minor cleanup in sequencer_demo

examples/demo/sequencer_demo.cpp

@@ -1,5 +1,6 @@
 #include <cctype>
 #include <chrono>
+#include <iomanip>
 #include <thread>
 #include <unordered_map>
 #include <utility>
@@ -55,44 +56,56 @@ int main(int /*argc*/, char* /*argv*/[]) {
   Musician musician;
   musician.SetTempo(kInitialTempo);
 
+  // Create the instrument.
   auto instrument = musician.CreateInstrument<SynthInstrument>(kFrameRate);
   instrument.SetControl(SynthInstrument::Control::kGain, kGain);
   instrument.SetControl(SynthInstrument::Control::kOscillatorType, kOscillatorType);
   instrument.SetControl(SynthInstrument::Control::kAttack, kAttack);
   instrument.SetControl(SynthInstrument::Control::kRelease, kRelease);
+
   instrument.SetNoteOnEvent([](double pitch, double /*intensity*/) {
-    ConsoleLog() << "Note{" << barely::MidiNumberFromPitch(pitch) << "}";
+    ConsoleLog() << "Playing {" << barely::MidiNumberFromPitch(pitch) << "}";
   });
 
+  // Create the performer.
   auto performer = musician.CreatePerformer();
   performer.SetLooping(true);
   performer.SetLoopBeginPosition(3.0);
   performer.SetLoopLength(5.0);
 
-  const auto play_note_fn = [&](double duration, double pitch) {
-    return [&instrument, &performer, pitch, duration]() {
-      instrument.SetNoteOn(pitch);
-      performer.ScheduleOneOffTask([&instrument, pitch]() { instrument.SetNoteOff(pitch); },
-                                   performer.GetPosition() + duration);
-    };
+  // Build the score.
+  struct Note {
+    Task task;
+    bool is_muted = false;
+  };
+  std::vector<Note> notes;
+
+  ConsoleLog() << "Notes:";
+  const auto create_note_fn = [&](double position, double duration, double pitch) {
+    const int index = static_cast<int>(notes.size());
+    ConsoleLog() << std::setprecision(2) << "[" << index << "] (" << position << ", " << duration
+                 << ")\t{" << barely::MidiNumberFromPitch(pitch) << "}";
+
+    return performer.CreateTask(
+        [&instrument, &performer, &notes, duration, pitch, index]() {
+          if (!notes[index].is_muted) {
+            instrument.SetNoteOn(pitch);
+            performer.ScheduleOneOffTask([&instrument, pitch]() { instrument.SetNoteOff(pitch); },
+                                         performer.GetPosition() + duration);
+          }
+        },
+        position);
   };
 
-  std::vector<std::pair<double, TaskDefinition::Callback>> score;
-  score.emplace_back(0.0, play_note_fn(1.0, barely::kPitchC4));
-  score.emplace_back(1.0, play_note_fn(1.0, barely::kPitchD4));
-  score.emplace_back(2.0, play_note_fn(1.0, barely::kPitchE4));
-  score.emplace_back(3.0, play_note_fn(1.0, barely::kPitchF4));
-  score.emplace_back(4.0, play_note_fn(1.0, barely::kPitchG4));
-  score.emplace_back(5.0, play_note_fn(1.0 / 3.0, barely::kPitchG4));
-  score.emplace_back(5 + 1.0 / 3.0, play_note_fn(1.0 / 3.0, barely::kPitchA4));
-  score.emplace_back(5 + 2.0 / 3.0, play_note_fn(1.0 / 3.0, barely::kPitchB4));
-  score.emplace_back(6.0, play_note_fn(2.0, barely::kPitchC5));
-
-  std::unordered_map<int, Task> tasks;
-  int index = 0;
-  for (const auto& [position, callback] : score) {
-    tasks.emplace(index++, performer.CreateTask(callback, position));
-  }
+  notes.emplace_back(create_note_fn(0.0, 1.0, barely::kPitchC4));
+  notes.emplace_back(create_note_fn(1.0, 1.0, barely::kPitchD4));
+  notes.emplace_back(create_note_fn(2.0, 1.0, barely::kPitchE4));
+  notes.emplace_back(create_note_fn(3.0, 1.0, barely::kPitchF4));
+  notes.emplace_back(create_note_fn(4.0, 1.0, barely::kPitchG4));
+  notes.emplace_back(create_note_fn(5.0, 1.0 / 3.0, barely::kPitchG4));
+  notes.emplace_back(create_note_fn(5 + 1.0 / 3.0, 1.0 / 3.0, barely::kPitchA4));
+  notes.emplace_back(create_note_fn(5 + 2.0 / 3.0, 1.0 / 3.0, barely::kPitchB4));
+  notes.emplace_back(create_note_fn(6.0, 2.0, barely::kPitchC5));
 
   // Audio process callback.
   const auto process_callback = [&](double* output) {
@@ -110,15 +123,9 @@ int main(int /*argc*/, char* /*argv*/[]) {
       return;
     }
     if (const int index = static_cast<int>(key - '0'); index > 0 && index < 10) {
-      // Toggle score.
-      if (const auto it = tasks.find(index - 1); it != tasks.end()) {
-        tasks.erase(it);
-        ConsoleLog() << "Removed note " << index;
-      } else {
-        const auto& [position, callback] = score[index - 1];
-        tasks.emplace(index - 1, performer.CreateTask(callback, position));
-        ConsoleLog() << "Added note " << index;
-      }
+      // Toggle note.
+      notes[index].is_muted = !notes[index].is_muted;
+      ConsoleLog() << (notes[index].is_muted ? "Muted" : "Unmuted") << " [" << index << "]";
       return;
     }
     // Adjust tempo.