Re: CPaintDC class

Hi there,

    I have some form drawing code that uses the CPaintDC class and
it works fine. But I am just wondering if it is as good as using
BeginPaint and EndPaint.

    I know this class calls these 2 methods anyway, but I am unsure
as to whether it takes in for account the invalid rectangle whilst
calling it's BitBlt method.

    For example, if I declare "CPaintDC dc(myWindowHandle)" and the
paint event args specify that only a small portion of the entire
surface is to be repainted does BitBlt only paint said region?

    ------

    Let's say only the rectangle (100,100,150,150) needs
repainting.... ------

    CPaintDC dc(m_hWnd);
    CRect rc; GetClientRect(&rc);

    //Clear the buffer
    m_memDC.FillRect(&rc,m_bkgrnd);

    //Draw to the buffer here
    ...

    //Blit the buffer
    dc.BitBlt(rc.left,
        rc.top,
        rc.right,
        rc.bottom,
        m_memDC,
        rc.left,
        rc.top,
        SRCCOPY);

    ------

    Does BitBlt actual perform a block copy of the entire rectangle
specified, or only the one that is specified in the paint arguments?