unit1.pas

《Delphi7编程100例》代码,书配资料

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    Panel1: TPanel;
    Button2: TButton;
    procedure FormDestroy(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure FormResize(Sender: TObject);
  private
    { Private declarations }
    procedure DoVisible;
    procedure DoInvisible;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  FullRgn, ClientRgn, CtlRgn : THandle;

implementation

{$R *.DFM}

procedure TForm1.DoInvisible;
var
  AControl : TControl;
  A, Margin, X, Y, CtlX, CtlY : Integer;
begin
  Margin := ( Width - ClientWidth ) div 2;
  FullRgn := CreateRectRgn(0, 0, Width, Height);
  X := Margin;
  Y := Height - ClientHeight - Margin;
  ClientRgn := CreateRectRgn( X, Y, X + ClientWidth, Y + ClientHeight );
  CombineRgn( FullRgn, FullRgn, ClientRgn, RGN_DIFF );
  for A := 0 to ControlCount - 1 do begin
    AControl := Controls[A];
    if ( AControl is TWinControl ) or ( AControl is TGraphicControl )
        then with AControl do begin
      if Visible then begin
        CtlX := X + Left;
        CtlY := Y + Top;
        CtlRgn := CreateRectRgn( CtlX, CtlY, CtlX + Width, CtlY + Height );
        CombineRgn( FullRgn, FullRgn, CtlRgn, RGN_OR );
      end;
    end;
  end;
  SetWindowRgn(Handle, FullRgn, TRUE);
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  DeleteObject(ClientRgn);
  DeleteObject(FullRgn);
  DeleteObject(CtlRgn);
end;

procedure TForm1.DoVisible;
begin
  FullRgn := CreateRectRgn(0, 0, Width, Height);
  CombineRgn(FullRgn, FullRgn, FullRgn, RGN_COPY);
  SetWindowRgn(Handle, FullRgn, TRUE);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  DoInvisible;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  if Button1.Caption = 'Show' then begin
    DoVisible;
    Button1.Caption := 'Hide';
  end
  else begin
    DoInvisible;
    Button1.Caption := 'Show';
  end;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  Application.Terminate;
end;

procedure TForm1.FormResize(Sender: TObject);
begin
  if Button1.Caption = 'Show' then
    DoInvisible
  else
    DoVisible;
end;

end.