有时候根据具体需求，我们可能要改变窗口的形状。使用API函数SetWindowRgn可以改变一个窗体的可见范围。
使用API函数CreateRoundRectRgn()函数可以创建一个圆角矩形区域。
图片ID为：IDB_BACKBMP
BOOL CDemoDlg::OnInitDialog()
{
CDialog::OnInitDialog();
// Set the icon for this dialog. The framework does this automatically
// when the application's main window is not a dialog
SetIcon(m_hIcon, TRUE); // Set big icon
SetIcon(m_hIcon, FALSE); // Set small icon
// TODO: Add extra initialization here
m_back.LoadBitmap(IDB_BACKBMP);
CRgn rgn;
rgn.CreateRoundRectRgn(3,3,700,650,20,20);
SetWindowRgn(rgn,TRUE);
return TRUE; // return TRUE unless you set the focus to a control
}
void CDemoDlg::OnPaint()
{
CPaintDC dc(this); // device context for painting
CDC picDC;
picDC.CreateCompatibleDC (&dc);
CBitmap *pOldBmp;
pOldBmp = picDC.SelectObject (&m_back);
BITMAP bm;
m_back.GetBitmap(&bm);
dc.BitBlt (0,0,bm.bmWidth ,bm.bmHeight,&picDC,0,0,SRCCOPY);
dc.SelectObject(pOldBmp);
}
void OnSize(UINT nType, int cx, int cy)
{
CDialog::OnSize(nType, cx, cy);
// TODO: 在此处添加消息处理程序代码
CRgn MyRgn;
CRect rect;
GetWindowRect(&rect);
rect -= rect.TopLeft();
MyRgn.CreateRoundRectRgn(rect.left,rect.top, rect.right, rect.bottom, 3,3);
SetWindowRgn(MyRgn,TRUE);
}