GIF transparency

#include <olectl.h>
    
    HRESULT Load(LPCTSTR szFile)
    {
        CComPtr<IStream> pStream;
        
        // Load the file to a memory stream
        HRESULT hr = FileToStream(szFile, &pStream);

        if (SUCCEEDED(hr))
        {
            // Decode the picture
            hr = ::OleLoadPicture(
                    pStream,            // [in] Pointer to the stream that contains picture's data
                    0,                    // [in] Number of bytes read from the stream (0 == entire)
                    true,                // [in] Loose original format if true
                    IID_IPicture,        // [in] Requested interface
                    (void**)&m_pPicture // [out] IPictire object on success
                    );
        }

        return hr;
    }

    HRESULT DrawImg(HDC hdc, const RECT& rcBounds)
    {
        if (m_pPicture)
        {
            // Get the width and the height of the picture
            long hmWidth = 0, hmHeight = 0;
            m_pPicture->get_Width(&hmWidth);
            m_pPicture->get_Height(&hmHeight);

            // Convert himetric to pixels
            int nWidth    = MulDiv(hmWidth, ::GetDeviceCaps(hdc, LOGPIXELSX), HIMETRIC_INCH);
            int nHeight    = MulDiv(hmHeight, ::GetDeviceCaps(hdc, LOGPIXELSY), HIMETRIC_INCH);

            // Display the picture using IPicture::Render
            return m_pPicture->Render(
                hdc,                            // [in] Handle of device context on which to render the image
                rcBounds.left,                    // [in] Horizontal position of image in hdc
                rcBounds.top,                    // [in] Vertical position of image in hdc
                rcBounds.right - rcBounds.left,    // [in] Horizontal dimension of destination rectangle
                rcBounds.bottom - rcBounds.top, // [in] Vertical dimension of destination rectangle
                0,                                // [in] Horizontal offset in source picture
                hmHeight,                        // [in] Vertical offset in source picture
                hmWidth,                        // [in] Amount to copy horizontally in source picture
                -hmHeight,                        // [in] Amount to copy vertically in source picture
                &rcBounds                        // [in, optional] Pointer to position of destination for a metafile hdc
                );
        }

        return E_UNEXPECTED;
    }