fribidi_reorder_line (3) - Linux Manuals

fribidi_reorder_line: reorder a line of logical string to visual

NAME

fribidi_reorder_line - reorder a line of logical string to visual

SYNOPSIS

#include <fribidi.h>

extern FriBidiLevel fribidi_reorder_line
(
       FriBidiFlags flags,

       const FriBidiCharType *bidi_types,

       const FriBidiStrIndex len,

       const FriBidiStrIndex off,

       const FriBidiParType base_dir,

       FriBidiLevel *embedding_levels,

       FriBidiChar *visual_str,

       FriBidiStrIndex *map

);

PARAMETERS

FriBidiFlags flags

Reorder flags.

const FriBidiCharType *bidi_types

Input list of bidi types as returned by fribidi_get_bidi_types().

Since there are 23 possible values for a const FriBidiCharType, they are not all listed here.

const FriBidiStrIndex len

Input length of the line.

const FriBidiStrIndex off

Input offset of the beginning of the line in the paragraph.

const FriBidiParType base_dir

Resolved paragraph base direction.

Possible values for a const FriBidiParType are as follows:

FRIBIDI_PAR_LTR

Left-To-Right paragraph.

FRIBIDI_PAR_RTL

Right-To-Left paragraph.

FRIBIDI_PAR_ON

DirectiOn-Neutral paragraph.

FRIBIDI_PAR_WLTR

Weak Left To Right paragraph.

FRIBIDI_PAR_WRTL

Weak Right To Left paragraph.

FriBidiLevel *embedding_levels

Input list of embedding levels, as returned by fribidi_get_par_embedding_levels.

FriBidiChar *visual_str

Visual string to reorder.

FriBidiStrIndex *map

A map of string indices which is reordered to reflect where each glyph ends up.

DESCRIPTION

This function reorders the characters in a line of text from logical to final visual order. This function implements part 4 of rule L1, and rules L2 and L3 of the Unicode Bidirectional Algorithm available at http://www.unicode.org/reports/tr9/#Reordering_Resolved_Levels.

As a side effect it also sets position maps if not NULL.

You should provide the resolved paragraph direction and embedding levels as set by fribidi_get_par_embedding_levels(). Also note that the embedding levels may change a bit. To be exact, the embedding level of any sequence of white space at the end of line is reset to the paragraph embedding level (That is part 4 of rule L1).

Note that the bidi types and embedding levels are not reordered. You can reorder these (or any other) arrays using the map later. The user is responsible to initialize map to something sensible, like an identity mapping, or pass NULL if no map is needed.

There is an optional part to this function, which is whether non-spacing marks for right-to-left parts of the text should be reordered to come after their base characters in the visual string or not. Most rendering engines expect this behavior, but console-based systems for example do not like it. This is controlled by the FRIBIDI_FLAG_REORDER_NSM flag. The flag is on in FRIBIDI_FLAGS_DEFAULT.

RETURNS

Maximum level found in this line plus one, or zero if any error occurred (memory allocation failure most probably).