From f13bf96d555a7ec69a54d2568845e96ac4498794 Mon Sep 17 00:00:00 2001
From: Jeremy Nimmer <jeremy.nimmer@tri.global>
Date: Mon, 12 Jul 2021 19:40:45 -0700
Subject: [PATCH] [pydrake] Add bindings for LcmScopeSystem (#15309)

---
 bindings/pydrake/systems/lcm_py.cc        | 28 +++++++++++++++++++++++
 bindings/pydrake/systems/test/lcm_test.py | 12 ++++++++++
 2 files changed, 40 insertions(+)

diff --git a/bindings/pydrake/systems/lcm_py.cc b/bindings/pydrake/systems/lcm_py.cc
index 4da4cb0a3556..199277c85514 100644
--- a/bindings/pydrake/systems/lcm_py.cc
+++ b/bindings/pydrake/systems/lcm_py.cc
@@ -11,6 +11,7 @@
 #include "drake/systems/lcm/connect_lcm_scope.h"
 #include "drake/systems/lcm/lcm_interface_system.h"
 #include "drake/systems/lcm/lcm_publisher_system.h"
+#include "drake/systems/lcm/lcm_scope_system.h"
 #include "drake/systems/lcm/lcm_subscriber_system.h"
 #include "drake/systems/lcm/serializer.h"
 
@@ -169,6 +170,33 @@ PYBIND11_MODULE(lcm, m) {
             py::arg("timeout") = -1, cls_doc.WaitForMessage.doc);
   }
 
+  {
+    using Class = LcmScopeSystem;
+    constexpr auto& cls_doc = doc.LcmScopeSystem;
+    py::class_<Class, LeafSystem<double>>(m, "LcmScopeSystem")
+        .def(py::init<int>(), py::arg("size"), cls_doc.ctor.doc)
+        .def_static(
+            "AddToBuilder",
+            [](systems::DiagramBuilder<double>* builder,
+                drake::lcm::DrakeLcmInterface* lcm,
+                const OutputPort<double>& signal, const std::string& channel,
+                double publish_period) {
+              auto [scope, publisher] = LcmScopeSystem::AddToBuilder(
+                  builder, lcm, signal, channel, publish_period);
+              // Annotate the proper rvp on the tuple of pointers.
+              py::object py_builder = py::cast(builder, py_rvp::reference);
+              py::list result;
+              result.append(
+                  py::cast(scope, py_rvp::reference_internal, py_builder));
+              result.append(
+                  py::cast(publisher, py_rvp::reference_internal, py_builder));
+              return result;
+            },
+            py::arg("builder"), py::arg("lcm"), py::arg("signal"),
+            py::arg("channel"), py::arg("publish_period"),
+            cls_doc.AddToBuilder.doc);
+  }
+
   m.def("ConnectLcmScope", &ConnectLcmScope, py::arg("src"), py::arg("channel"),
       py::arg("builder"), py::arg("lcm") = nullptr,
       py::arg("publish_period") = 0.0, py::keep_alive<0, 2>(),
diff --git a/bindings/pydrake/systems/test/lcm_test.py b/bindings/pydrake/systems/test/lcm_test.py
index 76b73e8dcd38..0ada060fe3d2 100644
--- a/bindings/pydrake/systems/test/lcm_test.py
+++ b/bindings/pydrake/systems/test/lcm_test.py
@@ -192,6 +192,18 @@ def test_diagram_publisher(self):
         diagram = builder.Build()
         diagram.Publish(diagram.CreateDefaultContext())
 
+    def test_lcm_scope(self):
+        builder = DiagramBuilder()
+        source = builder.AddSystem(ConstantVectorSource(np.zeros(4)))
+        scope, publisher = mut.LcmScopeSystem.AddToBuilder(
+            builder=builder,
+            lcm=DrakeLcm(),
+            signal=source.get_output_port(0),
+            channel="TEST_CHANNEL",
+            publish_period=0.001)
+        self.assertIsInstance(scope, mut.LcmScopeSystem)
+        self.assertIsInstance(publisher, mut.LcmPublisherSystem)
+
     def test_connect_lcm_scope(self):
         builder = DiagramBuilder()
         source = builder.AddSystem(ConstantVectorSource(np.zeros(4)))