Delphi 实现无窗口移动（发WM_NCHITTEST消息计算，然后再发WM_SYSCOMMAND消息，带参数SC_DRAGMOVE）

procedure imgListMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
private
 procedure WMNCHITTEST(var Msg: TWMNCHITTEST); message WM_NCHITTEST;


procedure TfrmStartHit.WMNCHITTEST(var Msg: TWMNCHITTEST);
const
  cOffset = 10;
var
  vPoint: TPoint;
begin
  inherited;
  vPoint := ScreenToClient(Point(Msg.XPos, Msg.YPos));
  if PtInRect(Rect(0, 0, cOffset, cOffset), vPoint) then
    Msg.Result := HTTOPLEFT
  else if PtInRect(Rect(Width - cOffset, Height - cOffset, Width, Height), vPoint) then
    Msg.Result := HTBOTTOMRIGHT
  else if PtInRect(Rect(Width - cOffset, 0, Width, cOffset), vPoint) then
    Msg.Result := HTTOPRIGHT
  else if PtInRect(Rect(0, Height - cOffset, cOffset, Height), vPoint) then
    Msg.Result := HTBOTTOMLEFT
  else if PtInRect(Rect(cOffset, 0, Width - cOffset, cOffset), vPoint) then
    Msg.Result := HTTOP
  else if PtInRect(Rect(0, cOffset, cOffset, Height - cOffset), vPoint) then
    Msg.Result := HTLEFT
  else if PtInRect(Rect(Width - cOffset, cOffset, Width, Height - cOffset), vPoint) then
    Msg.Result := HTRIGHT
  else if PtInRect(Rect(cOffset, Height - cOffset, Width - cOffset, Height), vPoint) then
    Msg.Result := HTBOTTOM;
end;


procedure TfrmStartHit.imgListMouseDown(Sender: TObject;
  Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
const
  SC_DRAGMOVE = $F012;
begin
  if (Button = mbLeft) then
  begin
    ReleaseCapture;
    (Self as TControl).Perform(WM_SYSCOMMAND, SC_DRAGMOVE, 0);
  end;
end;