### 3.1.29 `ChordSquare`

In a chord grid, this grob represents one chord square. It helps place `GridChordName` grobs, and draws lines to separate them. Note that this grob only draws the diagonal lines in a square. The borders of the square are drawn by `StaffSymbol` and `BarLine`.

`ChordSquare` objects are created by: `Chord_square_engraver`.

Standard settings:

`measure-division-chord-placement-alist` (association list (list of pairs)):
```'(((1) (0 . 0))
((1/2 1/2) (-0.4 . 0.4) (0.4 . -0.4))
((1/2 1/4 1/4)
(-0.4 . 0.4)
(0 . -0.65)
(0.63 . 0))
((1/4 1/4 1/2)
(-0.63 . 0)
(0 . 0.65)
(0.4 . -0.4))
((1/4 1/4 1/4 1/4)
(-0.63 . 0)
(0 . 0.7)
(0 . -0.65)
(0.63 . 0))
((1/4 3/4) (-0.63 . 0) (0.38 . 0))
((3/4 1/4) (-0.38 . 0) (0.63 . 0)))
```

An alist mapping measure divisions (see the `measure-division` property) to lists of coordinates (number pairs) applied to the chord names of a chord square. Coordinates are normalized between -1 and 1 within the square.

`measure-division-lines-alist` (association list (list of pairs)):
```'(((1))
((1/2 1/2) (-1 -1 1 1))
((1/2 1/4 1/4) (-1 -1 1 1) (0 0 1 -1))
((1/4 1/4 1/2) (-1 -1 1 1) (-1 1 0 0))
((1/4 1/4 1/4 1/4) (-1 -1 1 1) (-1 1 1 -1))
((1/4 3/4) (-1 -1 0 0) (-1 1 0 0))
((3/4 1/4) (0 0 1 -1) (0 0 1 1)))
```

An alist mapping measure divisions (see the `measure-division` property) to lists of lines to draw in the square, given as 4-element lists: `(x-start y-start x-end y-end)`.

`stencil` (stencil):

`chord-square::print`

The symbol to print.

`X-extent` (pair of numbers):

`chord-square::width`

Extent (size) in the X direction, measured in staff-space units, relative to object’s reference point.

`Y-extent` (pair of numbers):

`#<unpure-pure-container #<procedure chord-square::height (grob)> >`

Extent (size) in the Y direction, measured in staff-space units, relative to object’s reference point.

This object supports the following interface(s): `chord-square-interface`, `grob-interface`, `line-interface` and `spanner-interface`.

This object is of class Spanner (characterized by `spanner-interface`).