Delphi的繪圖功能[3] - 矩形類圖形

unit Unit1;
interface
uses
　Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
　Dialogs, StdCtrls;
type
　TForm1 = class(TForm)
　　Button1: TButton;
　　Button2: TButton;
　　Button3: TButton;
　　Button4: TButton;
　　Button5: TButton;
　　procedure FormCreate(Sender: TObject);
　　procedure Button1Click(Sender: TObject);
　　procedure Button2Click(Sender: TObject);
　　procedure Button3Click(Sender: TObject);
　　procedure Button4Click(Sender: TObject);
　　procedure Button5Click(Sender: TObject);
　end;
var
　Form1: TForm1;
implementation
{$R *.dfm}
var
　btn: TButton;
const
　y1 = 10;
　y2 = 80;

{先設置畫筆畫刷}procedure TForm1.FormCreate(Sender: TObject);
begin
　Canvas.Pen.Width := 4;
　Canvas.Pen.Color := clRed;
　Canvas.Brush.Color := clWhite;
end;{給出左上角和右下角的坐標就可以繪制矩形}procedure TForm1.Button1Click(Sender: TObject);
begin
　btn := TButton(Sender);
　Canvas.Rectangle(btn.Left, y1, btn.Left+btn.Width, y2);
end;{給出一個矩形結構做參數也可以繪制矩形}procedure TForm1.Button2Click(Sender: TObject);
var
　R: TRect; {定義一個矩形結構}
begin
　btn := TButton(Sender);
　R := Rect(btn.Left, y1, btn.Left+btn.Width, y2);
　Canvas.Rectangle(R);
end;

{繪制圓角矩形; 最後兩個參數是設置圓角的}procedure TForm1.Button3Click(Sender: TObject);
begin
　btn := TButton(Sender);
　Canvas.RoundRect(btn.Left, y1, btn.Left+btn.Width, y2, 20,20);
end;

{繪制焦點矩形; 它不受畫筆的影響; 它的顏色是和畫刷的顏色進行某種運算得來的}procedure TForm1.Button4Click(Sender: TObject);
var
　R: TRect;
begin
　btn := TButton(Sender);
　R := Rect(btn.Left, y1, btn.Left+btn.Width, y2);
　Canvas.DrawFocusRect(R);
end;

{矩形描邊, 用的不是畫筆是畫刷}procedure TForm1.Button5Click(Sender: TObject);
var
　R: TRect;
begin
　btn := TButton(Sender);
　R := Rect(btn.Left, y1, btn.Left+btn.Width, y2);
　Canvas.FrameRect(R);
end;
end.

//效果圖: