LineDDA的一个例子

核心提示：unit Unit1; interfaceusesWindows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,Dialogs, ExtCtrls, StdCtrls, Buttons;typeTfmMain = class(TFor

unit Unit1;

interface

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

type
　TfmMain = class(TForm)
　　PRocedure FormPaint(Sender: TObject);
　end;

var
　fmMain: TfmMain;
　A: Byte;

implementation

uses math;
{$R *.dfm}

procedure c(X,Y:Integer; ACanvas:TCanvas);stdcall;
begin
　Inc(A,2);
　ACanvas.Pen.Width := 5;
　if Odd(A mod 31) then
　　ACanvas.Pen.Color := clWhite
　else
　　ACanvas.Pen.Color := clBlack;
　ACanvas.MoveTo(x,y);
　ACanvas.LineTo(x,y);
end;

procedure TfmMain.FormPaint(Sender: TObject);
begin
　LineDDA(0,20,width,20,@c,LongInt(Canvas));
　LineDDA(0,0,width,Height,@c,LongInt(Canvas));
end;

end.