Delphi实例之绘制正弦函数图像

Delphi实例之绘制正弦函数图像

 unit Unit1;

 interface

 uses
   Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
   Dialogs, StdCtrls, ExtCtrls;

 type
   TForm1 = class(TForm)
     Image1: TImage;
     Button1: TButton;
     Label1: TLabel;
     Label2: TLabel;
     Label3: TLabel;
     Label4: TLabel;
     Label5: TLabel;
     Label6: TLabel;
     procedure Button1Click(Sender: TObject);
   private
     { Private declarations }
   public
     { Public declarations }
   end;

 var
   Form1: TForm1;

 implementation

 {$R *.dfm}

 procedure TForm1.Button1Click(Sender: TObject);
 var
   x,l:Integer;
   y,a:double;
 begin
   Image1.Picture.Bitmap:=TBitMap.Create;
   Image1.Picture.Bitmap.Width:=Image1.Width;
   Image1.Picture.Bitmap.Height:=Image1.Height;
   l:=Image1.Picture.Bitmap.Width;
     {下面的语句用于绘制直角坐标系}
   Image1.Canvas.MoveTo(,(Image1.Height div ));
   Image1.Canvas.Pen.Color:=clBlue;
   Image1.Canvas.LineTo(Image1.Width,(Image1.Height div ));{绘制函数图像X轴}
   Image1.Canvas.MoveTo((Image1.Width div ),Image1.Height);
   Image1.Canvas.LineTo((Image1.Width div ),);{绘制函数图像Y轴}
   for x:= to l do
     begin
       a:=(x/l)**Pi;{角度化弧度}
       y:=sin(*a);{为了加强美观效果，这里讲振幅设为2}
       y:=y*(Image1.Picture.Bitmap.Height/);
       y:=y+(Image1.Picture.Bitmap.Height/);
       Image1.Picture.Bitmap.Canvas.Brush.Style:=bsSolid;
       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}
     end;
   label1.Visible:=true;
   Label2.Visible:=true;
   label3.Visible:=true;
   Label4.Visible:=true;
   label5.Visible:=true;
   Label6.Visible:=true;
 end;

 end.

注意，这里我用了四个标签，分别用于显示X,Y,0,f(x)=sinx，并事先将它们的Visible属性设为False，当图像绘制完成后在将Visible改为True。