用mfc畫動態直線--“橡皮線”

筆記：程式碼在CView.cpp裡實現

//CView

CPoint m_ptSpoint;  //起始點
CPoint m_ptEpoint;  //最終點
bool m_click;

//上面三個變數也可定義在Cview.h裡

void CDrawLineView::OnLButtonDown(UINT nFlags, CPoint point)
{
	// TODO: 在此新增訊息處理程式程式碼和/或呼叫預設值

	m_ptSpoint =m_ptEpoint= point;
	m_click = true;

	CView::OnLButtonDown(nFlags,
 
 point);
}


void CDrawLineView::OnLButtonUp(UINT nFlags, CPoint point)
{
	// TODO: 在此新增訊息處理程式程式碼和/或呼叫預設值

	m_click = false;
	
	CView::OnLButtonUp(nFlags, point);
}


void CDrawLineView::OnMouseMove(UINT nFlags, CPoint point)
{
	// TODO: 在此新增訊息處理程式程式碼和/或呼叫預設值

	CDC*p = GetDC();
	if (m_click == true)
	{
		p-
 
>SetROP2(R2_NOT);
		p->MoveTo(m_ptSpoint);
		p->LineTo(m_ptEpoint);
		m_ptEpoint = point;
		p->MoveTo(m_ptSpoint);
		p->LineTo(m_ptEpoint);
	}

	CView::OnMouseMove(nFlags, point);
}