyCenter(Self);
  S := InputBox('请输入命令', '命令：', '');。//此时InputBox对Form1居中
    。。。。
end;

//Demo3:其他窗体，自动居中
procedure TForm1.btnCommandClick(Sender: TObject);
var
  F:TMyForm;
  S: String;
begin
  NextModalFormMoveToMyCenter(Self);
  F:=TMyForm.Create(Self);
  F.ShowModal;//此时 F对Form1居中
end;