[Digikam-devel] Preview behaviour

[Mikolaj Machowski]

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.

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.

> 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.

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

It highlights two problems: 1) when reporting zoom in preview digiKam
should report zoom of real image. 2) your patch should differentiate
between slider/zoom button action and real 'fit to window'. However with
properly fixed 1), 2) shouldn't be frequent situation.

m.