448882 - Viewpoint is lost when zooming in on a web page

Status: RESOLVED WORKSFORME

(Core :: Layout, defect)

Description

[Ken Saunders]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.1) Gecko/2008070208 Firefox/3.0.1
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.1) Gecko/2008070208 Firefox/3.0.1

Whether it be by using full page zoom or text zoom only, the viewpoint that a user is focused on in a web page gets lost when zooming in.


Reproducible: Always

Steps to Reproduce:
1. Visually select an area on a web page to focus on.
2. Zoom in on that web page by using Ctrl+ "+" in Windows and Linux, and Cmd+ "+" on Mac .
3. While I'm not sure what magnification level it is, you will usually lose your viewpoint by the 5th time that you use the zoom shortcut. This will vary depending upon the amount of screen space that you have allotted for viewing a web page.


Actual Results:  
The viewpoint that you were initially focused on in a web page will gradually be moved downward (until completely out of site) for each time that you use the zoom keyboard shortcut.

Expected Results:  
The zoom function in Firefox should increase the text size (and images if that option is chosen) without causing a user's viewpoint on a web page to be moved out of focus.


I ran this test under several different conditions including using a new and empty (default) Firefox profile, one with many add-ons that caused my web page viewing area to be decreased, and also in full screen mode.
The results were all the same. The only noticeable difference was in the amount of steps that it took to lose my focused viewpoint.

Screen shots
http://www.accessfirefox.org/Firefox_3_Zoom_Bug.php

Comment 1

[Ken Saunders]

Forgot to mention that the Glazoom add-on allows users to zoom in on a web page without losing the focused viewpoint.

Glazoom
https://addons.mozilla.org/en-US/firefox/addon/6489 

Comment 2

[Otto de Voogd [:ottodv]]

Confirming that this happens on Firefox 3 in Linux too.
On a very long page, viewpoint is lost already the first time that one uses Ctrl + and the second time you use ctrl - and if you had jumped to an anchor, zooming in or out does not reposition your viewpoint at the anchor either.

Comment 3

[Robert O'Callahan (:roc) (email my personal email if necessary)]

The easiest way to fix this is probably in chrome, but we could also make a more general fix in layout by remembering when we start reflow which elements are visible at the top of each scrollframe and trying to preserve that.

Comment 4

[Aaron Leventhal]

Robert, we can wait for the more general fix. Should we move this to Core -> Layout?

Comment 5

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Yes. But I don't think anyone's planning to work on that "general fix" anytime soon.

Comment 6

[Aaron Leventhal]

-> Firefox General for the simpler fix

Comment 7

[Kevin Brosnan]

64926

Comment 8

[Tyler Downer [He/Him]]

Reporter, please retest with Firefox 3.6.12 or later in a fresh profile (http://support.mozilla.com/kb/Managing+profiles). Also update your plugins (flash, adobe reader, java, quicktime, silverlight, etc.) Go to the developer's website and download the latest version from there. If you no longer see this issue, please close this bug as RESOLVED, WORKSFORME. If you do see the bug, please post a comment.

Comment 9

[Otto de Voogd [:ottodv]]

Not the reporter, but as I commented too I tested this on Firefox 3.6.12 and 4.0b6 on Linux both with a fresh profile as well as Firefox 3.5.15 on Linux without a fresh profile. In all three cases zooming in and out on a long page appears to work the same way.

Zooming after jumping to an anchor (page.html#anchor) somewhere in the middle of a long page, keeps the anchor position in the visible part of the screen most of the time. Scrolling to a position and visually taking the top of the visible part as an imaginary anchor results in the same behavior.

Sometimes (though rarely), after zooming, the visible part of the page starts just below the anchor (real or imaginary), making the anchor itself not visible.

However usually the anchor jumps down the screen a bit when zooming in or out, meaning that a bit of content above the anchor becomes visible.

Both these things result in a (short) moment during which you have to visually search for your anchor, while not being entirely sure that it is still on the visible part of your screen.

Is this resolved or not? It's certainly a massive improvement on the way it was as the anchor usually stays visible. Though personally I'd prefer the visible part of the page to start exactly at the anchor position, so as not to have to reposition my visual focus when zooming.

Comment 10

[Tyler Downer [He/Him]]

No reply, INCOMPLETE. Please retest with Firefox 3.6.12 or later and a new profile (http://support.mozilla.com/kb/Managing+profiles). If you continue to see this issue with the newest firefox and a new profile, then please comment on this bug.

Comment 11

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Reopening.

Comment 12

[Pablo]

I was unable to replicate this on windows 10 and ubuntu 20 using firefox release 93.