Add new paragraph justification option "Maximum letter spacing"
to distribute letters on (part of) the available blank area of the
justified line instead of overstretching word spacing, like DTP
software do.
This improves typography a lot, allowing typesetting visually better
i.e. more readable paragraphs, minimizing or removing rivers and
too big word spacing (which was common in columns or text without
hyphenation).
* Add spin box to Alignment in paragraph formatting dialog window,
(also add spin boxes for future Minimum and the alternative
percent-based Desired letter spacing, see CharKerning);
For example (only ASCII visualization!), 100% maximum letter
spacing adds a space character-width blank space between the
characters, including the original space:
0%:
Lorem ipsum
pellentesque dolores
vitae.
100%:
L o r e m i p s u m
pellentesque dolores
vitae.
Normal value: 3%-5% (or more for very narrow columns), which means
e.g. 1-2 twips (twip = 1/20 pt) letter spacing in a ~12 pt text.
Note: resolution of the custom letter spacing is only 1 twip yet.
* Store properties in paragraph model:
css::style::ParagraphProperties::ParaPropLetterSpacingMaximum
css::style::ParagraphProperties::ParaPropLetterSpacingMinimum
Note: desired letter spacing is already supported by ODF/UNO,
see css::style::CharacterProperties::CharKerning.
* Implement visual layout of maximum letter spacing.
Note: after the last character of the line, there is an
unwanted letter-spacing, yet (which is visible only with
big letter-spacing values).
* Add ODF import/export (loext:letter-spacing-maximum and
loext:letter-spacing-minimum)
* Add ODF unit test.
Note: hyphenated lines and lines with multiple portions do not
yet use custom letter spacing, yet.
Change-Id: Ieac9f21631b90ae46bed4501f12da0d15ed84d63
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/188653
Tested-by: László Németh <nemeth@numbertext.org>
Tested-by: Jenkins
Reviewed-by: László Németh <nemeth@numbertext.org>
László Németh
f83a04c510