Should img be named from content?

[WilcoFiers]

This came up during the AGWG call when discussing the svg element with explicit role has non-empty accessible name ACT rule. Why should an img only be named from author? Take the following example:

<svg xmlns="http://www.w3.org/2000/svg" role="img" width="100" height="100">
	<circle cx="50" cy="50" r="40" fill="yellow"></circle>
	<text x="50%" y="50%" dominant-baseline="middle" text-anchor="middle">
		Yellow circle
	</text>
</svg>

It seems a little counter-intuitive that the content of the text node isn't used to give this img an accessible name. Definitely if there is a title element, or aria-label that should be used, but absent those, wouldn't it make sense to use text content if there is any?

[carmacleod]

SVG title element does name an image (in ACCNAME step 2D).

In the Yellow circle example, it may seem to make sense to allow name from content... however SVGs can have all sorts of text content, like all of the labels on a graph, or all of the instructions on a map, etc., which would result in a pretty verbose flat string that wouldn't be very useful as a name.

I think that the best naming strategy for the Yellow circle example is to use aria-labelledby to point to the Yellow circle text element.

[aleventhal]

role img has "Children Presentational: True", meaning that browsers may enforce them to be leaf objects. There would be no descendant content in the accessible tree. Since browsers use the accessible object subtree (and not DOM subtree), this might be a nonstarter.

Changing Children Presentational to be false is probably a no go as well, as ATs expect an image to be a leaf.

[WilcoFiers]

@carmacleod I understand that it uses title if one exists, but why not have it fallback to text content if any exists?

@aleventhal I'm not suggesting to change presentational children. I agree with you that that could be problematic. But something can have presentational children and still be named from content. Buttons have this for example.

[carmacleod]

@WilcoFiers

I understand that it uses title if one exists, but why not have it fallback to text content if any exists?

Because if we did that, then the name of this SVG would be "2008 2009 2010 2011 2012 15 10 5 0 Weeks".

[pkra]

This idea feels more like a suggestion for handling author errors, https://w3c.github.io/aria/#document-handling_author-errors.

[aleventhal]

@aleventhal I'm not suggesting to change presentational children. I agree with you that that could be problematic. But something can have presentational children and still be named from content. Buttons have this for example.

Hmm, that's a good point. It might work.

Actually FYI neither Firefox nor Chrome enforce presentational children on buttons anymore, because there were too many cases where buttons had important interactive children. See issue #1174 .

[WilcoFiers]

Because if we did that, then the name of this SVG would be "2008 2009 2010 2011 2012 15 10 5 0 Weeks".

Can you explain why that would be? The way I understand it, the title element in svg takes priority in the accessible name computation. Name from content only used if there is no native attribute/element to give an accessible name. At least, that's my reading of it.

[scottaohara]

@WilcoFiers, Carolyn's example that you quoted has no <title>.

[WilcoFiers]

@scottaohara My bad, but it does it have role=img either. How is it relevant to this?

[carmacleod]

@WilcoFiers
I guess my point was that SVGs can be complex, with many random text elements... charts, graphs, maps, word art, cartoons containing text, etc, etc. SVGs can be - and often are - marked up as role="img". Naming of SVGs (or any img, whether or not it contains an SVG) needs to be a deliberate consideration by the author, and not just guessed by the UA based on text content. So the spec should not recommend that img be named from content. If a user agent or AT wants to use text content as a fallback, that is up to them. However, validators should continue to flag missing names on img.

[scottaohara]

How is it relevant to this?

seems relevant since if it had a role=img it'd get a poor accessible name, as Carolyn describes. If it did have a <title> would it then be expected to provide the name to the image/svg, or would it become part of the image's name from child elements?

[WilcoFiers]

If an svg with role=img has both a <title> and a <text> node, the title would be the accessible name, the text would not be included. This is because accName does not get to the "name from content" step if there is a native element or attribute that provides an accessible name, which <title> is for <svg>.

@carmacleod is the point of what you're suggesting then to ensure that that svg is flagged as having invalid ARIA because img requires an accessible name?

[carmacleod]

@carmacleod is the point of what you're suggesting then to ensure that that svg is flagged as having invalid ARIA because img requires an accessible name?

Yes.

[Edit: Actually, not quite sure what you mean by "flagged as having invalid ARIA"? The role="img" is valid on svg (see svg in the SVG Role Mapping Table). It's just the missing name that would be invalid.]