Add dialog box to change current BPM

src/editor_state.cpp

@@ -1278,6 +1278,24 @@ void EditorState::display_sync_menu() {
     ImGui::End();
 }
 
+void EditorState::display_bpm_change_menu() {
+    if (ImGui::Begin("Insert BPM Change", &show_bpm_change_menu)) {
+        auto bpm = std::visit(
+            [&](const auto& pos){return applicable_timing->bpm_at(pos);},
+            playback_position
+        );
+        ImGui::PushItemWidth(-70.0f);
+        if (feis::InputDecimal("BPM", &bpm, ImGuiInputTextFlags_EnterReturnsTrue)) {
+            if (bpm > 0) {
+                auto new_timing = *applicable_timing;
+                new_timing.insert(better::BPMAtBeat{bpm, current_snaped_beats()});
+                replace_applicable_timing_with(new_timing);
+            }
+        }
+    }
+    ImGui::End();
+}
+
 bool EditorState::needs_to_save() const {
     return not history.current_state_is_saved();
 };

src/editor_state.hpp

@@ -179,6 +179,9 @@ public:
     bool show_sync_menu = false;
     void display_sync_menu();
 
+    bool show_bpm_change_menu = false;
+    void display_bpm_change_menu();
+
     enum class SaveOutcome {
         UserSaved,
         UserDeclindedSaving,

src/main.cpp

@@ -519,6 +519,9 @@ int main() {
             if (editor_state->show_sync_menu) {
                 editor_state->display_sync_menu();
             }
+            if (editor_state->show_bpm_change_menu) {
+                editor_state->display_bpm_change_menu();
+            }
         } else {
             bg.render(window);
         }
@@ -644,6 +647,9 @@ int main() {
                 if (ImGui::MenuItem("Adjust Sync")) {
                     editor_state->show_sync_menu = true;
                 }
+                if (ImGui::MenuItem("Insert BPM Change")) {
+                    editor_state->show_bpm_change_menu = true;
+                }
                 ImGui::EndMenu();
             }
             if (ImGui::BeginMenu("Notes", editor_state.has_value())) {