SC 2.5.8 Pointer Target Spacing - Suggested reformulation of pointer clearance calculation

[wittjeff]

on behalf of edX

I am concerned about the scenario where there is a small target positioned close to a larger target, as with the profile image and associate Zoom icon button shown at https://www.w3.org/WAI/WCAG22/Understanding/pointer-target-spacing. Specifically, I don't think people will generally infer that they can use whitespace outside the icon area as active touch target space, so the number of touch/click errors will remain high in these scenarios even if the criterion is satisfied as it is currently formulated. Below I offer an alternative formulation which I believe better matches the goal of the criterion as stated, without any tradeoffs.

Instead of "For each target, there is an area with a width and height of at least 44 CSS pixels that includes it, and no other targets,"
I suggest using "For each target, the horizontal or vertical distance between the center of the target and the closest edge of the nearest interactive target is at least 22 CSS pixels."
The same exceptions should apply.

[alastc]

Just pinging @WilcoFiers, this is an interesting alternative approach.

[detlevhfischer]

Proposed Working Group response:
Thank you for your recommendation.
The Mobile Accessibility Task Force has in the meantime reconsidered the approach and decided to withdraw Pointer Target Spacing due to concerns that it implied a risk that authors would reduce target size to meet the spacing requirement within given space constraints. We have therefore proposed an alternative SC, Target Size:

Target Size (AA)
The size of the target for pointer inputs is at least 26 by 26 CSS pixels except when:

• Inline: The target is in a sentence or block of text;
• User Agent Control: The size of the target is determined by the user agent and is not modified by the author;
• Essential: A particular presentation of the target is essential to the information being conveyed.

[alastc]

Hi @wittjeff, I think the updated criteria text makes this update redundant, do you agree? If so we can close this issue.

[wittjeff]

@alastc I don't see how the revised language addresses the small-target-next-to-large-target scenario. I don't see a whole lot of need for minimum target sizes (well, not for noticeability anyway); the core issue seems to be one of interference by nearby active targets. With those scenarios in mind, it is intuitive to want to move toward larger touch targets, but I don't think that is the core issue. The minimal reserved area idea was a step closer but still a bit off the mark.
I don't mean to be belligerent but I fear my original suggestion wasn't understood, so I'll restate it:
With your new suggested SC, with a minimum 26x26 target size, you might accomplish the main goal of avoiding (most) inadvertent other-target-hits, but at the cost of requiring unreasonably large targets for quite a few scenarios. Please consider instead this formulation:

Target Clearance Radius (AA)
For each interactive target, the horizontal or vertical distance between the center of the target and the closest edge of the nearest interactive target is at least 13 CSS pixels except when:
Inline: The target is in a sentence or block of text;
User Agent Control: The size of the target is determined by the user agent and is not modified by the author;
Essential: A particular presentation of the target is essential to the information being conveyed.

If we need to bump the 13px minimum radius to some other value, then lets do that based on some empirical research.
This way we can still have small targets like (?) buttons (for More Information) in sensible places. The minimum distance to nearest interactive target method also allows overlapping use of white space between targets.

[alastc]

I don't see a whole lot of need for minimum target sizes (well, not for noticeability anyway)

The history is that the current Target Size SC was going to be at level AA, but there were too many issues so it was moved to AAA.

The proposal for Target Spacing was trying to get around those issues, but when it comes to toolbars and navigation lists, it still introduces a massive change.

So the aim in order of preference is:

• Large target sizes so they are easy to hit;
• Target size + spacing to reduce the chance of making an error;
• Prevent very small targets.

None of these are to do with noticability, just about target sizing & likelihood of being able to hit the right target once you know it is there.

For each interactive target, the horizontal or vertical distance between the center of the target and the closest edge of the nearest interactive target is at least 13 CSS pixels

To check my understanding, this is essentially allowing for spacing rather than a minimum size?

We've had some fairly long discussion on the spacing and/or target size aspect, and once you get down to the small sizes the issues that come up, come up for both. I.e. allowing for spacing didn't make it easier to meet.

Also, with that formulation you could have 5px square targets, which seems odd.

[alastc]

Hi everyone,

The text of the success criterion has been significantly updated, and the group believes it resolves the issue so this issue is being closed. There will be another review opened soon.