feat(tracker): implement basic tracker keys

go4k/tracker/keyevent.go

@@ -3,15 +3,110 @@ package tracker
 import (
 	"gioui.org/io/key"
 	"os"
+	"strconv"
 )
 
+var noteMap = map[string]byte{
+	"Z": 0,
+	"S": 1,
+	"X": 2,
+	"D": 3,
+	"C": 4,
+	"V": 5,
+	"G": 6,
+	"B": 7,
+	"H": 8,
+	"N": 9,
+	"J": 10,
+	"M": 11,
+	"Q": 12,
+	"2": 13,
+	"W": 14,
+	"3": 15,
+	"E": 16,
+	"R": 17,
+	"5": 18,
+	"T": 19,
+	"6": 20,
+	"Y": 21,
+	"7": 22,
+	"U": 23,
+}
+
 // KeyEvent handles incoming key events and returns true if repaint is needed.
 func (t *Tracker) KeyEvent(e key.Event) bool {
 	if e.State == key.Press {
+		if t.CursorColumn == 0 {
+			if val, ok := noteMap[e.Name]; ok {
+				t.NotePressed(val)
+				return true
+			}
+		} else {
+			if iv, err := strconv.ParseInt(e.Name, 16, 8); err == nil {
+				t.NumberPressed(byte(iv))
+				return true
+			}
+		}
 		switch e.Name {
 		case key.NameEscape:
 			os.Exit(0)
+		case key.NameUpArrow:
+			t.CursorRow = (t.CursorRow + t.song.PatternRows() - 1) % t.song.PatternRows()
+			return true
+		case key.NameDownArrow:
+			t.CursorRow = (t.CursorRow + 1) % t.song.PatternRows()
+			return true
+		case key.NameLeftArrow:
+			if t.CursorColumn == 0 {
+				t.ActiveTrack = (t.ActiveTrack + len(t.song.Tracks) - 1) % len(t.song.Tracks)
+				t.CursorColumn = 2
+			} else {
+				t.CursorColumn--
+			}
+			return true
+		case key.NameRightArrow:
+			if t.CursorColumn == 2 {
+				t.ActiveTrack = (t.ActiveTrack + 1) % len(t.song.Tracks)
+				t.CursorColumn = 0
+			} else {
+				t.CursorColumn++
+			}
+			return true
+		case key.NameTab:
+			if e.Modifiers.Contain(key.ModShift) {
+				t.ActiveTrack = (t.ActiveTrack + len(t.song.Tracks) - 1) % len(t.song.Tracks)
+			} else {
+				t.ActiveTrack = (t.ActiveTrack + 1) % len(t.song.Tracks)
+			}
+			t.CursorColumn = 0
+			return true
 		}
 	}
 	return false
 }
+
+// setCurrent sets the (note) value in current pattern under cursor to iv
+func (t *Tracker) setCurrent(iv byte) {
+	t.song.Patterns[t.song.Tracks[t.ActiveTrack].Sequence[t.DisplayPattern]][t.CursorRow] = iv
+}
+
+// getCurrent returns the current (note) value in current pattern under the cursor
+func (t *Tracker) getCurrent() byte {
+	return t.song.Patterns[t.song.Tracks[t.ActiveTrack].Sequence[t.DisplayPattern]][t.CursorRow]
+}
+
+// NotePressed handles incoming key presses while in the note column
+func (t *Tracker) NotePressed(val byte) {
+	t.setCurrent(getNoteValue(t.CurrentOctave, val))
+}
+
+// NumberPressed handles incoming presses while in either of the hex number columns
+func (t *Tracker) NumberPressed(iv byte) {
+	val := t.getCurrent()
+	if t.CursorColumn == 1 {
+		val = ((iv & 0xF) << 4) | (val & 0xF)
+	} else if t.CursorColumn == 2 {
+		val = (val & 0xF0) | (iv & 0xF)
+	}
+	t.setCurrent(val)
+}

go4k/tracker/music.go

@@ -19,6 +19,7 @@ var notes = []string{
 	"B-",
 }
 
+// valueAsNote returns the textual representation of a note value
 func valueAsNote(val byte) string {
 	octave := (val - baseNote) / 12
 	oNote := (val - baseNote) % 12
@@ -27,3 +28,8 @@ func valueAsNote(val byte) string {
 	}
 	return fmt.Sprintf("%s%d", notes[oNote], octave)
 }
+
+// noteValue return the note value for a particular note and octave combination
+func getNoteValue(octave, note byte) byte {
+	return baseNote + (octave * 12) + note
+}

go4k/tracker/tracker.go

@@ -12,11 +12,13 @@ type Tracker struct {
 	CursorColumn   int
 	DisplayPattern int
 	ActiveTrack    int
+	CurrentOctave  byte
 }
 
 func New() *Tracker {
 	return &Tracker{
-		QuitButton: new(widget.Clickable),
-		song:       defaultSong,
+		QuitButton:    new(widget.Clickable),
+		CurrentOctave: 4,
+		song:          defaultSong,
 	}
 }