createrectregionindirectu.pas

DelphiWin32核心API参考光盘内容.是学习书籍中的源码,便于学习.

unit CreateRectRegionIndirectU;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
var
  RegionHandle: HRGN;    // a handle to the region
begin
  {create a rectangular region the size of the form's client area}
  RegionHandle := CreateRectRgnIndirect(Form1.ClientRect);

  {initialize the brush}
  Canvas.Brush.Style := bsDiagCross;
  Canvas.Brush.Color := clRed;

  {fill the rectangular region}
  FillRgn(Canvas.Handle, RegionHandle, Canvas.Brush.Handle);

  {we no longer need the region, so delete it}
  DeleteObject(RegionHandle);
end;

end.