As soon as I saw Gus Mueller’s offer of a free license for anyone writing a decent plug-in for Acorn, I felt moved to exploit his generosity contribute to the nascent plug-in community. So I quickly slapped together a possibly-useful filter, which ended up being a simple wrapper for a Core Image kernel (my first). Obviously that should be repackaged as an Image Unit. However, it did crash in a confusing way for a while, which is good, because it inspired me to write (most of) a test rig: a command-line tool which loads a given Acorn plug-in and runs each action it registers.
Then I started on a new plug-in, which is UI-centric and therefore can’t usefully be tested on the command line.
As such, the test rig isn’t ready, but the new plug-in is. It adds an Export… menu item to Acorn’s File menu, allowing the export of any file format supported by ImageIO – currently BMP, GIF, JPEG, JPEG 2000, OpenEXR, PDF, Photoshop, PICT, PNG, SGI, TGA and TIFF. Some of these are already supported by Acorn. But hey, some aren’t.
Plug-in and source code (MIT/X11 license) available here.
Is it possible to hook this up to the File->Save As… dialog too?
Probably, but it would involve interfering with the working of the application in a fiddly and possibly fragile way, which I don’t consider to be motivated. If you feel that this would be an important feature, lobby Gus to implement it. (The code for the plug-in is licensed in such a way that he could use it as a starting point.)
The forum thread would probably be a good place, because it’s public. Requesting it in a bug report (from Acorn’s Help menu) would probably also be useful, because that way it will end up in Gus’s bug and feature tracking system. If you do both, say so in the messages.