Creating HBITMAP from memory buffer

Question

I have an application which loads some blob data out of a database which can represent png formatted or raw binary data for various bitmaps and icons. This is being stored

Answer 1

A slight variation on the answer provided by AJG85, that employs SHCreateMemStream in place of CreateStreamOnHGlobal. SHCreateMemStream was introduced as a public API in Windows Vista, and provides the benefit of creating an IStream over an existing region in memory, thus avoiding an additional memory allocation:

#include 
#include 
#include 
#include 

#include 

#pragma comment(lib, "Shlwapi.lib")
#if defined(_DEBUG)
#    pragma comment(lib, "comsuppwd.lib")
#else
#    pragma comment(lib, "comsuppw.lib")
#endif


HBITMAP from_data(std::vector const& data)
{
    if (data.empty())
    {
        _com_issue_error(E_INVALIDARG);
    }

    auto const stream { ::SHCreateMemStream(&data[0], static_cast(data.size())) };
    if (!stream)
    {
        _com_issue_error(E_OUTOFMEMORY);
    }
    _COM_SMARTPTR_TYPEDEF(IStream, __uuidof(IStream));
    IStreamPtr sp_stream { stream, false };

    CImage img {};
    _com_util::CheckError(img.Load(sp_stream));

    return img.Detach();
}

This implementation either throws a _com_error, or returns an HBITMAP that refers to the image constructed from the in-memory data.

When the function returns, the memory buffer can be safely freed. The returned HBITMAP is owned by the caller, and needs to be released with a call to DeleteObject.