protected override bool TryCreateViewer(FileInfo fileInfo, out HandlerResult?handlerResult)
{
var pcchOut = 0u;
var riid = typeof(IPreviewHandler).GUID.ToString("B");
if (PInvoke.AssocQueryString(ASSOCF.ASSOCF_INIT_DEFAULTTOSTAR, ASSOCSTR.ASSOCSTR_SHELLEXTENSION, fileInfo.Extension, riid, Span <char> .Empty, ref pcchOut).Failed)
{
handlerResult = default;
return(false);
}
var shellFileControl = new ShellFileControl();
using (shellFileControl.Initialize())
{
shellFileControl.Loaded += (_, _) => shellFileControl.Open(fileInfo);
}
handlerResult = new HandlerResult {
Viewer = shellFileControl
};
return(true);
}
// ReSharper disable once InconsistentNaming
private static bool TryGetPreviewHandlerCLSID(FileInfo fileInfo, out Guid clsid)
{
var pcchOut = 40u;
Span <char> pszOut = stackalloc char[(int)pcchOut];
var riid = typeof(IPreviewHandler).GUID.ToString("B");
if (PInvoke.AssocQueryString(ASSOCF.ASSOCF_INIT_DEFAULTTOSTAR, ASSOCSTR.ASSOCSTR_SHELLEXTENSION, fileInfo.Extension, riid, pszOut, ref pcchOut).Failed)
{
clsid = Guid.Empty;
return(false);
}
clsid = Guid.Parse(pszOut[..(int)(pcchOut - 1)]);
