Keyboard Simulator Benchmark

Introduction

This benchmark utilizes several different interface styles. The primary function of the program is to provide both visual and audio feedback to the user that a virtual piano key has been pressed. The user may also insert a note anywhere into the staff, as well as delete old notes. These features are indicative of a direct manipulation style of interface.  The benchmark also uses several menus, which enables it to test the menu interface style. Single character commands (keyboard shortcuts) are also included for more efficient use of the program.

This benchmark is similar to many keyboard and midi simulators found on the market today. CakeWalk, a popular music composition program for Macintosh and Windows, allows the user to press virtual piano keys to compose music. The midikeys program available on IRIX (SGI) platforms is another program which provides a virtual keyboard on which the user can play.

The keyboard simulator benchmark tests the ability of the implementing toolkit to provide semantic feedback to the user in the form of polygon coloring and sound playing using a MIDI interface. The benchmark also tests the ability to directly manipulate the notes through insertion and deletion. The menus and single character commands (keyboard shortcuts) are quite typical of many commercial applications and are direct representations of the menu and single character command interface styles. Since both playing sounds and supporting undo/multiple undo are common features in many modern programs, these features were included to test the capabilities of the toolkit being used to implement the benchmark. The keyboard simulator benchmark also tests the ability of the implementing system to draw different filled and unfilled polygonal shapes.

Description

Presentation

• The top section, which contains a musical staff and a play button.
• The staff consists of five horizontal lines that are equally spaced.
• The staff is placed in panel that can be scrolled on the x-axis. In other words, as new notes are played, if more are drawn than can fit in the initially visible staff area, the staff is scrolled to the left to provide more room for drawing notes.
• The user can insert a note anywhere in the staff by clicking the mouse while over the staff. The staff only allows the user to place the cursor,  insert notes, or delete notes.
• To the right of the staff and scrollable panel, there is a button labeled 'Play'.
• The bottom section, which contains a 'keyboard' and a group of three radio buttons.
• The keyboard contains several sets of polygons: the main set of keys, which are 14 rectangles, and the sharps/flats which are rectangles about half the length and size of the main keys (see figure).
• The keys are also labeled according to their corresponding note - allowing for novice users to know which key is being played.
• A panel beside the keyboard, which has a label 'Notes:', below which are three radio buttons - these buttons are mutually exclusive.
• The buttons are labeled, from top to bottom, 'Quarter Note', 'Half Note', and 'Whole Note'.

Menus

Note: the keyboard shortcuts refer to a 'Meta-?' key combination, where 'Meta' is the appropriate key for the platform that the benchmark is implemented on, such as Esc, Ctrl, or Cmd, and '?' is the other key, to be pressed concurrently.

• File - which contains:
• Quit - choosing this causes the program to exit. There should also be a keyboard shortcut equivalent for the quit option, of the form 'Meta-q'.
• Save - allows the current composition (all of the notes in the staff) to be saved to a file. A dialog should pop-up when 'Save' is chosen, allowing the user to choose a file name.  A keyboard shortcut of 'Meta-s' should be provided.
• The format for the saved file is not particularly important.  It should simply allow a file to be saved (and later opened) that accurately represents the current notes in the staff.
• Open - allows the user to open a previously generated composition. Choosing this option should open a file choosing dialog.  The notes from the file should be inserted into an empty staff. 'Meta-o' should be the keyboard shortcut for 'Open'.
• Edit - which contains:
• Delete - the note to the left of the cursor is deleted.The backspace/delete key should provide the shortcut functionality.
• Undo - the last action performed is undone.  For example, if a note is cut, pressing undo un-cuts the note.  If a note is pasted, undo should un-insert it.  The undo function should allow multiple undo, so a history of actions involving cut/past/delete and new note playing (which is just inserting the notes at the rightmost end of the staff) should be kept to be undone.  The keyboard shortcut for undo should be 'Meta-z'.


Keyboard Shortcuts: There should be shortcut keys available for switching between the three radio buttons for the note types:

• 'q': enables the Quarter Note radio button
• 'h': enables the Half Note radio button
• 'w': enables the Whole Note radio button

Operation

• A key is played when the user moves the mouse (pointer) inside one of the rectangles representing a key and presses the mouse button. (Left mouse button only if a multiple button mouse).
• Important: The sharps and flats (the smaller, black keys) are present only for consistency with a piano keyboard. For this benchmark, they can't actually be played so should not provide any semantic feedback to the user indicating that they have been pressed, and no notes should sound/be drawn if the user presses a mouse button when the mouse is inside one of the sharp/flat rectangles.
• When a key is played, the rectangle representing that key should change color for 1/2 of a second. If the current foreground color for that key is light gray, it should turn dark gray for 1/2 of a second, then back to the foreground color. (Note: the length of the color change can be modified for a more realistic keyboard effect if necessary).
• Synchronously with the key press, the note should be played. For more information on playing the sounds, see the section 'Playing Sounds' below
• The key press also results in the corresponding note being drawn onto the staff in the top section of the program. For more info on the drawing of the note, see the section entitled 'Drawing Notes' below.
• Important: The radio button which is currently selected should directly affect both the sound that is played as well as the note that is drawn in the staff. Each key should be played as a  quarter, half, or whole note, and the note that is drawn should correspond to the radio button that was selected when it was played (see 'Drawing Notes').

• Sounds should be played using MIDI and the computer's sound card.  The sounds will be for each of the keys (two octaves), and will include quarter, half, and whole notes. Since the sharps/flats are present for visual consistency with a piano keyboard and can't actually be 'played', no sounds should be played for the sharps and flats.
• The sounds will be played when the user presses a key on the keyboard, and when all of the notes are being played (when the 'Play' button is pushed - see 'Playing a Composition' below).

• A note is drawn in the staff when a user plays a key.
• The notes should be drawn from left to right in the staff. If there is no more room visible in the staff, the staff panel should auto scroll to the left when a note is added.
• The staff should behave like a 'text field', with the individual notes acting like characters in a text field.  The user should be able to select a location by clicking in that location, and the user should be able to either (a) delete the note to the left, or (b) insert a new note.   Group selection, cut and paste,  and drag and drop do not need to be impemented.
• Note: If the user has a specific location selected on the staff (by clicking with the mouse), a newly played note should be inserted into this location.  If there are notes to the right of this insertion point, those notes should be shifted to the right.
• The cursor, to indicate the current insert/delete position, should be placed directly over a note. In effect, the cursor should 'snap' to the closest note.
• The user can insert a note into the staff. It may be useful to have the staff

divided into an invisible horizontal grid, so that if the user selects anywhere in a cell the note
is inserted at a specific horizontal position.  This grid will allow equal horizontal spacing of the notes in the staff.
• If the user deletes a note, any notes to the right of this note should shift to the left - effectively removing any 'blank' spaces in the staff.  Likewise, If a note is inserted with blank space to the left of it, the note should be shifted to the left until the blank space is removed.  The basic idea is that the notes should be 'packed' from the left to the right. Any blank space between notes should be removed by re-drawing the notes.
Note Style
• By convention, notes between the first 'C' key and up to (but not including) the first 'B' are drawn with their tail up and attached to the right side of the circle, while keys from the 'B' through the next octave are drawn with their tail pointing down from the left side of the circle.
• In the figure above - the 14 notes drawn on the staff correspond to the 14 keys from left to right. The first six notes drawn are from the C to B range, while the next eight are from B through the next octave.
• Quarter notes should be filled circles with tails.
• Half notes are non-filled circles with tails.
• Whole notes are non-filled circles with no tails.
• The exact size is not essential - but it is important that the circle part of each note should fit between the lines of the staff - so the diameter should be equivalent to the line spacing of the staff. The tail should be about twice the diameter.
• The notes should be drawn with an equidistant spacing - the exact distance is up to the implementer of the benchmark, but approximately 3 times the diameter of the note is recommended.

• When the user chooses Undo from the Edit menu (or presses the keyboard shortcut key), the last action (cut, delete, paste/insert -- including a new note added by playing a key) should be undone.
• The benchmark should support multiple undo - so if the user chooses undo three times after pressing three piano keys in a row, the last three notes added to the staff should be removed.
• If the user inserts a note, then deletes a different note, then inserts another note, pressing undo three times should do the following: remove the last note played, un-delete the note, remove the note.

• When the 'Play' button is pressed, the appropriate sounds for all of the notes currently in the staff will be played.
• The notes in the staff should be played from left to right.
• It may be necessary, depending upon the implementation, to have a short delay between notes if, when played, they all run together.
• Because there are quarter, half, and whole notes for each key, however, it should be possible to just play the notes one after the other to get the correct sound.

Features Not Included