ui: a badge bar with a Trigger badge, and the trigger form in the slide-over

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/ui_app.hpp

@@ -130,6 +130,22 @@ struct SlideOver {
 };
 constexpr int kSlideOverWidth = 360;
 
+/// One badge: a button with a name and a state line. `page` is the slide-over page it opens.
+struct Badge {
+  GtkWidget* button = nullptr;
+  GtkWidget* name = nullptr;
+  GtkWidget* state = nullptr;
+  std::string page;
+};
+/// The badge bar under the plot (src/ui_badges.cpp).
+struct BadgeBar {
+  GtkWidget* bar = nullptr;           ///< main-window.ui `badge_bar`, fixed height
+  GtkWidget* signals_slot = nullptr;  ///< left; empty in step 1, step 2 fills it
+  GtkWidget* system_slot = nullptr;   ///< right: Trigger, Source
+  Badge trigger;
+  Badge source;                       ///< task 3
+};
+
 struct App {
   ScopeModel* model = nullptr;
   Acquisition* acq = nullptr;
@@ -140,6 +156,11 @@ struct App {
   /// The `GtkOverlay` around `plot_box` (`main-window.ui`), which the slide-over panel is a child of.
   GtkWidget* plot_overlay = nullptr;
   SlideOver slideover;
+  /// The badge bar under the plot (`main-window.ui` `badge_bar`, with its two slots).
+  BadgeBar badges;
+  GtkWidget* badge_bar = nullptr;
+  GtkWidget* badge_signals = nullptr;
+  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
   /// count is.
@@ -1901,6 +1922,12 @@ bool slideover_escape(App& app);                         // closes if open; true
 /// x, y in the overlay's coordinates; closes unless the point is inside the panel; true when it closed.
 bool slideover_click_away(App& app, double x, double y);
 gboolean slideover_probe(gpointer user);  // UDPSCOPE_PROBE_SLIDEOVER_MS
+/// The badge bar (`src/ui_badges.cpp`): setup is reached by the object it configures.
+/// The Trigger badge's state word. Pure, so the probe can assert the whole table.
+const char* trigger_badge_state(bool enabled, bool armed, bool pending, bool has_event);
+void build_badge_bar(App& app);  // after build_slideover and after the toolbar (it reads trigger_toggle)
+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
 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