image decoding

[Malvoz]

Using Nu html checker, I was alerted of:

Error: Attribute decoding not allowed on element img at this point.

And because it is not in the w3c spec yet, I thought I should flag for the img.decode() and <img decoding> attribute here.

[chaals]

Is there a browser where the decode tests pass - and likewise for implementations of the attribute...

[Malvoz]

@chaals
I'm sorry for not getting back to you sooner. I did manual decode testing which failed in
Edge 41.16299.15.0 and Firefox 58.0.2 but passed all tests in Chrome 64.0.3282.167:

Result	Test Name	Message
Pass	HTMLImageElement.prototype.decode(), basic tests. Image with PNG src decodes with undefined.
Pass	HTMLImageElement.prototype.decode(), basic tests. Image with PNG data URL src decodes with undefined.
Pass	HTMLImageElement.prototype.decode(), basic tests. Image with SVG src decodes with undefined.
Pass	HTMLImageElement.prototype.decode(), basic tests. Non-existent src fails decode.
Pass	HTMLImageElement.prototype.decode(), basic tests. Inactive document fails decode.
Pass	HTMLImageElement.prototype.decode(), basic tests. Adopted active image into inactive document fails decode.
Pass	HTMLImageElement.prototype.decode(), basic tests. Adopted inactive image into active document succeeds.
Pass	HTMLImageElement.prototype.decode(), basic tests. Corrupt image in src fails decode.
Pass	HTMLImageElement.prototype.decode(), basic tests. Image without src/srcset fails decode.
Pass	HTMLImageElement.prototype.decode(), basic tests. Multiple decodes for images with src succeed.
Pass	HTMLImageElement.prototype.decode(), basic tests. Image with PNG srcset decodes with undefined.
Pass	HTMLImageElement.prototype.decode(), basic tests. Image with SVG srcset decodes with undefined.
Pass	HTMLImageElement.prototype.decode(), basic tests. Non-existent srcset fails decode.
Pass	HTMLImageElement.prototype.decode(), basic tests. Multiple decodes for images with srcset succeed.

[chaals]

Given apparent intent to implement this in Firefox now I am happy to get it into this version, marked 'at risk'.

[chaals]

Hopefully we can get it in this or the next milestone, although without more movement on implementation in another browser I'm not going to rush for this...

[cynthia]

This has been lumped into a somewhat unrelated pull request - see #1287.