Увеличительное стекло

void __fastcall TForm1::Button1Click(TObject *Sender)
{
        Graphics::TBitmap * pctr = new Graphics::TBitmap;
        pctr->LoadFromFile(OpenPictureDialog1->FileName);
        Form1->Canvas->Draw(20, 20, pctr);
}

void __fastcall TForm1::Image1MouseMove(TObject *Sender, TShiftState Shift, int X, int Y)
{
  ZoomIt(Image1->Picture,Image2->Picture,X,Y,8);
}
//---------------------------------------------------------------------------
void __fastcall TForm1::ZoomIt(TObject *Source,TObject *Target,
                        int X,int Y,int Zoom )
{
  int Sw,Sh,Tw,Th,Dw,Dh;
  int SX1,SX2,SY1,SY2;
  int TX1,TX2,TY1,TY2;
 
  TPicture *so = (TPicture *)Source;
  TPicture *ta = (TPicture *)Target;
 
  Sw = so->Bitmap->Width;
  Sh = so->Bitmap->Height;
  Tw = ta->Bitmap->Width;
  Th = ta->Bitmap->Height;
  Dw = Tw/2;
  Dh = Th/2;
 
  TX1 = 0;
  TX2 = Tw;
  TY1 = 0;
  TY2 = Th;
 
  SX1 = X-Dw/Zoom;
  SX2 = X+Dw/Zoom;
  SY1 = Y-Dh/Zoom;
  SY2 = Y+Dh/Zoom;
 
  if (SX1<0) {
    TX1 = TX1-(SX1*Zoom);
    SX1 = 00;
  }
  if (SX2>Sw) {
    TX2 = TX2+(Sw-SX2)*Zoom;  SX2 = Sw;
  }
  if (SY1<0) {
    TY1 = TY1-(SY1*Zoom);
    SY1 = 00;
  }
  if (SY2>Sh) {
    TY2 = TY2+(Sh-SY2)*Zoom;
    SY2 = Sh;
  }
 
  ta->Bitmap->Canvas->Brush->Color = clBlack;
  ta->Bitmap->Canvas->FillRect(Rect(0,0,Tw,Th));
  ta->Bitmap->Canvas->CopyRect(Rect(TX1,TY1,TX2,TY2),
                               so->Bitmap->Canvas,
                               Rect(SX1,SY1,SX2,SY2));
}

      TRect RE;
 
      RE.left = 0; RE.top = 0;
      RE.right = Image2->Width ;
      RE.bottom = Image2->Height ;
      Image2->Picture->Bitmap->PixelFormat = pf24bit;
      Image2->Picture->Bitmap->Width       = Image2->Width ;
      Image2->Picture->Bitmap->Height      = Image2->Height ;
      Image2->Picture->Bitmap->Canvas->Brush->Color = clBlack;
      Image2->Picture->Bitmap->Canvas->FillRect(RE);

    HDC hdc = GetDC(bmp->Handle);
    HBITMAP hbmp = bmp->Handle;
    FIBITMAP *dib = 0;
    BITMAP bm;
    GetObject(hbmp, sizeof(BITMAP), (LPSTR)&bm);
    dib = FreeImage_Allocate(bm.bmWidth, bm.bmHeight, bm.bmBitsPixel);
    int nColors = FreeImage_GetColorsUsed(dib);
    int Success = GetDIBits(hdc, hbmp, 0, FreeImage_GetHeight(dib),
    FreeImage_GetBits(dib), FreeImage_GetInfo(dib), DIB_RGB_COLORS);
    FreeImage_GetInfoHeader(dib)->biClrUsed = nColors;
    FreeImage_GetInfoHeader(dib)->biClrImportant = nColors;
 
    FIBITMAP *_dib = FreeImage_Rescale(dib, w, h, FILTER_BICUBIC);
 
    FreeImage_Unload(dib);
 
    bmp->Handle = CreateDIBitmap(hdc, FreeImage_GetInfoHeader(_dib),
    CBM_INIT, FreeImage_GetBits(_dib), FreeImage_GetInfo(_dib), DIB_RGB_COLORS);
 
    FreeImage_Unload(_dib);