RGAA 3.2016 - Rule 1.3.12

Summary

This test consists in detecting informative canvas images with an alternative text and thus defining the applicability of the test.

Human check will be then needed to determine whether the alternative is well rendered by assistive technologies.

Business description

Criterion

1.3

Test

1.3.12

Description

Pour chaque image bitmap (balise canvas) porteuse d’information et possédant une alternative (contenu entre <canvas> et </canvas>), cette alternative est-elle correctement restituée par les technologies d’assistance ?

Level

A

Technical description

Scope

Page

Decision level

Semi-Decidable

Algorithm

Selection

Set1

All the <canvas> tags of the page not within a link, not identified as captcha and with a not empty text (see Notes about captcha detection) (canvas:not(a canvas):not(:matchesOwn(^\s*$)))

Set2

All the elements of Set1 identified as informative image by marker usage (see Notes for details about detection through marker)

Set3

All the elements of Set1 identified neither as informative image, nor as decorative image by marker usage (see Notes for details about detection through marker)

Process

Test1

For each element of Set2, raise a MessageA.

Test2

For each element of Set3, raise a MessageB.

MessageA : Check the restitution by assistive technologies of the alternative of informative images
  • code : CheckAtRestitutionOfAlternativeOfInformativeImage
  • status: Pre-Qualified
  • parameter : text, tag name, snippet
  • present in source : yes
MessageB : Check nature of image and the restitution by assistive technologies of their alternative
  • code : CheckNatureOfImageAndAtRestitutionOfAlternative
  • status: Pre-Qualified
  • parameter : text, tag name, snippet
  • present in source : yes

Analysis

Not Applicable

The page has no canvas image with a not empty text (Set1 is empty)

Pre-Qualified

In all other cases

Notes

Markers

Informative images markers are set through the INFORMATIVE_IMAGE_MARKER parameter.

Decorative images markers are set through the DECORATIVE_IMAGE_MARKER parameter.

The value(s) passed as marker(s) will be checked against the following attributes:

  • class
  • id
  • role

Captcha detection

An element is identified as a CAPTCHA when the "captcha" occurrence is found :

  • on one attribute of the element
  • or within the text of the element
  • or on one attribute of one parent of the element
  • or within the text of one parent of the element
  • or on one attribute of a sibling of the element
  • or within the text of a sibling of the element

TestCases

TestCases files for rule 1.3.12