Text Size

From Low Vision Accessibility Task Force

SC Shortname

Text Size

SC Text

Except for images of text, text can be resized without assistive technology up to the user agent maximum without loss of content and functionality.

Current WCAG 1.4.4

Except for captions and images of text, text can be resized without assistive technology up to 200 percent without loss of content or functionality.

Proposed Change:

Except for captions and images of text, text can be resized without assistive technology up to 200 percent @@the user agent maximum without loss of content and functionality@@.

Suggested Priority Level

Level A

Related Glossary additions or changes

None

What Principle and Guideline the SC falls within.

Principle 1, Guideline 1.4.4 Resize text

Description

A person can increase or decrease text-size only. Non-text content does not change. A key functionality to preserve is that complete lines of text fit within the viewport. For any block of text, the last word of a line is the immediate predecessor of the first word in the next line in reading order. No exceptions. Also, text fits within bounding boxes, lines, and columns if present. Finally, margins should not change with text size.

Benefits

Some people need larger text in order to perceive letters. Although increasing size is most common, some people with tunnel vision and good visual acuity may prefer smaller letters so they can see more words at a time.

Example issues:

  • Text settings don't increase the text in tool-tip text and other pop-up text
  • Text settings don't increase the text in images
  • Text settings don't increase the text in maps

User Need - Text Size: Users can change the text size (font size) of all text, without zooming the entire interface. - Source: Accessibility Requirements for People with Low Vision, Section 3.3.1: text size

Testability

  1. Display content in a user agent.
  2. Increase text size to the maximum.
  3. Check whether text scales and is perceivable.

Expected Results

  • Check #3 is true.

Techniques

All Existing Techniques for Changed SC

New Techniques

  • Ensuring that there is no loss of content or functionality when the text resizes and text containers do not change when resized up to user agent maximum. To be based on G179, which is currently limited to a 200% maximum.
  • Failure of Success Criterion 1.4.4 when resizing visually rendered text up to user agent maximum causes the text, image or controls to be clipped, truncated or obscured. To be based on F69, which is currently limited to a 200% maximum.

Related Information

Actions

Articles

  • Font size - Education and Outreach Working Group Tutorial

Email

GitHub

Minutes

TPAC 2016

  • TPAC Minutes - September 19, 2016
    • Text Size (LV) #11
    • Jim: We'll continue working on it, and refine it.
    • Jim: It got very complex when we tried to modify SCs, as they build on each other.
    • MichaelC: Don't want to fret about what it fits under, just get them out there, and we'll sort (and filter) them later. Could end up with some re-structuring, where similar ones get combined.
    • Mark: The relationship to colour contrast, we have designers get prickly when picking thin typefaces. When you visually look at it, there are not many pixels with sufficient colour contrast.
    • JamesN: The standard says you can test it without anti-aliasing on, so these would pass.
    • MichaelC: We've run into issues before where issues with the guidelines are actually ok, but some testing practices weren't quite right. Might need to provide better guidance on testing.
    • Kathy: When you have a thin font, 4.5:1 may not be sufficient, LVTF might want to look at thin fonts?
    • MichaelC: Imagining a function that detects the widths.
  • Jim's TPAC notes - 27 September 2016
    1. need a maximum. if higher than 200, need a higher conformance level (AA or AAA)
    2. need and SC about not losing content.

Wiki Pages

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