unit1.pas

《深入Delphi的多媒体编程》实例源代码

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs;

type
  TForm1 = class(TForm)
    procedure FormMouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  Flag:Boolean;
  Start_Point:TPoint;

implementation

{$R *.DFM}
procedure TForm1.FormCreate(Sender: TObject);
begin
 Flag:=False;
end;

procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
 if Flag=False then
  begin//单击第一下记录起点坐标
   Start_Point.X:=X;
   Start_Point.Y:=Y;
   Flag:=True;
  end
 else//单击第二下时画出直线
  begin
   Canvas.Pen.Color:=clBlack;
   Canvas.MoveTo(Start_Point.X,Start_Point.Y);
   Canvas.LineTo(X,Y);
   Flag:=False;
  end;
end;

end.