用DLL中的函数在主对话框的控件上绘图，如按钮或Static
对话框按钮响应：
void CTest2Dlg::OnButton4()
{
typedef void(*pDrawLinePP)(CDC *pDC,CWnd *pWnd,CPoint pt1,CPoint pt2);
HINSTANCE hDLL;
pDrawLinePP DrawLine1;
hDLL=LoadLibrary("WBDLL.dll");//加载动态链接库MyDll.dll文件；
DrawLine1 = (pDrawLinePP)GetProcAddress(hDLL,"DrawLinePP");
CDC *pDC;
pDC = GetDlgItem(IDC_BUTTON4)->GetDC();
CPoint pt1,pt2,pt3;
pt1.x = 20;
pt1.y = 0;
pt2.x = 20;
pt2.y = 50;
pt3.x = 60;
pt3.y = 50;
DrawLine1(pDC,this,pt1,pt2);
DrawLine1(pDC,this,pt1,pt3);
pDC = GetDlgItem(IDC_STATIC_FRAME)->GetDC();
DrawLine1(pDC,GetDlgItem(IDC_STATIC_FRAME),pt1,pt2);
DrawLine1(pDC,GetDlgItem(IDC_STATIC_FRAME),pt1,pt3);
FreeLibrary(hDLL);//卸载MyDll.dll文件；
}
DLL
extern "C" __declspec(dllexport) int TextFun1(int a, int b);
extern "C" __declspec(dllexport) void FunStr(CString str1,CString str2,char * chr);
extern "C" __declspec(dllexport) void DrawLine(CDC *pDC,CDialog *pDlg);
extern "C" __declspec(dllexport) void DrawLinePointToPoint(CDC *pDC,CDialog *pDlg,CPoint pt1,CPoint pt2);
extern "C" __declspec(dllexport) void DrawLinePP(CDC *pDC,CWnd *pWnd,CPoint pt1,CPoint pt2);
void DrawLinePointToPoint(CDC *pDC,CDialog *pDlg,CPoint pt1,CPoint pt2)
{
pDC->MoveTo(pt1);
pDC->LineTo(pt2);
}
//在CWnd对象上绘图
void DrawLinePP(CDC *pDC,CWnd *pWnd,CPoint pt1,CPoint pt2)
{
pDC->MoveTo(pt1);
pDC->LineTo(pt2);
}