LilyPond Beginnershandleiding

Hoofdstuk 4: Tweaking output 108
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Since the length of stems and many other length-related properties are always calculated relative
to the value of the staff-space property these are automatically scaled down in length too.
Note that this affects only the vertical scale of the ossia – the horizontal scale is determined by
the layout of the main music in order to remain synchronized with it, so it is not affected by
any of these changes in size. Of course, if the scale of all the main music were changed in this
way then the horizontal spacing would be affected. This is discussed later in the layout section.
This, then, completes the creation of an ossia. The sizes and lengths of all other objects may
be modified in analogous ways.
For small changes in scale, as in the example above, the thickness of the various drawn lines
such as bar lines, beams, hairpins, slurs, etc does not usually require global adjustment. If the
thickness of any particular layout object needs to be adjusted this can be best achieved by
overriding its thickness property. An example of changing the thickness of slurs was shown
above in Sectie 4.2.1 [Properties of layout objects], pagina 93. The thickness of all drawn objects
(i.e., those not produced from a font) may be changed in the same way.
4.4 Placement of objects
4.4.1 Automatic behavior
There are some objects in musical notation that belong to the staff and there are other objects
that should be placed outside the staff. These are called within-staff objects and outside-staff
objects respectively.
Within-staff objects are those that are located on the staff – note heads, stems, accidentals,
etc. The positions of these are usually fixed by the music itself – they are vertically positioned
on specific lines of the staff or are tied to other objects that are so positioned. Collisions of note
heads, stems and accidentals in closely set chords are normally avoided automatically. There are
commands and overrides which can modify this automatic behavior, as we shall shortly see.
Objects belonging outside the staff include things such as rehearsal marks, text and dynamic
markings. LilyPond’s rule for the vertical placement of outside-staff objects is to place them as
close to the staff as possible but not so close that they collide with any other object. LilyPond
uses the outside-staff-priority property to determine the order in which the objects should
be placed, as follows.
First, LilyPond places all the within-staff objects. Then it sorts the outside-staff objects
according to their outside-staff-priority. The outside-staff objects are taken one by one,
beginning with the object with the lowest outside-staff-priority, and placed so that they do
not collide with any objects that have already been placed. That is, if two outside-staff grobs are
competing for the same space, the one with the lower outside-staff-priority will be placed
closer to the staff. If two objects have the same outside-staff-priority the one encountered
first will be placed closer to the staff.