透明按钮

 

/**//*
 *    画项
 */
void CImageButton::OnDrawItem(int nIDCtl, LPDRAWITEMSTRUCT lpDrawItemStruct) 
{
    CDC *pDC = CDC::FromHandle(lpDrawItemStruct->hDC);
    CRect rc(lpDrawItemStruct->rcItem);
    pDC->SelectStockObject(NULL_BRUSH);
    pDC->Ellipse(rc);
}

/**//*
 *    擦除背景
 */
BOOL CImageButton::OnEraseBkgnd(CDC* pDC) 
{
    CWnd *pParent = GetParent();   
    CRect rc;

    GetWindowRect(rc);
    pParent->ScreenToClient(rc);
    pParent->InvalidateRect(rc,false);
    pParent->UpdateWindow();
    CDC *dcParent = pParent->GetDC();   
    pDC->BitBlt(0,0,rc.Width(),rc.Height(),dcParent,rc.left,rc.top,SRCCOPY);
    pParent->ReleaseDC(dcParent);
    return true;
}