Bidirectional Text: Pango Reference Manual

## Bidirectional Text

Bidirectional Text — Types and functions to help with handling bidirectional text

## Functions

PangoDirection | pango_unichar_direction ()
PangoDirection | pango_find_base_dir ()
gboolean | pango_get_mirror_char ()
PangoBidiType | pango_bidi_type_for_unichar ()

## Types and Values

enum | PangoDirection
enum | PangoBidiType

## Object Hierarchy

        GEnum
        ├── PangoBidiType
        ╰── PangoDirection

## Description

Pango supports bidirectional text (like Arabic and Hebrew) automatically. Some applications however, need some help to correctly handle bidirectional text.

The PangoDirection type can be used with `pango_context_set_base_dir()` to instruct Pango about direction of text, though in most cases Pango detects that correctly and automatically. The rest of the facilities in this section are used internally by Pango already, and are provided to help applications that need more direct control over bidirectional setting of text.

## Functions

### pango_unichar_direction ()

    PangoDirection
    pango_unichar_direction (gunichar ch);

Determines the inherent direction of a character; either `PANGO_DIRECTION_LTR`, `PANGO_DIRECTION_RTL`, or `PANGO_DIRECTION_NEUTRAL`.

This function is useful to categorize characters into left-to-right letters, right-to-left letters, and everything else. If full Unicode bidirectional type of a character is needed, `pango_bidi_type_for_unichar()` can be used instead.

#### Parameters

ch | a Unicode character |

#### Returns

the direction of the character.

### pango_find_base_dir ()

    PangoDirection
    pango_find_base_dir (const gchar *text,
                         gint length);

Searches a string the first character that has a strong direction, according to the Unicode bidirectional algorithm.

#### Parameters

text | the text to process |
length | length of `text` in bytes (may be -1 if `text` is nul-terminated) |

#### Returns

The direction corresponding to the first strong character. If no such character is found, then `PANGO_DIRECTION_NEUTRAL` is returned.

Since: 1.4

### pango_get_mirror_char ()

    gboolean
    pango_get_mirror_char (gunichar ch,
                           gunichar *mirrored_ch);

`pango_get_mirror_char` is deprecated and should not be used in newly-written code.

If `ch` has the Unicode mirrored property and there is another Unicode character that typically has a glyph that is the mirror image of `ch` 's glyph, puts that character in the address pointed to by `mirrored_ch` .

Use `g_unichar_get_mirror_char()` instead; the docs for that function provide full details.

#### Parameters

ch | a Unicode character |
mirrored_ch | location to store the mirrored character |

#### Returns

`TRUE` if `ch` has a mirrored character and `mirrored_ch` is filled in, `FALSE` otherwise

### pango_bidi_type_for_unichar ()

    PangoBidiType
    pango_bidi_type_for_unichar (gunichar ch);

Determines the normative bidirectional character type of a character, as specified in the Unicode Character Database.

A simplified version of this function is available as `pango_unichar_direction()`.

#### Parameters

ch | a Unicode character |

#### Returns

the bidirectional character type, as used in the Unicode bidirectional algorithm.

Since: 1.22

## Types and Values

### enum PangoDirection

The PangoDirection type represents a direction in the Unicode bidirectional algorithm; not every value in this enumeration makes sense for every usage of PangoDirection; for example, the return value of `pango_unichar_direction()` and `pango_find_base_dir()` cannot be `PANGO_DIRECTION_WEAK_LTR` or `PANGO_DIRECTION_WEAK_RTL`, since every character is either neutral or has a strong direction; on the other hand `PANGO_DIRECTION_NEUTRAL` doesn't make sense to pass to `pango_itemize_with_base_dir()`.

The `PANGO_DIRECTION_TTB_LTR`, `PANGO_DIRECTION_TTB_RTL` values come from an earlier interpretation of this enumeration as the writing direction of a block of text and are no longer used; See PangoGravity for how vertical text is handled in Pango.

#### Members

PANGO_DIRECTION_LTR | A strong left-to-right direction |
PANGO_DIRECTION_RTL | A strong right-to-left direction |
PANGO_DIRECTION_TTB_LTR | Deprecated value; treated the same as `PANGO_DIRECTION_RTL`. |
PANGO_DIRECTION_TTB_RTL | Deprecated value; treated the same as `PANGO_DIRECTION_LTR` |
PANGO_DIRECTION_WEAK_LTR | A weak left-to-right direction |
PANGO_DIRECTION_WEAK_RTL | A weak right-to-left direction |
PANGO_DIRECTION_NEUTRAL | No direction specified |

### enum PangoBidiType

The PangoBidiType type represents the bidirectional character type of a Unicode character as specified by the

Unicode bidirectional algorithm.

#### Members

PANGO_BIDI_TYPE_L | Left-to-Right |
PANGO_BIDI_TYPE_LRE | Left-to-Right Embedding |
PANGO_BIDI_TYPE_LRO | Left-to-Right Override |
PANGO_BIDI_TYPE_R | Right-to-Left |
PANGO_BIDI_TYPE_AL | Right-to-Left Arabic |
PANGO_BIDI_TYPE_RLE | Right-to-Left Embedding |
PANGO_BIDI_TYPE_RLO | Right-to-Left Override |
PANGO_BIDI_TYPE_PDF | Pop Directional Format |
PANGO_BIDI_TYPE_EN | European Number |
PANGO_BIDI_TYPE_ES | European Number Separator |
PANGO_BIDI_TYPE_ET | European Number Terminator |
PANGO_BIDI_TYPE_AN | Arabic Number |
PANGO_BIDI_TYPE_CS | Common Number Separator |
PANGO_BIDI_TYPE_NSM | Nonspacing Mark |
PANGO_BIDI_TYPE_BN | Boundary Neutral |
PANGO_BIDI_TYPE_B | Paragraph Separator |
PANGO_BIDI_TYPE_S | Segment Separator |
PANGO_BIDI_TYPE_WS | Whitespace |
PANGO_BIDI_TYPE_ON | Other Neutrals |

Since: 1.22

## See Also

pango_context_get_base_dir(), `pango_context_set_base_dir()`, `pango_itemize_with_base_dir()`