CSS Text Module Level 4

1. -Introduction

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2. -Transforming Text

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3. -White Space Processing

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3.1. -White Space Collapsing: the text-space-collapse property

This section is still under discussion and may change in future drafts.

Need a property name

This property declares whether and how - white space inside the element is - collapsed. Values have the following meanings, which must be interpreted - according to the white space processing rules:

- -

collapse - -

- This value directs user agents to collapse sequences of white space - into a single character - (or in some cases, no character). - - -

preserve - -

- This value prevents user agents - from collapsing sequences of white space. - Line feeds are preserved as forced line breaks. - - -

preserve-breaks - -

- This value collapses white space as for collapse, but preserves - line feeds as forced line breaks. - - -

discard - -

- This value directs user agents to "discard" all white space in the - element. - Issue: Does this preserve line break opportunities or no? Do we need a "hide" value? - -

@namespace m "http://www.w3.org/1998/Math/MathML";
-m|* {
-  text-space-collapse: discard;
-}
-m|mi, m|mn, m|mo, m|ms, m|mtext {
-  text-space-collapse: trim-inner;
-}
-

This section is still under discussion and may change in future drafts.

3.2. -White Space Trimming: the text-space-trim property

This property allows authors to specify trimming behavior - at the beginning and end of a box. - Values have the following meanings, - which must be interpreted according to the white space processing rules:

- -

trim-inner - -

- For block containers this value directs UAs to discard all whitespace - at the beginning of the element up to and including the last line feed - before the first non-white-space character in the element as well as - to discard all white space at the end of the element starting with the - first line feed after the last non-white-space character in the element. - For other elements this value directs UAs to discard all whitespace - at the beginning and end of the element. - - -

consume-before - -

- This value directs the UA to collapse all collapsible whitespace - immediately before the start of the element. - - -

consume-after - -

- This value directs the UA to collapse all collapsible whitespace - immediately after the end of the element. - -

dt { display: inline; }
-dt + dt:before { content: ", "; text-space-collapse: consume-before; }
-

4. -Line Breaking and Word Boundaries

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5. -Text Wrapping

Text wrapping is controlled by the text-wrap and overflow-wrap properties:

Add final level 3 overflow-wrap

5.1. -Text Wrap Settings: the text-wrap property

This property specifies the mode for text wrapping. Possible values:

- -

normal - -

- Lines may break at allowed break points, as determined by the - line-breaking rules in effect. Line breaking behavior defined - for the WJ, ZW, and GL line-breaking classes in - [UAX14] must be honored. - - -

nowrap - -

- Lines may not break; text that does not fit within the block container - overflows it. - - -

avoid - -

- Line breaking is suppressed within the element: the UA may only break - within the element if there are no other valid break points in the - line. If the text breaks, line-breaking restrictions are honored as for - normal. - - -

Should this maybe be handled by break-inside?

- - - -

balance - -

- Same as normal for inline-level elements. - For block-level elements that - contain line boxes as direct children, - line breaks are chosen to balance - the inline-size those line boxes consume, - if better balance than normal is possible. - This must not change the number of line boxes - the block would contain - if text-wrap were set to normal. - - -

For balancing purposes, - the inline-size to consider includes - any length taken up - by floats that shorten the line box. - The inline-size to consider comes before - any adjustments for justification. - Line boxes are balanced when the standard deviation - from the average inline-size consumed - is reduced over the block - (including lines that end in a forced break).

- - - -

The exact algorithm is UA-defined.

- - - -

UAs may treat this value as normal if there are more than ten lines to balance.

- - - -

Regardless of the text-wrap value, lines always break at forced breaks: - for all values, line-breaking behavior defined for the BK, CR, LF, CM - NL, and SG line breaking classes in [UAX14] must - be honored.

When text-wrap is set to normal or - avoid, UAs that allow breaks at punctuation other than spaces - should prioritize breakpoints. - For example, if breaks after slashes have a lower priority than spaces, - the sequence “check /etc” will never break between the ‘/’ and the ‘e’. - The UA may use the width of the containing block, the text’s language, - and other factors in assigning priorities. - As long as care is taken to avoid such awkward breaks, allowing breaks at - appropriate punctuation other than spaces is recommended, as it results - in more even-looking margins, particularly in narrow measures.

5.1.1. -Example of using 'text-wrap: avoid' in presenting a footer

footer { text-wrap: avoid; /* inherits to all descendants */ }
-

<footer>
-<venue>27th Internationalization and Unicode Conference</venue>
-&#8226; <date>April 7, 2005</date> &#8226;
-<place>Berlin, Germany</place>
-</footer>
-

27th Internationalization and Unicode Conference •
-April 7, 2005 • Berlin, Germany
-

27th Internationalization and Unicode
-Conference • April 7, 2005 •
-Berlin, Germany
-

27th Internationalization and Unicode Conference • April
-7, 2005 • Berlin, Germany
-

6. -Last Line Minimum Length

7. -Shorthand for White Space and Wrapping: the white-space property

Diff needs to have the shorthand details

8. -Breaking Within Words

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8.1. -Hyphens: the hyphenate-character property

This property specifies strings that are shown between parts of - hyphenated words. The auto value means that the user agent should - find an appropriate value, preferably from the same source as the - hyphenation dictionary. If a string is specified, it appears at - the end of the line before a hyphenation break.

article { hyphenate-character: "\2010" }
-

- Both hyphens triggered by automatic hyphenation and - hyphens triggered by soft hyphens are rendered according to - hyphenate-character. - -

8.2. -Hyphenation Size Limit: the hyphenate-limit-zone property

Is hyphenate-limit-zone a good name? Comments/suggestions? - -

This property specifies the maximum amount of unfilled space (before - justification) that may be left in the line box before hyphenation is - triggered to pull part of a word from the next line back up into the - current line.

8.3. -Hyphenation Character Limits: the hyphenate-limit-chars property

This property specifies the minimum number of characters in a - hyphenated word. If the word does not meet the required minimum - number of characters in the word / before the hyphen / after the - hyphen, then the word must not be hyphenated. Nonspacing combining - marks (Unicode class) and intra-word - punctuation (Unicode classes P*) do not count towards the minimum.

If three values are specified, the first value is the required - minimum for the total characters in a word, the second value is - the minimum for characters before the hyphenation point, and - the third value is the minimum for characters after the hyphenation - point. If the third value is missing, it is the same as the second. - If the second value is missing, then it is auto. The auto - value means that the UA chooses a value that adapts to the current - layout.

Unless the UA is able to calculate a better value, it - is suggested that auto means 2 for before and after, and 5 for - the word total. - -

p { hyphenate-limit-chars: auto 3; }
-

8.4. -Hyphenation Line Limits: the hyphenate-limit-lines and hyphenate-limit-last properties

This property indicates the maximum number of successive hyphenated - lines in an element. The no-limit value means that there is no limit.

In some cases, user agents may not be able to honor the specified value. - (See overflow-wrap.) It is not defined whether hyphenation introduced by - such emergency breaking influences nearby hyphenation points.

This property indicates hyphenation behavior at the end of elements, - column, pages and spreads. A spread is a set of two pages that are - visible to the reader at the same time. Values are:

- -

none - -

- No restrictions imposed. - - -

always - -

- The last full line of the element, or the last line before any - column, page, or spread break inside the element should not be - hyphenated. - - -

column - -

- The last line before any column, page, or spread break inside - the element should not be hyphenated. - - -

page - -

- The last line before page or spread break inside the element - should not be hyphenated. - - -

spread - -

- The last line before any spread break inside the element should - not be hyphenated. - -

p { hyphenate-limit-last: always }
-div.chapter {  hyphenate-limit-last: spread }
-

This is just a
-simple example
-to show Antarc-
-tica.
-

This is just a
-simple example
-to        show
-Antarctica.
-

9. -Alignment and Justification

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Add this value to text-align

- -

<string> - - -

- The string must be a single character; otherwise the declaration must - be ignored. - When applied to a table cell, specifies the alignment character - around which the cell’s contents will align. See - below for further details and - how this value combines with keywords. - -

9.1. -Character-based Alignment in a Table Column

When multiple cells in a column have an alignment character specified, - the alignment character of each such cell in the column is centered along - a single column-parallel axis and the rest of the text in the column - shifted accordingly. (Note that the strings do not have to be the same - for each cell, although they usually are.)

TD { text-align: "." center }
-

<TABLE>
-<COL width="40">
-<TR> <TH>Long distance calls
-<TR> <TD> $1.30
-<TR> <TD> $2.50
-<TR> <TD> $10.80
-<TR> <TD> $111.01
-<TR> <TD> $85.
-<TR> <TD> N/A
-<TR> <TD> $.05
-<TR> <TD> $.06
-</TABLE>
-

+---------------------+
-| Long distance calls |
-+---------------------+
-|        $11.30       |
-|        $22.50       |
-|         $0.80       |
-|    $200567.01       |
-|        $85.         |
-|        N/A          |
-|          $.05       |
-|          $.06       |
-+---------------------+
-

A keyword value may be specified in conjunction with the <string> - value; if it is not given, it defaults to right. This value is used:

- -
• - when character-based alignment is applied to boxes that are not table - cells. - -
• - when the text wraps to multiple lines (at unforced break points). - -
• - when a character-aligned cell spans more than one column. In this - case the keyword alignment value is used to determine which column’s - axis to align with: the leftmost column for left, the rightmost - column for right and center, the startmost column for start, - the endmost column for end. - -
• - when the column is wide enough that the character alignment alone does - not determine the positions of its character-aligned contents. In this - case the keyword alignment of the first cell in the column with a - specified alignment character is used to slide the position of the - character-aligned contents to match the keyword alignment insofar as - possible without changing the width of the column. - For center, the UA may center - the aligned contents using its extremes, center the alignment axis - itself (insofar as possible), or optically center the aligned contents - some other way (such as by taking a weighted average of the extent of - the cells' contents to either side of the axis). - -

- Right alignment is used by default for character-based - alignment because numbering systems are almost all left-to-right even - in right-to-left writing systems, and the primary use case of - character-based alignment is for numerical alignment. -

If the alignment character appears more than once in the text, the first - instance is used for alignment. If the alignment character does not appear - in a cell at all, the string is aligned as if the alignment character had - been inserted at the end of its contents.

Character-based alignment occurs before table cell width computation so - that auto width computations can leave enough space for alignment. - Whether column-spanning cells participate in the alignment prior to - or after width computation is undefined. - If width constraints on the cell contents prevent full alignment - throughout the column, the resulting alignment is undefined.

10. -Spacing

Add final level 3 word-spacing, letter-spacing

10.1. -Character Class Spacing: the text-spacing property

This property controls spacing between adjacent characters - on the same line within the same inline formatting context - using a set of character-class-based rules. - Such spacing can either be created between or trimmed from the affected glyphs. - Values are defined as follows:

- -

normal - -

- Specifies the baseline behavior, - equivalent to space-start allow-end trim-adjacent. - - -

none - -

- Turns off all text-spacing features. - All fullwidth characters are set with full-width glyphs. - - -

ideograph-alpha - -

- Creates 1/4em extra spacing between runs of - ideographs and non-ideographic letters. - - -

Note: A commonly used algorithm for determining this behavior is specified in [JLREQ].

- - - -

ideograph-numeric - -

- Creates 1/4em extra spacing between runs of - ideographs and non-ideographic numerals glyphs. - - -

Note: A commonly used algorithm for determining this behavior is specified in [JLREQ].

- - - -

punctuation - -

- Creates extra non-breaking spacing around punctuation as required by language-specific typographic conventions. - - -

In this level, if the element’s content language is French, - narrow no-break space (U+202F) and no-break space (U+00A0) is inserted - where required by French typographic guidelines. - Otherwise this value has no effect. - However future specifications may add automatic spacing behavior for other languages.

- - - -

space-start - -

- Set fullwidth opening punctuation with full-width glyphs (spaced) - at the start of each line. - - -

trim-start - -

- Set fullwidth opening punctuation with half-width glyphs (flush) - at the start of each line. - - -

allow-end - -

- Set fullwidth closing punctuation with half-width glyphs (flush) - at the end of each line - if it does not otherwise fit prior to justification; - otherwise set the punctuation with full-width glyphs. - - -

space-end - -

- Set fullwidth opening punctuation with full-width glyphs (spaced) - at the start of each line. - - -

trim-end - -

- Set fullwidth closing punctuation with half-width glyphs (flush) - at the end of each line. - - -

space-adjacent - -

- Set fullwidth opening punctuation with full-width glyphs (spaced) - when not at the start of the line. - Set fullwidth closing punctuation with full-width glyphs (spaced) - when not at the end of the line. - - -

trim-adjacent - -

- Collapse spacing between punctuation glyphs - as described below. - - -

no-compress - -

- Justification may not compress text-spacing. - (If this value is not specified, the justification process may reduce autospacing - except when the spacing is at the start or end of the line.) - - -

Note: An example of compression rules is given for Japanese - in 3.8 Line Adjustment in [JLREQ].

- - -

This property is additive with the word-spacing and letter-spacing properties. - That is, the amount of spacing contributed by the letter-spacing setting (if any) - is added to the spacing created by text-spacing. - The same applies to word-spacing.

At element boundaries, the amount of extra spacing introduced between characters - is determined by and rendered within the innermost element that contains the boundary. - If the extra spacing is applied to a particular glyph, - then the spacing is determined by the innermost element containing that glyph.

Note: Values other than normal, none, trim-start, trim-end, and space-end - are at-risk and may be dropped from this level of CSS. - They are defined here currently to help work out a complete design of this feature.

Support for this property is optional. - It is strongly recommended for UAs that wish to support CJK typography.

It was requested to add a value for doubling the space after periods.

10.1.1. -Fullwidth Punctuation Collapsing

Typically, fullwidth characters have glyphs with the same advance width - as a standard Han character (e.g. 水 U+6C34). - However, many fullwidth punctuation glyphs only take up part of the fullwidth design space. - Thus such punctuation are not always set fullwidth. - Several values of text-spacing allow the author to control - when such characters are set half-width (typically half the width of an ideograph) - and when they are set full-width.

In order to set the text as specified, the UA will need to either

- -
• - trim (kern) the blank half of the glyphs, - if they are given full-width and must be set half-width, or - -
• - add space to the glyphs, - if they are given half-width must be set full-width. - -

Some fonts use proportional glyphs for fullwidth punctuation characters. - For such proportional glyphs, the given advance width is considered - simultaneously full-width and half-width: no space is added or removed.

- The advance width of a standard Han character - can be determined either from font metrics - such as the OpenType ideo and idtp baselines for the opposite writing mode, - or by taking the advance width of a Han character such as 水 U+6C34. - (The opposite writing mode must be used because some fonts are compressed - so that the characters are not square.) - More information on OpenType metrics can be found - in the OpenType spec. - Note that if 水 U+6C34, 卜 U+535C, and 一 U+4E00 do not all have the same advance width, - the font has proportional ideographs - and the fullwidth advance width cannot be reliably determined by measuring glyphs. - -

Unless text-spacing is set to space-adjacent or none - (or the font has proportional fullwidth punctuation glyphs), - the UA must collapse the space typically associated with such full width glyphs - as follows:

- -
• - Set fullwidth opening punctuation half-width if the previous character is - a fullwidth opening punctuation, - fullwidth middle dot punctuation, - or ideographic space (U+3000). - Else set it full-width. - -
• - Set fullwidth closing punctuation half-width if the next character is - a fullwidth closing punctuation, - fullwidth middle dot punctuation, - or ideographic space (U+3000). - Else set it full-width. - -
• - Set fullwidth closing punctuation followed by fullwidth opening punctuation - each at "3/4-width", i.e. halfway between full-width and half-width. - -

10.1.2. -Text Spacing Character Classes

In the context of this property the following definitions apply:

Classes and Unicode code points need to be reviewed.

- -

ideographs - -

Includes all typographic character units [CSS3TEXT] whose base character is listed below: - -

- -
• All characters in the range of U+3041 to U+30FF, - except those that belong to Unicode Punctuation [P*] category. - -
• CJK Strokes (U+31C0 to U+31EF). - -
• Katakana Phonetic Extensions (U+31F0 to U+31FF). - -
• All characters that belongs to Han Unicode Script Property [UAX24]. - -

- - - -

ion-ideographic letters - -

- Includes all typographic character units that - belong to Unicode Letters [L*] and Mark [M*] category, - except when any of the following conditions are met: - -

- -
• is defined as ideograph. - -
• is categorized as East Asian Fullwidth (F) by [UAX11]. - -
• is upright in vertical text flow using the text-orientation property - or the text-combine-upright property. - -

- - - -

non-ideographic numerals - -

- Includes all typographic character units that - belong to the Unicode Decimal Digit Number [Nd] category, - except when any of the following conditions are met: - -

- -
• is categorized as East Asian Fullwidth (F) by [UAX11]. - -
• is upright in vertical text flow using the text-orientation property - or the text-combine-upright property. - -

- - - -

fullwidth opening punctuation - -

- Includes any opening punctuation character (Unicode category Ps) - that belongs to the CJK Symbols and Punctuation block (U+3000–U+303F) - or is categorized as East Asian Fullwidth (F) by [UAX11]. - Also includes LEFT SINGLE QUOTATION MARK (U+2018) and LEFT DOUBLE QUOTATION MARK (U+201C). - When trimmed, the left (for horizontal text) or top (for vertical text) half is kerned. - - -

fullwidth closing punctuation - -

- Includes any closing punctuation character (Unicode category Pe) - that belongs to the CJK Symbols and Punctuation block (U+3000–U+303F) - or is categorized as East Asian Fullwidth (F) by [UAX11]. - Also includes RIGHT SINGLE QUOTATION MARK (U+2019) and RIGHT DOUBLE QUOTATION MARK (U+201D). - May also include fullwidth colon punctuation and/or fullwidth dot punctuation (see below). - When trimmed, the right (for horizontal text) or bottom (for vertical text) half is kerned. - - -

fullwidth middle dot punctuation - -

- Includes MIDDLE DOT (U+00B7), HYPHENATION POINT (U+2027), and KATAKANA MIDDLE DOT (U+30FB). - May also include fullwidth colon punctuation and/or fullwidth dot punctuation (see below). - - -

fullwidth colon punctuation - -

- Includes FULLWIDTH COLON (U+FF1A) and FULLWIDTH SEMICOLON (U+FF1B). - - -

fullwidth dot punctuation - -

- Includes - IDEOGRAPHIC COMMA (U+3001), - IDEOGRAPHIC FULL STOP (U+3002), - FULLWIDTH COMMA (U+FF0C), - FULLWIDTH FULL STOP (U+FF0E). - -

Whether fullwidth colon punctuation and fullwidth dot punctuation - should be considered fullwidth closing punctuation or fullwidth middle dot punctuation - depends on where in the glyph’s box the punctuation is drawn. - If the punctuation is centered, - then it should be considered middle dot punctuation. - If the punctuation is drawn to one side (left in horizontal text, top in vertical text) - and the other half is therefore blank - then the punctuation should be considered closing punctuation and trimmed accordingly.

The UA must classify fullwidth colon punctuation and fullwidth dot punctuation - under either the fullwidth closing punctuation category or the fullwidth middle dot punctuation category - as appropriate. - The UA may rely on language conventions and the writing mode (horizontal vs. vertical), - and/or font information to determine this categorization. - The UA may also add additional characters to any category as appropriate.

10.1.3. -Japanese Paragraph-start Conventions in CSS

- Japanese has three common start-edge typesetting schemes, - which are distinguished by their handling of opening brackets. - - -

- - -

Positioning of opening brackets at line head [JLREQ] -

-

- - - -

Assuming a UA style sheet of p { margin: 1em 0; }, - CSS can achieve the Japanese typesetting styles with the following rules:

- - - -

- -
• - Brackets flush with indent, flush with other lines (first scheme): - -

  p { /* Flush alignment */
  -  margin: 0;
  -  text-indent: 1em;
  -  text-spacing: trim-start;
  -}
  -

  - - - -
• - Brackets preserve fullwidth spacing on all lines (second scheme): - -

  p { /* Fullwidth alignment */
  -  margin: 0;
  -  text-indent: 1em;
  -  text-spacing: normal;
  -}
  -

  - - - -
• - Brackets hang in indent, flush with other lines (third scheme): - -

  p { /* Hanging alignment */
  -  margin: 0;
  -  text-indent: 1em;
  -  text-spacing: trim-start;
  -  hanging-punctuation: first;
  -}
  -

  - - - -

- - -

11. -Edge Effects

Add final level 3 content

-Acknowledgements

Add final level 3 list, with Randy Edmunds and Florian Rivoal added