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5.4.9 Aligning objects

Graphical objects which support the self-alignment-interface and/or the side-position-interface can be aligned to a previously placed object in a variety of ways. For a list of these objects, see self-alignment-interface and side-position-interface.

All graphical objects have a reference point, a horizontal extent and a vertical extent. The horizontal extent is a pair of numbers giving the displacements from the reference point of the left and right edges, displacements to the left being negative. The vertical extent is a pair of numbers giving the displacement from the reference point to the bottom and top edges, displacements down being negative.

An object’s position on a staff is given by the values of the X-offset and Y-offset properties. The value of X-offset gives the displacement from the X coordinate of the reference point of the parent object, and the value of Y-offset gives the displacement from the center line of the staff. The values of X-offset and Y-offset may be set directly or may be set to be calculated by procedures in order to achieve alignment with the parent object.

For example, an accidental can be repositioned vertically by setting Y-offset but any changes to X-offset have no effect.

Rehearsal marks may be aligned with breakable objects such as bar lines, clef symbols, time signature symbols and key signatures. There are special properties to be found in the break-aligned-interface for positioning rehearsal marks on such objects.

See also

Notation Reference: Using the break-alignable-interface.

Extending LilyPond: Callback functions.

Setting X-offset and Y-offset directly
Using the side-position-interface
Using the self-alignment-interface
Using the break-alignable-interface