[Digikam-devel] [Bug 140131] No zoom in image preview

[Frank Siegert]

Arnd Baecker wrote:
> - And another one: I happen to press the left-mouse
>   (having panning in mind) quite frequently, which brings
>   me back to the thumbnail view (which I did not want;-) - not sure
>   if this is optimal from the useability point of view
>   (I know that the "return-on-left-click" was a wish brought
>    up a while ago...;-)

It was me, who brought up this wish back then, and I still do like it very
much to go forth and back with simple clicks. But of course these new
developments in F3-preview require some adjustments. It would be perfect in
my opinion, if you could go back on a single click, while it would pan on
dragging your mouse (i.e. holding down the click and move the mouse). This
would nicely account for both needs, wouldn't it? I don't know, whether
this is easy with Qt/KDE.

> There is maybe one very important point:
> the zoom as it is presently done, uses a reduced-size version of the
> underlying image, right?
> So while it is nice to be able to zoom in, it does not allow for
> a judgement of the image quality (in contrast to the image editor).
> Do you think that there is a way to use the actual image
> (maybe from a certain zoom-level on?) But that would (quite
> certainly?) slow things down...
> 
> In particular for the upcoming light-table I think it is important
> to compare the real images, not just up-scaled ones
> 
> Uups: I just realized that for zooming in, the image editor also
> some interpolation is done, so that that one does not see the single
> pixels, but some nicely interpolated version?

A solution might be the following: While you move the slider, the image
could be fast-scaled, and when you release the slider, the pixmap could be
smoothly replaced in the background by the real picture.
Same for Zoom+ and Zoom- buttons: on button click, immediately display a
fast scaled version, and with a short delay after release, if the buttons
has not been clicked again, replace it by the real picture.


And one more point about the slider tooltip: When you hover over the zoom
slider in F3 preview, it shows the zoom as tooltip (outside of the window,
as mentioned before). If you now switch to another window/desktop (e.g.
with Alt-Tab), the zoom-tooltip stays there.

-- 
Thanks,
Frank