IShellItem::BindToHandler fails for too many file types

Question

Hello,

I'm trying to extract a thumbnail from the given file below.

For this I use SHCreateItemFromParsingName and IShellItem::BindToHandler. For several file types this works fine, but for various other file types BindToHandler only returns E_NOTIMPL Not implemented. and I am not sure why.

Normally thumbnails can be registered through thumbnail providers. Is there another method I am not aware of? This would explain why the example above fails. I stripped down the code to the absolut minimum:

   #include <windows.h>  
   #include <shlobj.h>  
   #include <thumbcache.h>  
   #include <iostream>  
   #include <shellapi.h>  
     
   #pragma comment(lib, "SHELL32.LIB")  
   #pragma comment(lib, "Comctl32.lib")  
     
   int wmain(int argc, wchar_t* argv[], wchar_t* envp[]) {  
   HRESULT hr = CoInitializeEx(NULL, COINIT_APARTMENTTHREADED | COINIT_DISABLE_OLE1DDE);  
     if (!SUCCEEDED(hr))  
     {  
       return -1;  
     }  
     
   IShellItem* psi = nullptr;  
     hr = SHCreateItemFromParsingName(argv[1], NULL, IID_PPV_ARGS(&psi));  
     if (SUCCEEDED(hr)) {  
       IThumbnailProvider* pThumbProvider;  
       hr = psi->BindToHandler(NULL, BHID_ThumbnailHandler, IID_PPV_ARGS(&pThumbProvider));  
       if (SUCCEEDED(hr)) {  
         std::wcout << L"this line never succeeds";  
       }  
     }  
     return 0;  
   }  

Could anyone help out and explain what might go wrong here?

Answer 1

This test works for me with a .clip file =>

    PIDLIST_ABSOLUTE pidl;  
    HRESULT hr = SHParseDisplayName(L"C:\\Users\\Christian\\Documents\\illustration.clip", NULL, &pidl, 0, NULL);
    IShellItemImageFactory* pShellItemImageFactory;
    hr = SHCreateItemFromIDList(pidl, IID_PPV_ARGS(&pShellItemImageFactory));
    HBITMAP hBitmap;
    SIZE size;
    size.cx = 320;
    size.cy = 200;
    hr = pShellItemImageFactory->GetImage(size, SIIGBF_RESIZETOFIT | SIIGBF_THUMBNAILONLY, &hBitmap);
    // Test display on screen
    HDC hDC = GetDC(NULL);
    HDC hDCMem = CreateCompatibleDC(hDC);
    HBITMAP hBitmapOld = (HBITMAP)SelectObject(hDCMem, hBitmap);
    BitBlt(hDC, 0, 0, size.cx, size.cy, hDCMem, 0, 0, SRCCOPY);
    SelectObject(hDCMem, hBitmapOld);
    DeleteObject(hDCMem);
    ReleaseDC(NULL, hDC);

Answer 2

You can refer to this Extract thumbnail for any file in Windows question which provides a solution that extracts a thumbnail.

Answer 3

Thanks for sharing! I will try this, but isn't there a C++ solution for this?