19.09.2025, 12:37
Here is another AI answer, I fed everything including the source code from this thread ...
It is not possible to use the IPreviewHandler interface to display full visual previews of DOCX or XLSX files without Microsoft Office (Word/Excel) installed on the user's PC. The preview handlers for these file formats are registered by Office itself in the Windows registry under the relevant ShellEx keys (like the {8895b1c6-b41f-4c1c-a562-0d564250836f} GUID shown in the code). Without Office, those CLSIDs are not present, and CoCreateInstance will fail to instantiate the handler.
Everything (from voidtools) relies on the same system-registered IPreviewHandlers as Windows File Explorer. If previews work on your PCs without Office 365, it's likely because a perpetual version of Office (e.g., 2019 or 2021) is installed, providing the necessary handlers—Office 365 refers specifically to the subscription model, not all Office installations.
The Microsoft Office Compatibility Pack does not register preview handlers; it only enables opening/editing newer formats in older Office versions. LibreOffice and similar free alternatives also do not register IPreviewHandler for DOCX/XLSX in Explorer or compatible apps like Everything. Windows itself has no built-in handlers for these formats without Office.
To implement this in PowerBASIC using Jose's shobjidl.inc, you could adapt the provided C code logic to query the registry for the CLSID (via RegOpenKeyEx, RegQueryValueEx, etc.), then use CoCreateInstance to get the IPreviewHandler interface pointer, followed by calls to IInitializeWithFile (or IInitializeWithStream), SetWindow, SetRect, and DoPreview. However, this will only succeed if the handler is registered (i.e., Office is installed). Without it, you'd need to fall back to custom rendering, which is impractical for full visual fidelity—DOCX/XLSX are complex ZIP+XML formats requiring parsing layouts, fonts, embeds, formulas, etc.
Alternatives without Office:
- Third-party tools like QuickLook or Seer can preview these files, but they don't integrate via IPreviewHandler and require installation.
- Embed a WebBrowser or WebView2 control in your app to load the file via Office Online (requires internet) or a local library like Mammoth.js for basic DOCX-to-HTML conversion (but loses full visuals).
- Use COM/ActiveX components if available (e.g., paid ones like Aspose or free limited viewers), but none are drop-in replacements without extra setup.
If your goal is truly zero dependencies on Office-like software, the short answer is no for full visual previews via IPreviewHandler or similar native means.
It is not possible to use the IPreviewHandler interface to display full visual previews of DOCX or XLSX files without Microsoft Office (Word/Excel) installed on the user's PC. The preview handlers for these file formats are registered by Office itself in the Windows registry under the relevant ShellEx keys (like the {8895b1c6-b41f-4c1c-a562-0d564250836f} GUID shown in the code). Without Office, those CLSIDs are not present, and CoCreateInstance will fail to instantiate the handler.
Everything (from voidtools) relies on the same system-registered IPreviewHandlers as Windows File Explorer. If previews work on your PCs without Office 365, it's likely because a perpetual version of Office (e.g., 2019 or 2021) is installed, providing the necessary handlers—Office 365 refers specifically to the subscription model, not all Office installations.
The Microsoft Office Compatibility Pack does not register preview handlers; it only enables opening/editing newer formats in older Office versions. LibreOffice and similar free alternatives also do not register IPreviewHandler for DOCX/XLSX in Explorer or compatible apps like Everything. Windows itself has no built-in handlers for these formats without Office.
To implement this in PowerBASIC using Jose's shobjidl.inc, you could adapt the provided C code logic to query the registry for the CLSID (via RegOpenKeyEx, RegQueryValueEx, etc.), then use CoCreateInstance to get the IPreviewHandler interface pointer, followed by calls to IInitializeWithFile (or IInitializeWithStream), SetWindow, SetRect, and DoPreview. However, this will only succeed if the handler is registered (i.e., Office is installed). Without it, you'd need to fall back to custom rendering, which is impractical for full visual fidelity—DOCX/XLSX are complex ZIP+XML formats requiring parsing layouts, fonts, embeds, formulas, etc.
Alternatives without Office:
- Third-party tools like QuickLook or Seer can preview these files, but they don't integrate via IPreviewHandler and require installation.
- Embed a WebBrowser or WebView2 control in your app to load the file via Office Online (requires internet) or a local library like Mammoth.js for basic DOCX-to-HTML conversion (but loses full visuals).
- Use COM/ActiveX components if available (e.g., paid ones like Aspose or free limited viewers), but none are drop-in replacements without extra setup.
If your goal is truly zero dependencies on Office-like software, the short answer is no for full visual previews via IPreviewHandler or similar native means.