Size (all content) (LV)

[allanj-uaag]

SC Shortname

Size (all content)

SC Text

Users can change the size of all content.

Current:

None

Proposed:

Add the following bullet to 1.4.8 Visual Presentation:

Users can change the size of all content.

Suggested Priority Level

Level A

Related Glossary additions or changes

None.

What Principle and Guideline the SC falls within.

Principle 1, Guideline 1.4.8 Visual Presentation

Description

Zoom functions preserve all spatial relationships on the page and all functionality continues to be available.

Simply put: a person can make everything bigger or smaller as needed.

Benefits

Some people need to increase the size of all interface content in order to perceive information. Although increasing size is most common, some people with tunnel vision and good visual acuity may prefer to decrease the size so they can see more information at a time.

Source: Accessibility Requirements for People with Low Vision, Section 3.3.5: Size of All Content

Testability

1. Display content in a user agent.
2. Increase zoom to the maximum.
3. Decrease zoom to the minimum.
4. Check whether all content scales and is perceivable with no loss of content or functionality (e.g. boxes do not overlap, controls are not obscured or separated from their labels, etc.).

Expected Results

• Check #4 is true.

Techniques

All existing techniques for Proposed New SC: "Size (all content)"

1. G146: Using liquid layout and AND using measurements that are relative to other measurements in the content by using one or more of the following techniques:
   • https://www.w3.org/TR/WCAG20-TECHS/C12 C12: Using percent for font sizes (CSS) OR
   • C13: Using named font sizes (CSS) OR
   • C14: Using em units for font sizes (CSS) OR
   • C24: Using percentage values in CSS for container sizes (CSS) OR
   • FLASH33: Using relative values for Flash object dimensions (Flash)
   • SCR34: Calculating size and position in a way that scales with text size (Scripting) OR
2. G206: Providing options within the content to switch to a layout that does not require the user to scroll horizontally to read a line of text

New Techniques

1. Using fluid grids. Ref: fluid grids
2. Using em based media queries. Ref: em based media queries
3. Using responsive images. Ref: HTML picture element and srcset attribute
4. @@ Consider a failure technique on fixed sized containers and fixed position content??
5. @@ Consider a failure technique on "Interfering with a user agent's ability to zoom" i.e., author using: maximum-scale or minimum-scale or user-scalable=no or user-scalable=0 in the meta element ?? @@ Note: In Pinch zoom thread on the WCAG list people did not seem to be in favor of this as a failure.

Related Information

Actions

• ACTION-73: Write sc - size of all elements - on Laura Carlson, August 25, 2016
• ACTION-82: Update user needs/requirements with change size of all elements->content - on Shawn Henry, September 1, 2016

Articles

Zoom Articles

• Don't Disable Zoom - Adrian Roselli
• Don't disable pinch to zoom - Jamie Knight
• What's the point of 'meta viewport user-scalable=no' in the Google Maps API - Stack Overflow
• Browser zoom great for accessibility - Alastair Campbell
• Zoom for Fixed and Responsive Sites - Alastair Campbell
• Why Browser Zoom Sucks for Low Vision Users (slide deck) Denis Boudreau
• The Two Types of Browser Zoom - Jeff Atwood

Responsive Images Articles

• Built-in Browser Support for Responsive Images - Pearl Chen
• What Does Responsive Web Design Have to Do with Accessibility? - Jonathan Avila
• Responsive Web Design: Preserving Images' Aspect Ratio - Bruce Lawson
• Bruce Lawson picture and friends HTML responsive images (Video) - Bruce Lawson
• Improving Responsive Images with the Picture Element - Annarita Tranfici
• Responsive Images Done Right: A Guide To <picture> And srcset - Eric Portis
• Bringing Responsive Images to Browsers - Mat Marquis

Email

• lvtf-ACTION-73: Write SC - size of all elements - LVTF List
• Thread: Jonathan's concern: Zoom in responsive drops content - WCAG WG List
• Thread: Enabling Zoom on Mobile Devices - WCAG WG List
• Thread: Pinch zoom - WCAG WG List
• Thread: Any official clarification on Text-only zoom and RWD? - WebAIM
• Thread: Browser zooming sufficient for WCAG 1.4.4 (resize text) - WebAIM

GitHub

• WCAG 1.4.8 item 5 200% Raised by Jim Allan, 16 June 2016
• Reference to 200% zoom implies WCAG requires text zoom only - WAI Tutorial GitHub Issue 293, raised by David MacDonald, 31 March 2015

Minutes

• LVTF Minutes 15 September 2016
• LVTF Minutes 01 September 2016
• LVTF Minutes 14 Jul 2016
• LVTF Minutes 12 May 2016
• LVTF Minutes 20 Jan 2016

Tools

• Always Zoom - Matt Brubeck
• Zoom - Chrome Extension
• zoomWheel - Chrome Web Store
• Change text, image, and video sizes (zoom) - Chrome Help
• Font size and zoom - increase the size of web pages (Firefox) - Mozilla Support

Wiki Pages

• Use cases - LVTF Wiki
• Possible wording from Jason/David for LVTF re: zoom without horizontal scroll - WCAG WG Wiki
• Semantic Zoom - InfoVis Wiki
• Zoom - InfoVis Wiki

[DavidMacDonald]

There is a friendly amendment here. https://www.w3.org/WAI/GL/wiki/Possible_wording_from_Jason/David_for_LVTF_re:_zoom_without_horizontal_scroll

[alastc]

I think this one needs replacing with Resize Content: https://www.w3.org/WAI/GL/low-vision-a11y-tf/wiki/Size_of_all_elements

[DavidMacDonald]

totally agree w/ Alastair

[allanj-uaag]

closed replace by #77