NAME

CSS::Yamaantaka - Converts direction of Cascading Style Sheet (CSS)

SYNOPSIS

  use CSS::Yamaantaka;
  
  $ya = CSS::Yamaantaka->new('lr_tb' => 'tb_rl');
  $css_source_vertical_rl = $ya->transform($css_source);

DESCRIPTION

As Yamāntaka has many legs, texts can run in various directions: left to right and right to left horizontally; vertically with lines extending right to left and left to right.

CSS::Yamaantaka replaces things directed to "left" or "horizontal-tb" in a Cascading Style Sheet (CSS) file such as float, padding, margin with values directed to "right" or "vertical-rl", and so on.

Transforming directions

Four directions of documents are supported:

lr-tb

The direction specified by { direction: ltr; writing-mode: horizontal-tb; }. For example, most Western writing systems employ it.

rl-tb

The direction specified by { direction: rtl; writing-mode: horizontal-tb; }. For example, some Middle Eastern writing systems employ it.

tb-lr

The direction specified by { writing-mode: vertical-lr; }. For example, several North Asian writing systems employ it.

lr-tb

The direction specified by { writing-mode: vertical-rl; }. East Asian writing systems with vertical layout employ it.

This module chooses transformation by source & resulting directions:

  +-----------+-------------+-------------+-------------+--------------+
  | from \ to | lr-tb       : rl-tb       : tb-lr       : tb-rl        |
  +-----------+-------------+-------------+-------------+--------------+
  | lr-tb     |      -      : MirrorH     : MirrorTL_BR : RotateR      |
  | rl-tb     | MirrorH     :      -      : RotateL*    : MirrorTR_BL* |
  | tb-lr     | MirrorTL_BR : RotateR     :      -      : MirrorV      |
  | tb-rl     | RotateL     : MirrorTR_BL : MirrorV     :       -      |
  +-----------+-------------+-------------+-------------+--------------+
   * Assumed text-orientation: sideways-left.

Each transformation changes line-relative box directions ("right" / "left" of text-align, float and clear, and "top" / "bottom" of vertical-align), physical box directions ("top" / "right" / "bottom" / "left"), global directions specified by body element ("ltr" / "rtl") and direction swapping (horizontal / vertical) as below:

  +-------------+-----------+--------------------------+--------+------+
  |             | line-rel. | box directions           : g. dir : h/v  |
  +-------------+-----------+--------------------------+--------+------+
  | MirrorH     | revert h. : revert horizontally      : revert :   -  |
  | MirrorV     |     -     : revert horizontally      : revert :   -  |
  | RotateR     |     -     : rotate clockwise         : revert : swap |
  | RotateL     |     -     : rotate counter-clockwise : revert : swap |
  | MirrorTL_BR |     -     : revert with tl-br axis   :    -   : swap |
  | MirrorTR_BL |     -     : revert with tr-bl axis   :    -   : swap |
  +-------------+-----------+--------------------------+--------+------+

Currently, this module won't fix line-relative text directions ("rtl" / "ltr").

Constructor

new ( SRC => DEST, [ options... ] )

Creates new CSS::Yamaantaka object.

SRC and DEST are the original and resulting directions. Available directions are 'lr_tb', 'rl_tb', 'tb_lr' and 'tb_rl'. Their synonyms are 'ltr', 'rtl', 'vertical-lr' and 'vertical-rl', respectively.

Following options are available.

flip_url => 0|1

Fixes "top"/"right"/"bottom"/"left" string within URLs. Default is 0, won't fix.

swap_ltr_rtl_in_url => 0|1

Fixes "ltr"/"rtl" string within URLs, if needed. Default is 0, won't fix.

ignore_bad_bgp => 0|1

Ignores unmirrorable background-position values. Default is 0, won't ignore and will croak it.

flip_cursor => 0|1

Fixes positions "n"/"e"/"s"/"w" and so on within cursor properties. Default is 1, will fix.

Methods

body_direction

Get direction property or dir attribute of body element thought to be appropriate. Returns 'ltr', 'rtl' or undef (unknown).

text_orientation

Get text-orientation property of texts assumed. Returns 'sideways-left' or undef (upright or sideways-right is assumed).

transform ( $lines, [ options... ] )

Runs the fixing functions against CSS source.

$lines is a string. Following options are available.

swap_ltr_rtl_in_url => 0|1

Overrides this flag if param is set.

flip_url => 0|1

Overrides this flag if param is set.

flip_cursor => 0|1

Overrides this flag if param is set.

Returns same lines directions are changed.

writing_mode

Get writing-mode property of texts thought to be appropriate. Returns 'horizontal-tb', 'vertical-lr', 'vertical-rl' or undef (unknown).

VERSION

Consult $VERSION variable.

SEE ALSO

CSS::Janus

Extended CSSJanus supporting vertical-rl writing-mode: http://www.epubcafe.jp/download

AUTHOR

Hatuka*nezumi - IKEDA Soji <hatuka(at)nezumi.nu>.

COPYRIGHT

Copyright (C) 2013 Hatuka*nezumi - IKEDA Soji.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

cpanm CSS::Janus

perl -MCPAN -e shell
install CSS::Janus