This test consists in checking whether the textual alternative of each object svg that convey information is relevant.
- S’il est présent, le contenu de l’attribut
- S’il est présent, le contenu de l’attribut WAI-ARIA
- S’il est présent, le passage de texte associé via l’attribut WAI-ARIA
Il existe une gestion de cas particuliers lorsque l’image est utilisée comme CAPTCHA ou comme image-test. Dans cette situation, où il n’est pas possible de donner une alternative pertinente sans détruire l’objet du CAPTCHA ou du test, le critère est non applicable.
Decidable with marker
<svg> tags, not within a link and not identified as captcha (see Notes about captcha detection)
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)
All the elements of Set2 with a textual alternative (see Notes for details about textual alternative detection).
All the elements of Set3 with a textual alternative (see Notes for details about textual alternative detection).
The page has no
<svg> tag with a textual alternative (Set2 is empty)
At least one
<svg> tag, identified as informative, has a textual alternative that is not pertinent (Test1 returns
false for at least one element)
In all other cases
The textual alternative can be set by the presence of any the following elements :
- Text associated via the
- Presence of an
That order has to be respected to compute the textual alternative.
For instance, if some text associated via the
aria-labelledby WAI-ARIA attribute and an
attribute are both present, the content of the text associated via the
aria-labelledby WAI-ARIA attribute is
considered as the textual alternative.
The content of the textual alternative is seen as not relevant if :
- only composed of non-alphanumerical characters
- it has an extension of image type (loaded by the nomenclature named ImageFileExtensions composed of : jpg, gif, jpeg, png, bmp)
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:
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