- From: Elika Etemad via cvs-syncmail <cvsmail@w3.org>
- Date: Tue, 07 Jun 2011 04:29:58 +0000
- To: public-css-commits@w3.org
Update of /sources/public/csswg/css3-writing-modes
In directory hutz:/tmp/cvs-serv23726
Modified Files:
Overview.html Overview.src.html
Log Message:
Clarifications to baseline alignment
Index: Overview.html
===================================================================
RCS file: /sources/public/csswg/css3-writing-modes/Overview.html,v
retrieving revision 1.160
retrieving revision 1.161
diff -u -d -r1.160 -r1.161
--- Overview.html 7 Jun 2011 02:47:07 -0000 1.160
+++ Overview.html 7 Jun 2011 04:29:56 -0000 1.161
@@ -206,10 +206,6 @@
<li><a href="#text-orientation"><span class=secno>5.1. </span> Orienting
Text: the ‘<code class=property>text-orientation</code>’
property</a>
- <ul class=toc>
- <li><a href="#vertical-typesetting"><span class=secno>5.1.1. </span>
- Vertical Typesetting</a>
- </ul>
</ul>
<li><a href="#abstract-box"><span class=secno>6. </span> Abstract Box
@@ -286,15 +282,15 @@
<li class=no-num><a href="#bidi-html"> Appendix A: Bidi Rules for HTML</a>
+ <li class=no-num><a href="#character-properties">Appendix Q Characters and
+ Properties</a>
+
<li class=no-num><a href="#script-orientations">Appendix B:
Bi-orientational Transformations</a>
<li class=no-num><a href="#vertical-typesetting-details">Appendix C:
Vertical Typesetting Synthesis</a>
- <li class=no-num><a href="#character-properties">Appendix Q Characters and
- Properties</a>
-
<li class=no-num><a href="#intrinsic-sizing">Appendix D: Intrinsic
Dimensions</a>
<ul class=toc>
@@ -1355,18 +1351,30 @@
<h3 id=baseline-alignment><span class=secno>4.4. </span> Baseline Alignment</h3>
- <p>The dominant baseline is used in CSS for alignment in two cases:
+ <p>The <dfn id=dominant-baseline>dominant baseline</dfn> (which <a
+ href="#text-baselines">can change</a> based on the writing mode) is used
+ in CSS for alignment in two cases:
<ul>
- <li>Aligning glyphs from different fonts within the same inline box. The
- glyphs are aligned by matching up the positions of the dominant baseline.
-
+ <li><strong>Aligning glyphs from different fonts within the same inline
+ box.</strong> The glyphs are aligned by matching up the positions of the
+ dominant baseline in their corresponding fonts.
- <li>Aligning a child inline within its parent. The child is aligned to the
- parent by matching the parent's dominant baseline to the same baseline in
- the child. (E.g. if the parent's dominant baseline is alphabetic, then
- the child's alphabetic baseline is matched to the parent's alphabetic
- baseline, even if the child's dominant baseline is something else.)
+ <li><strong>Aligning a child inline-level box within its parent.</strong>
+ For the ‘<code class=property>vertical-align</code>’ value of
+ ‘<a href="#baseline"><code class=css>baseline</code></a>’,
+ child is aligned to the parent by matching the parent's dominant baseline
+ to the same baseline in the child. (E.g. if the parent's dominant
+ baseline is alphabetic, then the child's alphabetic baseline is matched
+ to the parent's alphabetic baseline, even if the child's dominant
+ baseline is something else.) For values of ‘<code
+ class=css>sub</code>’, ‘<code class=css>super</code>’,
+ ‘<code class=css><length></code>’, and ‘<code
+ class=css><percentage></code>’, the baselines are aligned as
+ for ‘<a href="#baseline"><code
+ class=css>baseline</code></a>’, but the child is shifted according
+ to the offset given by its ‘<code
+ class=property>vertical-align</code>’ value.
<div class=example>
<p>Given following sample markup:
@@ -1387,16 +1395,6 @@
</div>
</div>
- <p>Baseline alignment in this fashion is used with the following values
- of ‘<code class=property>vertical-align</code>’: ‘<a
- href="#baseline"><code class=css>baseline</code></a>’,
- ‘<code class=css>sub</code>’, ‘<code
- class=css>super</code>’, <length>, <percentage>. In
- the latter cases, the baselines are aligned as for ‘<a
- href="#baseline"><code class=css>baseline</code></a>’, but the
- child is shifted according to the offset given by its ‘<code
- class=property>vertical-align</code>’ value.
-
<div class=example>
<p>If we assign ‘<code class=css>vertical-align:
super</code>’ to the <code>.inner</code> element from the example
@@ -1551,15 +1549,10 @@
sets the orientation of the line. Current values only have an effect in
vertical writing modes.
- <p id=grapheme-cluster>In this section only, the term <dfn
- id=character>character</dfn> is defined as <em>extended grapheme
- cluster</em> per <a href="#UAX29"
- rel=biblioentry>[UAX29]<!--{{!UAX29}}--></a>. It is roughly equivalent to
- what a language user considers to be a character or a basic unit of the
- script (which might not be a single Unicode codepoint). The UA may further
- tailor the definition as allowed by Unicode. See <a
- href="#character-properties">Character Properties</a> for detailed
- information on determing character properties.
+ <p>For readability, the term <a href="#character"><i>character</i></a> is
+ used in place of <em>extended grapheme cluster</em> in this section. See
+ <a href="#character-properties">Characters and Properties</a> for further
+ details.
<p>Values have the following meanings:
@@ -1615,11 +1608,15 @@
<p>If set on a non-replaced inline whose parent is not ‘<a
href="#sideways-left"><code class=css>sideways-left</code></a>’,
- this forces ‘<a href="#isolate"><code
- class=css>isolate</code></a>’ to be added to the computed value of
- ‘<a href="#unicode-bidi0"><code
- class=property>unicode-bidi</code></a>’. Layout of text is exactly
- as for ‘<a href="#sideways-right"><code
+ this forces bidi isolation: the ‘<a href="#normal"><code
+ class=css>normal</code></a>’ and ‘<a href="#embed"><code
+ class=css>embed</code></a>’ values of ‘<a
+ href="#unicode-bidi0"><code
+ class=property>unicode-bidi</code></a>’ compute to ‘<a
+ href="#isolate"><code class=css>isolate</code></a>’, and ‘<a
+ href="#bidi-override"><code class=css>bidi-override</code></a>’
+ computes to ‘<code class=css>bidi-override isolate</code>’.
+ Layout of text is exactly as for ‘<a href="#sideways-right"><code
class=css>sideways-right</code></a>’ except that the text content
and baseline table of each of the element's inline boxes is mirrored
around a vertical axis along the center of its content box. The
@@ -1633,7 +1630,7 @@
class=property>text-orientation</code></a>’ value other than
‘<a href="#sideways-left"><code
class=css>sideways-left</code></a>’, an analogous transformation
- is applied.
+ (and bidi isolation) is applied.
<dt><dfn id=sideways>sideways</dfn>
@@ -1683,6 +1680,26 @@
and sideways-right (writing-mode is vertical-rl)</p>
</div>
+ <p>The orientation of characters belonging to the Common, Inherited, and
+ Unknown script categories may be UA- or font-dependent in vertical
+ typographic modes:
+
+ <ul>
+ <li>
+ <p>If the font and font system support mixed-orientation typesetting
+ (e.g. the OpenType font used has the <code>vrt2</code>), the UA should
+ rely on that feature to set ‘<a href="#vertical-right"><code
+ class=css>vertical-right</code></a>’ text. Similarly if the font
+ and font system support upright typesetting (e.g. the OpenType font used
+ has the <code>vert</code> feature) then the UA should rely on that
+ feature to set ‘<a href="#upright"><code
+ class=css>upright</code></a>’ text.
+
+ <li>
+ <p>If the UA needs to synthesize such features, then the settings in <a
+ href="#vertical-typesetting-details">Appendix C</a> are recommended.
+ </ul>
+
<div class=example>
<p>In the following example, the root element of a horizontal-only
document is set to use ‘<a href="#sideways"><code
@@ -1701,39 +1718,6 @@
</pre>
</div>
- <h4 id=vertical-typesetting><span class=secno>5.1.1. </span> Vertical
- Typesetting</h4>
-
- <p>In vertical typographic modes, any character belonging to a vertical
- script <em>must</em> be set using its base character's intrinsic
- orientation. (See <a href="#script-orientations">Appendix B</a>.)
- Characters belonging to horizontal-only scripts must set sideways (for
- ‘<a href="#vertical-right"><code
- class=css>vertical-right</code></a>’) or set upright (for ‘<a
- href="#upright"><code class=css>upright</code></a>’) depending on
- the ‘<a href="#text-orientation0"><code
- class=property>text-orientation</code></a>’ property.
-
- <p>The orientation of characters belonging to the Common, Inherited, and
- Unknown script categories may be UA- or font-dependent in vertical
- typographic modes:
-
- <ul>
- <li>
- <p>If the font and font system support mixed-orientation typesetting, the
- UA should rely on that feature to set ‘<a
- href="#vertical-right"><code class=css>vertical-right</code></a>’
- text. Similarly if the font and font system support upright typesetting
- then the UA should rely on that feature to set ‘<a
- href="#upright"><code class=css>upright</code></a>’ text.
-
- <li>
- <p>If the UA needs to synthesize such features (e.g. if an OpenType font
- has only the <code>vert</code> but not the <code>vrt2</code> feature),
- then the settings in <a href="#vertical-typesetting-details">Appendix
- C</a> are recommended.
- </ul>
-
<h2 id=abstract-box><span class=secno>6. </span> Abstract Box Terminology</h2>
<p><a href="#CSS21" rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a> defines
@@ -2967,6 +2951,56 @@
{ unicode-bidi: isolate; }
</pre>
+ <h2 class=no-num id=character-properties>Appendix Q Characters and
+ Properties</h2>
+
+ <p>Unicode defines three character-level properties that are referenced in
+ CSS Writing Modes:
+
+ <dl>
+ <dt><a href="http://www.unicode.org/reports/tr11/#Definitions">East Asian
+ width</a>
+
+ <dd>Defined in <a href="#UAX11"
+ rel=biblioentry>[UAX11]<!--{{!UAX11}}--></a> and given as the
+ East_Asian_Width property.
+
+ <dt><a
+ href="http://www.unicode.org/reports/tr44/#General_Category_Values">General
+ Category</a>
+
+ <dd>Defined in <a href="#UAX44"
+ rel=biblioentry>[UAX44]<!--{{!UAX44}}--></a> and given as the
+ General_Category property.
+
+ <dt><a href="http://www.unicode.org/reports/tr24/#Values">Script
+ property</a>
+
+ <dd>Defined in <a href="#UAX24"
+ rel=biblioentry>[UAX24]<!--{{!UAX24}}--></a> and given as the Script
+ property. (UAs should include any ScriptExtensions.txt assignments in
+ this mapping.)
+ </dl>
+
+ <p id=grapheme-cluster>In several sections (as noted), the term <dfn
+ id=character>character</dfn> is defined as <em>extended grapheme
+ cluster</em> per <a href="#UAX29"
+ rel=biblioentry>[UAX29]<!--{{!UAX29}}--></a>. It is roughly equivalent to
+ what a language user considers to be a character or a basic unit of the
+ script (which might not be a single Unicode codepoint). The UA may further
+ tailor this definition as allowed by Unicode.
+
+ <p>Unicode defines properties for characters, but for ‘<a
+ href="#text-orientation0"><code
+ class=property>text-orientation</code></a>’ and <a
+ href=vertical-typesetting-details>Vertical Typesetting Synthesis</a>, it
+ is necessary to determine the properties of a grapheme cluster. For the
+ purposes of CSS Writing Modes, the properties of a grapheme cluster are
+ given by its base character—except in one case: grapheme clusters
+ formed with an Enclosing Mark (Me) of the Common script are considered to
+ be Other Symbols (So) in the Common script. They are assumed to have the
+ same Unicode properties as the Replacement Character U+FFFD.
+
<h2 class=no-num id=script-orientations>Appendix B: Bi-orientational
Transformations</h2>
@@ -3077,6 +3111,12 @@
<p><em>This appendix is non-normative.</em>
+ <p>This section defines an algorithm for automatic typesetting of vertical
+ text. For readability, the term <a href="#character"><i>character</i></a>
+ is used in place of <em>extended grapheme cluster</em> in this section.
+ See <a href="#character-properties">Characters and Properties</a> for
+ further details.
+
<p class=issue>This section needs careful review.
<p>When ‘<a href="#text-orientation0"><code
@@ -3100,9 +3140,10 @@
settings if possible).
<li>Set any other characters that are assigned to a script (i.e. do not
- belong to the Common, Inherited, or Unknown scripts) <a
- href="#vertical-typesetting">as required by ‘<code
- class=property>text-orientation</code>’</a>.
+ belong to the Common, Inherited, or Unknown scripts) as required by
+ ‘<a href="#text-orientation0"><code
+ class=property>text-orientation</code></a>’ and <a
+ href="#script-orientations">Appendix B</a>.
</ol>
<p>When ‘<a href="#text-orientation0"><code
@@ -3174,47 +3215,6 @@
of these are present, the font is considered to have vertical font
settings available.
- <h2 class=no-num id=character-properties>Appendix Q Characters and
- Properties</h2>
-
- <p>Unicode only defines properties for characters, but in the definition of
- ‘<a href="#text-orientation0"><code
- class=property>text-orientation</code></a>’ and in <a
- href=vertical-typesetting-details>Vertical Typesetting Synthesis</a>, it
- is necessary to determine the properties of a grapheme cluster. For the
- purposes of CSS Writing Modes, the properties of a grapheme cluster are
- given by its base character—except in one case: grapheme clusters
- formed with an Enclosing Mark (Me) of the Common script are considered to
- be Other Symbols (So) in the Common script having the same Unicode
- properties as the Replacement Character U+FFFD.
-
- <p>Unicode defines three properties that are referenced here:
-
- <dl>
- <dt><a href="http://www.unicode.org/reports/tr11/#Definitions">East Asian
- width</a>
-
- <dd>Defined in <a href="#UAX11"
- rel=biblioentry>[UAX11]<!--{{UAX11}}--></a> and given as the
- East_Asian_Width property.
-
- <dt><a
- href="http://www.unicode.org/reports/tr44/#General_Category_Values">General
- Category</a>
-
- <dd>Defined in <a href="#UAX44"
- rel=biblioentry>[UAX44]<!--{{UAX44}}--></a> and given as the
- General_Category property.
-
- <dt><a href="http://www.unicode.org/reports/tr24/#Values">Script
- property</a>
-
- <dd>Defined in <a href="#UAX24"
- rel=biblioentry>[UAX24]<!--{{UAX24}}--></a> and given as the Script
- property. (UAs should include any ScriptExtensions.txt assignments in
- this mapping.)
- </dl>
-
<h2 class=no-num id=intrinsic-sizing>Appendix D: Intrinsic Dimensions</h2>
<p><em>This section is normative.</em>
@@ -3581,6 +3581,16 @@
</dd>
<!---->
+ <dt id=UAX44>[UAX44]
+
+ <dd>Mark Davis; Ken Whistler. <a
+ href="http://www.unicode.org/reports/tr44/tr44-6.html"><cite>Unicode
+ Character Database.</cite></a> 8 October 2010. Unicode Standard Annex
+ #44. URL: <a
+ href="http://www.unicode.org/reports/tr44/tr44-6.html">http://www.unicode.org/reports/tr44/tr44-6.html</a>
+ </dd>
+ <!---->
+
<dt id=UNICODE>[UNICODE]
<dd>The Unicode Consortium. <a
@@ -3661,36 +3671,6 @@
</dd>
<!---->
- <dt id=UAX11>[UAX11]
-
- <dd>Asmus Freytag. <a
- href="http://www.unicode.org/unicode/reports/tr11/tr11-8.html"><cite>East
- Asian Width.</cite></a> 23 March 2001. Unicode Standard Annex #11. URL:
- <a
- href="http://www.unicode.org/unicode/reports/tr11/tr11-8.html">http://www.unicode.org/unicode/reports/tr11/tr11-8.html</a>
- </dd>
- <!---->
-
- <dt id=UAX24>[UAX24]
-
- <dd>Mark Davis; Ken Whistler. <a
- href="http://www.unicode.org/reports/tr24/"><cite>Unicode Script
- Property.</cite></a> 27 September 2010. Unicode Standard Annex #24. URL:
- <a
- href="http://www.unicode.org/reports/tr24/">http://www.unicode.org/reports/tr24/</a>
- </dd>
- <!---->
-
- <dt id=UAX44>[UAX44]
-
- <dd>Mark Davis; Ken Whistler. <a
- href="http://www.unicode.org/reports/tr44/tr44-6.html"><cite>Unicode
- Character Database.</cite></a> 8 October 2010. Unicode Standard Annex
- #44. URL: <a
- href="http://www.unicode.org/reports/tr44/tr44-6.html">http://www.unicode.org/reports/tr44/tr44-6.html</a>
- </dd>
- <!---->
-
<dt id=UTN22>[UTN22]
<dd>Elika J. Etemad. <a href="http://unicode.org/notes/tn22/"><cite>Robust
Index: Overview.src.html
===================================================================
RCS file: /sources/public/csswg/css3-writing-modes/Overview.src.html,v
retrieving revision 1.170
retrieving revision 1.171
diff -u -d -r1.170 -r1.171
--- Overview.src.html 7 Jun 2011 04:03:40 -0000 1.170
+++ Overview.src.html 7 Jun 2011 04:29:56 -0000 1.171
@@ -968,17 +968,24 @@
<h3 id="baseline-alignment">
Baseline Alignment</h3>
- <p>The dominant baseline is used in CSS for alignment in two cases:
+ <p>The <dfn>dominant baseline</dfn>
+ (which <a href="#text-baselines">can change</a> based on the writing mode)
+ is used in CSS for alignment in two cases:
<ul>
- <li>Aligning glyphs from different fonts within the same inline box.
+ <li><strong>Aligning glyphs from different fonts within the same inline box.</strong>
The glyphs are aligned by matching up the positions of the dominant
- baseline.
- <li>Aligning a child inline within its parent. The child is aligned to
+ baseline in their corresponding fonts.
+ <li><strong>Aligning a child inline-level box within its parent.</strong>
+ For the 'vertical-align' value of ''baseline'', child is aligned to
the parent by matching the parent's dominant baseline to the same
baseline in the child. (E.g. if the parent's dominant baseline is
alphabetic, then the child's alphabetic baseline is matched to the
parent's alphabetic baseline, even if the child's dominant baseline
is something else.)
+ For values of ''sub'', ''super'', ''<length>'', and
+ ''<percentage>'', the baselines are aligned as for ''baseline'',
+ but the child is shifted according to the offset given by its
+ 'vertical-align' value.
<div class="example">
<p>Given following sample markup:
<pre><p><span class="outer">Ap <span class="inner"><i>ji</i></span></span></p></pre>
@@ -992,11 +999,6 @@
<p><img alt="" src="baseline-align-sizes.gif">
</div>
</div>
- <p>Baseline alignment in this fashion is used with the following values of
- 'vertical-align': ''baseline'', ''sub'', ''super'', <length>,
- <percentage>. In the latter cases, the baselines are aligned as
- for ''baseline'', but the child is shifted according to the offset given
- by its 'vertical-align' value.
<div class="example">
<p>If we assign ''vertical-align: super'' to the <code>.inner</code>
Received on Tuesday, 7 June 2011 04:30:00 UTC