Add preliminary chord analysis

With this commit, challenges are disabled (for the moment), and
scherzo will analyze the notes pressed as a chord.

Currently, only the four basic types of triads (augemented, major,
minor, and dminished) are recognized, and these only in root position.

diff --git a/scherzo.c b/scherzo.c
index 5de614807aca4c8b1f30b2d3a979f0f9803d1cb0..9b0e2d9ced96bc43dfcf5f8c388d373549c8923f 100644 (file)
--- a/scherzo.c
+++ b/scherzo.c
@@ -24,6 +24,8 @@
 #include "score.h"
 #include "mnemon.h"
 
+#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0]))
+
 #define unused(foo) foo __attribute__((unused))
 
 #define MIDI_BUF_SIZE 4096
@@ -48,6 +50,7 @@ typedef struct scherzo
     int staff_height;
     score_staff_t *treble;
     score_staff_t *bass;
+    score_chord_t *chord;
     int midi_fd;
     snd_midi_event_t *snd_midi_event;
 
@@ -120,9 +123,14 @@ on_key_press_event (GtkWidget *widget,
                    void *user_data)
 {
     scherzo_t *scherzo = user_data;
-    int octave = scherzo->challenge.note->octave;
+    int octave;
     score_pitch_t pitch;
 
+    if (scherzo->challenge.note)
+       octave = scherzo->challenge.note->octave;
+    else
+       octave = 4;
+
     switch (key->keyval) {
     case GDK_KEY_plus:
     case GDK_KEY_KP_Add:
@@ -196,9 +204,14 @@ on_key_release_event (unused (GtkWidget *widget),
                      void *user_data)
 {
     scherzo_t *scherzo = user_data;
-    int octave = scherzo->challenge.note->octave;
+    int octave;
     score_pitch_t pitch;
 
+    if (scherzo->challenge.note)
+       octave = scherzo->challenge.note->octave;
+    else
+       octave = 4;
+
     switch (key->keyval) {
     case GDK_KEY_c:
     case GDK_KEY_C:
@@ -245,6 +258,55 @@ on_key_release_event (unused (GtkWidget *widget),
     return FALSE;
 }
 
+static unsigned char
+_score_pitch_and_octave_to_midi (score_pitch_t pitch,
+                                int octave)
+{
+    unsigned char midi_note = 12 * (octave + 1);
+
+    switch (SCORE_PITCH_NAME (pitch)) {
+    case SCORE_PITCH_NAME_C:
+       break;
+    case SCORE_PITCH_NAME_D:
+       midi_note += 2;
+       break;
+    case SCORE_PITCH_NAME_E:
+       midi_note += 4;
+       break;
+    case SCORE_PITCH_NAME_F:
+       midi_note += 5;
+       break;
+    case SCORE_PITCH_NAME_G:
+       midi_note += 7;
+       break;
+    case SCORE_PITCH_NAME_A:
+       midi_note += 9;
+       break;
+    case SCORE_PITCH_NAME_B:
+       midi_note += 11;
+       break;
+    }
+
+    switch (SCORE_PITCH_ACCIDENTAL (pitch)) {
+    case SCORE_PITCH_ACCIDENTAL_DOUBLE_FLAT:
+       midi_note -= 2;
+       break;
+    case SCORE_PITCH_ACCIDENTAL_FLAT:
+       midi_note -= 1;
+       break;
+    case SCORE_PITCH_ACCIDENTAL_NATURAL:
+       break;
+    case SCORE_PITCH_ACCIDENTAL_SHARP:
+       midi_note += 1;
+       break;
+    case SCORE_PITCH_ACCIDENTAL_DOUBLE_SHARP:
+       midi_note += 2;
+       break;
+    }
+
+    return midi_note;
+}
+
 static void
 _midi_to_score_pitch_and_octave (unsigned char midi_note,
                                 score_pitch_t *pitch,
@@ -293,13 +355,138 @@ _midi_to_score_pitch_and_octave (unsigned char midi_note,
     }
 }
 
+/* Determine a chord name (if any) from the current notes pressed */
+
+typedef struct analyzed_note {
+    /* Original note being analzyed. */
+    score_note_t *note;
+
+    /* Absolute pitch (expressed as midi number). */
+    int midi_pitch;
+
+    /* Pitch relative to bass note. */
+    int relative_pitch;
+} analyzed_note_t;
+
+static int
+_compare_analyzed_note (const void *va, const void *vb)
+{
+    const analyzed_note_t *a = va, *b = vb;
+
+    return a->midi_pitch - b->midi_pitch;
+}
+
+static int
+_chord_signature_matches (analyzed_note_t *notes,
+                         int num_notes,
+                         int *signature_pitches,
+                         int num_signature_pitches)
+{
+    int n, s;
+
+    for (n = 0, s = 0; s < num_signature_pitches; s++) {
+       if (n >= num_notes)
+           return 0;
+       if (notes[n].relative_pitch != signature_pitches[s])
+           return 0;
+       n++;
+       /* Skip repeated notes in chord being tested. */
+       while (n < num_notes &&
+              notes[n].relative_pitch == signature_pitches[s])
+       {
+           n++;
+       }
+    }
+
+    return 1;
+}
+
+static void
+scherzo_analyze_chord (scherzo_t *scherzo)
+{
+    void *local = talloc_new (NULL);
+    analyzed_note_t *notes;
+    unsigned i, num_notes = scherzo->num_notes_pressed;
+    int bass_pitch;
+    const char *chord_name = NULL;
+
+    struct { int pitches[3]; const char *name; } triads[] = {
+       { {0, 4, 8}, "Augmented triad" },
+       { {0, 4, 7}, "Major triad" },
+       { {0, 3, 7}, "Minor triad" },
+       { {0, 3, 6}, "Diminished triad" }
+    };
+
+    if (scherzo->chord) {
+       score_remove_chord (scherzo->chord);
+       scherzo->chord = NULL;
+    }
+
+    if (num_notes == 0)
+       goto DONE;
+
+    notes = talloc_array (local, analyzed_note_t, num_notes);
+    if (notes == NULL)
+       goto DONE;
+
+    for (i = 0; i < num_notes; i++) {
+       score_note_t *note = scherzo->notes_pressed[i];
+       notes[i].note = note;
+       notes[i].midi_pitch = _score_pitch_and_octave_to_midi (note->pitch,
+                                                              note->octave);
+       /* Relative pitch will be filled in after sorting. */
+       notes[i].relative_pitch = 0;
+    }
+
+    qsort (notes, num_notes, sizeof (analyzed_note_t), _compare_analyzed_note);
+    
+    bass_pitch = notes[0].midi_pitch;
+
+    for (i = 0; i < num_notes; i++) {
+       notes[i].relative_pitch = notes[i].midi_pitch - bass_pitch;
+    }
+
+    for (i = 0; i < ARRAY_SIZE (triads); i++) {
+       if (_chord_signature_matches (notes, num_notes, triads[i].pitches, 3))
+           chord_name = triads[i].name;
+    }
+
+/*
+    for (i = 0; i < num_sevenths; i++) {
+       if (_chord_signature_matches (notes, num_notes, seventh[i].pitches, 4))
+           chord_name = seventh[i].name;
+    }
+*/
+
+    if (chord_name)
+       scherzo->chord = score_add_chord (scherzo->treble, chord_name);
+    else
+       scherzo->chord = score_add_chord (scherzo->treble, "Unknown or not a chord");
+
+DONE:
+    talloc_free (local);
+}
+
 static score_note_t *
 scherzo_add_note (scherzo_t *scherzo, score_pitch_t pitch, int octave)
 {
     score_staff_t *staff;
     score_note_t *note;
+    int i;
 
-    staff = scherzo->challenge.staff;
+    if (scherzo->challenge.note)
+       staff = scherzo->challenge.staff;
+    else
+       staff = scherzo->treble;
+
+    /* Do nothing if this note is already pressed. */
+    for (i = 0; i < scherzo->num_notes_pressed; i++) {
+       if (scherzo->notes_pressed[i]->pitch == pitch &&
+           scherzo->notes_pressed[i]->octave == octave)
+       {
+           return scherzo->notes_pressed[i];
+       }
+    }
 
     note = score_add_note (staff, pitch, octave, SCORE_DURATION_WHOLE);
 
@@ -315,6 +502,8 @@ scherzo_add_note (scherzo_t *scherzo, score_pitch_t pitch, int octave)
 
     scherzo->notes_pressed[scherzo->num_notes_pressed - 1] = note;
 
+    scherzo_analyze_chord (scherzo);
+
     return note;
 }
 
@@ -338,6 +527,8 @@ scherzo_remove_note (scherzo_t *scherzo, score_pitch_t pitch, int octave)
            i--;
        }
     }
+
+    scherzo_analyze_chord (scherzo);
 }
 
 static score_note_t *
@@ -448,6 +639,11 @@ _judge_note (scherzo_t *scherzo, score_note_t *note)
 {
     challenge_t *challenge = &scherzo->challenge;
 
+    if (! scherzo->challenge.note) {
+       score_set_note_color_rgb (note, 0.0, 0.0, 0.0); /* black */
+       return;
+    }
+
     if (note->pitch == challenge->note->pitch &&
        note->octave == challenge->note->octave)
     {
@@ -468,6 +664,9 @@ _score_challenge (scherzo_t *scherzo)
 {
     challenge_t *challenge = &scherzo->challenge;
 
+    if (! challenge->note)
+       return;
+
     if (! challenge->satisfied)
        return;
 
@@ -556,6 +755,8 @@ main (int argc, char *argv[])
     scherzo.treble = score_add_staff (scherzo.score, SCORE_CLEF_G);
     scherzo.bass = score_add_staff (scherzo.score, SCORE_CLEF_F);
 
+    scherzo.chord = NULL;
+
     scherzo.num_notes_pressed = 0;
     scherzo.notes_pressed = NULL;
 
@@ -564,7 +765,9 @@ main (int argc, char *argv[])
     mnemon_load_category (&scherzo.mnemon, "scherzo-notes");
 
     scherzo.challenge.note = NULL;
+/*
     _select_challenge (&scherzo);
+*/
 
     err = snd_midi_event_new (MIDI_BUF_SIZE, &scherzo.snd_midi_event);
     if (err) {

diff --git a/score.c b/score.c
index db07d5e9d57f33436688db8741d2a4442d519760..e319af0c238abaf594afee0088bc8c580de6f59e 100644 (file)
--- a/score.c
+++ b/score.c
@@ -26,6 +26,9 @@ struct score_staff
 {
     score_clef_t clef;
 
+    score_chord_t **chords;
+    int num_chords;
+
     score_note_t **notes;
     int num_notes;
 
@@ -178,6 +181,38 @@ _score_note_to_line (score_staff_t *staff, score_note_t *note)
     return c_line - (name - SCORE_PITCH_NAME_C) / 2.0 - 3.5 * (note->octave - 4);
 }
 
+/* chord->width is updated as a side effect */
+static void
+_draw_chord (score_t *score, cairo_t *cr,
+            score_staff_t *staff, score_chord_t *chord)
+{
+    cairo_text_extents_t chord_extents;
+    double total_staff_height;
+
+    /* XXX: The staff should manage this height itself. */
+    total_staff_height = (staff->upper_ledger_lines * score->space_height +
+                         score->staff_height +
+                         staff->lower_ledger_lines * score->space_height);
+
+    cairo_save (cr);
+
+    cairo_text_extents (cr, chord->name, &chord_extents);
+
+    cairo_select_font_face (cr, "serif", 0, 0);
+    cairo_set_font_size (cr, score->space_height * 3);
+
+    if (staff->clef == SCORE_CLEF_G)
+       cairo_move_to (cr, 0, - score->space_height * 0.5);
+    else
+       cairo_move_to (cr, 0, score->space_height * 0.5 + total_staff_height + chord_extents.y_bearing);
+
+    cairo_show_text (cr, chord->name);
+
+    chord->width = chord_extents.x_advance;
+
+    cairo_restore (cr);
+}
+
 static void
 _draw_note (score_t *score, cairo_t *cr,
            score_staff_t *staff, score_note_t *note)
@@ -300,6 +335,16 @@ _draw_staff (score_t *score, cairo_t *cr,
     /* Make space for clef before drawing notes */
     cairo_translate (cr, (int) (4 * score->space_height), 0);
 
+    /* Draw chord symbols */
+    cairo_save (cr);
+    {
+       for (i = 0; i < staff->num_chords; i++) {
+           _draw_chord (score, cr, staff, staff->chords[i]);
+           cairo_translate (cr, staff->chords[i]->width, 0.0);
+       }
+    }
+    cairo_restore (cr);
+
     /* Draw notes */
     for (i = 0; i < staff->num_notes; i++) {
        _draw_note (score, cr, staff, staff->notes[i]);
@@ -409,6 +454,9 @@ score_add_staff (score_t *score, score_clef_t clef)
     staff->notes = NULL;
     staff->num_notes = 0;
 
+    staff->chords = NULL;
+    staff->num_chords = 0;
+
     staff->upper_ledger_lines = 0;
     staff->lower_ledger_lines = 0;
 
@@ -427,6 +475,61 @@ score_add_staff (score_t *score, score_clef_t clef)
     return staff;
 }
 
+score_chord_t *
+score_add_chord (score_staff_t *staff,
+                const char *name)
+{
+    score_chord_t *chord;
+
+    chord = talloc (staff, score_chord_t);
+    if (chord == NULL)
+       return NULL;
+
+    chord->staff = staff;
+    chord->name = talloc_strdup (chord, name);
+
+    /* The width will get set correctly the first time _draw_chord is
+     * called. */
+    chord->width = 0.0;
+
+    staff->num_chords++;
+    staff->chords = talloc_realloc (staff,
+                                   staff->chords,
+                                   score_chord_t*,
+                                   staff->num_chords);
+    if (staff->chords == NULL) {
+       staff->num_chords = 0;
+       return NULL;
+    }
+
+    staff->chords[staff->num_chords - 1] = chord;
+
+    return chord;
+}
+
+void
+score_remove_chord (score_chord_t *chord)
+{
+    score_staff_t *staff = chord->staff;
+    int i;
+
+    for (i = 0; i < staff->num_chords; i++)
+       if (staff->chords[i] == chord)
+           break;
+
+    if (i == staff->num_chords)
+       return;
+
+    if (i < staff->num_chords - 1)
+    {
+       memmove (staff->chords + i,
+                staff->chords + i + 1, 
+                (staff->num_chords - 1 - i) * sizeof (score_chord_t *));
+    }
+
+    staff->num_chords -= 1;
+}
+
 score_note_t *
 score_add_note (score_staff_t *staff,
                score_pitch_t pitch,

diff --git a/score.h b/score.h
index fe627b8ad401ab489bd073ee47adcd530b6c8bd5..ea363538b95d47a5c75bf4dc78882f017a9797df 100644 (file)
--- a/score.h
+++ b/score.h
@@ -140,6 +140,14 @@ typedef struct score_note
     } color;
 } score_note_t;
 
+typedef struct score_chord
+{
+    score_staff_t *staff;
+
+    char *name;
+    double width;
+} score_chord_t;
+
 typedef enum score_clef
 {
     SCORE_CLEF_G,
@@ -191,7 +199,19 @@ score_add_note (score_staff_t *staff,
                int octave,
                score_duration_t);
 
-/* Remove the given note from the given staff. */
+/* Add a chord symbol of 'name' to a staff.
+ *
+ * For now, the chord symbols are free-form names.
+ */
+score_chord_t *
+score_add_chord (score_staff_t *staff,
+                const char * name);
+
+/* Remove the given chord from its staff. */
+void
+score_remove_chord (score_chord_t *chord);
+
+/* Remove the given note from its staff. */
 void
 score_remove_note (score_note_t *note);