Change EffortDisplay superclass from MessageFilterDisplay to RosTopicDisplay to avoid dropping messages with empty frame_id. (#1312)

Problem: EffortDisplay does not react on JointState messages with emty frame_id.
Also the following warning is displayed:

  [rviz2]: Message Filter dropping message: frame '' at time ..... for reason
  'the frame id of the message is empty'

Reason: MessageFilterDisplay uses tf2_ros::MessageFilter which checks
that frame_id is not empty. This mechanism is designed to perform message
frame change "on-fly" but it is nao applicable to JointState messages.

Solution: Use RosTopicDisplay instead of MessageFilterDisplay. Use type erased signal/slot
pair to ensure messages are processed in the main thread.

Author: disRecord

rviz_default_plugins/include/rviz_default_plugins/displays/effort/effort_display.hpp

@@ -38,7 +38,7 @@
 #include <string>
 
 #include <rclcpp/rclcpp.hpp>
-#include <rviz_common/message_filter_display.hpp>
+#include <rviz_common/ros_topic_display.hpp>
 #include <rviz_common/properties/bool_property.hpp>
 #include <rviz_common/properties/int_property.hpp>
 #include <rviz_common/properties/float_property.hpp>
@@ -90,7 +90,7 @@ public Q_SLOTS:
 };
 
 class RVIZ_DEFAULT_PLUGINS_PUBLIC EffortDisplay
-  : public rviz_common::MessageFilterDisplay<sensor_msgs::msg::JointState>
+  : public rviz_common::RosTopicDisplay<sensor_msgs::msg::JointState>
 {
   Q_OBJECT
 
@@ -122,6 +122,7 @@ private Q_SLOTS:
   void onEnable() override;
   void onDisable() override;
   void processMessage(sensor_msgs::msg::JointState::ConstSharedPtr msg) override;
+  void processTypeErasedMessage(std::shared_ptr<const void> type_erased_msg) override;
 
   void load();
   void clear();

rviz_default_plugins/src/rviz_default_plugins/displays/effort/effort_display.cpp

@@ -112,7 +112,7 @@ bool JointInfo::getEnabled() const
 }
 
 EffortDisplay::EffortDisplay()
-: rviz_common::MessageFilterDisplay<sensor_msgs::msg::JointState>()
+: rviz_common::RosTopicDisplay<sensor_msgs::msg::JointState>()
 {
   alpha_property_ = new rviz_common::properties::FloatProperty(
     "Alpha", 1.0f, "0 is fully transparent, 1.0 is fully opaque.",
@@ -155,7 +155,7 @@ EffortDisplay::~EffortDisplay()
 
 void EffortDisplay::onInitialize()
 {
-  MFDClass::onInitialize();
+  RTDClass::onInitialize();
   updateHistoryLength();
 }
 
@@ -170,7 +170,7 @@ void EffortDisplay::updateHistoryLength()
 // Clear the visuals by deleting their objects.
 void EffortDisplay::reset()
 {
-  MFDClass::reset();
+  RTDClass::reset();
   visuals_.clear();
 }
 
@@ -288,11 +288,23 @@ std::string concat(const std::string & prefix, const std::string & frame)
 
 void EffortDisplay::processMessage(sensor_msgs::msg::JointState::ConstSharedPtr msg)
 {
+  if (!msg) {
+    return;
+  }
+
+  // Use type erased signal/slot machinery to ensure messages are
+  // processed in the main thread.
+  Q_EMIT typeErasedMessageTaken(std::static_pointer_cast<const void>(msg));
+}
+
+void EffortDisplay::processTypeErasedMessage(std::shared_ptr<const void> type_erased_msg)
+{
+  auto msg = std::static_pointer_cast<const sensor_msgs::msg::JointState>(type_erased_msg);
+
   // Robot model might not be loaded yet
   if (!robot_model_) {
     setStatus(
-      rviz_common::properties::StatusLevel::Error,
-      "Process message",
+      rviz_common::properties::StatusLevel::Error, "Topic",
       QString("Robot model might not be loaded yet"));
     return;
   }