1069931 - Implement 'discard' element from SVG Animations

Status: RESOLVED FIXED

(Core :: SVG, enhancement)

Description

[err]

Attachment: svgt12_discard.svg

User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:35.0) Gecko/20100101 Firefox/35.0
Build ID: 20140918030202

Steps to reproduce:

See this test from Erik Dahlström, Opera Software:
http://xn--dahlstrm-t4a.net/svg/smil/svgt12_discard.svg
(also attached in case the link breaks)


Actual results:

Test fails: after 10 seconds still says "Loading..."


Expected results:

At the end of animation <discard> should remove its parent <g> so that the first element (<text>Load complete</text>) should become visible.

It already works in old Opera (Presto) and current Chrome, so it would be great to see this feature implemented in Firefox in order to start using it in practice.

Spec:
http://www.w3.org/TR/SVG2/struct.html#DiscardElement

Corresponding Chrome bug:
http://code.google.com/p/chromium/issues/detail?id=327339

Test from SVG 1.2 Tiny Test Suite, that works in Opera but doesn't work in Chrome for some reason:
http://www.w3.org/Graphics/SVG/Test/20080912/htmlObjectHarness/struct-discard-207-t.html

Comment 1

[Sebastian Zartner [:sebo]]

The <discard> element was moved to the SVG Animations spec. in the meantime.

Sebastian

Comment 2

[Kuba Niewiarowski]

Partially implemented in Chromium and marked as fixed, but still incomplete...

Comment 3

[Robert Longson [:longsonr]]

Attachment: Bug 1069931 - Implement 'discard' element from SVG Animations r=dholbert

Comment 4

[Robert Longson [:longsonr]]

Attachment: parser.txt

Comment 5

[Robert Longson [:longsonr]]

https://groups.google.com/a/mozilla.org/g/dev-platform/c/U4nufgUTdAk

Comment 6

[Henri Sivonen (:hsivonen)]

Comment on attachment 9325445 [details] [diff] [review]
parser.txt

Review of attachment 9325445 [details] [diff] [review]:
-----------------------------------------------------------------

r+ Thanks.

Comment 7

[Robert Longson [:longsonr]]

https://treeherder.mozilla.org/jobs?repo=try&revision=19296fc46e6e008970c4408bd209ef06d2d0cd38

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/86f62a648ef0
Implement 'discard' element from SVG Animations r=emilio,hsivonen,dholbert,frontend-codestyle-reviewers

Comment 9

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/50028 for changes under testing/web-platform/tests

Comment 10

[amarc]

https://hg.mozilla.org/mozilla-central/rev/86f62a648ef0

Comment 11

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Upstream PR merged by moz-wptsync-bot

Comment 12

[Donal Meehan [:dmeehan]]

:longonr could you consider nominating this for a release note? (Process info)
We could include it in the nightly only release notes.

Comment 13

[Robert Longson [:longsonr]]

Release Note Request (optional, but appreciated)
[Why is this notable]:
[Affects Firefox for Android]: yes
[Suggested wording]: Firefox has an implementation of the SVG discard element. The discard element was originally part of SVG 1.2 tiny and is now part of the SVG 2 animations specification. Currently enabled on nightly only but there will be a pref svg.discard.enabled that you can enable from Firefox 136.
[Links (documentation, blog post, etc)]:
https://svgwg.org/specs/animations/#DiscardElement
https://wpt.fyi/results/svg/animations/reftests?label=experimental&label=master&aligned
https://stackoverflow.com/questions/63411964/svg-animation-discard-element

Comment 14

[Robert Longson [:longsonr]]

Attachment: parser.txt

I think this is what you need to update the html parser code.

Comment 15

[Donal Meehan [:dmeehan]]

Thanks. Added to the Fx136 nightly release notes, please allow 30 minutes for the site to update.

Comment 16

[Henri Sivonen (:hsivonen)]

https://github.com/validator/htmlparser/commit/35dfe92021a02a9f4bd42015ad36ebbfc58cf68f

Thanks.

Comment 17

[Hamish Willee]

FF136 MDN docs for this can be tracked in https://github.com/mdn/content/issues/37939

I've written some test code, and I can verify that <discard> works as you would expect in a stand-alone SVG file that is included into HTML as an image. However when I try declare the same SVG inline with my HTML the discard does not appear to work. Is it expected to? Are there specific conditions that should block it doing so?

Comment 18

[Hamish Willee]

Also, do you know how I might get permission to use a modified version of that image linked above http://xn--dahlstrm-t4a.net/svg/smil/svgt12_discard.svg in the docs?

Comment 19

[Robert Longson [:longsonr]]

There are plenty of tests in https://wpt.fyi/results/svg/animations/reftests?label=master&label=experimental&aligned that you can modify.

There aren't any restrictions on discard in HTML e.g. https://wpt.fyi/results/svg/animations/discard-check-removal-order.html?label=experimental&label=master&aligned passes although that creates a discard element dynamically. In HTML discard (like all SVG) does need to be a descendant of an <svg> element. If you attach your testcase to this bug or send it to me directly I can take a look.

Comment 20

[Dianna Smith [:diannaS]]

removing nightly+ flag since this will be in the 137 release notes via bug 1945330

Comment 21

[Hamish Willee]

FYI, MDN work to unship this in 137/138 linked in https://bugzilla.mozilla.org/show_bug.cgi?id=1954608#c14