oracle基础知识讲义

				unit unitForm1;
				
				interface
				
				uses
				  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
				  ExtCtrls;
				
				type
				  TForm1 = class(TForm)
				    Image1: TImage;
				    procedure FormCreate(Sender: TObject);
				  private
				    { Private declarations }
				    FClientInstance,
				      FPrevClientProc: TFarProc;
				    procedure ClientWndProc(var Message: TMessage);
				
				  public
				    { Public declarations }
				  end;
				
				var
				  Form1: TForm1;
				
				implementation
				
				{$R *.DFM}
				
				{ TForm1 }
				
				procedure TForm1.ClientWndProc(var Message: TMessage);
				
				var
				  MyDC: hDC;
				  Ro, Co: Word;
				begin
				  with Message do
				    case Msg of
				      WM_ERASEBKGND:
				        begin
				          MyDC := TWMEraseBkGnd(Message).DC;
				          for Ro := 0 to ClientHeight div Image1.Picture.Height do
				            for Co := 0 to ClientWIDTH div Image1.Picture.Width do
				              BitBlt(MyDC, Co * Image1.Picture.Width, Ro * Image1.Picture.Height,
				                Image1.Picture.Width, Image1.Picture.Height,
				                Image1.Picture.Bitmap.Canvas.Handle, 0, 0, SRCCOPY);
				          Result := 1;
				        end;
				      else
				        Result := CallWindowProc(FPrevClientProc, ClientHandle, Msg, wParam, lParam);
				    end;
				
				
				end;
				
				procedure TForm1.FormCreate(Sender: TObject);
				begin
				  FClientInstance := MakeObjectInstance(ClientWndProc);
				  FPrevClientProc := Pointer(GetWindowLong(ClientHandle, GWL_WNDPROC));
				  SetWindowLong(ClientHandle, GWL_WNDPROC, LongInt(FClientInstance));
				end;
				
				end.