"High quality zoom" preview images are not aligned correctly

Bugs which have been reproduced by a second user or the developer, or features to do

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CaspianRoach
Posts: 27
Joined: Sat Feb 08, 2020 1:35 pm

"High quality zoom" preview images are not aligned correctly

Post by CaspianRoach »

Xnview 0.96.2, Windows 10 64.

Setting the "High Quality Zoom" setting to "Zoom-out" (default setting) causes the quick preview versions of images to become misaligned up and to the left. By 'quick preview' images I mean the low quality version of the image that is loaded and displayed before the full one is displayed, it is only displayed for a few milliseconds, depending on your hard drive/computer.

Here, I made a few videos:

Me scrolling through a couple of similar images quickly with "High Quality Zoom" set to "Zoom-out":
https://streamable.com/yu2xqe
Notice how the first few frames before the image finally 'settles in' to full quality, the image is pulled up and to the left a few pixels.

Me scrolling through a couple of similar images quickly with "High Quality Zoom" set to "Never":
https://streamable.com/atvqrn
We're still getting the low quality preview image, but this one is not misaligned and resolves without jumping around.

Note how much the whole image shifts around on the first video. It's not a very pleasant effect while you're scrolling through some heavy images.

If this is tied to the function/library you're using for the "High Quality Zoom" feature and is not fixable, the alternative solution would be in providing an option to turn off the quick preview images for the Viewer completely (which would be a preferrable behaviour for me personally)

This bug was not present in XnView Classic (because it didn't used to have the quick preview version of the image).

Here are the images that I recorded the video with https://drive.google.com/file/d/1iU3my2 ... sp=sharing
but this happens with a vast majority of images and is not restricted to just these.
CaspianRoach
Posts: 27
Joined: Sat Feb 08, 2020 1:35 pm

Re: "High quality zoom" preview images are not aligned correctly

Post by CaspianRoach »

Note that this bug only happens when "High Quality Zoom" is actually doing something — as in, if it's "Zoom-out" then the image needs to be at lower than 100% resolution for the effect to appear, 90% for example. This does not happen otherwise.
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xnview
Author of XnView
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Joined: Mon Oct 13, 2003 7:31 am
Location: France

Re: "High quality zoom" preview images are not aligned correctly

Post by xnview »

:bugconfirmed: Thanks to your detailed description I can reproduce
Pierre.
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xnview
Author of XnView
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Location: France

Re: "High quality zoom" preview images are not aligned correctly

Post by xnview »

is it possible to re-post your videos?
Pierre.
CaspianRoach
Posts: 27
Joined: Sat Feb 08, 2020 1:35 pm

Re: "High quality zoom" preview images are not aligned correctly

Post by CaspianRoach »

Certainly, i guess streamable deleted them, here they are on google drive:

with the misalign bug:
https://drive.google.com/file/d/15Cg0JV ... sp=sharing

without the misalign bug:
https://drive.google.com/file/d/1-BSblc ... sp=sharing

I tried recreating it with the same files with 0.99.7 and was able to reproduce it. (my CPU is a bit slow, might not be noticeable on fast machines)

For the moment, I've avoided the thing by using the 'dont use two-pass rendering' option you have recently added (working great by the way).