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Understanding Reflow: What It Means and Why It Is Essential for Low Vision

taught by: Wayne Dick

Session Summary:

This talk will explain the arcane language of the Reflow Criterion of WCAG 2.1. Implementing this correctly is vital to for people with low vision who need large print to read.


Understanding Refow for Low Vision

Most people with low vision need: Large print (200% to 400% normal) Lines of text that fit on the page (word-wrap).

Large print is to see the text. Word wrapping is to avoid massive scrolling (50 to 150 times normal).

What is large print? On paper normal print is around 10pt. That means 200% to 400% is 20pt to 40pt.

On a computer we measure size by pixels not points. Pixel size is relative to sizes the size of the device. Points are actual sizes: 1/72 inch = 1pt. How can you guarantee font sizes are the same across devices. Pixel size is variable. Point size is fixed. Web programmers assume that 16px =12pt, but 16px on a cell phone is NOT the same size as 16px on a big screen?

How can you define large print on a web page? 200% to 400% has no meaning if your base text size is relative to the device. The WCAG 2.1 Reflow Criterions solves this problem and states the result in a format that can be programmed. The language is not user friendly, but the complexity is necessary because it solves a difficult problem.

You will understand the meaning clearly when this talk is done.

How to make reflow work?

Reflow depends on responsive design or mobile layouts (if they play on a computer). Since most web pages are moving in that direction conformance depends on responsive design that includes that consider the landscape view on laptops and desktops. If a mobile version can run of laptops and desktops it can also be used.

What Could Go Wrong Headers and footers that stick to the top or bottom. Floating elements that interfere with text. Long URL’s and words like pneumonoultramicroscopicsilicovolcanoconiosis that run off the page. Preformatted text used incorrectly

What you will get? This talk will give a clear understanding of an important but difficult WCAG 2.1 criterion: SC 1.4.10. You will know what to do and how to avoid pitfalls to avoid.


Some familiarity with WCAG 2.0

Presentation Materials: