Obtaining HBitmap from HDC

[Andonic]

Hello all,
I'm trying to resize the image of a CStatic to the size of the CStatic itself, because usually the CStatic resizes automatically to the size of the picture, and I want just the opposite. For that purpose, I have tried to use the CDC function StretchBlt to resize the containing HBITMAP from the original size to the size of the CStatic.

This works well but when trying to obtain the HBITMAP from the resized CDC i just get a black image but with the correct size.

void WriteBmp(char* name,int W,int H,int Bpp,int* data)
{
  BITMAPINFO Bmi={0};
  Bmi.bmiHeader.biSize      = sizeof(BITMAPINFOHEADER);
  Bmi.bmiHeader.biWidth      =  W;
  Bmi.bmiHeader.biHeight      = H;
  Bmi.bmiHeader.biPlanes      = 1;
  Bmi.bmiHeader.biBitCount    = Bpp; 
  Bmi.bmiHeader.biCompression  = BI_RGB;
  Bmi.bmiHeader.biSizeImage    = W*H*Bpp/8; 


  FILE* image = fopen (name,"wb");
  if(image==0)
    return;
  int h = abs(Bmi.bmiHeader.biHeight);
  int w = abs(Bmi.bmiHeader.biWidth);
  Bmi.bmiHeader.biHeight=-h;
  Bmi.bmiHeader.biWidth=w;
  int sz = Bmi.bmiHeader.biSizeImage;

  BITMAPFILEHEADER bfh;
  bfh.bfType=('M'<<8)+'B'; 
  bfh.bfOffBits=sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER); 
  bfh.bfSize=sz+bfh.bfOffBits; 
  bfh.bfReserved1=0; 
  bfh.bfReserved2=0; 
   
  fwrite(&bfh,sizeof(bfh),1,image);
  fwrite(&Bmi.bmiHeader,sizeof(BITMAPINFOHEADER),1,image);
  fwrite(data,sz,1,image);
  fclose(image);
}

int GuardarHBITMAPenFichero(HBITMAP hbmp,CString nombreFichero)
{
        /// Save HBITMAP in the file nombreFichero
	
	BITMAP bm;
	
	GetObject(hbmp,sizeof(BITMAP),&bm);

	
	int Bps = bm.bmBitsPixel;
	int Width  = bm.bmWidth;
	int Height  = bm.bmHeight;

	int size = Bps/8 * ( Width * Height );
	BYTE *lpBits = new BYTE[size];

	BITMAPINFOHEADER bInfoHeader; 
	BITMAPINFO bInfo;
	::ZeroMemory(&bInfoHeader,sizeof(BITMAPINFOHEADER));
	bInfoHeader.biSize = sizeof(BITMAPINFOHEADER);     
	bInfoHeader.biWidth = Width;
	bInfoHeader.biHeight = -Height;// si negativo origen en la parte superior izquierda, si positivo en la parte inferior izquierda
	bInfoHeader.biPlanes = 1;
	bInfoHeader.biBitCount = 24 /*bit per pixel 24,32 */ ;
	bInfoHeader.biCompression = 0;  //RGB
	bInfoHeader.biSizeImage = bInfoHeader.biWidth*bInfoHeader.biHeight*bInfoHeader.biBitCount/8;

	bInfo.bmiHeader=bInfoHeader;
	HDC memDC = ::GetDC(0);
	HBITMAP OldBM = (HBITMAP)::SelectObject(memDC, hbmp );

	::GetDIBits(
		memDC,           // manipulador de contexto de dispositivo
		hbmp,      // manipulador de mapa de bits
		0,   // primera lÃ*nea a colocar en el mapa de bits de destino
		Height,   // número de lÃ*neas a copiar
		lpBits,    // dirección del array de bits del mapa de bits
		&bInfo, // dirección de estructura con datos del mapa de bits
		DIB_RGB_COLORS    // RGB o Ã*ndices de paleta
   );
	// lpbits es un puntero a byte a la ventana que quieres capturar
	
	
	WriteBmp((char*)(LPCSTR)nombreFichero,Width,Height,24,(int*)lpBits);

	delete [] lpBits;
	::DeleteDC(memDC);
	
	return 0;
}




HBITMAP Asignar(CStatic *panel,HBITMAP imagen)
{
      /// This function draws the HBITMAP in the panel with the size of the panel
	RECT r;
	BITMAP bm;

	GetObject(imagen,sizeof(BITMAP),&bm);

	int Width  = bm.bmWidth;  // width of the original image
	int Height  = bm.bmHeight; // height of the original image
	
	HBITMAP hResized_image;

		
	panel->GetWindowRect(&r); // size of the panel where we'll draw the image
	panel->ScreenToClient(&r);
	
	HDC panel_hdc;
	panel_hdc=panel->GetDC()->GetSafeHdc(); // HDC of the panel

	HDC DCOrigen = ::CreateCompatibleDC ( panel_hdc ); // We create a compatible HDC to draw the image in, this DCs' dimensions will be the image's ones.

	::SelectObject(DCOrigen,imagen); //We select the image into the HDC DCOrigen

/// here the image is resized
	StretchBlt(
			panel_hdc,      // manipulador del contexto de dispositivo de destino
			0, // coordenada x de la esquina superior izquierda del rectángulo de destino
			0, // coordenada y de la esquina superior izquierda del rectángulo de destino
			r.right-r.left,   // anchura del rectángulo de destino
			r.bottom-r.top,  // altura del rectángulo de destino
			DCOrigen,       // manipulador del contexto de dispositivo de origen
			0,  // coordenada x de la esquina superior izquierda del rectángulo de origen 
			0,  // coordenada y de la esquina superior izquierda del rectángulo de origen
			Width ,    // anchura del rectángulo de origen
			Height,   // altura del rectángulo de origen
			SRCCOPY       // código de operación de rastreo
	);

// I'm trying to get the HBITMAP of the resized HDC

	hResized_image=(HBITMAP)::GetCurrentObject(panel_hdc,           // handle to DC
	//											OBJ_BITMAP   // object type
	//											);

/// Save into a file  , save a black image
GuardarHBITMAPenFichero(hResized_image,"c:\\resized_HBITMAP.bmp");

/////
// Free resources ...
 
/////
	return resized_image;

}

The problem is that i haven't been able to get the correct HBITMAP of the resized HDC , when i save it in a file the result is a black image. Why doesn't this work? is there another way that works to get the HBITMAP from a HDC?