[linux-audio-dev] [a bit OT] scroll and zoom conventions

Hello all,

I'm trying to clear up my mind as to what conventions to follow
in a GUI for the actions of zooming in and out e.g. a spectrum
or an impulse response window. It's not the intention to launch
a debate about this, just to collect other people's ideas.

The accepted model for scrolling is that the user 'moves'
a *clipbox* that determines what part of the *content* is
visible. For example, when you drag a scrollbar to the right,
the clipbox moves to the right. What actually happens of course
is just the opposite: the clipbox remains static on the screen,
and the content moves to the left.

The other model is used as well, for example Acrobat Reader
lets you drag the content directly.

Now my question: what about zooming ? For keyboard shortcuts,
Ardour uses '+' to zoom out and '-' to zoom in. This is
consistent with the idea that the user modifies the clipbox.
But I still have to think before using it, each time, and I
could easily imagine using '+' to zoom in. In fact I have no
clear preference.
Then there's the questions of icons. If in addition to the
arrows in a scrollbar you would also have small buttons to
zoom in and out, what should they look like ?

  Zoom in Zoom out
     - +
    -><- <->

or the inverse ???

-- 
FA