Flutterby™! : Software hate 2007-09-30 19:50:26.073346+00

Software hate

2007-09-30 19:50:26.073346+00 by Dan Lyke 1 comments

Software hates for the day:

RSS2.0 changing the meaning of the link element.
Firefox constantly giving me the "you've successfully updated" screen on Windows. For the umpteenth freakin' time this morning. Which I've only noticed because I've been rebooting a lot because...
Windows has this feature where you can register a COM object to draw a thumbnail of your document when you're viewing a folder in thumbnail mode. There are two articles on the web describing this process, this one, written 5 years ago, which derives from this one from June of 2000. Nerdly hate continued in the comments.

It's quite simple, to do this you create an object type which implements the IExtractImage and one method of the IPersistFile interfaces, register it with the file extension in the registry, and, poof, you should get thumbnails when users browse directories with your files in them.

So the first thing to do is to create a COM object. COM is a mechanism for taking a relatively simple concept, dynamically linked shared libaries, and complexifying the hell out of their interface. In fairness, it does some cool things, like telling you what their API is so that you can integrate shared objects into scripting applications and explore their interface via automated tools. So if you have a DLL file, you can point a tool to it and say "show me how I can use this!".

But then... every COM class has a couple of incomprehensible long numbers called GUIDs associated with them. So although the interfaces have relatively comprehensible names, we quickly replace those names with things that look like {FC9850E3-9FC3-4C1F-8EE7-28F51EC014E1}.

Needless to say, the methods for creating COM objects has "evolved" over the years, apparently the state of the art now is to use a combination of C++ classes and preprocessor objects called "ATL". ATL is now at version 7, which corresponds to roughly 6 external releases, each subtly changing the interface from previous releases.

I have Microsoft Visual Studio .NET 2003. The aforementioned articles are from 2002 and 2000. So the first thing I have to do is to make them compile correctly, but, of course, since I've got a 4 year old version of the development environment, it seems like none of the documentation matches my released version.

But eventually we get something that we think is compiled correctly. The older simpler example doesn't compile because not all of the source code is available on the web, but the newer more complex one appears to. We even think that the registry knows how to find the objects correctly, because the (automatically converted) versions of the development environment "project" / "solution" / whatever files are inserting registry entries in the right place.

So, now we need to go make the association between file extension and this object. To do this, we go to HKEY_CLASSES_ROOT, and find the (for the sake of these examples) .SCB file extension. We see from the documetnation that there's either supposed to be an entry under this under "ShellEx" called "{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}". Most registry entries are case insensitive, some refer to the former as "Shellex", every document I can find about that latter long string of numbers has the lower case "d". I don't question what I don't understand.

But the documents disagree, because .SCB also points to something called "Scribble.Document", so we may make this same entry over there.

And then it's not clear which of the two GUIDs I have associated this object I should be putting in there, so I try both of them.

Rebooting in between each one, because you never know what Windows Explorer might cache.

All I want to do is write the implementation for 3 simple functions, one of which tells me which file I'm going to be previewing, one of which tells me what the format of the preview should be, and one of which asks for the preview. Should take me 3, maybe 4 hours, tops. I'm nine or ten hours into this mess, learning about crap deep insdie Widnows that'd make H.P. Lovecraft shudder in terror, I know that once I figure this stuff out I'll have both the "oh, that works" moment and the "I wasted how many hours of my life on...?" feeling of utter despair that accompanies any attempt to develop for Windows.