WinAPI: InvertRect - 翻转矩形中像素的颜色

unit Unit1;

interface

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

type
TForm1 = class(TForm)
Button1: TButton;
Button2: TButton;
procedure FormCreate(Sender: TObject);
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

var
R: TRect;

procedure TForm1.FormCreate(Sender: TObject);
begin
Button1.Caption := '绘制矩形';
Button2.Caption := '反色';
Self.Color := clWhite;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
R := Bounds(20, 20, 150, 100);
Randomize;
Canvas.Brush.Color := Random($FFFFFF);
Canvas.Pen.Color := Random($FFFFFF);
Canvas.Pen.Width := 10;
Canvas.Rectangle(R);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
InvertRect(Canvas.Handle, R);
end;

end.