StretchBlt 提高图片显示质量的方法

通过SetStretchMode(STRETCH_HALFTONE)实现，同时注意重新设置画刷起点

LRESULT CMainDlg::OnPaint(UINT uMsg, WPARAM wParam, LPARAM /*lParam*/, BOOL& bHandled) {
    CPaintDC dc(m_hWnd);
    CDC memDC;
    memDC.CreateCompatibleDC(dc);
    memDC.SelectBitmap((HBITMAP)m_cap_pic);
    dc.SetStretchBltMode(STRETCH_HALFTONE);
    ::SetBrushOrgEx(dc, 0, 0, NULL);
    dc.StretchBlt(m_rc_capture.left, m_rc_capture.top, m_rc_capture.Width(), 
        m_rc_capture.Height(), memDC, 0, 0, m_cap_pic.GetWidth(),
        m_cap_pic.GetHeight(), SRCCOPY);
    bHandled = FALSE;
    return 0;
}