Bug 403162

Summary:	wish: smoother and flicker-free changing between images
Product:	[Applications] gwenview	Reporter:	kdebugs
Component:	general	Assignee:	Gwenview Bugs <gwenview-bugs-null>
Status:	RESOLVED FIXED
Severity:	wishlist	CC:	bugs, kdebugs, nate
Priority:	NOR
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description kdebugs 2019-01-13 02:51:11 UTC

When using left/right arrow keys to move through a large directory of images, there is a disturbing flicker between each image being displayed (perhaps due to disk access and/or some other aspect of rendering the image to the screen.)

It would be very nice if gwenview would wait to overwrite the screen until the new image is ready to be rendered, so the switch from one image to the next was instantaneous and flicker-free.

Also nice: if gwenview could pre-buffer the next image whenever possible (whatever would be reached by the next right-arrow keystroke) so there was minimal delay when/if the key was pressed. If the user was last using the left-arrow to change images, gwenview could pre-buffer the previous image instead, etc.

(I'm on 18.04.3, apologies if any of this has already been done.)

Thanks for considering it!

Comment 1 kdebugs 2019-01-13 02:52:24 UTC

addendum: gwenview 18.04.3, Kubuntu 18.10

Comment 2 Nate Graham 2019-01-15 16:24:12 UTC

All of this was fixed in Gwenview 18.08 and beyond. :)

Comment 3 kdebugs 2020-05-04 22:04:54 UTC

Hello -- this is not working for me in Gwenview 19.12.3 on Kubuntu 20.04. When I change to the next image I am getting a black screen with a loading icon (the circle with gaps on left/right sides), and then the next image loads a split second later. I.e. the disturbing flicker is still there.

It'd be great if gwenview could wait until the image is loaded before displaying it. The black screen only serves to distract and flicker, AFAICT.

Note that I'm not talking about pre-loading, I'm talking about what happens when the image switches before the next image is pre-loaded: instead of blacking out the screen, it should just wait to draw, IMO.

Additionally, I'd love it if the "loading" icon could be moved off of the image to the info bar at the bottom or something, to avoid visual pollution of the image.

Thanks for considering!

Comment 4 alex dekker 2020-07-04 20:49:33 UTC

(In reply to Nate Graham from comment #2)
> All of this was fixed in Gwenview 18.08 and beyond. :)

Not as far as I can see, in 20.04. The current image is removed from the display and you get the background colour with a tiny "loading" circle, then the next image, when it's ready.
This is quite noticeable when browsing a large collection of similar images, eg stills from a CCTV camera.

Comment 5 Nate Graham 2020-07-06 16:05:19 UTC

This is a separate issue from the original one. Can you open a new bug report to track it? Thanks!

Comment 6 kdebugs 2020-07-06 17:33:19 UTC

Thanks Nate -- I filed bugs for flicker-free switching and pre-buffering:

Bug #423944 -- wish: flicker-free changing between images
Bug #423945 -- wish: pre-buffering of images to enable faster/smoother switching

Comment 7 Nate Graham 2020-07-06 19:20:36 UTC

Great, thanks!