VC中用MFC绘图程序方法

本页内容为：VC中用MFC绘图程序方法，该文章本站转载自网络，如有侵权请告之，我们将会及时将其删除，其正文内容如下：

首先我们说下通过鼠标的移动来绘制直线。

这里要捕获到鼠标的两个消息：WM_LBUTTONDOWN, WM_LBUTTONUP。响应WM_LBUTTONDOWN消息记录直线的起始点，响应WM_LBUTTONUP消息记录直线的终点并绘制直线。

好了，我们看看怎么响应。

void CDrawView::OnLButtonDown(UINT nFlags, CPoint point) { //MessageBox("Left Button Clicks DrawView"); m_ptOrigin = point ; //这里先定义了一个内部变量保存直线的起始点 CView::OnLButtonDown(nFlags, point); }

下面看看响应WM_LBUTTONUP消息记录直线的终点并绘制直线。

//方法一 void CDrawView::OnLButtonUp(UINT nFlags, CPoint point) { HDC hdc; hdc = ::GetDC(m_hWnd); //调用全局函数 MoveToEx(hdc,m_ptOrigin.x,m_ptOrigin.y,0); LineTo(hdc,point.x,point.y); ::ReleaseDC(m_hWnd,hdc); CView::OnLButtonUp(nFlags, point); } //方法二 void CDrawView::OnLButtonUp(UINT nFlags, CPoint point) { CDC *pDC = GetDC(); pDC->MoveTo(m_ptOrigin); pDC->LineTo(point); ReleaseDC(pDC); } //方法三 void CDrawView::OnLButtonUp(UINT nFlags, CPoint point) { CClientDC dc(this) ; //CClientDC对象构造的时候就调用了GetDC，析构的时候调用 ReleaseDC ，只能访问客户区 CClientDC dc(GetParent()); dc.MoveTo(m_ptOrigin); dc.LineTo(point); } //方法四 void CDrawView::OnLButtonUp(UINT nFlags, CPoint point) { CWindowDC dc(this) ; //CWindowDC可以访问客户区和非客户区 dc.MoveTo(m_ptOrigin); dc.LineTo(point); } void CDrawView::OnLButtonUp(UINT nFlags, CPoint point) { CWindowDC dc(GetDesktopWindow()) ; //现在可以访问桌面 dc.MoveTo(m_ptOrigin); dc.LineTo(point); }

连续线绘图：

思路：鼠标移动的信号被捕捉到，然后随时响应该信号，绘制图线。

这里要设置一个BOOL变量 m_bDraw 来判断是否鼠标左键按下了。

//画连续的线条 void CDrawView::OnMouseMove(UINT nFlags, CPoint point) { if ( m_bDraw ) { CClientDC dc(this) ; dc.MoveTo(m_ptOrigin); //移动到原来的点 dc.LineTo(point); //绘制直线 m_ptOrigin = point ; //将现在的点赋值给原来的坐标，以便下次调用 } CView::OnMouseMove(nFlags, point); } //改变画笔的颜色 void CDrawView::OnMouseMove(UINT nFlags, CPoint point) { if ( m_bDraw ) { CClientDC dc(this) ; CPen pen( PS_SOLID , 1 , RGB(255,128,128) ); CPen *pOldPen = dc.SelectObject(&pen); dc.MoveTo(m_ptOrigin); dc.LineTo(point); m_ptOrigin = point ; dc.SelectObject(pOldPen); } CView::OnMouseMove(nFlags, point); } //画扇型 void CDrawView::OnMouseMove(UINT nFlags, CPoint point) { if ( m_bDraw ) { CClientDC dc(this) ; CPen pen( PS_SOLID , 1 , RGB(255,128,128) ); CPen *pOldPen = dc.SelectObject(&pen); dc.MoveTo(m_ptOrigin); dc.LineTo(m_ptOld); dc.MoveTo(m_ptOrigin); dc.LineTo(point); m_ptOld = point ; dc.SelectObject(pOldPen); } CView::OnMouseMove(nFlags, point); } //画带边线的扇型 void CDrawView::OnMouseMove(UINT nFlags, CPoint point) { if ( m_bDraw ) { CClientDC dc(this) ; CPen pen( PS_SOLID , 1 , RGB(255,128,128) ); CPen *pOldPen = dc.SelectObject(&pen); dc.MoveTo(m_ptOrigin); dc.LineTo(m_ptOld); dc.MoveTo(m_ptOrigin); dc.LineTo(point); dc.MoveTo(m_ptOld); dc.LineTo(point); m_ptOld = point ; dc.SelectObject(pOldPen); } CView::OnMouseMove(nFlags, point); } //看看绘图的模式设置方法 void CDrawView::OnMouseMove(UINT nFlags, CPoint point) { if ( m_bDraw ) { CClientDC dc(this) ; dc.SetROP2(R2_BLACK); //绘图的模式设置,始终绘制黑色图形 CPen pen( PS_SOLID , 1 , RGB(255,128,128) ); CPen *pOldPen = dc.SelectObject(&pen); dc.MoveTo(m_ptOrigin); dc.LineTo(m_ptOld); dc.MoveTo(m_ptOrigin); dc.LineTo(point); dc.MoveTo(m_ptOld); dc.LineTo(point); m_ptOld = point ; dc.SelectObject(pOldPen); } CView::OnMouseMove(nFlags, point); }

到此，我们知道了一般地绘图方法了。