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Add better permalinks for AccName computation. #186

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Feb 7, 2023
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Add better permalinks for AccName computation. #186

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8fdfb63
Add better permalinks for AccName computation.
cookiecrook Feb 1, 2023
616a762
m. correcting some cascaded IDs and nits I missed in the initial commit
cookiecrook Feb 1, 2023
aebac70
m. add em tags around the visible text names for the steps
cookiecrook Feb 2, 2023
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Expand Up @@ -314,10 +314,10 @@ <h4>Terminology</h4>
<h4>Computation steps</h4>
<p>The text alternative for a given element is computed as follows:</p>
<ol>
<li id="step1">Set the <code>root node</code> to the given element, the <code>current node</code> to the <code>root node</code>, and the <code>total accumulated text</code> to the empty string (""). If the <code>root node</code>'s role prohibits naming, return the empty string ("").</li>
<li id="step2">Compute the text alternative for the <code>current node</code>:
<li id="comp_init" name="step1"><em>Initialization:</em> Set the <code>root node</code> to the given element, the <code>current node</code> to the <code>root node</code>, and the <code>total accumulated text</code> to the empty string (""). If the <code>root node</code>'s role prohibits naming, return the empty string ("").</li>
<li id="comp_computation" name="step2"><em>Computation:</em> Compute the text alternative for the <code>current node</code>:
<ol>
<li id="step2A">If the <code>current node</code> is <span class="informative">[=element/hidden=]</span> <strong>and is</strong>:
<li id="comp_hidden_not_referenced" name="step2A"><em>Hidden Not Referenced:</em> If the <code>current node</code> is <span class="informative">[=element/hidden=]</span> <strong>and is</strong>:
<ul>
<li><strong>Not</strong> part of an <code>aria-labelledby</code> or <code>aria-describedby</code> traversal, where the node directly referenced by that relation was hidden.</li>
<li><strong>Nor</strong> part of a native host language text alternative <a class="termref">element</a> (e.g. <code>label</code> in HTML) or <a class="termref">attribute</a> traversal, where the root of that traversal was hidden.</li>
Expand Down Expand Up @@ -354,25 +354,25 @@ <h4>Computation steps</h4>
</pre>
</details></div>
</li>
<li id="step2B">Otherwise:
<li id="comp_labelledby_overall" name="step2B">Otherwise:
<ul>
<li>if the <code>current node</code> has an <code>aria-labelledby</code> [=attribute=] that contains at least one valid IDREF, and the <code>current node</code> is not already part of an ongoing <code>aria-labelledby</code> or <code>aria-describedby</code> traversal, process its IDREFs in the order they occur: </li>
<li id="comp_labelledby"><em>LabelledBy:</em> If the <code>current node</code> has an <code>aria-labelledby</code> [=attribute=] that contains at least one valid IDREF, and the <code>current node</code> is not already part of an ongoing <code>aria-labelledby</code> or <code>aria-describedby</code> traversal, process its IDREFs in the order they occur: </li>
<ol>
<li id="step2B.i">Set the <code>accumulated text</code> to the empty string.</li>
<li id="step2B.ii">For each IDREF:
<li id="comp_labelledby_reset" name="step2B.i">Set the <code>accumulated text</code> to the empty string.</li>
<li id="comp_labelledby_foreach" name="step2B.ii">For each IDREF:
<ol>
<li id="step2B.ii.a">Set the <code>current node</code> to the node referenced by the IDREF.</li>
<li id="step2B.ii.b">Compute the text alternative of the <code>current node</code> beginning with step 2. Set the <code>result</code> to that text alternative.</li>
<li id="step2B.ii.c">Append the <code>result</code>, with a space, to the <code>accumulated text</code>.</li>
<li id="comp_labelledby_set_current" name="step2B.ii.a">Set the <code>current node</code> to the node referenced by the IDREF.</li>
<li id="comp_labelledby_recursion" name="step2B.ii.b"><em>LabelledBy Recursion:</em> Compute the text alternative of the <code>current node</code> beginning with the overall <a href="#comp_computation">Computation</a> step. Set the <code>result</code> to that text alternative.</li>
<li id="comp_labelledby_append" name="step2B.ii.c">Append the <code>result</code>, with a space, to the <code>accumulated text</code>.</li>
</ol>
</li>
<li id="step2B.iii">Return the <code>accumulated text</code> if it is not the empty string ("").</li>
<li id="comp_labelledby_return" name="step2B.iii">Return the <code>accumulated text</code> if it is not the empty string ("").</li>
</ol>
</li>
</ul>
<div><details>
<summary>Comment:</summary>
<p>The result of <a href="#step2B.ii.b">step 2B.ii.b</a> in combination with <a href="#step2A">step 2A</a> means that <a class="termref">user agents</a> MUST include all nodes in the subtree as part of the <a class="termref">accessible name</a> or <a class="termref">accessible description</a>, when the node referenced by <code>aria-labelledby</code> or <code>aria-describedby</code> is hidden.</p>
<p>The result of <a href="#comp_labelledby_recursion">LabelledBy Recursion</a> in combination with <a href="#comp_hidden_not_referenced">Hidden Not Referenced</a> means that <a class="termref">user agents</a> MUST include all nodes in the subtree as part of the <a class="termref">accessible name</a> or <a class="termref">accessible description</a>, when the node referenced by <code>aria-labelledby</code> or <code>aria-describedby</code> is hidden.</p>
<div><details>
<summary>Example:</summary>
<p>The following example shows the meaning of the clause "&#8230; and the <code>current node</code> is not already part of an <code>aria-labelledby</code> traversal &#8230;" .</p>
Expand All @@ -386,15 +386,15 @@ <h4>Computation steps</h4>
</pre>
</details></div>
</li>
<li id="step2C">Otherwise, if the <code>current node</code> is a control embedded within the label (e.g. any element directly referenced by <code>aria-labelledby</code>) for another <a class="termref">widget</a>, where the user can adjust the embedded control's value, then return the embedded control as part of the text alternative in the following manner:
<li id="comp_embedded_control" name="step2C"><em>Embedded Control:</em> Otherwise, if the <code>current node</code> is a control embedded within the label (e.g. any element directly referenced by <code>aria-labelledby</code>) for another <a class="termref">widget</a>, where the user can adjust the embedded control's value, then return the embedded control as part of the text alternative in the following manner:
<ul>
<li>If the embedded control has role <a class="role-reference" href="#textbox">textbox</a>, return its value.</li>
<li>If the embedded control has role <a class="role-reference" href="#combobox">combobox</a> or <a class="role-reference" href="#listbox">listbox</a>, return the text alternative of the chosen <a class="role-reference" href="#option">option</a>.</li>
<li>If the embedded control has role <a class="role-reference" href="#range">range</a> (e.g., a <a class="role-reference" href="#spinbutton">spinbutton</a> or <a class="role-reference" href="#slider">slider</a>):
<li id="comp_embedded_control_textbox"><em>Textbox:</em> If the embedded control has role <a class="role-reference" href="#textbox">textbox</a>, return its value.</li>
<li id="comp_embedded_control_combobox_or_listbox"><em>Combobox/Listbox:</em> If the embedded control has role <a class="role-reference" href="#combobox">combobox</a> or <a class="role-reference" href="#listbox">listbox</a>, return the text alternative of the chosen <a class="role-reference" href="#option">option</a>.</li>
<li id="comp_embedded_control_range"><em>Range:</em> If the embedded control has role <a class="role-reference" href="#range">range</a> (e.g., a <a class="role-reference" href="#spinbutton">spinbutton</a> or <a class="role-reference" href="#slider">slider</a>):
<ul>
<li>If the <code>aria-valuetext</code> property is present, return its value, </li>
<li>Otherwise, if the <code>aria-valuenow</code> property is present, return its value,</li>
<li>Otherwise, use the value as specified by a host language attribute. </li>
<li id="comp_embedded_control_range_valuetext">If the <code>aria-valuetext</code> property is present, return its value, </li>
<li id="comp_embedded_control_range_valuenow">Otherwise, if the <code>aria-valuenow</code> property is present, return its value,</li>
<li id="comp_embedded_control_range_host_language_value">Otherwise, use the value as specified by a host language attribute. </li>
</ul>
</li>
</ul>
Expand All @@ -404,9 +404,9 @@ <h4>Computation steps</h4>
<pre class="example highlight"><code>&lt;div role="checkbox" aria-checked="false"&gt;Flash the screen &lt;span role="textbox" aria-multiline="false"&gt; 5 &lt;/span&gt; times&lt;/div&gt;</code></pre>
</details></div>
</li>
<li id="step2D">Otherwise, if the <code>current node</code> has an <code>aria-label</code> [=attribute=] whose value is not undefined, not the empty string, nor, when trimmed of [=ascii whitespace|whitespace=], is not the empty string:
<li id="comp_label" name="step2D"><em>AriaLabel:</em> Otherwise, if the <code>current node</code> has an <code>aria-label</code> [=attribute=] whose value is not undefined, not the empty string, nor, when trimmed of [=ascii whitespace|whitespace=], is not the empty string:
<ul>
<li>If traversal of the <code>current node</code> is due to recursion <strong>and</strong> the <code>current node</code> is an embedded control as defined in step 2C, ignore <code>aria-label</code> and skip to rule 2C.</li>
<li>If traversal of the <code>current node</code> is due to recursion <strong>and</strong> the <code>current node</code> is an embedded control, ignore <code>aria-label</code> and skip to rule <a href="#comp_embedded_control">Embedded Control</a>.</li>
<li>Otherwise, return the value of <code>aria-label</code>.</li>
</ul>
<div><details>
Expand All @@ -425,40 +425,40 @@ <h4>Computation steps</h4>
&lt;/ul&gt;</code></pre>
</details></div>
</li>
<li id="step2E">Otherwise, if the <code>current node</code>'s native markup provides an [=attribute=] (e.g. <code>alt</code>) or [=element=] (e.g. HTML <code>label</code> or SVG <code>title</code>) that defines a text alternative, return that alternative in the form of a <code>flat string</code> as defined by the host language, unless the element is marked as presentational (<code>role="presentation"</code> or <code>role="none"</code>).
<li id="comp_host_language_label" name="step2E"><em>Host Language Label:</em> Otherwise, if the <code>current node</code>'s native markup provides an [=attribute=] (e.g. <code>alt</code>) or [=element=] (e.g. HTML <code>label</code> or SVG <code>title</code>) that defines a text alternative, return that alternative in the form of a <code>flat string</code> as defined by the host language, unless the element is marked as presentational (<code>role="presentation"</code> or <code>role="none"</code>).
<div class="note">See <a href="https://www.w3.org/TR/html-aam-1.0/#accessible-name-and-description-computation">HTML-AAM</a>, <a href="https://www.w3.org/TR/svg-aam-1.0/#mapping_additional_nd">SVG-AAM</a>, or other host language documentation for more information on markup that defines a text alternative.</div>
<div><details>
<summary>Comment:</summary>
<p>For example, in <abbr title="Hypertext Markup Language">HTML</abbr>, the <code>img</code> element's <code>alt</code> attribute defines a text alternative string, and the <code>label</code> element provides text for the referenced form element. In <abbr title="SVG2">SVG2</abbr>, the <code>desc</code> and <code>title</code> elements provide a description of their parent element. </p>
</details></div>
</li>
<li id="step2F">Otherwise, if the <code>current node's</code> <a class="termref">role</a> allows <a class="specref" href="#namefromcontent">name from content</a>, or if the <code>current node</code> is referenced by <code>aria-labelledby</code>, <code>aria-describedby</code>, or is a native host language text alternative [=element=] (e.g. <code>label</code> in HTML), or is a descendant of a native host language text alternative [=element=]:
<li id="comp_name_from_content" name="step2F"><em>Name From Content:</em> Otherwise, if the <code>current node's</code> <a class="termref">role</a> allows <a class="specref" href="#namefromcontent">name from content</a>, or if the <code>current node</code> is referenced by <code>aria-labelledby</code>, <code>aria-describedby</code>, or is a native host language text alternative [=element=] (e.g. <code>label</code> in HTML), or is a descendant of a native host language text alternative [=element=]:
<ol>
<li id="step2F.i">Set the <code>accumulated text</code> to the empty string.</li>
<li id="step2F.ii">Check for <abbr title="Cascading Style Sheets">CSS</abbr> generated textual content associated with the <code>current node</code> and include it in the <code>accumulated text</code>. The <abbr title="Cascading Style Sheets">CSS</abbr> <a href="https://www.w3.org/TR/CSS2/generate.html#before-after-content"><code>:before</code> and <code>:after</code></a> pseudo elements [[!CSS2]] can provide textual content for [=element|elements=] that have a content model.
<li id="comp_name_from_content_reset" name="step2F.i"><em>Name From Content Reset:</em> Set the <code>accumulated text</code> to the empty string.</li>
<li id="comp_name_from_content_pseudo_element" name="step2F.ii"><em>Name From Generated Content:</em> Check for <abbr title="Cascading Style Sheets">CSS</abbr> generated textual content associated with the <code>current node</code> and include it in the <code>accumulated text</code>. The <abbr title="Cascading Style Sheets">CSS</abbr> <a href="https://www.w3.org/TR/CSS2/generate.html#before-after-content"><code>::before</code> and <code>::after</code></a> pseudo elements [[!CSS2]] can provide textual content for [=element|elements=] that have a content model.
<ul>
<li>For <code>:before</code> pseudo elements, <a class="termref">User agents</a> MUST prepend <abbr title="Cascading Style Sheets">CSS</abbr> textual content, without a space, to the textual content of the <code>current node</code>. </li>
<li>For <code>:after</code> pseudo elements, <a class="termref">User agents</a> MUST append <abbr title="Cascading Style Sheets">CSS</abbr> textual content, without a space, to the textual content of the <code>current node</code>. </li>
<li id="comp_name_from_content_pseudo_element_before">For <code>::before</code> pseudo elements, <a class="termref">User agents</a> MUST prepend <abbr title="Cascading Style Sheets">CSS</abbr> textual content, without a space, to the textual content of the <code>current node</code>. </li>
<li id="comp_name_from_content_pseudo_element_after">For <code>::after</code> pseudo elements, <a class="termref">User agents</a> MUST append <abbr title="Cascading Style Sheets">CSS</abbr> textual content, without a space, to the textual content of the <code>current node</code>. </li>
</ul>
</li>
<li id="step2F.iii">For each child node of the <code>current node</code>:
<li id="comp_name_from_content_for_each_child" name="step2F.iii"><em>Name From Each Child:</em> For each child node of the <code>current node</code>:
<ol>
<li id="step2F.iii.a">Set the <code>current node</code> to the child node.</li>
<li id="step2F.iii.b">Compute the text alternative of the <code>current node</code> beginning with step 2. Set the <code>result</code> to that text alternative.</li>
<li id="step2F.iii.c">Append the <code>result</code> to the <code>accumulated text</code>. </li>
<li id="comp_name_from_content_for_each_child_set_current" name="step2F.iii.a">Set the <code>current node</code> to the child node.</li>
<li id="comp_name_from_content_for_each_child_recursion" name="step2F.iii.b">Compute the text alternative of the <code>current node</code> beginning with the overall <a href="#comp_computation">Computation</a> step. Set the <code>result</code> to that text alternative.</li>
<li id="comp_for_each_child_append" name="step2F.iii.c">Append the <code>result</code> to the <code>accumulated text</code>. </li>
</ol>
</li>
<li id="step2F.iv">Return the <code>accumulated text</code> if it is not the empty string ("").</li>
<li id="comp_name_from_content_return" name="step2F.iv">Return the <code>accumulated text</code> if it is not the empty string ("").</li>
</ol>
<p><strong>Important</strong>: Each [=nodes|node=] in the subtree is consulted only once. If text has been collected from a descendant, but is referenced by another IDREF in some descendant node, then that second, or subsequent, reference is not followed. This is done to avoid infinite loops. </p>
<div><details>
<summary>Comment:</summary>
<p>This step can apply to the child nodes themselves, which means the computation is recursive and results in text collected from all the elements in the <code>current node</code>'s subtree, no matter how deep it is. However, any given descendant [=nodes|node's=] text alternative can result from higher precedent markup described in steps B through D above, where "Namefrom: author" attributes provide the text alternative for the entire subtree. </p>
</details></div>
</li>
<li id="step2G">Otherwise, if the <code>current node</code> is a Text [=Node=], return its textual contents.</li>
<li id="step2H">Otherwise, if the <code>current node</code> is a descendant of an element whose <a class="termref">Accessible Name</a> or <a class="termref">Accessible Description</a> is being computed, and contains descendants, proceed to 2F.i.</li>
<li id="step2I">Otherwise, if the <code>current node</code> has a <a class="termref">Tooltip attribute</a>, return its value.
<li id="comp_text_node" name="step2G"><em>Text Node:</em> Otherwise, if the <code>current node</code> is a Text [=Node=], return its textual contents.</li>
<li id="comp_recursive_name_from_content" name="step2H"><em>Recursive Name From Content:</em> Otherwise, if the <code>current node</code> is a descendant of an element whose <a class="termref">Accessible Name</a> or <a class="termref">Accessible Description</a> is being computed, and contains descendants, proceed to <a href="#comp_name_from_content_reset">Name From Content Reset</a>.</li>
<li id="comp_tooltip" name="step2I"><em>Tooltip:</em> Otherwise, if the <code>current node</code> has a <a class="termref">Tooltip attribute</a>, return its value.
<div><details>
<summary>Comment:</summary>
<p>Tooltip attributes are used only if nothing else, including subtree content, has provided results. </p>
Expand Down