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|
// notenlesen is a sight-reading trainer webapp.
//
// A single quarter note is rendered on a staff (treble or bass clef, with
// ledger lines and accidentals). The user answers by pressing a key on an
// on-screen piano. Each attempt's correctness and reply time is recorded in
// SQLite, and the next note is chosen by a per-key, difficulty-weighted
// random picker (harder/slower/unseen keys appear more often).
//
// Correctness is by piano key (pitch): F#/Gb map to the same key and are
// interchangeable. Difficulty is tracked per MIDI pitch.
//
// Usage: notenlesen -db <path> -addr <host:port>
//
// Routes:
//
// GET / the single-page app (HTML/JS/CSS inline)
// GET /next JSON: the next note to render
// POST /answer JSON: record an attempt, returns whether it was correct
package main
import (
"database/sql"
"encoding/json"
"flag"
"fmt"
"io"
"log"
"math/rand"
"net/http"
"os"
"path/filepath"
"sort"
"strconv"
"strings"
"time"
_ "modernc.org/sqlite"
)
// ============================================================================
// Schema + migrations
// ============================================================================
// Each migration is applied exactly once, in order, tracked by schema_version.
// Never modify an existing migration — add a new one instead.
const migration001 = `
CREATE TABLE schema_version (
version INTEGER PRIMARY KEY,
applied_at INTEGER NOT NULL
);
-- One row per answered note. Source of truth for the picker.
-- Difficulty is aggregated per *written note* (clef + spelling), i.e. the thing
-- as it appears on paper, not per piano key.
-- midi: pitch of the shown note (used only to grade the key press)
-- clef: "treble" | "bass" (part of the written-note identity)
-- spelling: shown VexFlow spelling, e.g. "F#/4" (part of the identity)
-- answer_midi: pitch the user pressed (NULL if skipped)
-- correct: 1 if answer_midi pitch == midi
-- reply_ms: time from render to first press
CREATE TABLE attempts (
id INTEGER PRIMARY KEY AUTOINCREMENT,
created_at INTEGER NOT NULL,
clef TEXT NOT NULL,
midi INTEGER NOT NULL,
spelling TEXT NOT NULL,
answer_midi INTEGER,
correct INTEGER NOT NULL,
reply_ms INTEGER NOT NULL
);
CREATE INDEX idx_attempts_midi ON attempts(midi);
`
// migration002 indexes attempts by the written-note identity (clef + spelling),
// which is how difficulty is now aggregated: per "thing on the paper" rather
// than per piano key. Enharmonic spellings (C#/4 vs Db/4) and the same glyph in
// different clefs are tracked as distinct items.
const migration002 = `
CREATE INDEX idx_attempts_clef_spelling ON attempts(clef, spelling);
`
func runMigrations(db *sql.DB) error {
migrations := []struct {
version int
sql string
}{
{1, migration001},
{2, migration002},
}
// Ensure schema_version exists before we query it (first run).
// We detect "already applied" by querying; if the table is missing the
// query errors only for version 1, which we tolerate.
for _, m := range migrations {
var count int
err := db.QueryRow(
"SELECT COUNT(*) FROM schema_version WHERE version = ?", m.version,
).Scan(&count)
if err != nil && m.version != 1 {
return fmt.Errorf("check migration %d: %w", m.version, err)
}
if err == nil && count > 0 {
continue
}
tx, err := db.Begin()
if err != nil {
return fmt.Errorf("begin migration %d: %w", m.version, err)
}
if _, err := tx.Exec(m.sql); err != nil {
tx.Rollback()
return fmt.Errorf("exec migration %d: %w", m.version, err)
}
if _, err := tx.Exec(
"INSERT INTO schema_version (version, applied_at) VALUES (?, ?)",
m.version, time.Now().Unix(),
); err != nil {
tx.Rollback()
return fmt.Errorf("record migration %d: %w", m.version, err)
}
if err := tx.Commit(); err != nil {
return fmt.Errorf("commit migration %d: %w", m.version, err)
}
log.Printf("applied migration %d", m.version)
}
return nil
}
func initDB(path string) (*sql.DB, error) {
if dir := filepath.Dir(path); dir != "" {
if err := os.MkdirAll(dir, 0o755); err != nil {
return nil, fmt.Errorf("create db dir: %w", err)
}
}
// Pragmas travel in the DSN so they apply to every pooled connection:
// busy_timeout (a writer waits for the lock instead of failing with
// SQLITE_BUSY), and WAL so readers do not block the writer. A post-open
// db.Exec("PRAGMA …") would only configure whichever single pooled
// connection ran it, leaving the others at SQLite's defaults.
db, err := sql.Open("sqlite",
"file:"+path+"?_pragma=busy_timeout(5000)&_pragma=journal_mode(WAL)")
if err != nil {
return nil, fmt.Errorf("open db: %w", err)
}
if err := runMigrations(db); err != nil {
db.Close()
return nil, err
}
return db, nil
}
// ============================================================================
// Note model
// ============================================================================
//
// We identify each playable note by MIDI number. Middle C (C4) = MIDI 60.
// Pools:
// bass clef: C2 (36) .. C4 (60)
// treble clef: G3 (55) .. C6 (84)
// The pool includes accidentals (every semitone). Each generated note carries
// the clef it should be drawn in plus a VexFlow spelling.
const (
midiC2 = 36
midiC4 = 60
midiG3 = 55
midiC6 = 84
)
// note is a single prompt to render.
type note struct {
Clef string `json:"clef"` // "treble" | "bass"
MIDI int `json:"midi"` // tracked pitch
Key string `json:"key"` // VexFlow key, e.g. "c/4" or "c##/4"
Accidental string `json:"accidental"` // "", "#", "b", "##", "bb"
Spelling string `json:"spelling"` // e.g. "C#/4" (display/analysis)
}
func upperFirst(s string) string {
if s == "" {
return s
}
return string(s[0]-32) + s[1:]
}
// letterSemitone is the semitone offset of each natural letter above C.
var letterSemitone = map[byte]int{
'c': 0, 'd': 2, 'e': 4, 'f': 5, 'g': 7, 'a': 9, 'b': 11,
}
// accidentalSemitone is the semitone shift for each accidental.
var accidentalSemitone = map[string]int{
"": 0,
"#": 1,
"b": -1,
"##": 2,
"bb": -2,
}
// floorDiv divides a by b rounding toward negative infinity (unlike Go's /
// which truncates toward zero), so octave math is correct for negative inputs.
func floorDiv(a, b int) int {
q := a / b
if (a%b != 0) && ((a < 0) != (b < 0)) {
q--
}
return q
}
// spell builds a written note for the given pitch (MIDI) using the chosen
// natural letter and accidental, computing the octave so that the written note
// sounds at exactly that MIDI. Returns ok=false if letter+accidental cannot
// spell the pitch (shouldn't happen for the curated tables below).
func spell(midi int, clef, letter, accidental string) (note, bool) {
base, okL := letterSemitone[letter[0]]
shift, okA := accidentalSemitone[accidental]
if !okL || !okA {
return note{}, false
}
// The pitch class produced by this letter+accidental.
pc := ((base+shift)%12 + 12) % 12
if pc != ((midi%12)+12)%12 {
return note{}, false
}
// Choose the octave for the letter so the sounding pitch matches midi.
// sounding MIDI of "<letter><accidental>/<oct>" = (oct+1)*12 + base + shift,
// so oct = (midi - base - shift)/12 - 1, using floor division so negative
// numerators (low cross-spellings) round correctly.
num := midi - base - shift
oct := floorDiv(num, 12) - 1
if (oct+1)*12+base+shift != midi {
return note{}, false
}
key := fmt.Sprintf("%s%s/%d", letter, accidental, oct)
spelling := fmt.Sprintf("%s%s/%d", upperFirst(letter), accidental, oct)
return note{
Clef: clef,
MIDI: midi,
Key: key,
Accidental: accidental,
Spelling: spelling,
}, true
}
// spellingDef is one way to write a pitch class: a natural letter + accidental.
type spellingDef struct {
letter string
accidental string
advanced bool // true = only shown in advanced mode
}
// pitchSpellings lists, per MIDI pitch class (0=C .. 11=B), every spelling we
// support. The non-advanced entries are the "basic" set (7 naturals + the
// sharp/flat of each black key). Advanced entries add the white-key cross
// spellings (B#, Cb, E#, Fb) and the double accidentals (##, bb).
var pitchSpellings = [12][]spellingDef{
0: { // C
{"c", "", false},
{"b", "#", true}, // B#
{"d", "bb", true}, // Dbb
},
1: { // C# / Db
{"c", "#", false},
{"d", "b", false},
{"b", "##", true}, // B##
},
2: { // D
{"d", "", false},
{"c", "##", true}, // C##
{"e", "bb", true}, // Ebb
},
3: { // D# / Eb
{"d", "#", false},
{"e", "b", false},
{"f", "bb", true}, // Fbb
},
4: { // E
{"e", "", false},
{"f", "b", true}, // Fb
{"d", "##", true}, // D##
},
5: { // F
{"f", "", false},
{"e", "#", true}, // E#
{"g", "bb", true}, // Gbb
},
6: { // F# / Gb
{"f", "#", false},
{"g", "b", false},
{"e", "##", true}, // E##
},
7: { // G
{"g", "", false},
{"f", "##", true}, // F##
{"a", "bb", true}, // Abb
},
8: { // G# / Ab
{"g", "#", false},
{"a", "b", false},
},
9: { // A
{"a", "", false},
{"g", "##", true}, // G##
{"b", "bb", true}, // Bbb
},
10: { // A# / Bb
{"a", "#", false},
{"b", "b", false},
{"c", "bb", true}, // Cbb
},
11: { // B
{"b", "", false},
{"c", "b", true}, // Cb
{"a", "##", true}, // A##
},
}
// writtenNote pairs a renderable note with whether it is an advanced-only
// spelling (enharmonic cross-spelling or double accidental).
type writtenNote struct {
note note
advanced bool
}
// writtenNotesFor returns every distinct written note (thing on the paper) for
// a pitch in a clef, each tagged with whether it is advanced-only.
func writtenNotesFor(midi int, clef string) []writtenNote {
pc := ((midi % 12) + 12) % 12
var notes []writtenNote
for _, sd := range pitchSpellings[pc] {
n, ok := spell(midi, clef, sd.letter, sd.accidental)
if !ok {
continue
}
notes = append(notes, writtenNote{note: n, advanced: sd.advanced})
}
return notes
}
// poolEntry is a candidate prompt: a single written note (its full visual
// identity plus the pitch needed to grade the key press).
type poolEntry struct {
note note
key string // noteKey(clef, spelling): the stats aggregation key
advanced bool // true = only available in advanced (enharmonic) mode
}
func newPoolEntry(wn writtenNote) poolEntry {
return poolEntry{
note: wn.note,
key: noteKey(wn.note.Clef, wn.note.Spelling),
advanced: wn.advanced,
}
}
// buildPool enumerates every written note we may show, including advanced
// enharmonic spellings (each tagged so the picker can include/exclude them by
// mode). Each spelling is tracked and weighted independently.
func buildPool() []poolEntry {
var pool []poolEntry
for m := midiC2; m <= midiC4; m++ {
for _, wn := range writtenNotesFor(m, "bass") {
pool = append(pool, newPoolEntry(wn))
}
}
for m := midiG3; m <= midiC6; m++ {
for _, wn := range writtenNotesFor(m, "treble") {
pool = append(pool, newPoolEntry(wn))
}
}
return pool
}
// keyboardRange is the union span shown on the on-screen piano (C2..C6).
const (
keyboardLowMIDI = midiC2
keyboardHighMIDI = midiC6
)
// ============================================================================
// Picker: difficulty-weighted random selection
// ============================================================================
//
// weight(midi) combines:
// - unseen bonus: notes never attempted get a high weight so they show up
// - error penalty: lower recent success rate -> higher weight
// - slowness penalty: higher average reply time -> higher weight
// We compute stats per MIDI pitch (correctness is pitch-based).
// A reply slower than distractionThresholdMS is assumed to be a distraction
// (looked away, got interrupted) rather than a genuinely hard note. Instead of
// letting it inflate the note's average reply time, we record it as a neutral,
// unremarkable value (neutralReplyMS) so it neither rewards nor penalizes.
const (
distractionThresholdMS = 10000 // 10s
neutralReplyMS = 2000 // ~average reply, no difficulty influence
)
// sessionGapMS defines a practice session: a run of consecutive answers with no
// pause longer than this between them. A gap larger than this starts a new
// session. Used only for the live "Session" counter on the practice page.
const sessionGapMS = 5 * 60 * 1000 // 5 minutes
type keyStat struct {
attempts int
correct int
avgReply float64 // ms
}
// noteKey is the identity of a written note ("thing on the paper") used to
// aggregate difficulty statistics: clef + visual spelling (letter, accidental,
// octave). Enharmonic spellings (C#/4 vs Db/4) and the same glyph in different
// clefs (treble C/4 vs bass C/4) are therefore distinct items.
func noteKey(clef, spelling string) string {
return clef + "|" + spelling
}
// loadStats returns aggregate stats per written note (keyed by noteKey),
// computed over all recorded attempts.
func loadStats(db *sql.DB) (map[string]keyStat, error) {
rows, err := db.Query(`
SELECT clef, spelling,
COUNT(*) AS attempts,
SUM(correct) AS correct,
AVG(reply_ms) AS avg_reply
FROM attempts
WHERE answer_midi IS NOT NULL
GROUP BY clef, spelling
`)
if err != nil {
return nil, err
}
defer rows.Close()
stats := map[string]keyStat{}
for rows.Next() {
var clef, spelling string
var attempts, correct int
var avg sql.NullFloat64
if err := rows.Scan(&clef, &spelling, &attempts, &correct, &avg); err != nil {
return nil, err
}
stats[noteKey(clef, spelling)] = keyStat{
attempts: attempts, correct: correct, avgReply: avg.Float64,
}
}
return stats, rows.Err()
}
// sessionStat is the live counter for the current practice session: a run of
// answers with no pause longer than sessionGapMS between them.
type sessionStat struct {
Total int `json:"total"`
Correct int `json:"correct"`
}
// loadSessionStat computes the current session's correct/total from attempt
// timestamps. The session is the most recent contiguous run of attempts whose
// consecutive gaps are all <= sessionGapMS, ending at the latest attempt. If the
// most recent attempt is itself older than sessionGapMS, the session is just
// that run (it ends whenever the gap rule breaks). Returns {0,0} if no attempts.
func loadSessionStat(db *sql.DB) (sessionStat, error) {
// Scan attempts newest-first; stop as soon as a gap exceeds the threshold.
rows, err := db.Query(`
SELECT created_at, correct
FROM attempts
WHERE answer_midi IS NOT NULL
ORDER BY created_at DESC
`)
if err != nil {
return sessionStat{}, err
}
defer rows.Close()
var st sessionStat
var prev int64
first := true
for rows.Next() {
var createdAt int64
var correct int
if err := rows.Scan(&createdAt, &correct); err != nil {
return sessionStat{}, err
}
if !first && prev-createdAt > sessionGapMS {
break // gap too large: previous rows belong to an earlier session
}
st.Total++
st.Correct += correct
prev = createdAt
first = false
}
return st, rows.Err()
}
// weightFor turns a stat into a positive selection weight.
func weightFor(s keyStat, ok bool) float64 {
if !ok || s.attempts == 0 {
return 10.0 // unseen: strongly favored
}
successRate := float64(s.correct) / float64(s.attempts)
errPenalty := (1.0 - successRate) * 8.0 // up to +8 for always-wrong
// reply time penalty: normalize around 2s, cap contribution.
slow := s.avgReply / 2000.0
if slow > 3 {
slow = 3
}
slowPenalty := slow * 2.0 // up to +6 for very slow
return 1.0 + errPenalty + slowPenalty
}
// pickNote chooses the next written note using weighted-random selection.
// Each candidate is a distinct written note (including its sharp/flat spelling),
// weighted by its own per-note difficulty. If clef is "treble" or "bass", only
// that clef's entries are considered; any other value (e.g. "") uses all.
// When advanced is false, advanced-only enharmonic spellings are excluded.
// exclude is the noteKey of the previously shown note; it is skipped so the
// same note is never shown twice in a row (unless it's the only candidate).
func pickNote(pool []poolEntry, stats map[string]keyStat, rng *rand.Rand, clef, exclude string, advanced bool) note {
matchesMode := func(e poolEntry) bool {
if (clef == "treble" || clef == "bass") && e.note.Clef != clef {
return false
}
if e.advanced && !advanced {
return false
}
return true
}
// Filter the pool by clef/mode and the excluded previous note.
candidates := pool[:0:0]
for _, e := range pool {
if !matchesMode(e) || e.key == exclude {
continue
}
candidates = append(candidates, e)
}
// If filtering left nothing (e.g. the excluded note was the only candidate),
// fall back to the mode-matching pool ignoring the exclusion.
if len(candidates) == 0 {
for _, e := range pool {
if matchesMode(e) {
candidates = append(candidates, e)
}
}
}
if len(candidates) == 0 {
candidates = pool
}
weights := make([]float64, len(candidates))
var total float64
for i, e := range candidates {
s, ok := stats[e.key]
w := weightFor(s, ok)
weights[i] = w
total += w
}
r := rng.Float64() * total
for i, w := range weights {
r -= w
if r <= 0 {
return candidates[i].note
}
}
// Fallback (floating point edge): last entry.
return candidates[len(candidates)-1].note
}
// ============================================================================
// HTTP server
// ============================================================================
type server struct {
db *sql.DB
pool []poolEntry
rng *rand.Rand
}
func (s *server) handleNext(w http.ResponseWriter, r *http.Request) {
stats, err := loadStats(s.db)
if err != nil {
log.Printf("loadStats: %v", err)
http.Error(w, "db error", http.StatusInternalServerError)
return
}
// prevClef/prevSpelling identify the note just shown, so we can avoid
// repeating it. Empty when there is no previous note (first request).
exclude := ""
prevClef := r.URL.Query().Get("prevClef")
prevSpelling := r.URL.Query().Get("prevSpelling")
if prevClef != "" && prevSpelling != "" {
exclude = noteKey(prevClef, prevSpelling)
}
advanced := r.URL.Query().Get("advanced") == "1"
n := pickNote(s.pool, stats, s.rng, r.URL.Query().Get("clef"), exclude, advanced)
writeJSON(w, n)
}
type answerReq struct {
Clef string `json:"clef"`
MIDI int `json:"midi"`
Spelling string `json:"spelling"`
AnswerMIDI *int `json:"answer_midi"` // nil = skipped
ReplyMS int `json:"reply_ms"`
}
type answerResp struct {
Correct bool `json:"correct"`
MIDI int `json:"midi"`
Session sessionStat `json:"session"`
}
func (s *server) handleAnswer(w http.ResponseWriter, r *http.Request) {
var req answerReq
if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
http.Error(w, "bad request", http.StatusBadRequest)
return
}
// Correctness is by pitch: pressed key MIDI must equal shown MIDI.
correct := false
var answerMIDI sql.NullInt64
if req.AnswerMIDI != nil {
answerMIDI = sql.NullInt64{Int64: int64(*req.AnswerMIDI), Valid: true}
correct = *req.AnswerMIDI == req.MIDI
}
correctInt := 0
if correct {
correctInt = 1
}
// Normalize reply time. A reply slower than the distraction threshold is
// treated as a neutral, average reply (the user likely looked away) so it
// doesn't penalize the note. Negative values (clock skew) floor to 0.
replyMS := req.ReplyMS
if replyMS < 0 {
replyMS = 0
}
if replyMS > distractionThresholdMS {
replyMS = neutralReplyMS
}
_, err := s.db.Exec(`
INSERT INTO attempts
(created_at, clef, midi, spelling, answer_midi, correct, reply_ms)
VALUES (?, ?, ?, ?, ?, ?, ?)
`,
time.Now().UnixMilli(), req.Clef, req.MIDI, req.Spelling,
answerMIDI, correctInt, replyMS,
)
if err != nil {
log.Printf("insert attempt: %v", err)
http.Error(w, "db error", http.StatusInternalServerError)
return
}
sess, err := loadSessionStat(s.db)
if err != nil {
log.Printf("loadSessionStat: %v", err)
// Non-fatal: still return the answer result with a zero session.
}
writeJSON(w, answerResp{Correct: correct, MIDI: req.MIDI, Session: sess})
}
func (s *server) handleSession(w http.ResponseWriter, r *http.Request) {
sess, err := loadSessionStat(s.db)
if err != nil {
log.Printf("handleSession: %v", err)
http.Error(w, "db error", http.StatusInternalServerError)
return
}
writeJSON(w, sess)
}
func (s *server) handleIndex(w http.ResponseWriter, r *http.Request) {
if r.URL.Path != "/" {
http.NotFound(w, r)
return
}
w.Header().Set("Content-Type", "text/html; charset=utf-8")
page := strings.NewReplacer(
"__LOW_MIDI__", strconv.Itoa(keyboardLowMIDI),
"__HIGH_MIDI__", strconv.Itoa(keyboardHighMIDI),
).Replace(pageHTML)
io.WriteString(w, page)
}
// handleMidi serves the WebMIDI setup page, where the user identifies their
// MIDI device + channel by playing C-E-G (any octave). The detected (port,
// channel) pair is stored client-side in localStorage and used by the practice
// page to accept note-on input alongside the on-screen piano. The page is fully
// static (all logic is client-side WebMIDI).
func (s *server) handleMidi(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "text/html; charset=utf-8")
io.WriteString(w, midiPageHTML)
}
func writeJSON(w http.ResponseWriter, v any) {
w.Header().Set("Content-Type", "application/json; charset=utf-8")
if err := json.NewEncoder(w).Encode(v); err != nil {
log.Printf("encode json: %v", err)
}
}
// ============================================================================
// Stats page: selection probability per note
// ============================================================================
// statRow is one note's selection probability and underlying difficulty data.
type statRow struct {
Label string // e.g. "C#4"
Clef string // "treble" | "bass"
MIDI int // pitch
Key string // VexFlow key, e.g. "c#/4" (for staff rendering)
Accidental string // "", "#", "b", "##", "bb" (for staff rendering)
Advanced bool // advanced-only enharmonic spelling
Attempts int // recorded attempts
Correct int // recorded correct answers
AvgReply float64 // average reply time (ms), 0 if unseen
Weight float64 // selection weight
// Selection probability when playing in this clef's own mode, and in the
// combined "Both" mode (where treble+bass compete in one pool). For the
// requested mode (basic vs advanced): in basic mode advanced rows have 0.
ProbInClef float64
ProbBoth float64
}
// computeStatRows builds the per-written-note probability table from recorded
// stats. Each pool entry is one written note (including sharp/flat spelling).
// Probabilities are normalized over the notes available in the given mode
// (advanced=false excludes enharmonic spellings), matching the live picker.
func computeStatRows(pool []poolEntry, stats map[string]keyStat, advanced bool) []statRow {
inMode := func(e poolEntry) bool { return advanced || !e.advanced }
// Total weight across the in-mode pool ("Both" mode) and per clef.
var totalBoth float64
totalClef := map[string]float64{}
for _, e := range pool {
if !inMode(e) {
continue
}
s, ok := stats[e.key]
w := weightFor(s, ok)
totalBoth += w
totalClef[e.note.Clef] += w
}
rows := make([]statRow, 0, len(pool))
for _, e := range pool {
s, ok := stats[e.key]
w := weightFor(s, ok)
// Spelling is like "C#/4", which noteLabel turns into "C#4".
row := statRow{
Label: noteLabel(e.note.Spelling),
Clef: e.note.Clef,
MIDI: e.note.MIDI,
Key: e.note.Key,
Accidental: e.note.Accidental,
Advanced: e.advanced,
Attempts: s.attempts,
Correct: s.correct,
Weight: w,
}
if ok {
row.AvgReply = s.avgReply
}
// Probabilities only apply to notes available in the requested mode.
if inMode(e) {
if totalClef[e.note.Clef] > 0 {
row.ProbInClef = w / totalClef[e.note.Clef]
}
if totalBoth > 0 {
row.ProbBoth = w / totalBoth
}
}
rows = append(rows, row)
}
return rows
}
// noteLabel turns a VexFlow spelling like "C#/4" into a compact label "C#4".
func noteLabel(spelling string) string {
return strings.Replace(spelling, "/", "", 1)
}
func (s *server) handleStats(w http.ResponseWriter, r *http.Request) {
stats, err := loadStats(s.db)
if err != nil {
log.Printf("handleStats loadStats: %v", err)
http.Error(w, "db error", http.StatusInternalServerError)
return
}
advanced := r.URL.Query().Get("advanced") == "1"
allRows := computeStatRows(s.pool, stats, advanced)
// In normal mode, hide advanced-only spellings (they aren't in play).
rows := allRows[:0:0]
for _, row := range allRows {
if !advanced && row.Advanced {
continue
}
rows = append(rows, row)
}
// Sort by ProbBoth descending (most-likely-next first), then by pitch and
// label so the two spellings of a black key have a stable order.
sort.Slice(rows, func(i, j int) bool {
if rows[i].ProbBoth != rows[j].ProbBoth {
return rows[i].ProbBoth > rows[j].ProbBoth
}
if rows[i].MIDI != rows[j].MIDI {
return rows[i].MIDI < rows[j].MIDI
}
return rows[i].Label < rows[j].Label
})
w.Header().Set("Content-Type", "text/html; charset=utf-8")
var b strings.Builder
b.WriteString(statsHeaderHTML)
// Build the staff data: every in-mode note, in ascending pitch order per
// clef, with its selection probability (ProbBoth). The frontend renders
// these on a bass and a treble staff, tinting each note head by probability.
staffNotes := emitStaffNotes(rows)
if data, err := json.Marshal(staffNotes); err == nil {
b.WriteString(`<script>window.__STAFF_NOTES__ = `)
b.Write(data)
b.WriteString(";</script>\n")
}
// Mode switch link.
if advanced {
b.WriteString(`<p><strong>Advanced</strong> spellings shown. ` +
`<a class="navlink" href="/stats">Show normal only</a></p>` + "\n")
} else {
b.WriteString(`<p><strong>Normal</strong> spellings shown. ` +
`<a class="navlink" href="/stats?advanced=1">Include advanced enharmonics</a></p>` + "\n")
}
b.WriteString(`<table>
<thead><tr>
<th>Note</th><th>Clef</th><th>Attempts</th><th>Success</th>
<th>Avg reply</th><th>Weight</th><th>P (this clef)</th><th>P (both)</th>
</tr></thead>
<tbody>
`)
for _, row := range rows {
successCell := "—"
if row.Attempts > 0 {
successCell = fmt.Sprintf("%d/%d (%.0f%%)",
row.Correct, row.Attempts,
100*float64(row.Correct)/float64(row.Attempts))
}
replyCell := "—"
if row.Attempts > 0 {
replyCell = fmt.Sprintf("%.0f ms", row.AvgReply)
}
// Mark advanced spellings so they're distinguishable in the list.
noteCell := htmlEscape(row.Label)
if row.Advanced {
noteCell += ` <span class="adv">adv</span>`
}
// Heat the probability cell so harder/more-likely notes stand out.
fmt.Fprintf(&b,
`<tr>
<td class="note">%s</td><td>%s</td><td class="num">%d</td>
<td class="num">%s</td><td class="num">%s</td><td class="num">%.2f</td>
<td class="num">%s</td><td class="num">%s</td>
</tr>
`,
noteCell, row.Clef, row.Attempts,
successCell, replyCell, row.Weight,
probCell(row.ProbInClef), probCell(row.ProbBoth),
)
}
b.WriteString("</tbody></table>\n")
b.WriteString(statsFooterHTML)
io.WriteString(w, b.String())
}
// staffNote is one note to draw on a staff: its clef, VexFlow key/accidental,
// and selection probability (ProbBoth) used to tint the note head.
type staffNote struct {
Clef string `json:"clef"`
Key string `json:"key"`
Accidental string `json:"accidental"`
Prob float64 `json:"prob"`
}
// staffLetterOrder maps a natural letter to its diatonic index within an
// octave (C=0 .. B=6). Used to compute a note's vertical position on a staff.
var staffLetterOrder = map[byte]int{
'c': 0, 'd': 1, 'e': 2, 'f': 3, 'g': 4, 'a': 5, 'b': 6,
}
// staffStep returns a note's diatonic staff position from its VexFlow key
// ("<letter><acc?>/<octave>"), as octave*7 + letterIndex. This is the note
// head's vertical position on the staff, which (unlike MIDI) increases
// monotonically as you move up the lines/spaces. Used as a tiebreak so
// enharmonic spellings of one pitch (e.g. C#/4 on the C line vs Db/4 on the D
// line) order by where they actually sit, keeping note heads visually ascending.
func staffStep(key string) int {
if key == "" {
return 0
}
letter := key[0]
slash := strings.IndexByte(key, '/')
oct := 0
if slash >= 0 && slash+1 < len(key) {
if n, err := strconv.Atoi(key[slash+1:]); err == nil {
oct = n
}
}
return oct*7 + staffLetterOrder[letter]
}
// emitStaffNotes turns the (already in-mode-filtered) stat rows into a single
// run for client-side rendering. The notes form two sequential ascending runs:
// the whole bass clef (low to high) first, then the whole treble clef. Sorting
// by clef first keeps each clef's notes contiguous so the run only switches
// clef once; within a clef we sort by staff position (to keep enharmonic
// spellings ascending), then accidental for a stable order. "bass" < "treble"
// alphabetically, so the bass run comes first.
func emitStaffNotes(rows []statRow) []staffNote {
ordered := make([]statRow, len(rows))
copy(ordered, rows)
sort.Slice(ordered, func(i, j int) bool {
if ordered[i].Clef != ordered[j].Clef {
return ordered[i].Clef < ordered[j].Clef
}
si, sj := staffStep(ordered[i].Key), staffStep(ordered[j].Key)
if si != sj {
return si < sj
}
return ordered[i].Accidental < ordered[j].Accidental
})
out := make([]staffNote, 0, len(ordered))
for _, r := range ordered {
out = append(out, staffNote{
Clef: r.Clef,
Key: r.Key,
Accidental: r.Accidental,
Prob: r.ProbBoth,
})
}
return out
}
// probCell renders a probability as a percentage with a small inline bar.
func probCell(p float64) string {
pct := p * 100
bar := int(p * 200) // bar width factor
return fmt.Sprintf(
`<span class="bar" style="--w:%dpx"></span>%.1f%%`, bar, pct)
}
func htmlEscape(s string) string {
s = strings.ReplaceAll(s, "&", "&")
s = strings.ReplaceAll(s, "<", "<")
s = strings.ReplaceAll(s, ">", ">")
return s
}
func main() {
home, _ := os.UserHomeDir()
defaultDB := filepath.Join(home, ".local", "share", "notenlesen", "notenlesen.db")
dbPath := flag.String("db", defaultDB, "Path to the SQLite database")
addr := flag.String("addr", "127.0.0.1:8771", "Listen address")
flag.Parse()
db, err := initDB(*dbPath)
if err != nil {
fmt.Fprintf(os.Stderr, "notenlesen: %v\n", err)
os.Exit(1)
}
defer db.Close()
s := &server{
db: db,
pool: buildPool(),
rng: rand.New(rand.NewSource(time.Now().UnixNano())),
}
mux := http.NewServeMux()
mux.HandleFunc("GET /", s.handleIndex)
mux.HandleFunc("GET /next", s.handleNext)
mux.HandleFunc("POST /answer", s.handleAnswer)
mux.HandleFunc("GET /session", s.handleSession)
mux.HandleFunc("GET /stats", s.handleStats)
mux.HandleFunc("GET /midi", s.handleMidi)
fmt.Fprintf(os.Stderr, "notenlesen: listening on http://%s (db: %s)\n", *addr, *dbPath)
if err := http.ListenAndServe(*addr, mux); err != nil {
fmt.Fprintf(os.Stderr, "notenlesen: %v\n", err)
os.Exit(1)
}
}
// ============================================================================
// Inline frontend (HTML + CSS + JS)
// ============================================================================
//
// The page is a single template with two placeholders, __LOW_MIDI__ and
// __HIGH_MIDI__: the low and high MIDI numbers of the on-screen piano.
// VexFlow is loaded from a CDN.
const pageHTML = `<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>notenlesen — note reading trainer</title>
<script src="https://cdn.jsdelivr.net/npm/vexflow@4.2.3/build/cjs/vexflow.js"></script>
<style>
/* Light theme by default; the whole page follows the OS/browser setting. */
:root {
--bg: #f4f4f6;
--fg: #1b1b1f;
--stats: #5f6368;
--accent: #2f6fb0;
--good: #2e7d32;
--bad: #c62828;
--staff-bg: #ffffff;
--whitekey: #fafafa;
--whitekey-border: #999;
--whitekey-active: #cfe4f7;
--refkey: #dcdce0;
--blackkey: #222;
--blackkey-border: #222;
--blackkey-active: #3a6ea5;
--keylabel: #888;
}
@media (prefers-color-scheme: dark) {
:root {
--bg: #1b1b1f;
--fg: #e8e8ea;
--stats: #9aa0a6;
--accent: #5aa9e6;
--good: #4caf50;
--bad: #e05260;
--staff-bg: #15151a;
--whitekey: #2a2a30;
--whitekey-border: #888;
--whitekey-active: #3a6ea5;
--refkey: #3d3d46;
--blackkey: #43434d;
--blackkey-border: #aaa;
--blackkey-active: #3a6ea5;
--keylabel: #777;
}
}
* { box-sizing: border-box; }
body {
margin: 0;
font-family: system-ui, sans-serif;
background: var(--bg);
color: var(--fg);
display: flex;
flex-direction: column;
align-items: center;
min-height: 100vh;
}
h1 { font-weight: 500; margin: 1rem 0 .25rem; }
#stats { color: var(--stats); font-size: .9rem; margin-bottom: .5rem; min-height: 1.2em; }
#staff {
background: var(--staff-bg);
border-radius: 8px;
padding: .5rem;
margin: 1rem 0;
width: 360px;
height: 220px;
display: flex;
align-items: center;
justify-content: center;
}
/* Dark mode (follows OS/browser setting): invert the leadsheet (staff).
VexFlow draws in black on white; recolor the SVG strokes/fills to light. */
@media (prefers-color-scheme: dark) {
#staff svg path,
#staff svg rect,
#staff svg line,
#staff svg text {
stroke: var(--fg) !important;
fill: var(--fg) !important;
}
}
#feedback {
height: 1.5rem;
font-size: 1.2rem;
font-weight: 600;
margin-bottom: .5rem;
}
#feedback.good { color: var(--good); }
#feedback.bad { color: var(--bad); }
/* Piano */
#piano-wrap { width: 100%; overflow-x: auto; padding: 1rem; }
#piano {
position: relative;
height: 140px;
width: fit-content;
margin: 0 auto;
display: flex;
user-select: none;
}
.white {
position: relative;
width: 34px;
height: 140px;
background: var(--whitekey);
border: 1px solid var(--whitekey-border);
border-radius: 0 0 5px 5px;
cursor: pointer;
}
/* C4 (middle C): subtly shaded as a visual reference point. */
.white.ref { background: var(--refkey); }
.white:active, .white.active, .white.ref:active, .white.ref.active {
background: var(--whitekey-active);
}
.black {
position: absolute;
top: 0;
width: 22px;
height: 88px;
background: var(--blackkey);
border: 1px solid var(--blackkey-border);
border-radius: 0 0 4px 4px;
cursor: pointer;
z-index: 2;
}
.black:active, .black.active { background: var(--blackkey-active); }
.keylabel {
position: absolute;
bottom: 4px;
width: 100%;
text-align: center;
font-size: .6rem;
color: var(--keylabel);
pointer-events: none;
}
#staff-row {
display: flex;
align-items: center;
gap: .75rem;
}
#clef-buttons {
display: flex;
flex-direction: column;
gap: .4rem;
}
.clef-btn {
background: var(--whitekey);
color: var(--fg);
border: 1px solid var(--whitekey-border);
border-radius: 6px;
padding: .4rem .7rem;
cursor: pointer;
font-size: .85rem;
min-width: 4rem;
}
.clef-btn:hover { border-color: var(--accent); }
.clef-btn.active {
background: var(--accent);
border-color: var(--accent);
color: #fff;
font-weight: 600;
}
.navlink { color: var(--accent); text-decoration: none; font-size: .9rem; }
.navlink:hover { text-decoration: underline; }
.midi-status { font-size: .85rem; margin-left: .4rem; }
.midi-status.on { color: var(--good); }
.midi-status.off { color: var(--stats); }
/* Slider switch for the Advanced toggle. */
.switch {
display: flex;
align-items: center;
gap: .4rem;
cursor: pointer;
font-size: .8rem;
margin-top: .2rem;
user-select: none;
}
.switch input { position: absolute; opacity: 0; width: 0; height: 0; }
.switch .slider {
position: relative;
flex: 0 0 auto;
width: 2.2rem;
height: 1.2rem;
background: var(--whitekey-border);
border-radius: 1rem;
transition: background .15s ease;
}
.switch .slider::before {
content: "";
position: absolute;
top: 2px;
left: 2px;
width: calc(1.2rem - 4px);
height: calc(1.2rem - 4px);
background: #fff;
border-radius: 50%;
transition: transform .15s ease;
box-shadow: 0 1px 2px rgba(0,0,0,.3);
}
.switch input:checked + .slider { background: var(--accent); }
.switch input:checked + .slider::before { transform: translateX(1rem); }
.switch input:focus-visible + .slider { outline: 2px solid var(--accent); outline-offset: 2px; }
.switch-label { color: var(--fg); }
</style>
</head>
<body>
<h1>notenlesen</h1>
<div id="stats"></div>
<div id="staff-row">
<div id="clef-buttons">
<button class="clef-btn" data-clef="">Both</button>
<button class="clef-btn" data-clef="treble">Treble</button>
<button class="clef-btn" data-clef="bass">Bass</button>
<label class="switch" title="Include enharmonic spellings (B#, Cb, double sharps/flats)">
<input type="checkbox" id="advanced-btn">
<span class="slider"></span>
<span class="switch-label">Advanced</span>
</label>
</div>
<div id="staff"></div>
</div>
<div id="feedback"> </div>
<div id="piano-wrap"><div id="piano"></div></div>
<p>
<a href="/stats" class="navlink">View note statistics →</a>
·
<a href="/midi" class="navlink">MIDI setup →</a>
<span id="midi-status" class="midi-status"></span>
</p>
<script>
(function () {
"use strict";
// VexFlow UMD exposes a global named "Vex" (with .Flow) in the CJS build.
var VF = (window.Vex && window.Vex.Flow) || window.VexFlow;
var LOW_MIDI = __LOW_MIDI__;
var HIGH_MIDI = __HIGH_MIDI__;
var SHARP_PC = [
{letter:"C", acc:""}, {letter:"C", acc:"#"}, {letter:"D", acc:""},
{letter:"D", acc:"#"}, {letter:"E", acc:""}, {letter:"F", acc:""},
{letter:"F", acc:"#"}, {letter:"G", acc:""}, {letter:"G", acc:"#"},
{letter:"A", acc:""}, {letter:"A", acc:"#"}, {letter:"B", acc:""}
];
function isBlack(midi) { return SHARP_PC[((midi % 12) + 12) % 12].acc === "#"; }
function labelFor(midi) {
var pc = SHARP_PC[((midi % 12) + 12) % 12];
var octave = Math.floor(midi / 12) - 1;
return pc.letter + pc.acc + octave;
}
var staffEl = document.getElementById("staff");
var feedbackEl = document.getElementById("feedback");
var statsEl = document.getElementById("stats");
var current = null; // current note from /next
var shownAt = 0; // performance.now() when note was rendered
var locked = false; // ignore input between answer and next note
var session = { total: 0, correct: 0 };
var selectedClef = ""; // "" = both, "treble", or "bass"
var advancedMode = false; // include enharmonic spellings (B#, Cb, ##, bb)
function renderNote(n) {
staffEl.innerHTML = "";
var renderer = new VF.Renderer(staffEl, VF.Renderer.Backends.SVG);
renderer.resize(340, 200);
var ctx = renderer.getContext();
var stave = new VF.Stave(10, 40, 320);
stave.addClef(n.clef);
stave.setContext(ctx).draw();
var staveNote = new VF.StaveNote({
clef: n.clef,
keys: [n.key],
duration: "q"
});
if (n.accidental) {
staveNote.addModifier(new VF.Accidental(n.accidental), 0);
}
var voice = new VF.Voice({ num_beats: 1, beat_value: 4 });
voice.addTickables([staveNote]);
new VF.Formatter().joinVoices([voice]).format([voice], 240);
voice.draw(ctx, stave);
}
function setFeedback(text, kind) {
feedbackEl.textContent = text;
feedbackEl.className = kind || "";
}
function updateStats() {
var pct = session.total ? Math.round(100 * session.correct / session.total) : 0;
statsEl.textContent = "Session: " + session.correct + " / " + session.total +
" correct (" + pct + "%)";
}
function nextNote() {
locked = true;
// Pass the current (about-to-be-previous) note so the server avoids
// repeating it as the next note.
var params = [];
if (selectedClef) params.push("clef=" + encodeURIComponent(selectedClef));
if (advancedMode) params.push("advanced=1");
if (current) {
params.push("prevClef=" + encodeURIComponent(current.clef));
params.push("prevSpelling=" + encodeURIComponent(current.spelling));
}
var url = "/next" + (params.length ? "?" + params.join("&") : "");
fetch(url).then(function (r) { return r.json(); }).then(function (n) {
current = n;
renderNote(n);
setFeedback("\u00a0", "");
// Start the reply timer when the note is actually painted, not when the
// fetch resolved: rendering the SVG happens before the browser paints,
// so we wait for the next animation frame to avoid counting render lag.
requestAnimationFrame(function () {
shownAt = performance.now();
locked = false;
});
}).catch(function (e) {
setFeedback("error loading note", "bad");
console.error(e);
});
}
function answer(answerMidi) {
if (locked || !current) return;
locked = true;
var replyMs = Math.round(performance.now() - shownAt);
var body = {
clef: current.clef,
midi: current.midi,
spelling: current.spelling,
answer_midi: answerMidi,
reply_ms: replyMs
};
fetch("/answer", {
method: "POST",
headers: { "Content-Type": "application/json" },
body: JSON.stringify(body)
}).then(function (r) { return r.json(); }).then(function (res) {
// The session counter is computed server-side from attempt timestamps
// (a session = answers with no >5min pause between them), so it survives
// reloads and resets after a long break.
if (res.session) session = res.session;
if (res.correct) {
setFeedback("\u2713 correct", "good");
} else {
// Show the spelling that was actually displayed (e.g. "Gb3"), not a
// sharp spelling derived from the pitch.
setFeedback("\u2717 was " + current.spelling.replace("/", ""), "bad");
}
updateStats();
// brief pause so the user sees the result, then advance
setTimeout(nextNote, res.correct ? 350 : 900);
}).catch(function (e) {
locked = false;
console.error(e);
});
}
// Build the piano keyboard from LOW_MIDI..HIGH_MIDI.
function buildPiano() {
var piano = document.getElementById("piano");
var whiteWidth = 34;
// First pass: place white keys, remember their left offset by midi.
var whiteLeft = {};
var x = 0;
for (var m = LOW_MIDI; m <= HIGH_MIDI; m++) {
if (isBlack(m)) continue;
var w = document.createElement("div");
w.className = "white" + (m === 60 ? " ref" : ""); // 60 = C4 (middle C)
w.dataset.midi = m;
var lbl = document.createElement("span");
lbl.className = "keylabel";
lbl.textContent = labelFor(m);
w.appendChild(lbl);
piano.appendChild(w);
whiteLeft[m] = x;
x += whiteWidth;
}
// Second pass: place black keys absolutely, straddling the gap to the
// previous white key.
for (var b = LOW_MIDI; b <= HIGH_MIDI; b++) {
if (!isBlack(b)) continue;
var prevWhite = b - 1; // sharp sits above the white key below it
if (!(prevWhite in whiteLeft)) continue;
var k = document.createElement("div");
k.className = "black";
k.dataset.midi = b;
k.style.left = (whiteLeft[prevWhite] + whiteWidth - 11) + "px";
piano.appendChild(k);
}
// Use the click event: a real left click (press + release on the same
// key). It only fires for the primary button, so right/middle clicks are
// ignored, and it works for touch/pen too.
piano.addEventListener("click", function (ev) {
var t = ev.target.closest(".white, .black");
if (!t) return;
var midi = parseInt(t.dataset.midi, 10);
flashKey(midi);
answer(midi);
});
}
// flashKey briefly highlights the on-screen key for the given MIDI pitch,
// mirroring the visual feedback of a click. Used by both click and MIDI input.
// Notes outside the keyboard range have no key element and are ignored.
function flashKey(midi) {
var el = document.querySelector('[data-midi="' + midi + '"]');
if (!el) return;
el.classList.add("active");
setTimeout(function () { el.classList.remove("active"); }, 120);
}
// Clef selection: choose which clef the next notes use (persisted).
// Only buttons with a data-clef attribute are clef buttons (excludes the
// advanced toggle, which also carries the .clef-btn style).
var clefBtns = document.querySelectorAll(".clef-btn[data-clef]");
function applyClef(clef, advance) {
selectedClef = clef;
clefBtns.forEach(function (b) {
b.classList.toggle("active", b.dataset.clef === clef);
});
try { localStorage.setItem("notenlesen.clef", clef); } catch (e) {}
if (advance) nextNote();
}
clefBtns.forEach(function (b) {
b.addEventListener("click", function () { applyClef(b.dataset.clef, true); });
});
var savedClef = "";
try {
var sc = localStorage.getItem("notenlesen.clef");
if (sc === "treble" || sc === "bass" || sc === "") savedClef = sc;
} catch (e) {}
// Advanced mode toggle (slider switch): include enharmonic spellings.
var advancedBtn = document.getElementById("advanced-btn");
function applyAdvanced(on, advance) {
advancedMode = on;
advancedBtn.checked = on;
try { localStorage.setItem("notenlesen.advanced", on ? "1" : "0"); } catch (e) {}
if (advance) nextNote();
}
advancedBtn.addEventListener("change", function () {
applyAdvanced(advancedBtn.checked, true);
});
var savedAdvanced = false;
try { savedAdvanced = localStorage.getItem("notenlesen.advanced") === "1"; } catch (e) {}
// MIDI input: read the device + channel locked in on the /midi setup page and
// accept note-on from exactly that (port, channel) pair, alongside the
// on-screen piano. Only note-on (status 0x90, velocity > 0) triggers an
// answer; everything else is ignored. The setup page stores the pair in
// localStorage["notenlesen.midi"] as {portId, portName, channel}.
var midiStatusEl = document.getElementById("midi-status");
function setMidiStatus(text, on) {
if (!midiStatusEl) return;
midiStatusEl.textContent = text;
midiStatusEl.className = "midi-status " + (on ? "on" : "off");
}
// Parse a raw MIDI message into a note-on, or null for anything else.
function parseNoteOn(data) {
if (!data || data.length < 3) return null;
if ((data[0] & 0xf0) !== 0x90) return null; // not note-on
if (data[2] === 0) return null; // velocity 0 = note-off
return { channel: data[0] & 0x0f, note: data[1] };
}
function initMidi() {
var saved = null;
try {
var raw = localStorage.getItem("notenlesen.midi");
if (raw) saved = JSON.parse(raw);
} catch (e) {}
if (!saved) { setMidiStatus("(no MIDI device — set up)", false); return; }
if (!navigator.requestMIDIAccess) {
setMidiStatus("(MIDI unavailable in this browser)", false);
return;
}
navigator.requestMIDIAccess().then(function (access) {
function bind() {
var port = access.inputs.get(saved.portId);
if (!port) {
setMidiStatus("(MIDI device not connected — reload after plugging in)", false);
return;
}
port.onmidimessage = function (ev) {
var on = parseNoteOn(ev.data);
if (!on || on.channel !== saved.channel) return;
flashKey(on.note);
answer(on.note);
};
setMidiStatus("\u266a " + (saved.portName || "MIDI") +
" (ch " + (saved.channel + 1) + ")", true);
}
bind();
// Re-bind on plug/unplug so reconnecting just works (Chrome/Edge). Firefox
// does not fire statechange for hot-plug; there you reload the page.
access.onstatechange = bind;
}).catch(function () {
setMidiStatus("(MIDI access denied)", false);
});
}
if (!VF) {
setFeedback("VexFlow failed to load (needs network for CDN)", "bad");
return;
}
buildPiano();
updateStats();
// Initialize the session counter from the server (continues the current
// session if you reload within 5 minutes).
fetch("/session").then(function (r) { return r.json(); }).then(function (s) {
if (s) { session = s; updateStats(); }
}).catch(function () {});
applyClef(savedClef, false);
applyAdvanced(savedAdvanced, false);
initMidi();
nextNote();
})();
</script>
</body>
</html>
`
// statsHeaderHTML opens the /stats page (theme matches the main page, following
// the OS/browser light/dark setting). The table body is written between this
// header and statsFooterHTML.
const statsHeaderHTML = `<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>notenlesen — note statistics</title>
<script src="https://cdn.jsdelivr.net/npm/vexflow@4.2.3/build/cjs/vexflow.js"></script>
<style>
:root {
--bg: #f4f4f6;
--fg: #1b1b1f;
--stats: #5f6368;
--accent: #2f6fb0;
--good: #2e7d32;
--bad: #c62828;
--row-border: #ddd;
--bar: #9cc4ea;
--staff-bg: #ffffff;
}
@media (prefers-color-scheme: dark) {
:root {
--bg: #1b1b1f;
--fg: #e8e8ea;
--stats: #9aa0a6;
--accent: #5aa9e6;
--good: #4caf50;
--bad: #e05260;
--row-border: #333;
--bar: #3a6ea5;
--staff-bg: #15151a;
}
}
* { box-sizing: border-box; }
body {
margin: 0;
font-family: system-ui, sans-serif;
background: var(--bg);
color: var(--fg);
padding: 1.5rem;
max-width: 900px;
margin: 0 auto;
}
h1 { font-weight: 500; }
.navlink { color: var(--accent); text-decoration: none; font-size: .9rem; }
.navlink:hover { text-decoration: underline; }
p.intro { color: var(--stats); font-size: .9rem; max-width: 640px; }
table { border-collapse: collapse; width: 100%; margin-top: 1rem; }
th, td {
text-align: left;
padding: .35rem .6rem;
border-bottom: 1px solid var(--row-border);
font-size: .9rem;
white-space: nowrap;
}
th { color: var(--stats); font-weight: 600; }
td.note { font-weight: 600; font-variant-numeric: tabular-nums; }
td.num { text-align: right; font-variant-numeric: tabular-nums; }
.adv {
font-size: .7em;
font-weight: 600;
color: var(--bg);
background: var(--accent);
border-radius: 3px;
padding: 0 .3em;
vertical-align: middle;
}
.bar {
display: inline-block;
height: .6em;
width: var(--w);
background: var(--bar);
border-radius: 2px;
margin-right: .4rem;
vertical-align: baseline;
}
/* Weight staff: a single SVG with every in-mode note as one continuous run
(bass then treble), each note head tinted by its selection probability. */
#staves { margin: 1rem 0 1.5rem; }
#grand-staff {
background: var(--staff-bg);
border-radius: 8px;
padding: .5rem;
margin: .5rem 0;
overflow-x: auto;
}
/* Legend: a gradient strip showing the opacity ramp = selection probability,
from the faint floor (rarely shown) to fully opaque (most likely next).
The bar sits on the staff background and uses the note color (currentColor)
so it matches the actual note tint in both light and dark themes. */
#staff-legend {
display: flex;
align-items: center;
gap: .5rem;
font-size: .8rem;
color: var(--stats);
margin: .25rem 0 0 .25rem;
}
.legend-bar {
display: inline-block;
width: 140px;
height: .8em;
border-radius: 3px;
background:
linear-gradient(to right,
rgba(127,127,127,.12), rgba(127,127,127,1)),
var(--staff-bg);
border: 1px solid var(--row-border);
}
/* Note: the staff, clef and note glyphs are painted in the theme's
foreground color directly in JS (via VexFlow setStyle), so they show
correctly in both light and dark mode without any CSS recolor hack. */
</style>
</head>
<body>
<h1>Note statistics</h1>
<p><a href="/" class="navlink">← Back to practice</a></p>
<div id="staves">
<div id="grand-staff"></div>
<div id="staff-legend">
<span class="legend-label">fast & correct</span>
<span class="legend-bar"></span>
<span class="legend-label">to work on</span>
</div>
</div>
<p class="intro">
Selection probability of each written note, based on your recorded attempts.
On the staves above, every in-mode note is drawn in pitch order; each note
head is tinted by how likely it is to come up next (more opaque = more
likely). Tracking is per <em>thing on the paper</em>: enharmonic spellings
(e.g. C#4 vs Db4) and the same note in different clefs are counted
separately. Harder, slower, or never-seen notes get higher weight and so
appear more often. "P (this clef)" is the probability when practising only
that clef; "P (both)" is for the combined Both mode.
</p>
`
// statsFooterHTML closes the /stats page. It renders the weight staff from
// window.__STAFF_NOTES__ (emitted by handleStats): every in-mode note as one
// continuous run on a single staff line — the whole bass clef ascending, then a
// clef change to treble, then the whole treble clef ascending — laid out as
// 8-note bars across full-width system rows, each note head tinted by selection
// probability via the SVG opacity attribute.
const statsFooterHTML = `
<script>
(function () {
"use strict";
var VF = (window.Vex && window.Vex.Flow) || window.VexFlow;
var all = window.__STAFF_NOTES__ || [];
var root = document.getElementById("grand-staff");
if (!VF || !root || !all.length) return;
var MIN_OPACITY = 0.12; // floor so near-zero notes stay faintly visible
var NOTES_PER_BAR = 8; // a barline every 8 notes
var BEAM_GROUP = 4; // beam consecutive same-clef notes in groups of 4
var perNote = 30; // horizontal slot width per note
var clefPad = 50; // room for the clef at a row's left
var staffY = 30, staffH = 110;
// Tint is normalized against the most-probable note over the whole run, so a
// given opacity means the same thing everywhere on the page.
var maxProb = 0;
all.forEach(function (n) { if (n.prob > maxProb) maxProb = n.prob; });
// Split the run into fixed-size bars (used for barlines + beaming).
var bars = [];
for (var i = 0; i < all.length; i += NOTES_PER_BAR) {
bars.push(all.slice(i, i + NOTES_PER_BAR));
}
var barWidth = NOTES_PER_BAR * perNote;
var systemGap = 30; // vertical space between system rows in the single SVG
// Build an rgba() string from a "rgb(r, g, b)" base color and an alpha.
function rgba(base, alpha) {
var m = base.match(/rgba?\(([^)]+)\)/);
if (m) {
var p = m[1].split(",");
return "rgba(" + p[0].trim() + "," + p[1].trim() + "," + p[2].trim() +
"," + alpha + ")";
}
return base;
}
// renderStaff draws the whole staff into the single SVG. It reads the current
// theme colors each time, so calling it again after a light/dark switch
// repaints everything correctly. VexFlow has no built-in theming, so we paint
// explicitly: note glyphs in the foreground "ink" (tinted by probability),
// staff lines / ledger lines in the muted --stats gray (which is close to
// VexFlow's default soft gray and adapts per theme), clefs in full ink.
function renderStaff() {
root.innerHTML = "";
var cs = getComputedStyle(document.body);
var noteInk = cs.getPropertyValue("color").trim() || "rgb(27,27,31)";
var staffInkBase = cs.getPropertyValue("--stats").trim() || "#888";
// --stats may be a hex value; normalize to a usable stroke/fill color.
var staffInk = staffInkBase;
var noteInkSolid = rgba(noteInk, 1);
var realNotes = []; // {sn} collected for reference (tinted at creation)
var beamsToDraw = [];
// Fit as many bars per row as the container width allows (full-width
// systems wrapping down the page). The first bar of a row also shows the
// clef, so it is wider. Always at least one bar per row.
var avail = (root.clientWidth || 800) - 20;
var barsPerSystem = Math.floor((avail - clefPad) / barWidth);
if (barsPerSystem < 1) barsPerSystem = 1;
// Everything is drawn into ONE SVG: each system row is stacked at an
// increasing y offset rather than living in its own renderer.
var numSystems = Math.ceil(bars.length / barsPerSystem);
var firstRowBars = Math.min(barsPerSystem, bars.length);
var svgWidth = clefPad + firstRowBars * barWidth + 20;
var svgHeight = numSystems * (staffH + systemGap) + 20;
var renderer = new VF.Renderer(root, VF.Renderer.Backends.SVG);
renderer.resize(svgWidth, svgHeight);
var ctx = renderer.getContext();
// Track the clef in effect as we walk the run, so each row/bar starts in
// the correct clef and we only draw a clef-change glyph at the switch.
var runningClef = bars.length ? bars[0][0].clef : "treble";
var systemIndex = 0;
for (var s = 0; s < bars.length; s += barsPerSystem) {
var systemBars = bars.slice(s, s + barsPerSystem);
var rowY = staffY + systemIndex * (staffH + systemGap);
systemIndex++;
var x = 10;
systemBars.forEach(function (bar, bi) {
var w = barWidth + (bi === 0 ? clefPad : 0);
var stave = new VF.Stave(x, rowY, w);
// Every row's first bar restates the clef in effect at its start.
if (bi === 0) stave.addClef(runningClef);
// Staff lines in the muted staff ink...
stave.setStyle({ strokeStyle: staffInk, fillStyle: staffInk });
// ...but the clef and barlines (stave modifiers) in full note ink, so
// they read as solid foreground (black in light mode, white in dark).
var mods = stave.getModifiers ? stave.getModifiers() : [];
mods.forEach(function (m) {
if (m.setStyle) m.setStyle({ strokeStyle: noteInkSolid, fillStyle: noteInkSolid });
});
stave.setContext(ctx).draw();
var tickables = [];
var beamGroups = [], curGroup = null, curClef = null;
bar.forEach(function (n) {
// Insert a clef-change glyph when the run switches clef mid-line.
if (n.clef !== runningClef) {
var cn = new VF.ClefNote(n.clef, "small");
cn.setStyle({ fillStyle: noteInkSolid, strokeStyle: noteInkSolid });
tickables.push(cn);
runningClef = n.clef;
curGroup = null; curClef = null; // break beam across clef change
}
var sn = new VF.StaveNote({ clef: n.clef, keys: [n.key], duration: "8" });
if (n.accidental) sn.addModifier(new VF.Accidental(n.accidental), 0);
// Tint by selection probability: note ink with alpha. setStyle covers
// head + stem + accidental; ledger lines need their own style and use
// the muted staff ink so they read like the staff, not the data.
var op = maxProb > 0 ? n.prob / maxProb : 0;
if (op < MIN_OPACITY) op = MIN_OPACITY;
var color = rgba(noteInk, op.toFixed(3));
sn.setStyle({ fillStyle: color, strokeStyle: color });
if (sn.setLedgerLineStyle) {
sn.setLedgerLineStyle({ strokeStyle: staffInk, fillStyle: staffInk });
}
sn._op = op;
realNotes.push(sn);
tickables.push(sn);
// Beam consecutive same-clef notes in groups of BEAM_GROUP.
if (n.clef !== curClef || !curGroup || curGroup.length >= BEAM_GROUP) {
curGroup = []; beamGroups.push(curGroup); curClef = n.clef;
}
curGroup.push(sn);
});
// Construct the beams BEFORE drawing the voice. A Beam calls setBeam()
// on its notes when constructed, which suppresses their individual
// flags; if we drew the voice first, the flags would already be
// rendered and the beam would sit on top of them (flags AND beams).
// "true" enables autoStem: each group's stem direction is picked from
// its own notes.
beamGroups.forEach(function (g) {
if (g.length < 2) return;
var beam = new VF.Beam(g, true);
// Tint the beam to the group's strongest note so it reads with them.
var maxOp = 0;
g.forEach(function (sn) { if (sn._op > maxOp) maxOp = sn._op; });
var bc = rgba(noteInk, (maxOp || 1).toFixed(3));
beam.setStyle({ fillStyle: bc, strokeStyle: bc });
beamsToDraw.push(beam);
});
var voice = new VF.Voice({ num_beats: tickables.length, beat_value: 8 })
.setStrict(false).addTickables(tickables);
var fmtW = w - (bi === 0 ? clefPad : 0) - 16;
new VF.Formatter().joinVoices([voice]).format([voice], fmtW);
voice.draw(ctx, stave);
x += w;
});
}
beamsToDraw.forEach(function (b) { b.setContext(ctx).draw(); });
}
renderStaff();
// Repaint when the OS/browser light-dark preference changes, so the staff
// colors follow the theme without a reload.
var mq = window.matchMedia("(prefers-color-scheme: dark)");
if (mq.addEventListener) mq.addEventListener("change", renderStaff);
else if (mq.addListener) mq.addListener(renderStaff); // older browsers
})();
</script>
</body>
</html>
`
// ============================================================================
// MIDI setup page (/midi)
// ============================================================================
//
// A static page that uses the Web MIDI API to identify the user's device and
// channel. It listens on every input port and channel for the pitch-class
// sequence C -> E -> G (any octave), tracked independently per (port, channel),
// and locks onto whichever pair completes the run. The detected pair is stored
// in localStorage["notenlesen.midi"] as {portId, portName, channel}; the
// practice page reads it to accept note-on input from exactly that pair.
//
// Web MIDI requires a secure context (https or localhost); the page surfaces a
// clear message when it is unavailable or denied.
const midiPageHTML = `<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>notenlesen — MIDI setup</title>
<style>
:root {
--bg: #f4f4f6;
--fg: #1b1b1f;
--stats: #5f6368;
--accent: #2f6fb0;
--good: #2e7d32;
--bad: #c62828;
--row-border: #ddd;
--panel: #ffffff;
--step: #e6e6ea;
--step-done: #2e7d32;
--step-active: #2f6fb0;
}
@media (prefers-color-scheme: dark) {
:root {
--bg: #1b1b1f;
--fg: #e8e8ea;
--stats: #9aa0a6;
--accent: #5aa9e6;
--good: #4caf50;
--bad: #e05260;
--row-border: #333;
--panel: #15151a;
--step: #2a2a30;
--step-done: #4caf50;
--step-active: #5aa9e6;
}
}
* { box-sizing: border-box; }
body {
margin: 0;
font-family: system-ui, sans-serif;
background: var(--bg);
color: var(--fg);
padding: 1.5rem;
max-width: 760px;
margin: 0 auto;
}
h1 { font-weight: 500; }
h2 { font-weight: 500; font-size: 1.1rem; margin: 1.5rem 0 .5rem; }
.navlink { color: var(--accent); text-decoration: none; font-size: .9rem; }
.navlink:hover { text-decoration: underline; }
p.intro { color: var(--stats); font-size: .9rem; max-width: 640px; }
.panel {
background: var(--panel);
border: 1px solid var(--row-border);
border-radius: 8px;
padding: 1rem;
margin: 1rem 0;
}
.msg { font-size: .9rem; }
.msg.bad { color: var(--bad); }
.msg.good { color: var(--good); }
/* C-E-G step pills */
#steps { display: flex; gap: .6rem; margin: .75rem 0; }
.step {
width: 3rem; height: 3rem;
display: flex; align-items: center; justify-content: center;
border-radius: 8px;
background: var(--step);
font-size: 1.3rem; font-weight: 600;
border: 2px solid transparent;
}
.step.active { border-color: var(--step-active); }
.step.done { background: var(--step-done); color: #fff; }
/* device list */
ul.ports { list-style: none; padding: 0; margin: .5rem 0; }
ul.ports li {
padding: .35rem .5rem;
border-bottom: 1px solid var(--row-border);
font-size: .9rem;
font-variant-numeric: tabular-nums;
}
ul.ports li .pname { font-weight: 600; }
ul.ports li .pstate { color: var(--stats); font-size: .8rem; }
/* live message log */
#log {
font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
font-size: .8rem;
background: var(--panel);
border: 1px solid var(--row-border);
border-radius: 6px;
padding: .5rem;
height: 9rem;
overflow-y: auto;
white-space: pre-wrap;
}
#log .line { color: var(--stats); }
#log .line.match { color: var(--good); font-weight: 600; }
button.btn {
background: var(--accent);
color: #fff;
border: none;
border-radius: 6px;
padding: .45rem .9rem;
cursor: pointer;
font-size: .9rem;
}
button.btn.secondary {
background: transparent;
color: var(--accent);
border: 1px solid var(--accent);
}
code { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; }
</style>
</head>
<body>
<h1>MIDI setup</h1>
<p><a href="/" class="navlink">← Back to practice</a></p>
<p class="intro">
Connect a MIDI keyboard, then play <strong>C, then E, then G</strong> (any
octave). notenlesen listens on every port and channel and locks onto the
one that played the sequence — that exact device + channel is then used for
answering, alongside the on-screen piano. Web MIDI needs a secure context
(use <code>localhost</code> or https). Firefox supports Web MIDI but does
not detect devices plugged in after the page loads — connect your keyboard
first, then reload the page.
</p>
<div class="panel">
<h2>Status</h2>
<div id="status" class="msg">Requesting MIDI access…</div>
<div id="saved" class="msg"></div>
<p><button id="forget" class="btn secondary" style="display:none">Forget device</button></p>
</div>
<div class="panel">
<h2>Play C → E → G to identify your device</h2>
<div id="steps">
<div class="step" data-step="0">C</div>
<div class="step" data-step="1">E</div>
<div class="step" data-step="2">G</div>
</div>
<div id="detect" class="msg"></div>
</div>
<div class="panel">
<h2>Detected input ports</h2>
<ul id="ports" class="ports"><li>(none yet)</li></ul>
<h2>Incoming note-on messages</h2>
<div id="log"></div>
</div>
<script>
(function () {
"use strict";
var STORE_KEY = "notenlesen.midi";
// C-E-G as pitch classes (0=C, 4=E, 7=G); octave is ignored.
var SEQUENCE = [0, 4, 7];
var SEQ_LABEL = ["C", "E", "G"];
var statusEl = document.getElementById("status");
var savedEl = document.getElementById("saved");
var forgetBtn = document.getElementById("forget");
var detectEl = document.getElementById("detect");
var portsEl = document.getElementById("ports");
var logEl = document.getElementById("log");
var stepEls = Array.prototype.slice.call(document.querySelectorAll(".step"));
function noteLabel(midi) {
var names = ["C","C#","D","D#","E","F","F#","G","G#","A","A#","B"];
var pc = ((midi % 12) + 12) % 12;
var octave = Math.floor(midi / 12) - 1;
return names[pc] + octave;
}
// Parse a raw MIDI message into a note-on, or null for anything else.
// We act on note-on only (status 0x90..0x9F, velocity > 0); a note-on with
// velocity 0 is a note-off by convention and is ignored.
function parseNoteOn(data) {
if (!data || data.length < 3) return null;
var status = data[0] & 0xf0;
var channel = data[0] & 0x0f; // 0-based; displayed as channel+1
if (status !== 0x90) return null;
var velocity = data[2];
if (velocity === 0) return null;
return { channel: channel, note: data[1], velocity: velocity };
}
function setStatus(text, kind) {
statusEl.textContent = text;
statusEl.className = "msg" + (kind ? " " + kind : "");
}
function log(text, match) {
var div = document.createElement("div");
div.className = "line" + (match ? " match" : "");
div.textContent = text;
logEl.appendChild(div);
// keep the log bounded
while (logEl.childNodes.length > 200) logEl.removeChild(logEl.firstChild);
logEl.scrollTop = logEl.scrollHeight;
}
function showSaved() {
var raw = null;
try { raw = localStorage.getItem(STORE_KEY); } catch (e) {}
if (!raw) {
savedEl.textContent = "No device saved yet.";
savedEl.className = "msg";
forgetBtn.style.display = "none";
return null;
}
var saved = null;
try { saved = JSON.parse(raw); } catch (e) {}
if (!saved) { savedEl.textContent = ""; forgetBtn.style.display = "none"; return null; }
savedEl.innerHTML = "Saved: <strong>" + escapeHtml(saved.portName || saved.portId) +
"</strong>, channel " + (saved.channel + 1) + ".";
savedEl.className = "msg good";
forgetBtn.style.display = "";
return saved;
}
function escapeHtml(s) {
return String(s).replace(/[&<>]/g, function (c) {
return c === "&" ? "&" : c === "<" ? "<" : ">";
});
}
// Per-(port,channel) progress through the C-E-G sequence. Key is
// portId + "|" + channel; value is the index of the next expected note.
var progress = {};
function resetSteps() {
stepEls.forEach(function (el) { el.className = "step"; });
}
function paintSteps(idx) {
stepEls.forEach(function (el, i) {
el.className = "step" + (i < idx ? " done" : i === idx ? " active" : "");
});
}
function lockOnto(port, channel) {
var rec = { portId: port.id, portName: port.name || port.id, channel: channel };
try { localStorage.setItem(STORE_KEY, JSON.stringify(rec)); } catch (e) {}
progress = {};
stepEls.forEach(function (el) { el.className = "step done"; });
detectEl.textContent = "Locked onto " + (port.name || port.id) +
", channel " + (channel + 1) + ". You can go back to practice.";
detectEl.className = "msg good";
showSaved();
}
function handleSequence(port, channel, note) {
var key = port.id + "|" + channel;
var pc = ((note % 12) + 12) % 12;
var want = progress[key] || 0;
if (pc === SEQUENCE[want]) {
want++;
progress[key] = want;
paintSteps(want);
if (want >= SEQUENCE.length) {
lockOnto(port, channel);
}
} else if (pc === SEQUENCE[0]) {
// Wrong note, but it's a C: restart the run at step 1 for this pair.
progress[key] = 1;
paintSteps(1);
} else {
// Out-of-sequence note: reset this pair's progress.
progress[key] = 0;
paintSteps(0);
}
}
function midiAccess(access) {
setStatus("MIDI ready.", "good");
showSaved();
function refreshPorts() {
portsEl.innerHTML = "";
var any = false;
access.inputs.forEach(function (port) {
any = true;
var li = document.createElement("li");
li.innerHTML = "<span class=\"pname\">" + escapeHtml(port.name || port.id) +
"</span> <span class=\"pstate\">" +
escapeHtml((port.manufacturer || "") + " · " + port.state + "/" + port.connection) +
"</span>";
portsEl.appendChild(li);
});
if (!any) {
var li = document.createElement("li");
li.textContent = "(no input ports — connect a MIDI device)";
portsEl.appendChild(li);
}
}
function attach(port) {
port.onmidimessage = function (ev) {
var on = parseNoteOn(ev.data);
if (!on) return;
var line = (port.name || port.id) + " — ch " + (on.channel + 1) +
" — " + noteLabel(on.note) + " (" + on.note + ")";
var isSeqNote = SEQUENCE.indexOf(((on.note % 12) + 12) % 12) >= 0;
log(line, isSeqNote);
handleSequence(port, on.channel, on.note);
};
}
access.inputs.forEach(attach);
refreshPorts();
// Hot-plug events: works in Chrome/Edge. Firefox does not fire these, so a
// device connected after load only shows up after reloading the page.
access.onstatechange = function (ev) {
refreshPorts();
if (ev.port && ev.port.type === "input" && ev.port.state === "connected") {
attach(ev.port);
}
};
}
forgetBtn.addEventListener("click", function () {
try { localStorage.removeItem(STORE_KEY); } catch (e) {}
progress = {};
resetSteps();
detectEl.textContent = "Device forgotten. Play C-E-G to set a new one.";
detectEl.className = "msg";
showSaved();
});
if (!navigator.requestMIDIAccess) {
setStatus("Web MIDI is not available in this browser. Use a recent " +
"Chrome, Edge or Firefox, and make sure you're on localhost or https.", "bad");
showSaved();
return;
}
navigator.requestMIDIAccess().then(midiAccess).catch(function (e) {
setStatus("MIDI access denied or failed: " + (e && e.message ? e.message : e) +
". Web MIDI needs a secure context (localhost or https).", "bad");
showSaved();
});
})();
</script>
</body>
</html>
`
|