Open a File Dialog Box

OpenFileBox.cpp

// Specific Extensions
// https://cpp.hotexamples.com/examples/-/IFileDialog/SetFileTypeIndex/cpp-ifiledialog-setfiletypeindex-method-examples.html

PWSTR OpenFileBox(HWND hWnd) {
    HRESULT hr = CoInitializeEx(NULL, COINIT_APARTMENTTHREADED |
        COINIT_DISABLE_OLE1DDE);

    if (!SUCCEEDED(hr)) {
        return NULL;
    }

    IFileOpenDialog* pFileOpen;

    // Create the FileOpenDialog object.
    hr = CoCreateInstance(CLSID_FileOpenDialog, NULL, CLSCTX_ALL,
        IID_IFileOpenDialog, reinterpret_cast<void**>(&pFileOpen));

    COMDLG_FILTERSPEC filter[2];
    filter[0].pszName = L"JPEG(*.jpg;*.jpeg)";
    filter[0].pszSpec = L"*.jpg;*.jpeg";
    filter[1].pszName = L"Images (*.jpg;*.jpeg;*.png;*.cur)";
    filter[1].pszSpec = L"*.jpg;*.jpeg;*.png;*.cur";

    if (!SUCCEEDED(hr)) {
        return NULL;
    }

    // Show the Open dialog box.
    hr = pFileOpen->SetFileTypes(2, filter);
    hr = pFileOpen->SetFileTypeIndex(2);
    hr = pFileOpen->Show(hWnd);

    if (!SUCCEEDED(hr)) {
        return NULL;
    }

    IShellItem* pItem;
    hr = pFileOpen->GetResult(&pItem);

    if (!SUCCEEDED(hr)) {
        return NULL;
    }

    PWSTR pszFilePath;
    hr = pItem->GetDisplayName(SIGDN_FILESYSPATH, &pszFilePath);

    if (!SUCCEEDED(hr)) {
        return NULL;
    }

    pItem->Release();
    pFileOpen->Release();
    CoUninitialize();

    return pszFilePath;
}