hge 要写个限制box的代码

FBackSurface := TDirectDrawSurface.Create;
try
//    FBackSurface.SystemMemory := True;
    FBackSurface.Size := Point(GWidth, GHeight);
    nWidth := SurfaceX(GLeft) + GWidth;
    nHeight := SurfaceY(GTop) + GHeight;

    if (nWidth <> FBackSurface.Width) or (nHeight <> FBackSurface.Height) then begin
      FBackSurface.Size := Point(nWidth, nHeight);
//    end else begin
//      FBackSurface.Fill(0);
    end;