[Hackathon 2024][Niobium][Android] Usage of contentDescription should be required

[tdeffains]

Rule title

Accessibility: Provide contentDescription attribute for each UI element

Language and platform

XML - Android

Rule description

For accessibility purpose each UI element should be described for visual disabled user who will navigate through the application using Google TalkBack. See Google documentation. This description is provided by adding contentDescription attribute to the UI element.

Bad code:

<ImageView
        android:id="@+id/image_id"
        android:src="@drawable/ic_image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        />

Good code:

<ImageView
        android:id="@+id/image_id"
        android:src="@drawable/ic_image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:content_description="@string/image_description"
        />

Rule short description

contentDescription should be provided for each UI element.

Rule justification

Accessibility has become a major concern regarding mobile application development and it is part of WCAG requirements (WCAG 2.2).

Severity / Remediation Cost

Severity: Critical - regarding the accessibility category this flaw should be considered critical because users who need vocal assistance to navigate through the application will not be able to if this rule is not respected.

Remediation cost: Easy - add the contentDescription attribute. If the element should be not be considered by TalkBack the value can be set to null.

Implementation principle

• In the xml view files check if contentDescription attribute is provided for each UI elements (no matter the value which can be null). Beware of the following exceptions:
  • Don't provide descriptions for TextView elements. Android accessibility services automatically announce the text itself as the description. (Google documentation)
  • Don't provide description if the element has the importantForAccessibility attribute to "no" (used for graphical elements that are only used for decorative effect).