Bug 20473 – How should transition properties repeat when you have duplicates?

• Component: CSS
• Status: RESOLVED FIXED

[Chris Marrin]

Today in TOT transition properties are filled out like this:

    transition-property: left, top, width, height, opacity;
    transition-duration: 1s, 2s;

This will expand the duration to: 1s, 2s, 1s, 2s, 1s

according to the CSS rules.

But what should we do if you have duplicate property values like this:

    transition-property: opacity, left, opacity, top, width, opacity, height, opacity;

Here we have 8 property values, but the 3 duplicates get removed in RenderStyle::adjustTransitions(), leaving:

    left, top, width, height, opacity

but what should duration be in this case? Does it behave as though the unfilled values are filled in and then the duplicates removed, or should we remove duplicates and then fill out the values? Today we do the former, so duration ends up as:

    2s, 2s, 1s, 1s, 2s

Which should it be?

[Pierre-Olivier Latour]

We have a radar for it:
<rdar://problem/6480074> [transitions] spec needs to be clear how values repeat

[Simon Fraser (smfr)]

Spec was clarified, and the implementation matches it.