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Add a lang IDL Attribute to CanvasTextDrawingStyles, and clarify "direction" on same #10873

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Add a lang IDL Attribute to CanvasTextDrawingStyles, and clarify "direction" on same #10873

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eba506c
Add the lang IDL attribute to CanvasTextDrawingStyles
schenney-chromium Dec 18, 2024
caa22ca
Merge branch 'whatwg:main' into main
schenney-chromium Dec 18, 2024
488b95b
Fix Developer info
schenney-chromium Dec 18, 2024
01e6185
Merge branch 'whatwg:main' into main
schenney-chromium Jan 10, 2025
b6df5ee
Merge branch 'whatwg:main' into main
schenney-chromium Jan 22, 2025
1b5a1df
Post review revisions
schenney-chromium Jan 22, 2025
152e3a4
Clean up offscreen snapshot behavior
schenney-chromium Jan 23, 2025
60a5971
Fix the setter/getter for lang.
schenney-chromium Jan 23, 2025
720ff90
Next round of edits.
schenney-chromium Jan 23, 2025
c131fd6
Merge branch 'whatwg:main' into main
schenney-chromium Feb 3, 2025
119a4c5
Update the offscreen transfer steps, and clarify lang rules.
schenney-chromium Feb 3, 2025
25efd43
Text cleanup
schenney-chromium Feb 4, 2025
369688c
Post-review update
schenney-chromium Feb 5, 2025
7e5c880
Update link to content language
schenney-chromium Feb 5, 2025
37d7233
Minor cleanup
schenney-chromium Feb 14, 2025
e999e9e
Merge branch 'whatwg:main' into main
schenney-chromium Feb 21, 2025
f129f9b
Next iteration
schenney-chromium Feb 22, 2025
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Original file line number Diff line number Diff line change
Expand Up @@ -3956,6 +3956,7 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
<p>The following features are defined in <cite>CSS Text</cite>: <ref>CSSTEXT</ref></p>

<ul class="brief">
<li>The <dfn data-x-href="https://drafts.csswg.org/css-text-4/#content-language">content language</dfn> concept</li>
<li>The <dfn data-x-href="https://drafts.csswg.org/css-text/#text-transform-property">'text-transform'</dfn> property</li>
<li>The <dfn data-x-href="https://drafts.csswg.org/css-text/#white-space-property">'white-space'</dfn> property</li>
<li>The <dfn data-x-href="https://drafts.csswg.org/css-text/#text-align-property">'text-align'</dfn> property</li>
Expand Down Expand Up @@ -65680,13 +65681,21 @@ callback <dfn callback>BlobCallback</dfn> = undefined (<span>Blob</span>? blob);
and <code data-x="attr-canvas-height">height</code> content attributes of this
<code>canvas</code> element.</p></li>

<li><p>Set the <span data-x="offscreencanvas-placeholder">placeholder <code>canvas</code>
element</span> of <var>offscreenCanvas</var> to a weak reference to this <code>canvas</code>
element.</p></li>
<li><p>Set the <var>offscreenCanvas</var>'s <span
data-x="offscreencanvas-placeholder">placeholder <code>canvas</code> element</span>
to a weak reference to this <code>canvas</code> element.</p></li>

<li><p>Set this <code>canvas</code> element's <span data-x="concept-canvas-context-mode">context
mode</span> to <span data-x="concept-canvas-placeholder">placeholder</span>.</p></li>

<li><p>Set the <var>offscreenCanvas</var>'s <span
data-x="offscreencanvas-inherited-lang">inherited language</span> to the
<span>language</span> of this <code>canvas</code> element.</p></li>

<li><p>Set the <var>offscreenCanvas</var>'s <span
data-x="offscreencanvas-inherited-direction">inherited direction</span> to the <span
data-x="the directionality">directionality</span> of this <code>canvas</code> element.</p></li>

<li><p>Return <var>offscreenCanvas</var>.</p></li>
</ol>

Expand Down Expand Up @@ -65900,6 +65909,7 @@ interface mixin <dfn interface>CanvasPathDrawingStyles</dfn> {

interface mixin <dfn interface>CanvasTextDrawingStyles</dfn> {
// text
attribute DOMString <span data-x="dom-context-2d-lang">lang</span>; // (default: "inherit")
attribute DOMString <span data-x="dom-context-2d-font">font</span>; // (default 10px sans-serif)
attribute <span>CanvasTextAlign</span> <span data-x="dom-context-2d-textAlign">textAlign</span>; // (default: "start")
attribute <span>CanvasTextBaseline</span> <span data-x="dom-context-2d-textBaseline">textBaseline</span>; // (default: "alphabetic")
Expand Down Expand Up @@ -66406,6 +66416,7 @@ context.fillRect(100,0,50,50); // only this square remains</code></pre>
data-x="dom-context-2d-shadowOffsetX">shadowOffsetX</code>, <code
data-x="dom-context-2d-shadowOffsetY">shadowOffsetY</code>, <code
data-x="dom-context-2d-shadowBlur">shadowBlur</code>, <code
data-x="dom-context-2d-lang">lang</code>, <code
data-x="dom-context-2d-font">font</code>, <code
data-x="dom-context-2d-textAlign">textAlign</code>, <code
data-x="dom-context-2d-textBaseline">textBaseline</code>, <code
Expand Down Expand Up @@ -66897,13 +66908,28 @@ transform. ack Shaun Morris. -->
<h6>Text styles</h6>

<dl class="domintro">
<dt><code data-x=""><var>context</var>.<span subdfn data-x="dom-context-2d-lang">lang</span> [ = <var>value</var> ]</code></dt>
<dt><code data-x=""><var>styles</var>.<span data-x="dom-context-2d-lang">lang</span> [ = <var>value</var> ]</code></dt>
<dd>
<p>Returns the current language setting.</p>

<p>Can be set to a BCP 47 language tag, the empty string, or <span
data-x="dom-context-2d-lang-inherit">"inherit"</span>, to change the language used when
resolving fonts. The <span data-x="dom-context-2d-lang-inherit">"inherit"</span> string
takes the lanugage from the canvas element's language, or the associated Document when there
is no canvas element.</p>

<p>The default is <span data-x="dom-context-2d-lang-inherit">"inherit"</span>.</p>
</dd>

<dt><code data-x=""><var>context</var>.<span subdfn data-x="dom-context-2d-font">font</span> [ = <var>value</var> ]</code></dt>
<dt><code data-x=""><var>styles</var>.<span data-x="dom-context-2d-font">font</span> [ = <var>value</var> ]</code></dt>
<dd>
<p>Returns the current font settings.</p>

<p>Can be set, to change the font. The syntax is the same as for the CSS <span>'font'</span>
property; values that cannot be parsed as CSS font values are ignored.</p>
property; values that cannot be parsed as CSS font values are ignored. The default is "10px
sans-serif".</p>

<p>Relative keywords and lengths are computed relative to the font of the <code>canvas</code>
element.</p>
Expand Down Expand Up @@ -67140,6 +67166,20 @@ worker.postMessage(offscreenCanvas, [offscreenCanvas]);</code></pre>
data-x="dom-context-2d-textBaseline">textBaseline</code> attribute must initially have the value
<code data-x="dom-context-2d-textBaseline-alphabetic">alphabetic</code>.</p>

<p>Objects that implement the <code>CanvasTextDrawingStyles</code> interface have an
associated <dfn data-x="concept-CanvasTextDrawingStyles-language">language</dfn> value
which is a BCP 47 language tag, the empty string, or <span
data-x="dom-context-2d-lang-inherit">"inherit"</span>, used to localize font rendering.
Initially, the <span data-x="concept-CanvasTextDrawingStyles-language">language</span> must
be <span data-x="dom-context-2d-lang-inherit">"inherit"</span>.</p>

<p>The <dfn attribute for="CanvasTextDrawingStyles" data-x="dom-context-2d-lang"><code
data-x="dom-context-2d-lang">lang</code></dfn> getter step is to return
<span>this</span>'s <span data-x="concept-CanvasTextDrawingStyles-language">language</span>.</p>

<p>The <code data-x="dom-context-2d-lang">lang</code> setter step is to set <span>this</span>'s
<span data-x="concept-CanvasTextDrawingStyles-language">language</span> to the string.</p>
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Suggested change
<span data-x="concept-CanvasTextDrawingStyles-language">language</span> to the string.</p>
<span data-x="concept-CanvasTextDrawingStyles-language">language</span> to the given value.</p>


<p>The <dfn attribute for="CanvasTextDrawingStyles"><code
data-x="dom-context-2d-direction">direction</code></dfn> IDL attribute, on getting, must return
the current value. On setting, the current value must be changed to the new value. When the object
Expand Down Expand Up @@ -67269,6 +67309,27 @@ worker.postMessage(offscreenCanvas, [offscreenCanvas]);</code></pre>
<dd>The <span>em-under baseline</span></dd>
</dl>

<p>The <code data-x="dom-context-2d-lang">lang</code> attribute's allowed values are either
a value that is valid for the <code data-x="attr-lang">lang</code> element attribute, or the value
<dfn data-x="dom-context-2d-lang-inherit">"inherit"</dfn>.

<p>If the value is <span data-x="dom-context-2d-lang-inherit">"inherit"</span>, use the
following process to determine the value for the <dfn><code
data-x="dom-context-2d-inherited-language">inherited language</code></dfn> referred to in the
<span>text preparation algorithm</span> whenever that algorithm is run:</p>
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Instead of defining "inherited language", I'd inline this as part of the text preparation algorithm. Or define this as an algorithm that the text preparation algorithm calls.


<ol>
<li><p>If <var>object</var>'s <span>font style source object</span> is a <code>canvas</code>
element, then set the <code data-x="dom-context-2d-inherited-language">inherited
language</code> to the element's <span data-x="language">language</span>.</p></li>

<li><p>Otherwise, <var>object</var>'s <span>font style source object</span> is an
<code>OffscreenCanvas</code> object. Set the <code
data-x="dom-context-2d-inherited-language">inherited language</code> to the
<code>OffscreenCanvas</code>'s internal
<span data-x="offscreencanvas-inherited-lang">inherited language</span>.</p></li>
</ol>

<p>The <code data-x="dom-context-2d-direction">direction</code> attribute's allowed keywords are
as follows:</p>

Expand All @@ -67281,16 +67342,31 @@ worker.postMessage(offscreenCanvas, [offscreenCanvas]);</code></pre>

<dd><p>Treat input to the <span>text preparation algorithm</span> as right-to-left text.</p></dd>

<!--
<dt><dfn><code data-x="dom-context-2d-direction-auto">auto</code></dfn>
<dt><dfn enum-value for="CanvasDirection"><code data-x="dom-context-2d-direction-inherit">inherit</code></dfn>

<dd><p>Determine the direction from the input to the <span>text preparation algorithm</span>.</p></dd>
-->
<dd><p>Use the following process to determine the value for the
<dfn for="CanvasDirection"><code data-x="dom-context-2d-inherited-direction">inherited
direction</code></dfn> referred to in the <span>text preparation algorithm</span>:</p>
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But also the same issue as with "inherited language" applies here. This is better inlined or turned into its own algorithm that is called from text preparation.


<dt><dfn enum-value for="CanvasDirection"><code data-x="dom-context-2d-direction-inherit">inherit</code></dfn>
<ol>
<li><p>If <var>object</var>'s <span>font style source object</span> is a <code>canvas</code>
element:</p>
<ol>
<li><p>If the element has a <span>computed value</span> for
<span>'direction'</span> use that as the <span data-x="dom-context-2d-inherited-direction">inherited direction</span>.</p></li>

<dd><p>Default to the directionality of the <code>canvas</code> element or <code>Document</code>
as appropriate.</p></dd>
<li><p>Otherwise, use the <span data-x="the directionality">directionality</span>
of the element as the <span data-x="dom-context-2d-inherited-direction">inherited direction</span>.</p></li>
</ol>

<li><p>Otherwise, <var>object</var>'s <span>font style source object</span> is an
<code>OffscreenCanvas</code> object. Set the <span
data-x="dom-context-2d-inherited-direction">inherited direction</span> to the
<code>OffscreenCanvas</code>'s internal <span
data-x="offscreencanvas-inherited-direction">inherited
direction</span>.</p></li>
</ol>
</dd>
</dl>

<p>The <code data-x="dom-context-2d-fontKerning">fontKerning</code> attribute's allowed keywords
Expand Down Expand Up @@ -67399,6 +67475,24 @@ worker.postMessage(offscreenCanvas, [offscreenCanvas]);</code></pre>
<li><p>Let <var>font</var> be the current font of <var>target</var>, as given
by that object's <code data-x="dom-context-2d-font">font</code> attribute.</p></li>

<li>
<p>Apply the appropriate step from the following list to determine the value of <var>language</var>:</p>

<dl class="switch">

<dt>If the <var>target</var> object's <code
data-x="dom-context-2d-lang">lang</code> attribute has the value <span
data-x="dom-context-2d-lang-inherit">"inherit"</span></dt>
<dd>Let <var>language</var> be the <var>target</var>'s <span
data-x="dom-context-2d-inherited-language">inherited language</span>.</dd>

<dt>Otherwise</dt>
<dd>Let <var>language</var> be the <var>target</var>'s <code
data-x="dom-context-2d-lang">lang</code> attribute with the semantics of the <code
data-x="attr-lang">lang</code> element attribute.</dd>
</dl>
</li>

<li>
<p>Apply the appropriate step from the following list to determine the value of <var>direction</var>:</p>

Expand All @@ -67414,32 +67508,11 @@ worker.postMessage(offscreenCanvas, [offscreenCanvas]);</code></pre>
data-x="dom-context-2d-direction-rtl">rtl</code>"</dt>
<dd>Let <var>direction</var> be '<span data-x="concept-rtl">rtl</span>'.</dd>

<!--
<dt>If the <var>target</var> object's <code
data-x="dom-context-2d-direction">direction</code> attribute has the value "<code
data-x="dom-context-2d-direction-auto">auto</code>"</dt>
<dd>
Find the first character in <var>text</var> of bidirectional character type L, AL, or
R, if any. If such a character is found and it is of bidirectional character type AL or R,
then let <var>direction</var> be '<span data-x="concept-rtl">rtl</span>'; otherwise,
let <var>direction</var> be '<span data-x="concept-rtl">rtl</span>'. <ref>BIDI</ref>
</dd>
-->

<dt>If the <var>target</var> object's <span>font style source object</span> is an
element</dt>

<dd>Let <var>direction</var> be <span>the directionality</span> of the <var>target</var> object's <span>font style source object</span>.</dd>

<dt>If the <var>target</var> object's <span>font style source object</span> is a
<code>Document</code> with a non-null <span>document element</span></dt>

<dd>Let <var>direction</var> be <span>the directionality</span> of the <var>target</var>
object's <span>font style source object</span>'s <span>document element</span>.</dd>

<dt>Otherwise</dt>

<dd>Let <var>direction</var> be '<span data-x="concept-ltr">ltr</span>'.</dd>
data-x="dom-context-2d-direction-inherit">inherit</code>"</dt>
<dd>Let <var>direction</var> be the <var>target</var>'s <span
data-x="dom-context-2d-inherited-direction">inherited direction</span>.</dd>
</dl>
</li>

Expand All @@ -67456,6 +67529,10 @@ worker.postMessage(offscreenCanvas, [offscreenCanvas]);</code></pre>
</tr>
</thead>
<tbody>
<tr>
<td><span>content language</span></td>
<td><var>language</var></td>
</tr>
<tr>
<td><span>'direction'</span></td>
<td><var>direction</var></td>
Expand Down Expand Up @@ -71664,6 +71741,11 @@ interface <dfn interface>OffscreenCanvas</dfn> : <span>EventTarget</span> {
data-x="dom-OffscreenCanvas-height">height</code> attributes of the <code>OffscreenCanvas</code>
object. Initially, all the bitmap's pixels are <span>transparent black</span>.</p>

<p>An <code>OffscreenCanvas</code> object has an internal <dfn
data-x="offscreencanvas-inherited-lang">inherited language</dfn> and <dfn
data-x="offscreencanvas-inherited-direction">inherited direction</dfn> set when
the <code>OffscreenCanvas</code> is created.</p>

<p>An <code>OffscreenCanvas</code> object can have a rendering context bound to it. Initially,
it does not have a bound rendering context. To keep track of whether it has a rendering context
or not, and what kind of rendering context it is, an <code>OffscreenCanvas</code> object also
Expand All @@ -71684,9 +71766,37 @@ interface <dfn interface>OffscreenCanvas</dfn> : <span>EventTarget</span> {
array of <span>transparent black</span> pixels of the dimensions specified by <var>width</var> and
<var>height</var>; and its <code data-x="dom-OffscreenCanvas-width">width</code> and <code
data-x="dom-OffscreenCanvas-height">height</code> attributes initialized to <var>width</var> and
<var>height</var> respectively.</p>
<var>height</var> respectively. The <span data-x="offscreencanvas-inherited-lang">inherited
language</span> and <span data-x="offscreencanvas-inherited-direction">inherited direction</span>
internal values must be set as follows:</p>

<hr>
<ol>
<li><p>Let <var>global</var> be the <code>OffscreenCanvas</code>'s <span>relevant global
object</span>.</p></li>
<li><p>If <var>global</var> is a <code>Window</code> object:</p>
<ol>
<li><p>Let <var>Document</var> be the <var>global</var>'s
<span data-x="concept-document-window">associated <code>Document</code></span>.</p></li>

<li><p>Set the <code>OffscreenCanvas</code>'s <span
data-x="offscreencanvas-inherited-lang">inherited language</span> to the
<var>Document</var>'s <span data-x="language">language</span>.</p></li>

<li><p>Set the <code>OffscreenCanvas</code>'s <span
data-x="offscreencanvas-inherited-direction">inherited direction</span>
to the <var>Document</var>'s <span data-x="the directionality">directionality</span>.</p></li>
</ol>
</li>
<li><p>Otherwise:</p>
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Ditto.

<ol>
<li><p>Set the <span data-x="offscreencanvas-inherited-lang">inherited language</span>
to explicitly unknown.</p></li>

<li><p>Set the <span data-x="offscreencanvas-inherited-direction">inherited direction</span>
to "ltr".</p></li>
</ol>
</li>
</ol>

<p><code>OffscreenCanvas</code> objects are <span data-x="transferable
objects">transferable</span>. Their <span>transfer steps</span>, given <var>value</var> and
Expand All @@ -71703,11 +71813,18 @@ interface <dfn interface>OffscreenCanvas</dfn> : <span>EventTarget</span> {
<li><p>Let <var>width</var> and <var>height</var> be the dimensions of <var>value</var>'s <span
data-x="offscreencanvas-bitmap">bitmap</span>.</p></li>

<li><p>Let <var>language</var> and <var>direction</var> be the values of <var>value</var>'s
<span data-x="offscreencanvas-inherited-lang">inherited language</span> and
<span data-x="offscreencanvas-inherited-direction">inherited direction</span>.</p></li>

<li><p>Unset <var>value</var>'s <span data-x="offscreencanvas-bitmap">bitmap</span>.</p></li>

<li><p>Set <var>dataHolder</var>.[[Width]] to <var>width</var> and
<var>dataHolder</var>.[[Height]] to <var>height</var>.</p></li>

<li><p>Set <var>dataHolder</var>.[[Language]] to <var>language</var> and
<var>dataHolder</var>.[[Direction]] to <var>direction</var>.</p></li>

<li><p>Set <var>dataHolder</var>.[[PlaceholderCanvas]] to be a weak reference to
<var>value</var>'s <span data-x="offscreencanvas-placeholder">placeholder <code>canvas</code>
element</span>, if <var>value</var> has one, or null if it does not.</p></li>
Expand All @@ -71721,6 +71838,11 @@ interface <dfn interface>OffscreenCanvas</dfn> : <span>EventTarget</span> {
rectangular array of <span>transparent black</span> pixels with width given by
<var>dataHolder</var>.[[Width]] and height given by <var>dataHolder</var>.[[Height]].</p></li>

<li><p>Set <var>value</var>'s <span data-x="offscreencanvas-inherited-lang">inherited
language</span> to <var>dataHolder</var>.[[Language]] and <span
data-x="offscreencanvas-inherited-direction">inherited direction</span> to
<var>dataHolder</var>.[[Direction]].</p></li>

<li><p>If <var>dataHolder</var>.[[PlaceholderCanvas]] is not null, set <var>value</var>'s <span
data-x="offscreencanvas-placeholder">placeholder <code>canvas</code> element</span> to
<var>dataHolder</var>.[[PlaceholderCanvas]] (while maintaining the weak reference
Expand Down Expand Up @@ -147514,6 +147636,7 @@ INSERT INTERFACES HERE
Ştefan Vargyas,
Stefan Weiss,
Steffen Meschkat,
Stephen Chenney,
Stephen Ma,
Stephen Stewart,
Stephen White,
Expand Down