LilyPond Beginnershandleiding

Hoofdstuk 4: Tweaking output 91
The \overrideProperty command
There is another form of the override command, \overrideProperty, which is occasionally
required. We mention it here for completeness, but for details see Sectie “Difficult tweaks” in
Uitbreidingen.
The \tweak command
The final tweaking command which is available is \tweak. This should be used when several
objects occur at the same musical moment, but you only want to change the properties of
selected ones, such as a single note within a chord. Using \override would affect all the notes
within a chord, whereas \tweak affects just the following item in the input stream.
Here’s an example. Suppose we wish to change the size of the middle note head (the E) in a
C major chord. Let’s first see what \once \override would do:
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\once \override NoteHead.font-size = #-3
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We see the override affects all the note heads in the chord. This is because all the notes of a
chord occur at the same musical moment, and the action of \once is to apply the override to all
layout objects of the type specified which occur at the same musical moment as the \override
command itself.
The \tweak command operates in a different way. It acts on the immediately following item
in the input stream. In its simplest form, it is effective only on objects which are created directly
from the following item, essentially note heads and articulations.
So to return to our example, the size of the middle note of a chord would be changed in this
way:
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Note that the syntax of \tweak is different from that of the \override command. The
context should not be specified; in fact, it would generate an error to do so. Both context and
layout object are implied by the following item in the input stream. Note also that an equals
sign should not be present. So the simple form of the \tweak command is
\tweak layout-property #value
A \tweak command can also be used to modify just one in a series of articulations, as shown
here:
a4^"Black"
-\tweak color #red ^"Red"
-\tweak color #green _"Green"