unit1.pas

涂鸦桌面

unit Unit1;

interface

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

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

var
  Form1: TForm1;
implementation

{$R *.dfm}
//上面都是Delphi自动生成的代码
procedure TForm1.FormCreate(Sender: TObject);
begin
Brush.Style :=bsClear;
Tag:=0;  //使用Form的Tag属性作标志位
end;

procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
Tag:=1; //置位
Canvas.MoveTo(X,Y); //将Pen的位置移到当前
//取随机数
Randomize;
Canvas.Pen.Width := Random(30);//设置画笔的宽度
Canvas.Pen.Color :=RGB(Random(255),Random(255),Random(255));//设置画笔的颜色
end;

procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
begin
if Tag=1 then
begin
   Canvas.LineTo(x,y);//画线
end;
end;

procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
Tag:=0; //标志位
end;

procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
if key=27 then Close();//判断如果按下ESC键就退出程序
end;

end.