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WCAG 2.1 para Apps: Técnicas e Falhas para o Princípio de Acessibilidade Percetível
AMA | Agência para a Modernização Administrativa, I.P edited this page Feb 26, 2023
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4 Diretrizes, 29 Critérios de Sucesso
O meu desenvolvimente web ou aplicacional está ou não a cumprir os 50 critérios de sucesso? Responder a esta questão não parece um exercício difícil. Ele torna-se mais difícil quando percebemos que entre o texto dos critérios de sucesso e o pragmatismo do desenvolvimento há um iato significativo de interpretação.
A enumeração dos Critérios de Sucesso é feita nas WCAG de forma abstrata, bastante genérica e abrangente de forma a aplicar-se ao maior número de situações, agnóstica às tecnologias usadas e resistente ao tempo, evitando atualizações frequentes.
Apresenta-se a seguir um conjunto de técnicas consideradas suficientes para cumprir os Critérios de Sucesso que fazem parte das WCAG 2.1 do W3C/WAI. Também se apresenta um conjunto de falhas que, caso ocorram, levam ao incumprimento do respetivo Critério de Sucesso.
Critério de Sucesso 1.1.1 Conteúdo não Textual (nível A) - ver definição do Critério de Sucesso 1.1.1
Situação A - Se uma descrição curta pode servir o mesmo propósito e apresenta a mesma informação que o conteúdo não textual:
Técnicas para texto alternativo curto:
- G94: Providing short text alternative for non-text content that serves the same purpose and presents the same information as the non-text content
- ARIA6: Using aria-label to provide labels for objects
- ARIA10: Using aria-labelledby to provide a text alternative for non-text content
- G196: Using a text alternative on one item within a group of images that describes all items in the group
- H2: Combining adjacent image and text links for the same resource
- H35: Providing text alternatives on applet elements
- H37: Using alt attributes on img elements
- H53: Using the body of the object element
- H86: Providing text alternatives for ASCII art, emoticons, and leetspeak
Técnicas para texto alternativo curto:
- ARIA6: Using aria-label to provide labels for objects
- ARIA10: Using aria-labelledby to provide a text alternative for non-text content
- G196: Using a text alternative on one item within a group of images that describes all items in the group
- H2: Combining adjacent image and text links for the same resource
- H35: Providing text alternatives on applet elements
- H37: Using alt attributes on img elements
- H53: Using the body of the object element
- H86: Providing text alternatives for ASCII art, emoticons, and leetspeak
Técnicas para texto alternativo longo:
- ARIA15: Using aria-describedby to provide descriptions of images
- G73: Providing a long description in another location with a link to it that is immediately adjacent to the non-text content
- G74: Providing a long description in text near the non-text content, with a reference to the location of the long description in the short description
- G92: Providing long description for non-text content that serves the same purpose and presents the same information
- H45: Using longdesc
- H53: Using the body of the object element
G82: Providing a text alternative that identifies the purpose of the non-text content
Text alternative techniques for controls and input:
- ARIA6: Using aria-label to provide labels for objects
- ARIA9: Using aria-labelledby to concatenate a label from several text nodes
- H24: Providing text alternatives for the area elements of image maps
- H30: Providing link text that describes the purpose of a link for anchor elements
- H36: Using alt attributes on images used as submit buttons
- H44: Using label elements to associate text labels with form controls
- H65: Using the title attribute to identify form controls when the label element cannot be used
- ARIA6: Using aria-label to provide labels for objects
- ARIA9: Using aria-labelledby to concatenate a label from several text nodes
- H24: Providing text alternatives for the area elements of image maps
- H30: Providing link text that describes the purpose of a link for anchor elements
- H36: Using alt attributes on images used as submit buttons
- H44: Using label elements to associate text labels with form controls
- H65: Using the title attribute to identify form controls when the label element cannot be used
- G100: Providing a short text alternative which is the accepted name or a descriptive name of the non-text content
- G143: Providing a text alternative that describes the purpose of the CAPTCHA AND G144: Ensuring that the Web Page contains another CAPTCHA serving the same purpose using a different modality
- C9: Using CSS to include decorative images
- H67: Using null alt text and no title attribute on img elements for images that AT should ignore
- F3: Failure of Success Criterion 1.1.1 due to using CSS to include images that convey important information
- F13: Failure of Success Criterion 1.1.1 and 1.4.1 due to having a text alternative that does not include information that is conveyed by color differences in the image
- F20: Failure of Success Criterion 1.1.1 and 4.1.2 due to not updating text alternatives when changes to non-text content occur
- F30: Failure of Success Criterion 1.1.1 and 1.2.1 due to using text alternatives that are not alternatives (e.g., filenames or placeholder text)
- F38: Failure of Success Criterion 1.1.1 due to not marking up decorative images in HTML in a way that allows assistive technology to ignore them
- F39: Failure of Success Criterion 1.1.1 due to providing a text alternative that is not null (e.g., alt="spacer" or alt="image") for images that should be ignored by assistive technology
- F65: Failure of Success Criterion 1.1.1 due to omitting the alt attribute or text alternative on img elements, area elements, and input elements of type "image"
- F67: Failure of Success Criterion 1.1.1 and 1.2.1 due to providing long descriptions for non-text content that does not serve the same purpose or does not present the same information
- F71: Failure of Success Criterion 1.1.1 due to using text look-alikes to represent text without providing a text alternative
- F72: Failure of Success Criterion 1.1.1 due to using ASCII art without providing a text alternative
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