Piano: Fix insertion and deletion of notes

On mouse move the pressed button is not present in the event argument
which causes the corresponding code to never fire. Instead it now stores
the original mouse down event and acts according to that on mouse move.

Userland/Applications/Piano/RollWidget.cpp

@@ -185,61 +185,63 @@ void RollWidget::mousedown_event(GUI::MouseEvent& event)
     if (!widget_inner_rect().contains(event.x(), event.y()))
         return;
 
-    m_note_drag_start = event.position();
+    if (event.button() == GUI::MouseButton::Secondary) {
+        auto const time = roll_length * (static_cast<double>(get_note_for_x(event.x())) / m_num_notes);
+        auto const note = m_track_manager.current_track()->note_at(time, get_pitch_for_y(event.y()));
 
-    int y = (m_note_drag_start.value().y() + vertical_scrollbar().value()) - frame_thickness();
-    y /= note_height;
-    m_drag_note = (note_count - 1) - y;
+        if (note.has_value()) {
+            m_track_manager.current_track()->remove_note(note.value());
+            update();
+        }
+        return;
+    }
 
+    m_mousedown_event = event;
+}
+
+void RollWidget::mouseup_event(GUI::MouseEvent& event)
+{
     mousemove_event(event);
+    m_mousedown_event = {};
+}
+
+u8 RollWidget::get_pitch_for_y(int y) const
+{
+    return (note_count - 1) - ((y + vertical_scrollbar().value()) - frame_thickness()) / note_height;
+}
+
+int RollWidget::get_note_for_x(int x) const
+{
+    // There's a case where we can't just use x / m_note_width. For example, if
+    // your m_note_width is 3.1 you will have a rect starting at 3. When that
+    // leftmost pixel of the rect is clicked you will do 3 / 3.1 which is 0
+    // and not 1. We can avoid that case by shifting x by 1 if m_note_width is
+    // fractional, being careful not to shift out of bounds.
+    x = (x + horizontal_scrollbar().value()) - frame_thickness();
+    bool const note_width_is_fractional = m_note_width - static_cast<int>(m_note_width) != 0;
+    bool const x_is_not_last = x != widget_inner_rect().width() - 1;
+    if (note_width_is_fractional && x_is_not_last)
+        ++x;
+    x /= m_note_width;
+    return clamp(x, 0, m_num_notes - 1);
 }
 
 void RollWidget::mousemove_event(GUI::MouseEvent& event)
 {
-    if (!m_note_drag_start.has_value())
+    if (!m_mousedown_event.has_value())
         return;
 
-    if (m_note_drag_location.has_value()) {
-        // Clear previous note
-        m_track_manager.current_track()->remove_note(m_note_drag_location.value());
-    }
+    if (m_mousedown_event.value().button() == GUI::MouseButton::Primary) {
+        int const x_start = get_note_for_x(m_mousedown_event.value().x());
+        int const x_end = get_note_for_x(event.x());
 
-    // Right-Click deletes notes
-    if (event.button() == GUI::MouseButton::Secondary) {
+        const u32 on_sample = round(roll_length * (static_cast<double>(min(x_start, x_end)) / m_num_notes));
+        const u32 off_sample = round(roll_length * (static_cast<double>(max(x_start, x_end) + 1) / m_num_notes)) - 1;
+        auto const note = RollNote { on_sample, off_sample, get_pitch_for_y(m_mousedown_event.value().y()), 127 };
+
+        m_track_manager.current_track()->set_note(note);
         update();
-        return;
     }
-
-    auto get_note_x = [&](int x0) {
-        // There's a case where we can't just use x / m_note_width. For example, if
-        // your m_note_width is 3.1 you will have a rect starting at 3. When that
-        // leftmost pixel of the rect is clicked you will do 3 / 3.1 which is 0
-        // and not 1. We can avoid that case by shifting x by 1 if m_note_width is
-        // fractional, being careful not to shift out of bounds.
-        int x = (x0 + horizontal_scrollbar().value()) - frame_thickness();
-        bool note_width_is_fractional = m_note_width - static_cast<int>(m_note_width) != 0;
-        bool x_is_not_last = x != widget_inner_rect().width() - 1;
-        if (note_width_is_fractional && x_is_not_last)
-            ++x;
-        x /= m_note_width;
-        return clamp(x, 0, m_num_notes - 1);
-    };
-
-    int x0 = get_note_x(m_note_drag_start.value().x());
-    int x1 = get_note_x(event.x());
-
-    u32 on_sample = roll_length * (static_cast<double>(min(x0, x1)) / m_num_notes);
-    u32 off_sample = (roll_length * (static_cast<double>(max(x0, x1) + 1) / m_num_notes)) - 1;
-    m_note_drag_location = RollNote { on_sample, off_sample, (u8)m_drag_note, 127 };
-    m_track_manager.current_track()->set_note(m_note_drag_location.value());
-
-    update();
-}
-
-void RollWidget::mouseup_event([[maybe_unused]] GUI::MouseEvent& event)
-{
-    m_note_drag_start = {};
-    m_note_drag_location = {};
 }
 
 // FIXME: Implement zoom and horizontal scroll events in LibGUI, not here.

Userland/Applications/Piano/RollWidget.h

@@ -43,12 +43,13 @@ private:
     double m_note_width { 0.0 };
     int m_zoom_level { 1 };
 
-    Optional<Gfx::IntPoint> m_note_drag_start;
-    Optional<RollNote> m_note_drag_location;
-    int m_drag_note;
+    Optional<GUI::MouseEvent> m_mousedown_event;
 
     RefPtr<Gfx::Bitmap> m_background;
     int m_prev_zoom_level { m_zoom_level };
     int m_prev_scroll_x { horizontal_scrollbar().value() };
     int m_prev_scroll_y { vertical_scrollbar().value() };
+
+    u8 get_pitch_for_y(int y) const;
+    int get_note_for_x(int x) const;
 };

Userland/Libraries/LibDSP/Clip.cpp

@@ -14,6 +14,15 @@ Sample AudioClip::sample_at(u32 time)
     return m_samples[time];
 }
 
+Optional<RollNote> NoteClip::note_at(u32 time, u8 pitch) const
+{
+    for (auto& note : m_notes) {
+        if (time >= note.on_sample && time <= note.off_sample && pitch == note.pitch)
+            return note;
+    }
+    return {};
+}
+
 void NoteClip::set_note(RollNote note)
 {
     m_notes.remove_all_matching([&](auto const& other) {

Userland/Libraries/LibDSP/Clip.h

@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <AK/Forward.h>
 #include <AK/RefCounted.h>
 #include <AK/SinglyLinkedList.h>
 #include <AK/Types.h>
@@ -50,6 +51,7 @@ public:
     {
     }
 
+    Optional<RollNote> note_at(u32 time, u8 pitch) const;
     void set_note(RollNote note);
     // May do nothing; that's fine.
     void remove_note(RollNote note);

Userland/Libraries/LibDSP/Track.cpp

@@ -146,6 +146,16 @@ void AudioTrack::compute_current_clips_signal()
     TODO();
 }
 
+Optional<RollNote> NoteTrack::note_at(u32 time, u8 pitch) const
+{
+    for (auto& clip : m_clips) {
+        if (time >= clip.start() && time <= clip.end())
+            return clip.note_at(time, pitch);
+    }
+
+    return {};
+}
+
 void NoteTrack::set_note(RollNote note)
 {
     for (auto& clip : m_clips) {

Userland/Libraries/LibDSP/Track.h

@@ -80,6 +80,7 @@ public:
     bool check_processor_chain_valid() const override;
     ReadonlySpan<NonnullRefPtr<NoteClip>> notes() const { return m_clips.span(); }
 
+    Optional<RollNote> note_at(u32 time, u8 pitch) const;
     void set_note(RollNote note);
     void remove_note(RollNote note);