Skip to content

[css-writing-modes] Clarify how propagation from body works #4130

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Jul 21, 2019
Merged

[css-writing-modes] Clarify how propagation from body works #4130

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
37 changes: 30 additions & 7 deletions css-writing-modes-3/Overview.bs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,8 @@ Work Status: Testing
Group: csswg
ED: https://drafts.csswg.org/css-writing-modes-3/
TR: https://www.w3.org/TR/css-writing-modes-3/
Previous Version: https://www.w3.org/TR/2018/CR-css-writing-modes-3-20180524/
Previous Version: https://www.w3.org/TR/2017/CR-css-writing-modes-3-20171207/
Previous Version: https://www.w3.org/TR/2015/CR-css-writing-modes-3-20151215/
Issue Tracking: Tracker http://www.w3.org/Style/CSS/Tracker/products/30
Editor: Elika J. Etemad / fantasai, Invited Expert, http://fantasai.inkedblade.net/contact, w3cid 35400
Expand Down Expand Up @@ -2234,19 +2236,27 @@ Purely Physical Mappings</h3>
The Principal Writing Mode</h2>

<p>The <dfn export>principal writing mode</dfn> of the document
is determined by the 'writing-mode' and 'direction' values
specified on the root element.
is determined by the [=used value|used=] 'writing-mode', 'direction', and 'text-orientation' values
of the root element.
This writing mode is used, for example,
to determine the direction of scrolling
and the default <a>page progression</a> direction.

<p>As a special case for handling HTML documents,
if the root element has a <{body}> child element [[!HTML]],
the <a>principal writing mode</a> is instead taken
from the values of 'writing-mode' and 'direction' on the first such child element
instead of taken from the root element.
Note that this does not affect the values of 'writing-mode' or 'direction'
on the root element itself.
the [=used value=] of the of 'writing-mode' and 'direction' properties on root element
are taken
from the [=computed value|computed=] 'writing-mode' and 'direction'
of the first such child element instead of from the root element's own values.
The UA <em>may</em> also propagate the value of 'text-decoration' in this manner.
Note that this does not affect the computed values of 'writing-mode' or 'direction'
of the root element itself.

Note: Propagation is done on used values rather than computed values
to avoid disrupting other aspects of style computation,
such as [=inheritance=],
[[css-logical-1#box|logical property mapping logic]],
or [[css-values-4#lengths|length value computation]].

<h3 id="icb">
Propagation to the Initial Containing Block</h3>
Expand Down Expand Up @@ -2472,6 +2482,19 @@ Privacy and Security Considerations {#priv-sec}

<h2 class="no-num" id="changes">Changes</h2>

<h3 class="no-num" id="changes-201805">
Changes since the <a href="https://www.w3.org/TR/2018/CR-css-writing-modes-3-20180524/">May
2018 CSS Writing Modes Module Level 3 Candidate Recommendation</a></h3>

<ul>
<li>Clarified that propagation of the principal writing mode from the body element
to the initial containing block and viewport
does affect the used value on root element as well,
but not its computed value.
Also, optionally allow propagating 'text-orientation' as well.
(<a href="https://github.com/w3c/csswg-drafts/issues/3066">Issue 3066</a>)
</ul>

<h3 class="no-num" id="changes-201712">
Changes since the <a href="http://www.w3.org/TR/2015/CR-css-writing-modes-3-20171207/">December
2017 CSS Writing Modes Module Level 3 Candidate Recommendation</a></h3>
Expand Down
40 changes: 28 additions & 12 deletions css-writing-modes-4/Overview.bs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ Work Status: Testing
Group: csswg
ED: https://drafts.csswg.org/css-writing-modes-4/
TR: https://www.w3.org/TR/css-writing-modes-4/
Previous Version: https://www.w3.org/TR/2018/CR-css-writing-modes-4-20180524/
Issue Tracking: Tracker http://www.w3.org/Style/CSS/Tracker/products/30
Editor: Elika J. Etemad / fantasai, Invited Expert, http://fantasai.inkedblade.net/contact, w3cid 35400
Editor: Koji Ishii, Google, [email protected], w3cid 45369
Expand Down Expand Up @@ -2460,19 +2461,27 @@ Purely Physical Mappings</h3>
The Principal Writing Mode</h2>

<p>The <dfn export>principal writing mode</dfn> of the document
is determined by the 'writing-mode' and 'direction' values
specified on the root element.
is determined by the [=used value|used=] 'writing-mode', 'direction', and 'text-orientation' values
of the root element.
This writing mode is used, for example,
to determine the direction of scrolling
and the default <a>page progression</a> direction.

<p>As a special case for handling HTML documents,
if the root element has a <{body}> child element [[!HTML]],
the <a>principal writing mode</a> is instead taken
from the values of 'writing-mode' and 'direction' on the first such child element
instead of taken from the root element.
Note that this does not affect the values of 'writing-mode' or 'direction'
on the root element itself.
the [=used value=] of the of 'writing-mode' and 'direction' properties on root element
are taken
from the [=computed value|computed=] 'writing-mode' and 'direction'
of the first such child element instead of from the root element's own values.
The UA <em>may</em> also propagate the value of 'text-decoration' in this manner.
Note that this does not affect the computed values of 'writing-mode' or 'direction'
of the root element itself.

Note: Propagation is done on used values rather than computed values
to avoid disrupting other aspects of style computation,
such as [=inheritance=],
[[css-logical-1#box|logical property mapping logic]],
or [[css-values-4#lengths|length value computation]].

<h3 id="icb">
Propagation to the Initial Containing Block</h3>
Expand Down Expand Up @@ -2774,14 +2783,21 @@ Privacy and Security Considerations {#priv-sec}
or security considerations beyond “implement it correctly”.

<h2 class="no-num" id="changes">Changes</h2>
<!--
<h3 class="no-num" id="changes-201311">
Changes since the <a href="https://www.w3.org/TR/2014/CR-css-writing-modes-3-20140320/">March
2014 CSS Writing Modes Module Level 3 Candidate Recommendation</a></h3>

<h3 class="no-num" id="changes-201805">
Changes since the <a href="https://www.w3.org/TR/2018/CR-css-writing-modes-4-20180524">May
2018 CSS Writing Modes Module Level 4 Candidate Recommendation</a></h3>

<ul>
<li>
Clarified that propagation of the principal writing mode from the body element
to the initial containing block and viewport
does affect the used value on root element as well,
but not its computed value.
Also, optionally allow propagating 'text-orientation' as well.
This change was also applied to level 3.
(<a href="https://github.com/w3c/csswg-drafts/issues/3066">Issue 3066</a>)
</ul>
-->

<h3 id="additions">
New in Level 4</h3>
Expand Down