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<title>CPolyline类别定义及实作 画随意线的类别</title>
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>> <a href="../cbuilder.htm">C++ Builder</a> >> </small><font>具体而微的绘图程式</font>·CPolyline类别定义及实作
画随意线的类别</p>
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<p align="left"><font color="#FF0000" SIZE="2">·03-03 CPolyline类别定义及实作
画随意线的类别</font></p>
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<p>class CPolyline : public CShape</p>
<p>{</p>
<p> public:</p>
<p> POINT m_ptOrigin;</p>
<p> public:</p>
<p> CPolyline(TCanvas* pCanvas):CShape(pCanvas)
{}</p>
<p> virtual ~CPolyline() {}</p>
<p> virtual void OnMouseMove(int,int);</p>
<p> virtual void OnMouseDown(int,int);</p>
<p> virtual void OnMouseUp(int,int);</p>
<p>};</p>
<p>CPolyline类别其实和我们前面所写的涂鸦程式的行为模式极为类似，所以我就简单带过好了。</p>
<p>void CPolyline::OnMouseDown(int x,int y)</p>
<p>{</p>
<p> m_ptOrigin.x = x;</p>
<p> m_ptOrigin.y = y;</p>
<p> m_pCanvas->MoveTo(x,y);</p>
<p>}</p>
<p>void CPolyline::OnMouseMove(int x,int y)</p>
<p>{</p>
<p> m_pCanvas->LineTo(x,y);</p>
<p>}</p>
<p>void CPolyline::OnMouseUp(int x,int y)</p>
<p>{</p>
<p> m_pCanvas->LineTo(x,y);</p>
<p>}</p>
</font><p><font SIZE="2"></font><font color="#FF0000" SIZE="2">·03-04 CPolygon类别定义及实作
画多边形的类别</font></p><font SIZE="2">
<p>class CPolygon : public CPolyline</p>
<p>{</p>
<p> public:</p>
<p> CPolygon(TCanvas*
pCanvas):CPolyline(pCanvas){}</p>
<p> virtual ~CPolygon() {}</p>
<p> virtual void OnMouseUp(int,int);</p>
<p>};</p>
<p>CPolygon是CPolyline的子类别，其差别仅在於它会将首尾两点连接，使其成为一个多边形，因此我们就直接由CPolyline继承而来，只改写其OnMouseUp成员函式即可。</p>
<p>void CPolygon::OnMouseUp(int x,int y)</p>
<p>{</p>
<p> m_pCanvas->MoveTo(m_ptOrigin.x,m_ptOrigin.y);</p>
<p> m_pCanvas->LineTo(x,y);</p>
<p>}</p>
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>> <a href="../cbuilder.htm">C++ Builder</a> >> </small><font>具体而微的绘图程式</font>·CPolyline类别定义及实作
画随意线的类别</p>
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