MFC当分辨率不够时自动添加滚动条

afx_msg void OnVScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar);

BEGIN_MESSAGE_MAP(CLicenseModuleMgr, CDialog)
	
	ON_WM_CTLCOLOR()
	ON_WM_VSCROLL()

END_MESSAGE_MAP()

BOOL CxxxMgr::OnInitDialog()
{
	CDialog::OnInitDialog();
	// TODO:  Add extra initialization here

	//获取系统分辨率,判断是否显示进度条
	int iWide = 0;
	int iHeight = 0; 
	iWide = GetSystemMetrics(SM_CXSCREEN); //屏幕宽度 
	iHeight = GetSystemMetrics(SM_CYSCREEN); //屏幕高度

	RECT rt;
	SystemParametersInfo(SPI_GETWORKAREA, 0, (PVOID)&rt, 0); //获得工作区大小

	//任务栏在下面的高度 
	int iTaskBottomHeight = iHeight - rt.bottom;   

	//计算当前屏幕高度
	if ((iHeight - rt.bottom) > 0)
	{
		iHeight = rt.bottom;
	}

	//任务栏在上面的高度
	if (rt.top > 0)
	{
		iHeight = iHeight - rt.top;
	}

	//获取当前窗口高度
	CRect rect;
	this->GetWindowRect(&rect);

	SCROLLINFO vinfo;

	vinfo.cbSize =sizeof(vinfo);

	vinfo.fMask =SIF_ALL;

	vinfo.nPage = 10;//滚动块自身的长短，通常有如下关系：其长度/滚动条长度（含两个箭头）=nPage/(nMax+2)，

	//另外nPage取值-1时，滚动条会不见了。

	if (rect.Height() > iHeight - 10)
	{
		vinfo.nMax = 25;//滚动条所能滚动的最大值
		vinfo.nMin = 5;//滚动条所能滚动的最小值
	}
	else
	{
		vinfo.nMax = 20;//滚动条所能滚动的最大值
		vinfo.nMin = 20;//滚动条所能滚动的最小值
	}

	vinfo.nTrackPos =0;

	vinfo.nPos = 0;

	SetScrollInfo(SB_VERT | SBS_RIGHTALIGN, &vinfo);//即使上述步骤一不做，使用此条语句也可以显示滚动条

	return TRUE;  // return TRUE unless you set the focus to a control
	// EXCEPTION: OCX Property Pages should return FALSE
}

void CLicenseModuleMgr::OnVScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar)
{
	SCROLLINFO scrollinfo;

	GetScrollInfo(SB_VERT,&scrollinfo,SIF_ALL);

	switch (nSBCode)
	{
	case SB_BOTTOM: //滑块滚动到最底部

		ScrollWindow(0,(scrollinfo.nPos-scrollinfo.nMax)*10); //滚动屏幕

		scrollinfo.nPos = scrollinfo.nMax; //设定滑块新位置

		SetScrollInfo(SB_VERT,&scrollinfo,SIF_ALL); //更新滑块位置

		break;

	case SB_TOP: //滑块滚动到最顶部

		ScrollWindow(0,(scrollinfo.nPos-scrollinfo.nMin)*10);

		scrollinfo.nPos = scrollinfo.nMin;

		SetScrollInfo(SB_VERT,&scrollinfo,SIF_ALL);

		break;

	case SB_LINEUP: //单击上箭头

		scrollinfo.nPos -= 1;

		if (scrollinfo.nPos<scrollinfo.nMin)
		{
			scrollinfo.nPos = scrollinfo.nMin;
			break;
		}

		SetScrollInfo(SB_VERT,&scrollinfo,SIF_ALL);

		ScrollWindow(0,10);

		break;

	case SB_LINEDOWN: //单击下箭头

		scrollinfo.nPos += 1;

		if (scrollinfo.nPos>scrollinfo.nMax)
		{
			scrollinfo.nPos = scrollinfo.nMax;
			break;
		}

		SetScrollInfo(SB_VERT,&scrollinfo,SIF_ALL);

		ScrollWindow(0,-10);

		break;

	case SB_PAGEUP: //单击滑块上方空白区域

		scrollinfo.nPos -= 5;

		if (scrollinfo.nPos<scrollinfo.nMin)
		{
			scrollinfo.nPos = scrollinfo.nMin;
			break;
		}

		SetScrollInfo(SB_VERT,&scrollinfo,SIF_ALL);

		ScrollWindow(0,10*5);

		break;

	case SB_PAGEDOWN: //单击滑块下方空白区域

		scrollinfo.nPos += 5;

		if (scrollinfo.nPos>scrollinfo.nMax)
		{
			scrollinfo.nPos = scrollinfo.nMax;
			break;
		}

		SetScrollInfo(SB_VERT,&scrollinfo,SIF_ALL);

		ScrollWindow(0,-10*5);

		break;

	case SB_ENDSCROLL: //鼠标离开滑块，结束滑块拖动

		// MessageBox("SB_ENDSCROLL");

		break;

	case SB_THUMBPOSITION:

		// ScrollWindow(0,(scrollinfo.nPos-nPos)*10);

		// scrollinfo.nPos = nPos;

		// SetScrollInfo(SB_VERT,&scrollinfo,SIF_ALL);

		break;

	case SB_THUMBTRACK: //拖动滑块

		ScrollWindow(0,(scrollinfo.nPos-nPos)*10);

		scrollinfo.nPos = nPos;

		SetScrollInfo(SB_VERT,&scrollinfo,SIF_ALL);

		break;
	}

	CDialog::OnVScroll(nSBCode, nPos, pScrollBar);
}