为什么我的ATL控件不能画线？

Question

什么效果都没有，我把“SelectObject(di.hdcDraw,hPen);”去掉结果依然，为什么？
CBoard::CBoard()
{
hPen = CreatePen(PS_SOLID,3,RGB(0,255,0));
}HRESULT CBoard::OnDraw(ATL_DRAWINFO& di)
{
RECT& rc = *(RECT*)di.prcBounds;
// 将剪辑区域设置为 di.prcBounds 指定的矩形
HRGN hRgnOld = NULL;
if (GetClipRgn(di.hdcDraw, hRgnOld) != 1)
hRgnOld = NULL;
bool bSelectOldRgn = false; HRGN hRgnNew = CreateRectRgn(rc.left, rc.top, rc.right, rc.bottom); if (hRgnNew != NULL)
{
bSelectOldRgn = (SelectClipRgn(di.hdcDraw, hRgnNew) != ERROR);
}
Rectangle(di.hdcDraw, rc.left, rc.top, rc.right, rc.bottom);
SelectObject(di.hdcDraw,hPen);
MoveToEx(di.hdcDraw,0,0,NULL);
LineTo(di.hdcDraw,100,100);
if (bSelectOldRgn)
SelectClipRgn(di.hdcDraw, hRgnOld); return S_OK;
}

Answer 1

SelectClipRgn 不就把真个 dc 剪了吗

Answer 2

画个对角线试下：
MoveToEx(di.hdcDraw,rc.left,rc.top,NULL);
LineTo(di.hdcDraw,rc.right,rc.bottom);