I developed an intuitive interface for music notation.
I created this to facilitate picking notes for the fingering chart apps, and have utilized it in most every app since.
The instinctive gesture of touching the staff seemed so natural, and then to slide right for sharp and left for flat was simply the next step.
To make it easier to choose sharps or flats, I decided that touching along the right or left side would be a natural progression to automatically set a sharp or flat note.
The formulas for manipulating the images of notes and accidentals has developed over time, becoming more versatile and streamlined with each implementation.
Twelve Tone introduced the ability to notate more than one note on the same staff. Twelve actually. So I had to isolate the controls for each note to its own area. This opened up more opportunities and I hope to incorporate it into Vocal Exercises to allow the creation of custom exercises. Who knows what will be next.
The piano keyboard is familiar to us all whether the piano is our primary instrument or not. We have all been taught where middle C is - or at least how to find a C somewhere on the piano and we can guess which one is the most middle. So, the keyboard interface was started with a pretty obvious understanding.
You need to be able to play a key and not have any other key next to it play. Simple enough. I wanted more.
When learning to play the piano, I was taught that chromatic scales were written in sharps when ascending and flats when descending. So I incorporated this in the relationship between the piano and the notation. Glissandos or any time the finger was dragged to the right (up) the keyboard, (while also in the upper portion of the keyboard where the black keys are), the notes would be written in sharps. When dragging to the left, they would be written in flats.
The problem of how to notate with a specific accidental by using the keyboard had been solved.