Making an LV2 plugin GUI (yes, in Inkscape)

Told you I'd be back.

So I made this pretty UI last post but I never really told you how to actually use it (I'm assuming you've read the previous 2 posts, this is the 3rd in the series). Since I'm "only a plugin developer," that's what I'm going to apply it to. Now I've been making audio plugins for longer than I can hold my breath, but I've never bothered to make one with a GUI. GUI coding seems so boring compared to DSP and it's so subjective (user: "that GUI is so unintuitive/natural/cluttered/inefficient/pretty/ugly/slow etc. etc....") and I actually like the idea of using your ears rather than a silly visual curve, but I can't deny, a pretty GUI does increase usership. Look at the Calf plugins...

Anyhow, regardless of whether its right or wrong I'm going to make GUIs (that are completely optional, you can always use the host generated UI). I think with the infamous cellular automaton synth I will actually be able to make it easier to use, so the GUI is justifiable, but other than that they're all eye candy, so why not make 'em sweet? So I'll draw them first, then worry about making them an actual UI. I've been trying to do this drawing-first strategy for years but once I started toying with svg2cairo I thought I might actually be able to do it this time. Actually as I'm writing this paragraph the ball is still up in the air, so it might not pan out, but I'm pretty confident by the time you read the last paragraph in this almost-tutorial I'll have a plugin with a GUI.

(*EDIT 14 Sept 2015 - a big mistake was pointed out to me in my LV2_UI instantiation, updated below).

So lets rip into it:

Drawing a GUI in Inkscape

So I got all excited and posted that last article about a lot of the technical stuff to make a GUI in Inkscape, but after posting it I realized it makes quite a few assumptions, so I'm going to add a few follow on posts, some of which (mostly this one) should have been written first. So its a prequel. Or a Part 0. Something like that.

Anyway the biggest assumption I made is that you are proficient in inkscape. Perhaps you are, but I wasn't until I started trying to draw GUIs in it. So basically all my skills are honed to this purpose. I'm not qualified to give a real inkscape tutorial so you should probably stop reading right now, but just in case I can help someone out there make a cool GUI I'll press onward.