Invalidate之后，再写lineto为什么就不行了

Question

我做了2个按钮，按button1对按钮画边框，再按button2时清空边框，在button2上画，但是好像不行，我另做了一个按钮button3，在button3中调用Invalidate(TRUE); 再按botton2时画button2时就没问题，在线等
void CLinetDlg::OnButton1() 
{ CWnd* pWnd=GetDlgItem(IDC_BUTTON1);
CDC* pDC=pWnd->GetDC();
CPen pen(PS_SOLID,2,RGB(255,0,0));
CPen * pOldPen=pDC->SelectObject(&pen);  
pDC->MoveTo(0,0); 
pDC->LineTo(0,200); 

  pDC->MoveTo(0,200); 
pDC->LineTo(200,200);  pDC->MoveTo(200,200); 
pDC->LineTo(200,0);  pDC->MoveTo(200,0); 
pDC->LineTo(0,0);
pDC->SelectObject(pOldPen); ReleaseDC(pDC);
}void CLinetDlg::OnButton2() 
{ Invalidate(TRUE); CWnd* pWnd1=GetDlgItem(IDC_BUTTON2);
CDC* pDC=pWnd1->GetDC();
CPen pen1(PS_SOLID,2,RGB(255,0,0));
CPen * pOldPen1=pDC->SelectObject(&pen1);   pDC->MoveTo(0,0); 
pDC->LineTo(0,200); 

  pDC->MoveTo(0,200); 
pDC->LineTo(200,200);  pDC->MoveTo(200,200); 
pDC->LineTo(200,0);  pDC->MoveTo(200,0); 
pDC->LineTo(0,0);
pDC->SelectObject(pOldPen1);}

Answer 1

pen是不是没有删除啊浪费资源啊
结尾加上：
pDC->SelectObject(pOldPen);
pen.DeleteObject();

Answer 2

谢谢楼上，可是我在button2里面先调用 Invalidate(TRUE);后面画的东西，一闪，就没了，我把Invalidate(TRUE);单独放在button3里面，先调用，再修改button2代码画，就可以
void CLinetDlg::OnButton2() 
{
CWnd* pWnd1=GetDlgItem(IDC_BUTTON2);
CDC* pDC=pWnd1->GetDC();
CPen pen1(PS_SOLID,2,RGB(255,0,0));
CPen * pOldPen1=pDC->SelectObject(&pen1);   pDC->MoveTo(0,0); 
pDC->LineTo(0,200); 

  pDC->MoveTo(0,200); 
pDC->LineTo(200,200);  pDC->MoveTo(200,200); 
pDC->LineTo(200,0);  pDC->MoveTo(200,0); 
pDC->LineTo(0,0);
pDC->SelectObject(pOldPen1); pen1.DeleteObject();
}void CLinetDlg::OnButton3() 
{

Invalidate(TRUE);
}

Answer 3

我做了2个按钮，按button1对按钮画边框，再按button2时清空边框，在button2上画，但是好像不行，我另做了一个按钮button3，在button3中调用Invalidate(TRUE); 再按botton2时画button2时就没问
被你说得晕糊糊的

Answer 4

OnButton2() 改成这样试试void CLinetDlg::OnButton2() 
{ CWnd* pWnd=GetDlgItem(IDC_BUTTON1);
CDC* pDC=pWnd->GetDC();
CPen pen(PS_SOLID,2,RGB(255,0,0));
CPen * pOldPen=pDC->SelectObject(&pen);  
         pDC->SetROP2(R2_NOTXORPEN); 
pDC->MoveTo(0,0); 
pDC->LineTo(0,200); 

  pDC->MoveTo(0,200); 
pDC->LineTo(200,200);  pDC->MoveTo(200,200); 
pDC->LineTo(200,0);  pDC->MoveTo(200,0); 
pDC->LineTo(0,0);
pDC->SelectObject(pOldPen);
ReleaseDC(pDC);
CWnd* pWnd1=GetDlgItem(IDC_BUTTON2);
pDC=pWnd1->GetDC();
CPen * pOldPen1=pDC->SelectObject(&pen);   pDC->MoveTo(0,0); 
pDC->LineTo(0,200); 

  pDC->MoveTo(0,200); 
pDC->LineTo(200,200);  pDC->MoveTo(200,200); 
pDC->LineTo(200,0);  pDC->MoveTo(200,0); 
pDC->LineTo(0,0);
pDC->SelectObject(pOldPen1);
         pen.DeleteObject();
ReleaseDC(pDC);}

Answer 5

我搞定了，谢谢各位帮忙的朋友，将绘图代码写在OnPaint里面才可以，用一个全局变量判断具体画在哪个控件内。