Techniques for WCAG 2.0

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# G142: Using a technology that has commonly-available user agents that support zoom

## Applicability

All technologies with user-agent provided zoom capability.

This technique relates to:

- Success Criterion 1.4.4 (Resize text)
  - How to Meet 1.4.4 (Resize text)
  - Understanding Success Criterion 1.4.4 (Resize text)

## User Agent and Assistive Technology Support Notes

The Zoom functionality in IE 7.0 does not always scale uniformly when absolute positioning is used and the page is scaled smaller. Microsoft Internet Explorer 7.0 supports both Zoom and Text Size changes for fonts set with %, em or named sizes.

Opera 9 supports Zoom.

Firefox 2 and below supports only text size changes, but can change the size of pt and px fonts as well as %, em and named sizes.

Firefox 3 supports both zoom and text size changes.

## Description

The objective of this technique is to ensure content can be scaled uniformly by using a Web technology supported by user agents that change text size via a Zoom tool.

Content authored in technologies that are supported by user agents that can scale content uniformly (that is, zoom into content) satisfy this Success Criterion. Because this technique relies completely on user agent functionality, it is critical to test with a wide variety of user agents.

This technique requires that the zoom function preserve all spatial relationships on the page and that all functionality continues to be available.

## Examples

- Internet Explorer 7 and Opera 9 provide a zoom function that scales HTML/CSS page content uniformly.

- To allow users to resize text, Adobe Reader provides a magnification tool that scales PDF pages uniformly.

## Related Techniques

(none currently listed)

## Tests

### Procedure

1. Display content in a user agent

2. Zoom content to 200%

3. Check whether all content and functionality is available

### Expected Results

- Check #3 is true.

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