[Digikam-devel] Preview behaviour

[Arnd Baecker]

Hi Mikolaj,

thanks a lot for testing, some comments below:

On Thu, 17 Apr 2008, Mikolaj Machowski wrote:

> Dnia Thursday 17 of April 2008, Arnd Baecker napisał:
> > Hi,
> >
> > there are a couple of small issues, which nag me for a while:
> >
> > a) CTRL+ALT+0 should behave as a toggle between
> >    fit-to-window and 100% zoom
> >    (also for the light-table and image-editor)
>
> Works, thanks.
>
> > b) the slider should "snap" to 100% when one is in the range
> >    95% < x < 105%
>
> Works, thanks. But IMO this should go further: snapping should work also
> zoom factors: fit into window; fit width; fit height. But it would
> require to compute snapping factors for each image separately.

Ok, this wish makes sense. However, it is
not that easy to implement. So I would suggest that this
should be filed as a separate wish in the BKO.

> Another place where "snapping" could help are zoom buttons: when
> clicking on them it should stop not only on apparently random chosen
> steps but also: fit to window; fit width; fit height; 100%. It should
> work in all appropriate places: preview mode, lighttable, Image Editor.

Not sure that I understand...
Would you like to have additional buttons?

> > c) CTRL+ALT+0 should be centered
>
> Works, thanks.
>
> > d) moving the slider, the view should stay centered
>
> With these two I have little problem. It works as advertised of course
> but let's assume I navigated (in 50% zoom) to one place in image and
> used slider to zoom in this interested fragment. But zooming with slider
> causes centering of image and I lost this fragment from view. My
> proposition:
>
> When starting from 'fit window' - go to center, but in other cases let keep
> this same place as focus point.

Well, I hoped I would get away with it, but you caught me - well spotted!
I thought about implementing this as you proposed, but
it was not obvious ...
OK, I will think about how to solve this.

> One case where your patch creates problems. When browsing in preview
> mode with option of full size preview turned off digiKam uses some
> "virtual thumbnails". Their size (at least in my testing case) is very
> similar to size of screen. It means that 'fit to window' size of preview
> oscillates around 90-100% and your patch enforces 100% of zoom making
> images larger than preview area. This is really uncomfortable.

Hmm, but that's how a 100% view has to look
(because of the "virtual thumbnail" size). I don't think
my patch can be blaimed here ... ;-)

> Problem
> vanishes when using option "Albums->Embedded preview load full image
> size". I hope I am clear...

Yes, absolutely. Personally I  only use
"Albums->Embedded preview load full size".

> It highlights two problems: 1) when reporting zoom in preview digiKam
> should report zoom of real image.

Yes. This also needs a separate entry in the BKO.

> 2) your patch should differentiate
> between slider/zoom button action and real 'fit to window'.

I don't see this as the intended feature of this *small* patch
(but maybe I don't understand what you propose ...;-)
It just does
- make CTRL+ALT+0 a toggle
- snap to 100% for the slider
- make CTRL+ALT+0 centered
- moving the slider, keep the view centered
Only for the last point, there is something which has
to be improved, as you pointed out.
All the rest is just using the code-base which is already there.

Of course this does not mean the points you raise
are invalid, but fixing the reduced preview
(and the given zoom percentages) is
beyond the scope of this patch (and would
require quite substantial changes in the overall code ...).

> However with
> properly fixed 1), 2) shouldn't be frequent situation.


Thanks a lot for testing!

Best, Arnd