[Audacity-devel] Vertical Zooming

[Dominic M. <do...@mi...>]

> I hope to finish vertical track resizing tonight.  It's coming along
> really well; I think everyone will like it. 

I mean to say "vertical zooming".  I'm very tired.  Luckily I think
the quality of my code is much better than the quality of my English.
Anyway, the code is checked in.

I did a lot of refactoring while I was adding this feature, and I
think that both wave display and Envelope editing are now much more
robust and consistent than they were before.

Summary of changes:

* Mouse-over the track vertical ruler and the cursor changes to a
   zoom cursor.  (Do we want a slightly different cursor for
   vertical zooming?)

* The zoom cursor has a "+", which changes to a "-" when you
   press shift.  This works with the normal zoom tool, too.
   I think this is a good idea because it makes the user
   interface more "discoverable".

* Click to zoom in by 2x and recenter. Shift-click or Right-click
   to zoom out.

* Click and drag to zoom to a region.  There's a maximum amount
   you're allowed to zoom in.

* The ranges -1...1 and -2...2 are "special".  An attempt to zoom
   that places you very roughly in that range will always snap
   to that exact range.  Otherwise there was no easy way to get
   back to -1...1 once you'd been zooming for a while.

* Envelope editing works while zoomed in.  This was quite tricky,
   but the code is pretty clean and robust now, I think.

* The Waveform dB display works, but doesn't allow zooming.
   I changed the dB range to -36...0, because the view we had
   before (-90...0) was not very useful in my opinion.  I'd be
   happy if somebody wants to make this a preference - all of
   the code that uses it is abstracted now, and the #define is in
   Envelope.h

I can't imagine that I didn't introduce a bug or two.  Please let
me know what you find.  I do think it's complete and stable enough
that it won't get in the way of 1.2.0, though.

- Dominic