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Adapting Text (original issues 79, 78, & 74) #124
Latest text and info:
No loss of content or functionality on a webpage is caused by overriding:
Suggested Priority Level
What Principle and Guideline the SC falls within.
Principle 1, Guideline 1.4
The intent of this Success Criterion is to help ensure that people with low vision who override font family, text colors, and spacing can perceive content. People with low vision often must override author settings via user stylesheet, bookmarklet, extension or application such as VIP-PDF Reader.
This SC sets metrics for a normative testable baseline. Testable values (Verdana/white&black/EMs) are intended to provide a standard baseline, any particular user is likely to choose different values (especially font & color). The point is that this baseline is used to test the layout and functionality, and if it works then it is robust enough for certain user-adaptations (up to a point).
Verdana was chosen as a testing measure because it is a web safe font that is designed with a large x-height (the lowercase letters are bigger compared to the uppercase letters) and extra space between characters so they don't touch. If Verdana works most other fonts should work too.
White on black was chosen because if that combination works, 99% of all other combinations should be able to be overridden.
Line-height, letter-spacing, and word-spacing metrics were chosen as measures based on Research. McLeish ran from .04 to .25 em tests (Wayne E. Dick PhD analyzed the McLeish study and translated from points). McLeish found an increasing curve in reading speed of actual materials up to .25, but it really started to flatten at .20. Previous studies that reported no improvement started at .5em. Right at the flat point. Hence Wayne recommends letter spacing be 0.12em, and word spacing be 0.16em for this SC.
The plan is to start testing sites with these metrics on the various user-agent tools, primarily bookmarklets created specifically for this. See where problems surface. Adjust measures if needed. And then provide techniques.
Using a bookmarklet, user stylesheet, or VIP-PDF Reader change:
Hi @KimberleeD ,
Thank you for your comment on the February 14, 2017 survey. You indicated, "This proposed SC needs more discussion" and asked:
Yes. People with low vision need to be able to read text. The plan is to start testing sites with these metrics on the various user-agent tools, primarily bookmarklets created specifically for this. See where problems surface. Adjust measures if needed. And then provide techniques.
Thank you for your comment on the February 14, 2017 survey. You indicated "Accept this proposed SC into the Editor's Draft" and wrote:
You may be right, David. With most sites implementing responsive design it may hopefully be less of an issue.
In any event, it may depend on the measures we end up with. As I said to Kim the plan is to start testing sites with these metrics on the various user-agent tools, primarily bookmarklets created specifically for this. See where problems surface. Adjust measures if needed. And then provide techniques.
Hi @jasonjgw ,
Thank you for your comment on the February 14, 2017 survey, Jason. You indicated "Accept this proposed SC into the Editor's Draft" and wrote:
This has been discussed at length and the SC text has been through many iterations.
It still is a conundrum.
Currently the underlying requirement is unfortunately not to allow overriding font, spacing and color to any value desired by the user. Instead it is to allow overriding to specific values due to the SC criteria of testability.
@alastc has explained the underlying rationale of the hard-coded metrics approach:
Jason, can you suggest SC text that would:
We would all love to change it, if it is possible.
Thank you very much,
To make this easier for draft readers to swallow, consider adding a normative note that the resulting transformed webpage would not also be required to conform. The key is to not lose content or break navigation, forms, etc. Mostly this comes into play when messing with color, and this could be extra important to state given all the new criteria being proposed. Example might be an input field that is highlighted dark red on validation error no longer has the author's desired contrast. It's been a while since I've used style extensions regularly to alter content, but I remember often paying a price on such things for the benefit of being able to read the bulk of content.