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The user is first presented with the splash screen that has persisted since our first iteration. This splash screen is consistent with other Android applications and generally serves as a confirmation to the user that they clicked the right application and that everything is working correctly.
The user clicks the button to continue to his music library, which lists the compositions stored in the phone’s internal memory. The compositions are sorted in alphabetical order. When the library is empty, an indication is shown on the screen (“User Library (Empty)”), based on feedback from the heuristic evaluations.
Another request was a “long-click” functionality that gives additional information about the indicated song.
These details can only be edited in Edit Mode.
The new song settings screen is displayed when the user chooses to create a new composition. Default values were requested in the heuristic evaluations.
In Edit Mode, the user can add and remove notes as well as change clef, meter, key signature, title, and tempo. The ability to modify all of these song fields was requested in heuristic evaluation.
The user is given feedback when the buttons are clicked to add notes or flats / sharps / naturals to the screen. This was an original design choice because it gives the user a hint regarding the mode of the application.
When the user adds notes to the song, they snap vertically and horizontally for compact and consistent spacing. Accidentals can only be added to notes (not rests) and snap to a location near their note. 
When the user places enough notes on the screen, they can move a subsequent screen and continue placing notes. We originally wanted the user to scroll the score to the left using a finger swipe, but we feel the current implementation is more consistent with the moded note placement.
The application supports menu screens that are consistent with all other Android application screens and are prompted by the phone’s physical menu button. The “Back” button is disabled in both Playback and Edit modes to preserve implementation invariants.
Placing dynamics (p, pp, mp, etc.) is achieved by clicking the dynamics button, choosing a particular dynamic from the list, and placing it on the screen. The screen greys out the areas where a dynamic is not allowed to be placed, making it very obvious to the user where to press.
Playback Mode gives a simplified view consistent with Edit Mode. An arrow points to each note as it is played.
Implementation
Android Limitations
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