VC ：在对话框中绘图

主要代码如下：
显示代码如下：
CDC * pDialogDC = GetDC();
Invalidate();
UpdateWindow();
CPen pen(PS_SOLID,2,RGB(255,0,0));
pDialogDC->SelectObject(&pen);

for (int i = 0;i < picVector.size(); i++)
{

switch(picVector[i]->picFlag)
{
case 0:
pDialogDC->MoveTo(picVector[i]->startPoint);
pDialogDC->LineTo(picVector[i]->endPoint);
break;
case 1:
pDialogDC->Ellipse(picVector[i]->startPoint.x,picVector[i]->startPoint.y,picVector[i]->endPoint.x,picVector[i]->endPoint.y);
break;
case 2:
pDialogDC->Rectangle(picVector[i]->startPoint.x,picVector[i]->startPoint.y,picVector[i]->endPoint.x,picVector[i]->endPoint.y);
break;
}
}
ReleaseDC(pDialogDC);
往vector容器中添加获取的元素（包括所画图的类型，鼠标按下、抬起两点）：
void CForwardBackDlg::OnLButtonUp(UINT nFlags, CPoint point)
{
// TODO: Add your message handler code here and/or call default
upPoint = point;

CPicture * pPic = new CPicture();

pPic->picFlag = style;
pPic->startPoint = downPoint;
pPic->endPoint = upPoint;
picVector.push_back(pPic);
bakeupVector.push_back(pPic);
//delete pPic;//检查传递到容器中是否是地址传递，答案： 是
Invalidate();//只刷新对话框中控件 不刷新对话框自身
//UpdateWindow();
CDialog::OnLButtonUp(nFlags, point);
}
撤销代码如下：
if(picVector.size() > 0)
{
//delete picVector[picVector.size() - 1];
picVector.pop_back();

参考：

void CForwardBackDlg::OnPaint()
{ 
     CDC * pControlDC = GetDC();
     Invalidate();
     UpdateWindow();
     pControlDC->SelectStockObject(BLACK_BRUSH);
     pControlDC->Rectangle(0,0,100,100);
     ReleaseDC(pControlDC);

}