SF.net SVN: docutils:[9935 ] trunk/docutils/docs

milde--- via Docutils-checkins <[email protected]>
Newsgroups gmane.text.docutils.cvs
Message-ID <[email protected]>
Revision: 9935
          http://sourceforge.net/p/docutils/code/9935
Author:   milde
Date:     2024-09-20 08:32:28 +0000 (Fri, 20 Sep 2024)
Log Message:
-----------
Update documentation around length specifications.

Modified Paths:
--------------
    trunk/docutils/docs/index.rst
    trunk/docutils/docs/ref/rst/directives.rst
    trunk/docutils/docs/ref/rst/restructuredtext.rst
    trunk/docutils/docs/user/latex.rst
    trunk/docutils/docs/user/manpage.rst

Modified: trunk/docutils/docs/index.rst
===================================================================
--- trunk/docutils/docs/index.rst	2024-09-20 06:31:07 UTC (rev 9934)
+++ trunk/docutils/docs/index.rst	2024-09-20 08:32:28 UTC (rev 9935)
@@ -95,7 +95,7 @@
   * `Docutils Mailing Lists <user/mailing-lists.html>`__
   * `Docutils Link List <user/links.html>`__
 
-Writer-specific:
+_`Writer-specific`:
   * `Docutils HTML Writers <user/html.html>`__
   * `Easy Slide Shows With reStructuredText & S5 <user/slide-shows.html>`__
   * `Docutils LaTeX Writer <user/latex.html>`__

Modified: trunk/docutils/docs/ref/rst/directives.rst
===================================================================
--- trunk/docutils/docs/ref/rst/directives.rst	2024-09-20 06:31:07 UTC (rev 9934)
+++ trunk/docutils/docs/ref/rst/directives.rst	2024-09-20 08:32:28 UTC (rev 9935)
@@ -194,7 +194,7 @@
 .. _HTML4:
 .. _html4 writer: ../../user/html.html#html4css1
 .. _HTML5:
-.. _html5 writer: ../../user/html.html#html5-polyglot
+.. _html5 writer: ../../user/html.html#html5
 .. _LaTeX: ../../user/latex.html#image-inclusion
 .. _ODT: ../../user/odt.html
 .. _manpage: ../../user/manpage.html
@@ -289,9 +289,9 @@
 ``scale`` : integer percentage (the "%" symbol is optional)
     The uniform scaling factor of the image.  The default is "100 %",
     i.e. no scaling.
-    Docutils tries to determine dimensions from the image file
-    if no ``height`` or ``width`` options are specified
-    (requires the `Python Imaging Library`_).
+    If the output format does not support a scaling attribute (e.g. HTML),
+    the Docutils writer tries to determine missing size specifications from
+    the  image file (requires the `Python Imaging Library`_).
 
     .. _target:
 
@@ -312,8 +312,8 @@
    The behaviour may change for the ODT and XML writers but
    images cannot be embedded in a LaTeX source.
 
-.. [#] SVG images are directly included, other images are base64_ encoded
-   and included as a `data URI`_.
+.. [#] The `HTML5 writer`_, embeds SVG images directly and other images
+   as base64_ encoded `data URI`_.
 
 .. _lazy loading attribute: https://html.spec.whatwg.org/multipage/
     urls-and-fetching.html#lazy-loading-attributes
@@ -1107,9 +1107,9 @@
     "auto" delegates the determination of column widths to the backend
     (LaTeX, the HTML browser, ...).
 
-  .. TODO
-     Add option ``missing-cells`` with keywords "strict", "fill", "span"?
-     (cf. [feature-requests:#103])
+.. TODO
+    Add option ``missing-cells`` with keywords "strict", "fill", "span"?
+    (cf. [feature-requests:#103])
 
 
 ----------------
@@ -2167,7 +2167,7 @@
 
       .. image:: bild.png
          :alt:   example picture
-         :name: my picture
+         :name:  my picture
 
     is the recommended syntax alternative to a preceding
     `hyperlink target`_ ::
@@ -2204,7 +2204,7 @@
   A _`list of integers` may be comma- or whitespace-separated.
 
 :_`length`: number, optionally followed by one of the
-  supported `length units`_
+  `supported length units`_
 
   Handling of values without unit depends on the writer/output format.
   See the writer specific documentation in the `user doc`__ for details.
@@ -2217,6 +2217,11 @@
   The `root_prefix`_ configuration setting can be used to tell Docutils
   to interpret paths starting with "/" relative to a "project directory".
 
+:_`percentage`: number followed by the percent sign '%'
+
+  Percentage values are relative to other values, depending on the
+  context in which they occur.
+
 :_`text`: free text
 
   Possible restrictions are given in parentheses.
@@ -2241,8 +2246,7 @@
     restructuredtext.html#external-hyperlink-targets
 .. _hyperlink references: restructuredtext.html#hyperlink-references
 .. _hyperlink target: restructuredtext.html#hyperlink-targets
-.. _length units: restructuredtext.html#length-units
-.. _percentage: restructuredtext.html#percentage-units
+.. _supported length units: restructuredtext.html#length-units
 .. _reference name:
 .. _reference names: restructuredtext.html#reference-names
 .. _reStructuredText table: restructuredtext.html#tables

Modified: trunk/docutils/docs/ref/rst/restructuredtext.rst
===================================================================
--- trunk/docutils/docs/ref/rst/restructuredtext.rst	2024-09-20 06:31:07 UTC (rev 9934)
+++ trunk/docutils/docs/ref/rst/restructuredtext.rst	2024-09-20 08:32:28 UTC (rev 9935)
@@ -3072,55 +3072,66 @@
    RFC3986_.
 
 
-Units
-=====
+Measures and Units
+==================
 
-All measures consist of a positive floating point number in standard
-(non-scientific) notation and a unit, possibly separated by one or
-more spaces.
+*Measures* consist of a positive floating point number in standard
+(non-scientific) notation and an optional unit, possibly separated
+by one or more spaces.
 
-Units are only supported where explicitly mentioned in the reference
-manuals.
+Measures are only supported where explicitly mentioned in the reference
+manuals (`directive option`_ values of type "length__" or "percentage__").
+In the `document tree`_, they are stored in attributes of type `measure`_.
 
+.. _directive option: `directive options`_
+__ directives.html#length
+__ directives.html#percentage
 
+
 Length Units
 ------------
 
-The following length units are supported by the reStructuredText
-parser:
+The reStructuredText parser supports the `length units in CSS2`_. [#]_
+Unit identifiers are case-sensitive (in contrast to CSS):
 
-* em (em unit, the element's font size)
-* ex (ex unit, x-height of the element’s font)
-* mm (millimeters; 1 mm = 1/1000 m)
-* cm (centimeters; 1 cm = 10 mm)
-* in (inches; 1 in = 2.54 cm = 96 px)
-* px (pixels, 1 px = 1/96 in) [#]_
-* pt (points; 1 pt = 1/72 in)
-* pc (picas; 1 pc = 1/6 in = 12 pt)
+.. class:: align-center
 
-This set corresponds to the `length units in CSS2`_ (a subset of `length
-units in CSS3`_).
+====  =======================  ================================
+em    the element's font size
+----  ---------------------------------------------------------
+ex    x-height of the element's font
+----  ---------------------------------------------------------
+cm    centimeters              1 cm = 10 mm
+mm    millimeters              1 mm = 1/1000 m
+in    inches                   1 in = 2.54 cm = 96 px
+pc    picas                    1 pc = 1/6 in = 12 pt
+pt    points                   1 pt = 1/72 in
+px    pixels                   1 px = 3/4 pt = 1/96 in [#]_
+====  =======================  ================================
 
-.. [#] In LaTeX, the default definition is 1 px = 1/72 in (cf. `How to
-   configure the size of a pixel`_ in the LaTeX writer documentation).
+The following are all valid length values:
+"1.5em", "20 mm", ".5 in", "42".
 
-The following are all valid length values: "1.5em", "20 mm", ".5in".
+It is up to the processing system to provide a fallback/workaround or
+raise an error if the output format does not support a unit or
+values without unit.  For the behaviour of the Docutils writers,
+see the `writer documentation`_.
 
-Length values without unit are completed with a writer-dependent
-default (e.g. "px" with HTML, "pt" with `latex2e`). See the writer
-specific documentation in the `user doc`__ for details.
+.. [#] a subset of `length units in CSS3`_
+.. [#] In LaTeX, the default definition is 1 px = 1 pt = 1/72 in
+   (cf. section `Length units <../../user/latex.html#length-units>`__
+   in the LaTeX writer documentation).
 
 .. _length units in CSS2:
    https://www.w3.org/TR/CSS2/syndata.html#length-units
 .. _length units in CSS3:
    https://www.w3.org/TR/css-values-3/#lengths
-.. _How to configure the size of a pixel:
-   ../../user/latex.html#size-of-a-pixel
-__ ../../index.html#introductory-tutorial-material-for-end-users
+.. _XSL units: https://www.w3.org/TR/xsl/#d0e5752
 
-Percentage Units
-----------------
 
+Percentage Unit
+---------------
+
 Percentage values have a percent sign ("%") as unit.  Percentage
 values are relative to other values, depending on the context in which
 they occur.
@@ -3143,6 +3154,8 @@
 .. _reStructuredText: https://docutils.sourceforge.io/rst.html
 .. _Docutils: https://docutils.sourceforge.io/
 
+.. _writer documentation: ../../index.html#writer-specific
+
 .. _character_level_inline_markup:
     ../../user/config.html#character-level-inline-markup
 .. _footnote_references:
@@ -3249,6 +3262,7 @@
 .. _`<version>`: ../doctree.html#version
 .. _"classes" attribute:  ../doctree.html#classes
 .. _identifier key: ../doctree.html#identifiers
+.. _`measure`: ../doctree.html#measure
 .. _metadata title: ../doctree.html#title-attribute
 
 .. _Docutils Generic DTD: ../docutils.dtd
@@ -3257,6 +3271,7 @@
     ../../howto/i18n.html#docutils-language-module
 
 .. _PEP 258: ../../peps/pep-0258.html
+.. _writer:
 .. _writers: ../../peps/pep-0258.html#writers
 
 .. _transforms: ../../api/transforms.html

Modified: trunk/docutils/docs/user/latex.rst
===================================================================
--- trunk/docutils/docs/user/latex.rst	2024-09-20 06:31:07 UTC (rev 9934)
+++ trunk/docutils/docs/user/latex.rst	2024-09-20 08:32:28 UTC (rev 9935)
@@ -86,44 +86,54 @@
 .. _docutils.sty: https://ctan.org/pkg/docutils
 
 
+.. _length unit:
 
 Length units
 ------------
 
-LaTeX supports all `length units`_ defined for Docutils plus the
-following less common units:
+The LaTeX writer supports all `reStructuredText length units`_
+with the following peculiarities:
 
-.. class:: narrow
+* In LaTeX, the size of the *pixel unit* `can be configured
+  <size of a "px"_>`__. It defaults to **1 px = 1/72 in**
+  while the `CSS3 pixel unit`_ is defined as 1 px = 1/96 in.
 
-:dd: didôt (1 dd = 1238/1157 pt)
-:cc: cîcero (1 cc = 12 dd)
-:sp: scaled point (1sp = 1/65536pt)
-:bp: "big" point (`DTP point`) (1 bp  = 1/72 in)
+* LaTeX uses "pt" for the `American point`_ (*TeX point*), 1 pt = 1/72.25 in.
+  The `DTP point`_ (*Postscript point*) used in CSS is available in LaTeX
+  as *big point*, 1 bp = 1/72 in.
 
-The **default length unit** (added by the latex writer to length
-values without unit) is the `DTP point` "bp".
+  Lengths specified in the source with unit "pt" are written with unit
+  "bp" by the LaTeX writer.  In `raw LaTeX`_ and `custom style sheets`_,
+  the `DTP point` must be specified as "bp", while "pt" is interpreted as
+  `TeX point`.
 
-.. attention:: Different definitions of the unit "pt"!
+* The **default length unit** (added by the latex writer to length values
+  without unit) is the `DTP point` "**bp**".  It will change to "px" in
+  Docutils 1.0.
 
-   * In Docutils (as well as CSS) the unit symbol "pt" denotes the
-     `Postscript point` (`DTP point`).
+The TeX units:
 
-   * LaTeX uses "pt" for the typewriter's (or LaTeX) point,
-     which is unknown to Docutils and 0.3 % smaller.
+.. class:: align-center
 
-   * The `DTP point` is available in LaTeX as "bp" (big point):
+====  =========================  ===================
+ bp   "big" point (`DTP point`)  1 bp  = 1/72 in
+ cc   cîcero                     1 cc = 12 dd
+ dd   didôt                      1 dd = 1238/1157 pt
+ sp   scaled point               1sp = 1/65536pt
+====  =========================  ===================
 
-       1 pt = 1/72.25 in < 1 bp  = 1/72 in
+can be used in `raw LaTeX`_ and `custom style sheets`_ but not in
+reStructuredText.
 
-   Lengths specified in the document with unit "pt" will be given the
-   unit "bp" in the LaTeX source.
+.. _CSS3 pixel unit: https://www.w3.org/TR/css-values-3/#px
+.. _reStructuredText length units:
+    ../ref/rst/restructuredtext.html#length-units
+.. _American point:
+    https://en.wikipedia.org/wiki/Point_(typography)#American_points
+.. _DTP point:
+    https://en.wikipedia.org/wiki/Point_(typography)#Desktop_publishing_point
 
-   In `raw LaTeX`_ and `custom style sheets`_, the `DTP point` must be
-   specified as "bp", while "pt" is interpreted as `LaTeX point`.
 
-.. _length units: ../ref/rst/restructuredtext.html#length-units
-
-
 PDF generation
 ==============
 
@@ -444,7 +454,7 @@
   (Command ``\DUadmonition`` with legacy-class-functions_.)
 
 Default:
-  Typeset in a frame (90 % of text width).
+  Typeset in a frame (90 % of text width).
 
 The admonition title is typeset with the ``\DUtitle`` command (see `titles`_).
 
@@ -609,10 +619,10 @@
   ``\DUdocinfowidth``: the width for the `docinfo` table.
 
 Default:
-  90 % of text width: ``0.9\textwidth``
+  90 % of text width: ``0.9\textwidth``
 
 Example:
-  set to 70 % of text width::
+  set to 70 % of text width::
 
     \newlength{\DUdocinfowidth}
     \setlength{\DUdocinfowidth}{0.7\textwidth}
@@ -687,7 +697,7 @@
 caption numberings.
 
 Some document classes (e.g. KOMA-script_) provide additional configuration.
-Also see the related `LaTeX FAQ entry`__
+See also `The style of captions`_ in the LaTeX FAQ.
 
 Example
   ::
@@ -697,9 +707,8 @@
 
 .. _caption: https://ctan.org/pkg/caption
 .. _chngcntr: https://ctan.org/pkg/chngcntr
-__ http://www.tex.ac.uk/cgi-bin/texfaq2html?label=running-nos
+.. _The style of captions: https://texfaq.org/FAQ-captsty
 
-
 figure placement
 ----------------
 
@@ -1203,7 +1212,6 @@
 
 __ ../ref/rst/restructuredtext.html#line-blocks
 
-
 line spacing
 ------------
 
@@ -1605,31 +1613,24 @@
 
 __ https://docutils.sourceforge.io/docutils/docs/ref/rst/directives.html#sidebar
 
-size of a pixel
----------------
+size of a "px"
+--------------
 
-The *physical size* of a pixel depends on the resolution of the output
-device and is usually specified in *dots per inch* (DPI).
+The `length unit`_ "px" is `defined in pdfTeX and LuaTeX`__, the "XeTeX"
+writer uses the ``\pdfpxdimen`` macro as workaround.
 
-The *length unit* "px" is defined by the output format. For LaTeX, it is
-`defined in pdfTeX and LuaTeX`__ (the `xetex` writer emulates this
-definition).
-
 Default:
-  72 DPI, i.e. 1 px = 1/72 in. [#]_
+  1 px = 1/72 in
 
 Example:
-  Set the value to match the CSS definition
+  Set the value to match the `CSS3 pixel unit`_ 1 px = 1/96 in
   with the `LaTeX code`_::
 
     \pdfpxdimen=1in
-    \divide\pdfpxdimen by 96 % 1/96 inch
+    \divide\pdfpxdimen by 96
 
-.. [#] The `CSS length unit ``px```_ defaults to 1/96 inch.
-
 __ https://tex.stackexchange.com/questions/41370/
    what-are-the-possible-dimensions-sizes-units-latex-understands
-.. _CSS length unit ``px``: https://www.w3.org/TR/css-values-3/#px
 .. _reference pixel: https://www.w3.org/TR/css-values-3/#reference-pixel
 
 table style
@@ -2004,23 +2005,15 @@
 Why are my images too big?
 ``````````````````````````
 
-HTML-browsers use the actual screen resolution (usually around
-100 DPI).
+In LaTeX, the size of the *pixel unit* defaults to 1 px = 1/72 in
+while the `CSS3 pixel unit`_ is defined as 1 px = 1/96 in.
 
-The CSS specification suggests:
-
-  It is recommended that the reference pixel be the visual angle of one
-  pixel on a device with a pixel density of 96 DPI and a distance from the
-  reader of an arm's length.
-
-  -- https://www.w3.org/TR/CSS2/syndata.html#length-units
-
 This is why pixmap images without size specification or objects with a size
-specified in ``px`` tend to come too large in the PDF.
+specified in ``px`` tend to come out too large in the PDF.
 
 Solution:
-  Specify the image size in fixed units (``pt``, ``cm``, ``in``) or
-  configure the `size of a pixel`_ (length unit px).
+  Specify the image size in fixed `length units`_ (``pt``, ``cm``, ``in``, …)
+  or configure the `size of a "px"`_.
 
 
 Error ``illegal unit px``
@@ -2033,11 +2026,7 @@
 `pdfTeX` is used also for conversion into DVI format in all modern LaTeX
 distributions (since ca. 2006).
 
-If updating LaTeX is not an option, just remove the "px" from the length
-specification. HTML/CSS will default to "px" while the `latexe2` writer
-will add the fallback unit "bp".
 
-
 Error ``Symbol \textcurrency not provided`` ...
 ```````````````````````````````````````````````
 
@@ -2048,15 +2037,13 @@
     (textcomp)                font family ptm in TS1 encoding.
     (textcomp)                Default family used instead.
 
-(which in case of font family "ptm" is a false positive). Add either
+(which in case of font family "ptm" is a false positive).
 
-:warn: turn the error in a warning, use the default symbol (bitmap), or
-:force,almostfull: use the symbol provided by the font at the users
-                     risk,
+Add either ``warn`` (turn the error in a warning, use the default (bitmap)
+symbol), or ``force,almostfull`` (use the symbol provided by the font at
+the users risk) to the document options or use a different font package.
 
-to the document options or use a different font package.
 
-
 Warning: language … not supported
 `````````````````````````````````
 

Modified: trunk/docutils/docs/user/manpage.rst
===================================================================
--- trunk/docutils/docs/user/manpage.rst	2024-09-20 06:31:07 UTC (rev 9934)
+++ trunk/docutils/docs/user/manpage.rst	2024-09-20 08:32:28 UTC (rev 9935)
@@ -146,14 +146,27 @@
     offers opening the standard browser to that URI ... assuming OSC8 is
     supported.
 
-References
-==========
 
-Consult man pages from section 7: *man*, *man-pages*, *groff_man* and
-*groff_man_style*.
+Limitations
+===========
 
-.. [LMHT] `Linux Man Page Howto <https://tldp.org/HOWTO/Man-Page/>`__.
+The "manpage" writer does not support all `Docutils Document Tree`_ elements
+but a subset that is relevant for manual pages.
 
+The output is pure text, images are not included. Instead, the text
+description in their `"alt" attribute`_ is shown.
+
+.. TODO: a warning is given for image elements without `"alt" attribute`_.
+
+The "manpage" writer ignores element attributes specifying a measure_.
+
+.. _measure: ../ref/doctree.html#measure
+.. _"alt" attribute: ../ref/doctree.html#alt
+
+.. groff supports the CSS2 units except "ex", "mm", and "px"
+   https://www.gnu.org/software/groff/manual/groff.html#Measurements
+
+
 Conventions
 ===========
 
@@ -176,8 +189,9 @@
   but this is not done on typesetting devices like printers.  Check your
   output with a PostScript or PDF viewer before printing it.
 
-* [LMHT]_ Filenames are always in italics, except in C language
-  preprocessor inclusions in the SYNOPSIS section.  Use::
+* Filenames are always in italics, except in C language
+  preprocessor inclusions in the SYNOPSIS section. [LMHT]_
+  Use::
 
     .I /usr/include/stdio.h
 
@@ -185,4 +199,14 @@
 
     .B #include <stdio.h>
 
+
+References
+==========
+
+Consult man pages from section 7: *man*, *man-pages*, *groff_man* and
+*groff_man_style*.
+
+.. [LMHT] `Linux Man Page Howto <https://tldp.org/HOWTO/Man-Page/>`__.
+
 .. _Docutils: https://docutils.sourceforge.io/
+.. _Docutils Document Tree: ../ref/doctree.html

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