?? chap23.htm
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<title>范例二</title>
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<p><small><a href="../../../index.htm">首頁</a> >> <a href="../../program.htm">程序設計</a>
>> <a href="../cbuilder.htm">C++ Builder</a> >> </small>圖形程式設計基本觀念·范例二</p>
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<p><font SIZE="2" color="#FF0000">·簡易繪圖范例02</font></p>
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<p>范例二的輸出</p>
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<p><font SIZE="2"><img SRC="Image2.gif" WIDTH="458" HEIGHT="344">圖02</font></p>
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<p>這個范例使用了畫線的函式來畫出圖形，同樣地我們來看看其關鍵的函式LineTo及MoveTo：</p>
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<p>void __fastcall LineTo(int X, int Y);</p>
<p>函式說明</p>
<p>LineTo函式由畫筆位置畫一條至 (X,Y)點的直線，此直線不包含(X,Y)點，同時將畫筆位置移至
(X,Y)。此函式通常必須配合MoveTo來移動畫筆位置。</p>
<p>此直線使用Pen來繪制。</p>
<p>void __fastcall MoveTo(int X, int Y);</p>
<p>函式說明</p>
<p>MoveTo是用以在呼叫LineTo前設定畫筆位址值。呼叫此函式和直接設定PenPos屬性的效果相同。</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的關鍵部份，也就是實際負責繪圖的FormPaint部份，其中用了許多的叁角函數如sin,cos,M_PI等運算，我在此就不另加說明了，之所用使用了這些函數只是為了在介紹這些簡單的函式時，利用這些簡單函式所產生的美麗圖形，加深你的印象及學習效果罷了。電腦繪圖之所以迷人也在於此，它可以利用電腦強大的運算及繪圖能力，很容易地將一些復雜的圖顯示出來。</p>
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>> <a href="../cbuilder.htm">C++ Builder</a> >> </small>圖形程式設計基本觀念·范例二</p>
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