### 3.2.9 bar-line-interface

Print a special bar symbol. It replaces the regular bar symbol with a special symbol. The argument bartype is a string which specifies the kind of bar line to print.

The list of allowed glyphs and predefined bar lines can be found in ‘`scm/bar-line.scm`’.

`gap` is used for the gaps in dashed bar lines.

#### User settable properties:

> `allow-span-bar` (boolean)

>   If false, no inter-staff bar line will be created below this bar line.

> `bar-extent` (pair of numbers)

>   The Y-extent of the actual bar line. This may differ from `Y-extent` because it does not include the dots in a repeat bar line.

> `gap` (dimension, in staff space)

>   Size of a gap in a variable symbol.

> `glyph` (string)

>   A string determining what ‘style’ of glyph is typeset. Valid choices depend on the function that is reading this property.

>   In combination with (span) bar lines, it is a string resembling the bar line appearance in ASCII form.

> `glyph-name` (string)

>   The glyph name within the font.

>   In the context of (span) bar lines, glyph-name represents a processed form of `glyph`, where decisions about line breaking etc. are already taken.

> `hair-thickness` (number)

>   Thickness of the thin line in a bar line.

> `kern` (dimension, in staff space)

>   Amount of extra white space to add. For bar lines, this is the amount of space after a thick line.

> `rounded` (boolean)

>   Decide whether lines should be drawn rounded or not.

> `thin-kern` (number)

>   The space after a hair-line in a bar line.

> `thick-thickness` (number)

>   Bar line thickness, measured in `line-thickness`.

#### Internal properties:

> `has-span-bar` (pair)

>   A pair of grobs containing the span bars to be drawn below and above the staff. If no span bar is in a position, the respective element is set to `#f`.

This grob interface is used in the following graphical object(s): BarLine and SpanBar.

#### Internals Reference v2.18.2 (稳定分支).