VC实现自定义按钮响应拖动

void CMoveableButton::OnLButtonDown(UINT nFlags, CPoint point) 
{
    // TODO: Add your message handler code here and/or call default
    m_bStartMove = TRUE;
    CButton::OnLButtonDown(nFlags, point);
}

void CMoveableButton::OnLButtonUp(UINT nFlags, CPoint point) 
{
    // TODO: Add your message handler code here and/or call default
    m_bStartMove = FALSE;
    CButton::OnLButtonUp(nFlags, point);
}

void CMoveableButton::OnMouseMove(UINT nFlags, CPoint point) 
{
    // TODO: Add your message handler code here and/or call default
    if (m_bStartMove)
    {
        ReleaseCapture();
        SendMessage(WM_NCLBUTTONDOWN, (WPARAM)HTCAPTION, 0); 
    }
    CButton::OnMouseMove(nFlags, point);
}

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OnMouseMove的另一种写法：

void CMoveableButton::OnMouseMove(UINT nFlags, CPoint point) 
{
    // TODO: Add your message handler code here and/or call default
    if (m_bStartMove)
    {
        CRect rect;

        ClientToScreen(&point);
        this->GetParent()->ScreenToClient(&point);

        GetClientRect(&rect);
        point.Offset(-rect.Width()/2, -rect.Height()/2);
//        这里可能需要控制按钮的移动范围，使其不移动到界面外，方法：CWnd::SetWindowPlacement
// 　　也可以自己实现

        SetWindowPos(NULL, point.x , point.y , 0, 0, SWP_NOZORDER|SWP_NOSIZE);
//        afxDump<<point.x<<","<<point.y<<"\n";
        Invalidate();
    }
    CButton::OnMouseMove(nFlags, point);
}