evince: map pinch/expand gestures to zoom in/out actions

[Duncan McGreggor]

Once we've got rotate in place (bug #644498), let's get zoom working. Here's the gesture reference document:
  https://docs.google.com/View?id=dfkkjjcj_1482g457bcc7#5_2_Application_Gestures_53436_48553900979459286

This could be a little tricky, though, and we need to watch it carefully to avoid scope creep. Zooming happens in discrete amounts in evince (not smooth). So let's do this:
  1) map a pinch/expand gesture to one zoom in/out level
  2) review the usage of this with a couple folks
  3) maybe adjust the number of zoom levels associated with a given pinch/expand
  4) explore what level of effort would be involved to support smooth zooming, and likely open up a new ticket for that

[Rafi (rafi-seas)]

If it helps any, I modified bcmd_zoom in zathura a bit to handle "start zooming"
and fine grained incremental zoom control.

https://code.launchpad.net/~rafi-seas/+junk/zathura_fine_grain_control

From the looks of it, evince is actually quite similar, look at
ev_view_set_zoom. It does look like it supports arbitrary zooming. And the
relative mode might mean you don't need to initialize the zoom gesture.

One problem I hadn't started on is selecting focus point of the zoom.

Rafi

[Rafi (rafi-seas)]

My bad, ev_view_set_zoom was from a stale checkout of evince. The current
master has:

void
ev_document_model_set_scale (EvDocumentModel *model,
                             gdouble scale)

Looks like they removed the relative flag from the function. Still it shouldn't
be too hard to use.

On 09/21/10 15:19, Rafi Rubin wrote:
> If it helps any, I modified bcmd_zoom in zathura a bit to handle "start zooming"
> and fine grained incremental zoom control.
>
> https://code.launchpad.net/~rafi-seas/+junk/zathura_fine_grain_control
>
> From the looks of it, evince is actually quite similar, look at
> ev_view_set_zoom. It does look like it supports arbitrary zooming. And the
> relative mode might mean you don't need to initialize the zoom gesture.
>
> One problem I hadn't started on is selecting focus point of the zoom.
>
> Rafi

[Duncan McGreggor (oubiwann)]

Nice, Rafi! Thanks for the heads up.

[Duncan McGreggor (oubiwann)]

This is in-progress by Cody.

[Chase Douglas (chasedouglas)]

This has been released in the Ubuntu evince package.