Delphi实例之绘制正弦函数图像

 1 unit Unit1;
 2 
 3 interface
 4 
 5 uses
 6   Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
 7   Dialogs, StdCtrls, ExtCtrls;
 8 
 9 type
10   TForm1 = class(TForm)
11     Image1: TImage;
12     Button1: TButton;
13     Label1: TLabel;
14     Label2: TLabel;
15     Label3: TLabel;
16     Label4: TLabel;
17     Label5: TLabel;
18     Label6: TLabel;
19     procedure Button1Click(Sender: TObject);
20   private
21     { Private declarations }
22   public
23     { Public declarations }
24   end;
25 
26 var
27   Form1: TForm1;
28 
29 implementation
30 
31 {$R *.dfm}
32 
33 procedure TForm1.Button1Click(Sender: TObject);
34 var
35   x,l:Integer;
36   y,a:double;
37 begin
38   Image1.Picture.Bitmap:=TBitMap.Create;
39   Image1.Picture.Bitmap.Width:=Image1.Width;       
40   Image1.Picture.Bitmap.Height:=Image1.Height;
41   l:=Image1.Picture.Bitmap.Width;
     {下面的语句用于绘制直角坐标系}
42   Image1.Canvas.MoveTo(0,(Image1.Height div 2));
43   Image1.Canvas.Pen.Color:=clBlue;
44   Image1.Canvas.LineTo(Image1.Width,(Image1.Height div 2));{绘制函数图像X轴}
45   Image1.Canvas.MoveTo((Image1.Width div 2),Image1.Height);
46   Image1.Canvas.LineTo((Image1.Width div 2),0);{绘制函数图像Y轴}
47   for x:=0 to l do
48     begin
49       a:=(x/l)*2*Pi;{角度化弧度}
50       y:=sin(2*a);{为了加强美观效果，这里讲振幅设为2}
51       y:=y*(Image1.Picture.Bitmap.Height/2);
52       y:=y+(Image1.Picture.Bitmap.Height/2);
53       Image1.Picture.Bitmap.Canvas.Brush.Style:=bsSolid;
54       Image1.Picture.Bitmap.Canvas.Pixels[Trunc(x),Trunc(y)]:=clRed;{当然也可以用LineTo过程来实现，但是要注意设置Pen.Width到合适的值}
55     end;
56   label1.Visible:=true;
57   Label2.Visible:=true;
58   label3.Visible:=true;
59   Label4.Visible:=true;
60   label5.Visible:=true;
61   Label6.Visible:=true;
62 end;
63 
64 end.