351214 - Animated GIF as background-image (CSS) with single-loop will not restart (e.g. on hover) when the image has been loaded before

Status: RESOLVED INCOMPLETE

(Core :: Graphics: ImageLib, defect)

Description

[Thomas Wittek]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.8.0.6) Gecko/20060728 Firefox/1.5.0.6
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.8.0.6) Gecko/20060728 Firefox/1.5.0.6

If you have an animated GIF with a single loop as a background-image for a hovered link (or any other element) it will (correctly) restart the loop on every hover: http://zentrifuge.dyndns.biz:2380/files/ffcssbug_ok.html

(See also https://bugzilla.mozilla.org/show_bug.cgi?id=286962 where even that didn't work - but it seems to work now)

Now if this animated GIF has been loaded previously (by placing it in an img-tag or loading it with JavaScript or as the background-image of an other element) only the last frame will be displayed on hover:
http://zentrifuge.dyndns.biz:2380/files/ffcssbug_wrong.html

As this behaviour is quite inconsistent (restart anim on hover when not loaded elsewhere - don't restart else), I don't think that it is intended to be like this.

Reproducible: Always

Steps to Reproduce:
1. Create a single-loop animated GIF (e.g. "foo.gif")
2. Load this image on your website (img-tag, JavaScript, CSS background-image)
3. Create another element with the style #elementid:hover { background-image: url(foo.gif) no-repeat } for this element.
4. Move the mouse over the element.

Actual Results:  
The element will only show the last frame of the animation.

Expected Results:  
The animation should restart on every hover as it correctly does when the same image hasn't been preloaded anywhere else.

Tested on:
- Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.8.0.6) Gecko/20060728 Firefox/1.5.0.6
- Mozilla/5.0 (X11; U; Linux i686; de; rv:1.8.0.4) Gecko/20060608 Ubuntu/dapper-security Firefox/1.5.0.4
- Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.8.1b2) Gecko/20060821 Firefox/2.0b2

Opera 9, Konqueror, iE 6, and do it "right". Interestingly iE 7.0.5700.6 behaves like Firefox.

Comment 1

[Thomas Wittek]

Might also be remotely related to:
https://bugzilla.mozilla.org/show_bug.cgi?id=316138 and https://bugzilla.mozilla.org/show_bug.cgi?id=188924. But those Reports address slightly different issues.

Comment 2

[Adam Guthrie]

I think this is a dupe of bug 188924, but we'll leave this open since it's very concise and has a working testcase.

Comment 3

[Helder "Lthere" Magalhães]

(In reply to comment #2)
> I think this is a dupe of bug 188924, but we'll leave this open since it's very
> concise and has a working testcase.

This may also be closely related with bug 129986.

Comment 4

[Wayne Mery (:wsmwk)]

testcase URL no longer exists