ui: one badge per enabled signal, an N signals overflow, and the order kept in memory

src/ui_app.hpp

@@ -149,7 +149,11 @@ struct Badge {
   GtkWidget* name = nullptr;
   GtkWidget* state = nullptr;
   std::string page;
+  std::string signal_name;  ///< a signal badge: the signal it stands for; empty for the others
+  std::size_t signal = 0;   ///< a signal badge: its index in `ScopeModel::signals()` when it was built
 };
+/// The most signal badges the bar shows; beyond that one "N signals" badge stands for them all.
+inline constexpr std::size_t kMaxSignalBadges = 6;
 /// The badge bar under the plot (src/ui_badges.cpp).
 struct BadgeBar {
   GtkWidget* bar = nullptr;           ///< main-window.ui `badge_bar`, fixed height
@@ -157,6 +161,11 @@ struct BadgeBar {
   GtkWidget* system_slot = nullptr;   ///< right: Trigger, Source
   Badge trigger;
   Badge source;                       ///< opens the first source page; a read-out when the source has none
+  GtkWidget* signals_row = nullptr;   ///< the box inside the scroller: signal badges, then the "+"
+  /// One per shown enabled signal; empty when overflowed. `unique_ptr`: each button's "clicked" handler holds
+  /// a pointer to its `Badge`, which must not move when the vector does.
+  std::vector<std::unique_ptr<Badge>> signal_badges;
+  Badge overflow;                     ///< the "N signals" badge, used only beyond `kMaxSignalBadges`
   Badge plus;                         ///< the "+" in the signals slot: opens the `signals` page
 };
 
@@ -174,6 +183,8 @@ struct App {
   BadgeBar badges;
   GtkWidget* badge_bar = nullptr;
   GtkWidget* badge_signals = nullptr;
+  /// Signal names in the order the user left the badges (memory only; names not in it sort last).
+  std::vector<std::string> badge_order;
   GtkWidget* badge_system = nullptr;
   /// The one GL area, drawing the `RowSet`'s figure: every row is a row of that
   /// figure, so there is one widget, one context and one `::render` whatever the row
@@ -1952,6 +1963,9 @@ const char* trigger_badge_state(bool enabled, bool armed, bool pending, bool has
 void build_badge_bar(App& app);  // after build_slideover, the toolbar (it reads trigger_toggle) and build_source_panels (the Source badge's page)
 void sync_badge_bar(App& app);   // per tick and on every slide-over open/close; only writes what changed
 gboolean badges_probe(gpointer user);  // UDPSCOPE_PROBE_BADGES_MS
+/// Rebuilds the signal badges (one per enabled signal, or the "N signals" overflow) from the model.
+void sync_signal_badges(App& app);
+gboolean signal_badges_probe(gpointer user);  // UDPSCOPE_PROBE_SIGNAL_BADGES_MS
 gboolean source_kinds_probe_report(gpointer user);
 gboolean source_kinds_probe(gpointer user);
 /// MCC E-1608 end to end against `tools/mock_e1608.py`: the stream, the calibration, the panels and