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<p><small><a href="../../../index.htm">首页</a> >> <a href="../../program.htm">程序设计</a>
>> <a href="../cbuilder.htm">C++ Builder</a> >> </small>图形程式设计基本观念·范例二</p>
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<p><font SIZE="2" color="#FF0000">·简易绘图范例02</font></p>
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<p>范例二的输出</p>
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<p><font SIZE="2"><img SRC="Image2.gif" WIDTH="458" HEIGHT="344">图02</font></p>
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<p>这个范例使用了画线的函式来画出图形，同样地我们来看看其关键的函式LineTo及MoveTo：</p>
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<p>void __fastcall LineTo(int X, int Y);</p>
<p>函式说明</p>
<p>LineTo函式由画笔位置画一条至 (X,Y)点的直线，此直线不包含(X,Y)点，同时将画笔位置移至
(X,Y)。此函式通常必须配合MoveTo来移动画笔位置。</p>
<p>此直线使用Pen来绘制。</p>
<p>void __fastcall MoveTo(int X, int Y);</p>
<p>函式说明</p>
<p>MoveTo是用以在呼叫LineTo前设定画笔位址值。呼叫此函式和直接设定PenPos属性的效果相同。</p>
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<p>void __fastcall TForm1::FormPaint(TObject *Sender)</p>
<p>{</p>
<p> double A,x1,y1,x2,y2;</p>
<p> int D=150,E=50;</p>
<p> double L,M,O,P;</p>
<p> for (int i=0; i<240; i++)</p>
<p> {</p>
<p> A = i*M_PI/120;</p>
<p> L = D+D/3*(1+cos(12*A)/2)*cos(A);</p>
<p> x1 = 240+1.25*L*cos(A);</p>
<p> M = E+E/3*(1+sin(12*A)/2)*cos(A);</p>
<p> x2 = 240+1.25*M*cos(A);</p>
<p> O = D+D/3*(1+cos(10*A)/2)*sin(A);</p>
<p> y1 = 240-O*sin(A);</p>
<p> P = E+E/2*(1+cos(15*A)/2)*sin(A);</p>
<p> y2 = 240-P*sin(A);</p>
<p> Canvas->MoveTo(x1,y1);</p>
<p> Canvas->LineTo(x2,y2);</p>
<p> }</p>
<p>}</p>
<p>以上的程式列表就是范例02的关键部份，也就是实际负责绘图的FormPaint部份，其中用了许多的叁角函数如sin,cos,M_PI等运算，我在此就不另加说明了，之所用使用了这些函数只是为了在介绍这些简单的函式时，利用这些简单函式所产生的美丽图形，加深你的印象及学习效果罢了。电脑绘图之所以迷人也在於此，它可以利用电脑强大的运算及绘图能力，很容易地将一些复杂的图显示出来。</p>
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<p>·<small><a href="../../../index.htm">首页</a> >> <a href="../../program.htm">程序设计</a>
>> <a href="../cbuilder.htm">C++ Builder</a> >> </small>图形程式设计基本观念·范例二</p>
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