Key Signature

A key signature cannot be built or modified incrementally by adding or removing one alteration sign at a time. It must be built or modified globally:

  • Either by selecting a compound glyph and assigning the desired key shape,
  • Or by dragging and dropping the desired key shape from the shape palette.

Table of contents

  1. Flats and Sharps
  2. Naturals

Flats and Sharps

When dragging a “ghost” key from the shape palette, the ghost turns from dark-gray to green when we enter a staff and, as usual, a thin red segment is drawn from the ghost center to the staff mid line.

Moreover, the dragged key snaps immediately to the proper vertical position, according to the effective clef at the point of insertion.

For example, let’s insert a 2-sharp key, into the measure that follows the measure with a 3-sharp key:

Note the two sharp signs are located on F and C steps respectively, and they can move only horizontally until we release the mouse.
Once dropped, we can still set the key into editing mode and again shift the inserted key.


As of this writing, the Audiveris OMR engine can recognize all-sharp keys and all-flat keys but no key with natural signs inserted (be it a mix of naturals with sharp/flat signs, or a naturals-only key)

However, we have the ability to manually insert a cancel key – i.e. an all-natural key.

To do so, we drag the 1-natural key from the shape palette and move it to the desired insertion point.

When we enter the target staff, the 1-natural ghost key with turn as usual from dark-gray to green, but its configuration and position will be dynamically updated, to fit both:

  • The effective clef,
  • The effective key to be cancelled.

If for example the effective key is a 3-sharp key, the “cancel” key will be a 3-natural key, with each natural sign located according to the corresponding sharp sign to cancel:

Staff-relative location Cancel Key appearance

We notice that this works only when the ghost is located in a staff measure different from the staff measure that contains the key to be cancelled. This is so because there can’t exist two keys in the same staff measure.