Web Animations CSS: Support animation of stroke-dasharray property

Web Animations CSS: Support animation of stroke-dasharray property

The Web Animations implementation matches Firefox in all details except for
when animating to or from a value of 'none'. In this case, Firefox does not
animate, and the computed style is always 'none'. The Web Animations
implementation considers 'none' equivalent to a value of '0 0', as both result
in a solid line being drawn, and animates using an effective value of '0 0'.

The legacy implementation has a number of bugs ...
- The behavior when animating to or from a value of 'none' is odd.
- Values should be clipped to be non-negative. See http://crbug.com/305070.
- When lists consist of differing numbers of elements, we should repeat the
  lists to form a list of length equal to the lowest common multiple of the
  lengths of the individual lists. Currently we use a list of length equal to
  the multiple of the lengths of the individual lists.

BUG=257591
R=dstockwell

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=159552

[dstockwell, 2013-10-08 23:05:00]

Do we want to rebase this on top of https://codereview.chromium.org/26247003/ ?

[Steve Block, 2013-10-08 23:23:06]

> Do we want to rebase this on top of https://codereview.chromium.org/26247003/
?
Yes, we can share much of the logic. I'll wait for Alan's patch to land then see
how I can best re-use what he's got.

[Steve Block, 2013-10-08 23:27:11]

The only complication is that the logic here needs to special-case lists with
zero entries.

[Steve Block, 2013-10-11 01:26:43]

Rebased onto https://codereview.chromium.org/26247003

Ready for another look.

[dstockwell, 2013-10-13 23:35:51]

https://codereview.chromium.org/26292004/diff/40001/LayoutTests/animations/in...
File
LayoutTests/animations/interpolation/svg-stroke-dasharray-interpolation.html
(right):

https://codereview.chromium.org/26292004/diff/40001/LayoutTests/animations/in...
LayoutTests/animations/interpolation/svg-stroke-dasharray-interpolation.html:92:
{at: -0.2, is: ' 0 0'},
We should probably special case this so that it always produces 'none'.

https://codereview.chromium.org/26292004/diff/40001/Source/core/animation/Ani...
File Source/core/animation/AnimatableStrokeDasharrayList.cpp (right):

https://codereview.chromium.org/26292004/diff/40001/Source/core/animation/Ani...
Source/core/animation/AnimatableStrokeDasharrayList.cpp:67: if (from.isEmpty()
|| to.isEmpty()) {
Does it make sense to push this empty-list logic down into AnimatableRepeatable?
virtual valuesForEmptyList()

[dstockwell, 2013-10-13 23:38:22]

lgtm

https://codereview.chromium.org/26292004/diff/40001/Source/core/animation/Ani...
File Source/core/animation/AnimatableStrokeDasharrayList.cpp (right):

https://codereview.chromium.org/26292004/diff/40001/Source/core/animation/Ani...
Source/core/animation/AnimatableStrokeDasharrayList.cpp:43:
values.append(AnimatableSVGLength::create(lengths[i]));
can't this be m_values.append ?

[Steve Block, 2013-10-14 01:01:00]

https://codereview.chromium.org/26292004/diff/40001/LayoutTests/animations/in...
File
LayoutTests/animations/interpolation/svg-stroke-dasharray-interpolation.html
(right):

https://codereview.chromium.org/26292004/diff/40001/LayoutTests/animations/in...
LayoutTests/animations/interpolation/svg-stroke-dasharray-interpolation.html:92:
{at: -0.2, is: ' 0 0'},
On 2013/10/13 23:35:52, dstockwell wrote:
> We should probably special case this so that it always produces 'none'.

Done.

https://codereview.chromium.org/26292004/diff/40001/Source/core/animation/Ani...
File Source/core/animation/AnimatableStrokeDasharrayList.cpp (right):

https://codereview.chromium.org/26292004/diff/40001/Source/core/animation/Ani...
Source/core/animation/AnimatableStrokeDasharrayList.cpp:43:
values.append(AnimatableSVGLength::create(lengths[i]));
On 2013/10/13 23:38:22, dstockwell wrote:
> can't this be m_values.append ?

Done.

https://codereview.chromium.org/26292004/diff/40001/Source/core/animation/Ani...
Source/core/animation/AnimatableStrokeDasharrayList.cpp:67: if (from.isEmpty()
|| to.isEmpty()) {
We could, but it doesn't buy us much. We still need
AnimatableStrokeDasharrayList::interpolateTo() to be a wrapper around an
AnimatableRepeatable helper method (rather than calling
AnimatableRepeatable::interpolateTo() directly) so that the return value is a
AnimatableStrokeDasharrayList, rather than a AnimatableRepeatable.

I think we should wait to see what other derived classes of AnimatableRepeatable
look like.

[commit-bot: I haz the power, 2013-10-14 01:01:19]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/steveblock@chromium.org/26292004/51001

[commit-bot: I haz the power, 2013-10-14 01:41:07]

Retried try job too often on linux_blink_rel for step(s) webkit_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_blin...

[commit-bot: I haz the power, 2013-10-14 02:08:21]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/steveblock@chromium.org/26292004/51001

[commit-bot: I haz the power, 2013-10-14 02:36:44]

Change committed as 159552