Vista introduced an interface: IFileDialog::SetFilter, which allows me to setup a filter that will be called for every potential filename to see if it should be shown to the user.
Microsoft removed that in Windows 7, and didn't support it in XP.
I am trying to customize the our Open file dialog so that I can control which files are displayed to the end user. These files are marked internally with a product-code - there isn't anything in the filename itself to filter on (hence file extension filters are not useful here -= I need to actually interrogate each one to see if it is within the extra filter parameters that our users specified).
I would guess that Microsoft removed the SetFilter interface because too often it was too slow. I can imagine all sorts of similar ideas to this one which don't scale well for networks and cloud storage and what have you.
However, I need to know if there is an alternative interface that accomplishes the same goal, or if I really am restricted to only looking at the file extension for filtering purposes in my File dialogs?
Follow-up:
After looking further into CDN_INCLUDEITEM, which requires the pre-vista version of OPENFILENAME, I have found that this is the most useless API imaginable. It only filters NON-filesystem objects. In other words, you can't use it to filter files. Or folders. The very things one would filter 99.99% of the time for a file open or save dialog. Unbelievable!
There is a very old article by Paul DiLascia which offers the technique of removing each offending filename from the list view control each time the list view is updated.
However, I know from bitter experience that the list view can update over time. If you're looking at a large folder (many items) or the connection is a bit slow (heavily loaded server and/or large number of files), then the files are added to the dialog piecemeal. So one would have to filter out offending filenames repeatedly.
In fact, our current customized file open dialog uses a timer to look at the view's list of filenames periodically to see if any files of a given pattern exist, in order to enable another control. Otherwise it's possible to check for the existence of these files, find none, but a moment later the view updates to have more filenames, and no events are sent to your dialog to indicate that the view has been changed. In fact, my experience with having to write and maintain code for the common controls file dialogs over the years has been that Microsoft is not very cluefull when it comes to how to write such a thing. Events are incomplete, sent at not-useful times, repeated when not necessary, and whole classes of useful notifications don't exist.
Sadly, I think I might have to give up oh this idea. Unless someone has a thought as to how I might be able to keep up with the view spontaneously changing while the user is trying to interact with it (i.e. it would be awkward to go deleting out entries from the list view and changing the user's visual position, or highlighted files, or scroll position, etc.)