繪制思路：做一個(gè)自定義控件插入界面中
具體步驟：
（1）橫軸劃分為若干點(diǎn)，使用Moveto+Lineto連線，定時(shí)刷新實(shí)現(xiàn)動(dòng)態(tài)效果；
（2）在程序中，使用CPaintDC,CClientDc,CDC,CBitMap,CBrush等繪圖類；
（3）繪圖程序分為幾大部分：注冊(cè)類句柄、刷新機(jī)制、設(shè)定坐標(biāo)系、繪圖；
部分代碼如下：
BOOL CLineChartCtrl::RegisterWndClass(HINSTANCE hInstance)
{
WNDCLASSW wc;
wc.lpszClassName = TEXT("LineChartCtrl"); // matches class name in client
。。。
return (::RegisterClass(&wc) != 0 ); }
void CLineChartCtrl::InvalidateCtrl()
{
CClientDC dc(this);
CRect rcClient;
GetClientRect(rcClient);
if (m_MemDC.GetSafeHdc() == NULL)
{
m_MemDC.CreateCompatibleDC(&dc);
m_Bitmap.CreateCompatibleBitmap(&dc,rcClient.Width(),rcClient.Height());
m_MemDC.SelectObject(m_Bitmap);
m_MemDC.SetBkColor(RGB(255,255,255)); //靜態(tài)背景色
CBrush bkBrush(RGB(160,160,160));
m_MemDC.FillRect(rcClient,&bkBrush);
}
InvalidateRect(rcClient, FALSE);
}
float CLineChartCtrl::SetPos(int nIndex, float nPos)
{
。。。}
void CLineChartCtrl::OnPaint()
{
CPaintDC dc(this); // device context for painting
CRect rcClient;
GetClientRect(rcClient);
// draw scale
if (m_MemDC.GetSafeHdc() != NULL)
dc.BitBlt(0, 0, rcClient.Width(), rcClient.Height(), &m_MemDC, 0, 0, SRCCOPY);
}
void CLineChartCtrl::DrawSpike()
{
CRect rcClient;
GetClientRect(rcClient);
if (m_MemDC.GetSafeHdc() != NULL) //豎線間隔寬度
{
m_MemDC.BitBlt(0, 0, rcClient.Width(), rcClient.Height(), &m_MemDC, 20, 0, SRCCOPY);
// draw scale
CRect rcRight = rcClient;
rcRight.left = rcRight.right - 20;
m_MemDC.SetBkColor(RGB(255,255,255)); //運(yùn)行時(shí)背景色
CBrush bkBrush(RGB(160,160,160));
m_MemDC.FillRect(rcRight,&bkBrush);
static BOOL bDrawVerticle = FALSE;
bDrawVerticle = !bDrawVerticle;
if (bDrawVerticle)
{
CPen pen(PS_SOLID, 1, RGB(128,128,128)); //縱軸色
CPen* pOldPen = m_MemDC.SelectObject(&pen);
m_MemDC.MoveTo(CPoint(rcClient.right-2, rcClient.top));
m_MemDC.LineTo(CPoint(rcClient.right-2, rcClient.bottom));
m_MemDC.SelectObject(pOldPen);
}
int nCount = m_items.GetSize();
CLineChartItem* pItem;
CPoint ptOld, ptNew;
for (int i=0; i<nCount; i++)
{
pItem = m_items.GetAt(i);
float nRange = pItem->m_nUpper - pItem->m_nLower;
ptOld.x = rcRight.left-1; // Minus one to make sure to draw inside the area
ptNew.x = rcRight.right-1;
ptOld.y = (int)((((float)(nRange - pItem->m_nOldPos))/(float)nRange)
* (float)rcRight.Height());
ptNew.y = (int)((((float)(nRange - pItem->m_nPos))/(float)nRange)
* (float)rcRight.Height());
CPen pen(PS_SOLID, 1, pItem->m_colorLine);
CPen* pOldPen = m_MemDC.SelectObject(&pen);
m_MemDC.MoveTo(ptOld);
m_MemDC.LineTo(ptNew);
m_MemDC.SelectObject(pOldPen);
}
}
}
BOOL CLineChartCtrl::Add(COLORREF color, float Upper, float Lower)
{
CLineChartItem* pItem = new CLineChartItem;
pItem->m_colorLine = color;
pItem->m_nLower = Lower;
pItem->m_nUpper = Upper;
pItem->m_nPos = 0;
pItem->m_nOldPos = 0;
try
{
m_items.Add(pItem);
InvalidateCtrl();
return TRUE;
}
catch (CMemoryException* e)
{
if (pItem !=NULL)
delete pItem;
e->Delete();
return FALSE;
}
}
void CLineChartCtrl::Go()
{
DrawSpike();
Invalidate(FALSE);
}
注意的幾點(diǎn)：(1) Windows CE采用unicode，必須寫諸如WNDCLASSW;LoadCursorW;
(2) EVC下的CBrush不能使用兩個(gè)參數(shù)如CBrush(HS_Cross,RGB(0,0,0))；
(3)改動(dòng)stdAfx.h包含的頭文件；
(4)在void CVoltagecontrolDlg::DoDataExchange(CDataExchange* pDX)里加入 DDX_Control(pDX, IDC_LineChartCtrl, m_LineChart); 在BOOL CVoltagecontrolDlg::OnInitDialog()里加入 m_LineChart.SubclassDlgItem(IDC_LineChartCtrl, this);
(5)在設(shè)置自定義空間屬性ID必須為IDC_LineChartCtrl，CLASS為L(zhǎng)ineChartCtrl，相應(yīng)程序里的注冊(cè)句柄名稱也設(shè)成LineChartCtrl；
(6)程序中改變豎線間隔的是其寬度，而畫豎線的時(shí)間間隔是2*Timer；
現(xiàn)有的運(yùn)行效果：
橫軸采用五個(gè)Edit控件使時(shí)間數(shù)值能夠動(dòng)態(tài)變化；圖形繪制從坐標(biāo)軸右側(cè)開始,橫軸隨時(shí)間移動(dòng); 采樣時(shí)間為1S;達(dá)到控制精度(error<0.05)要求時(shí)停止采集數(shù)據(jù)并且彈出提示對(duì)話框。
問題：（1）運(yùn)行程序?qū)⒊霈F(xiàn)三個(gè)警告：位于Wincore.cpp的line 348,349,4199。選擇ignore后，可以運(yùn)行程序。
（2）縱軸坐標(biāo)通過實(shí)際值標(biāo)定，且沒有畫出刻度線。