Re: mouse zoom centred on mouse position.

[Mojca M. <moj...@gm...>]

On Wed, Jun 20, 2012 at 7:46 AM, Petr Mikulik wrote:
>
> I would propose to revise mouse zooming to comply more with that used in map
> software (maps.google.com, mapy.cz etc.). Thus:
> - mouse wheel zooms around current mouse position (it could zoom around
>  center if mouse is outside graph border)
> - Shift-wheel would move graph up/down (as now without Shift)
> - Ctrl-wheel would move graph left/right (now with Shift)

You forgot that google maps allows you to "drag and drop" to move
around the map. I believe that is not an option for gnuplot (but being
able to move around without holding some mouse button is crucial for
me to make navigation on maps at least somewhat usable).

I never use mouse wheel to scroll in google maps since it is
impossible to control the amount of zoom (clicking +/- would use at
least 17 different zoom steps, while I can only get 6 with the
"wheel"). But maybe that's only the case on macs with high precision
scrolling which is not taken into account on google maps. And I would
probably get used to it quickly if implemented properly.

> I find the current behaviour counterintuitive and thus actually not using it
> at all :-(

On modern Macs the natural way to navigate with mouse is for example
the following:
a) "wheel equivalent" (two fingers sliding on trackpad): move up/down
(like in web browsers), but also left/right - same as now
b) "pinch gesture": zoom in (usually it is uniform zooming, but one
has the information about the angle and could use that information to
zoom over a single axis, for example when angle is between +/- 22.5
degrees; and zooming in uniformly when angle is between 22.5 and 67.5
degrees etc.)

I'm not arguing against the change (I would welcome revised code
actually), I only wanted to point out that "intuitive behaviour" might
not necessary be universal across different hardware & software. I
definitely do miss more control in mousing events (being able to
scroll in smaller steps for example, or support for zooming in with a
pinch), but on the other hand the data I'm constantly dealing with
nowadays typically have 10^9 points, so I need my own viewer anyway
(to allow navigation without being awfully slow and running out of
memory, based on assumptions I can afford to take into account in my
own implementation & for my own data, not applicable to generic case
in gnuplot). And it is also true that AquaTerm would not support any
mousing at all.

The program I'm using now allows to select a range on x axis (drag and
drop just next to the axis) and a range on y axis (separately) to zoom
into selected range. That is also a lot more intuitive (once you know
about the option) and allows for selecting the area of interest with
great precision.

Mojca