test: probe the ctrl/alt keyboard zoom restriction through the app

src/ui.cpp

@@ -7181,6 +7181,48 @@ gboolean measures_probe_step(gpointer user) {
   return G_SOURCE_REMOVE;
 }
 
+/// Drives the plot's keyboard zoom with Ctrl and with Alt and reports which axis moved.
+/// Run it inside a pinned state (the pause probe makes a stable one) so the `_held`
+/// readings mean "the other axis did not move", not "the frame re-framed anyway":
+///   UDPSCOPE_PROBE_PAUSE_MS=1500 UDPSCOPE_PROBE_ZOOMKEYS_MS=2200
+gboolean zoomkeys_probe(gpointer user) {
+  App* a = static_cast<App*>(user);
+  if (a->rows->row_count() == 0 || a->rows->row(0).plot == nullptr) return G_SOURCE_REMOVE;
+  plot::Plot& p = *a->rows->row(0).plot;
+  const plot::u32 ax = a->rows->row(0).axis_x;
+  const plot::u32 ay = a->rows->row(0).axis_y;
+
+  plot::input::Controller* c =
+      a->area != nullptr ? a->area->row_controller(static_cast<plot::u32>(0)) : nullptr;
+  if (c == nullptr) {
+    std::fprintf(stderr, "[zoomkeys] no controller for row 0\n");
+    std::fflush(stderr);
+    return G_SOURCE_REMOVE;
+  }
+
+  const plot::Range x0 = p.x_range(ax);
+  const plot::Range y0 = p.y_range(ay);
+  c->on_key({plot::input::kKeyZoomIn,
+             static_cast<plot::u32>(plot::input::Mod::Ctrl), true});
+  const plot::Range x1 = p.x_range(ax);
+  const plot::Range y1 = p.y_range(ay);
+  const int y_held = std::abs(y1.span() - y0.span()) < 1e-9 ? 1 : 0;
+
+  c->on_key({plot::input::kKeyZoomIn,
+             static_cast<plot::u32>(plot::input::Mod::Alt), true});
+  const plot::Range x2 = p.x_range(ax);
+  const plot::Range y2 = p.y_range(ay);
+  const int x_held = std::abs(x2.span() - x1.span()) < 1e-9 ? 1 : 0;
+
+  std::fprintf(stderr,
+               "[zoomkeys] ctrl+plus x=[%.4f..%.4f]->[%.4f..%.4f] y_held=%d | "
+               "alt+plus y=[%.4f..%.4f]->[%.4f..%.4f] x_held=%d\n",
+               x0.min, x0.max, x1.min, x1.max, y_held, y1.min, y1.max, y2.min, y2.max,
+               x_held);
+  std::fflush(stderr);
+  return G_SOURCE_REMOVE;
+}
+
 int run_ui(int argc, char** argv, const Config& cfg, ScopeModel& model, Acquisition& acq,
            RowSet& rows) {
   (void)argc;
@@ -7261,6 +7303,9 @@ int run_ui(int argc, char** argv, const Config& cfg, ScopeModel& model, Acquisit
   if (const char* env = g_getenv("UDPSCOPE_EXPORT_MS")) {
     g_timeout_add(static_cast<guint>(std::atoi(env)), export_probe, &app);
   }
+  if (const char* env = g_getenv("UDPSCOPE_PROBE_ZOOMKEYS_MS")) {
+    g_timeout_add(static_cast<guint>(std::atoi(env)), zoomkeys_probe, &app);
+  }
 
   // Our own options were consumed by parse_args(); GTK would reject them, so only
   // the program name is handed to g_application_run().