Add configurable TF topics (#709)

* Set defaults in transform lister and expose them as args to the
  TransformLister
* Add CLI args in view_frames to change /tf and /tf_static topics

Signed-off-by: Ryan Friedman <25047695+Ryanf55@users.noreply.github.com>

tf2_ros/doc/cli_tools.rst

@@ -73,6 +73,13 @@ In the current working folder, you should now have a file called "frames_$(data)
 
 .. image:: images/view_frames.png
 
+
+If you need to view the frames from non-standard topics, you can override them like so:
+
+.. code-block:: bash
+
+   ros2 run tf2_tools view_frames --tf_topic=/foo  --tf_static_topic=bar
+
 Fields
 ~~~~~~
   * Recorded at time: shows the absolute timestamp when this graph was generated.

tf2_ros_py/tf2_ros/transform_listener.py

@@ -40,12 +40,15 @@
 from tf2_msgs.msg import TFMessage
 from threading import Thread
 
+DEFAULT_TF_TOPIC = '/tf'
+DEFAULT_STATIC_TF_TOPIC = '/tf_static'
 
 class TransformListener:
     """
     :class:`TransformListener` is a convenient way to listen for coordinate frame transformation info.
     This class takes an object that instantiates the :class:`BufferInterface` interface, to which
-    it propagates changes to the tf frame graph.
+    it propagates changes to the tf frame graph. It listens to both static and dynamic
+    transforms.
     """
     def __init__(
         self,
@@ -54,7 +57,9 @@ def __init__(
         *,
         spin_thread: bool = False,
         qos: Optional[Union[QoSProfile, int]] = None,
-        static_qos: Optional[Union[QoSProfile, int]] = None
+        static_qos: Optional[Union[QoSProfile, int]] = None,
+        tf_topic: str = DEFAULT_TF_TOPIC,
+        tf_static_topic: str = DEFAULT_STATIC_TF_TOPIC
     ) -> None:
         """
         Constructor.
@@ -64,6 +69,8 @@ def __init__(
         :param spin_thread: Whether to create a dedidcated thread to spin this node.
         :param qos: A QoSProfile or a history depth to apply to subscribers.
         :param static_qos: A QoSProfile or a history depth to apply to tf_static subscribers.
+        :param tf_topic: Which topic to listen to for dynamic transforms.
+        :param tf_static_topic: Which topic to listen to for static transforms.
         """
         if qos is None:
             qos = QoSProfile(
@@ -83,9 +90,9 @@ def __init__(
         # from another callback in the same group.
         self.group = ReentrantCallbackGroup()
         self.tf_sub = node.create_subscription(
-            TFMessage, '/tf', self.callback, qos, callback_group=self.group)
+            TFMessage, tf_topic, self.callback, qos, callback_group=self.group)
         self.tf_static_sub = node.create_subscription(
-            TFMessage, '/tf_static', self.static_callback, static_qos, callback_group=self.group)
+            TFMessage, tf_static_topic, self.static_callback, static_qos, callback_group=self.group)
 
         if spin_thread:
             self.executor = SingleThreadedExecutor()

tf2_tools/tf2_tools/view_frames.py

@@ -36,6 +36,7 @@
 import rclpy
 from tf2_msgs.srv import FrameGraph
 import tf2_ros
+from tf2_ros.transform_listener import DEFAULT_STATIC_TF_TOPIC, DEFAULT_TF_TOPIC
 
 import yaml
 
@@ -50,12 +51,19 @@ def main():
         '--wait-time', '-t', type=float, default=5.0,
         help='Listen to the /tf topic for this many seconds before rendering the frame tree')
     parser.add_argument('-o', '--output', help='Output filename')
+    parser.add_argument('--tf_topic', help='Topic for dynamic transforms',
+                        default=DEFAULT_TF_TOPIC)
+    parser.add_argument('--tf_static_topic', help='Topic for static transforms',
+                        default=DEFAULT_STATIC_TF_TOPIC)
+
     parsed_args = parser.parse_args(args=args_without_ros[1:])
 
     node = rclpy.create_node('view_frames')
 
     buf = tf2_ros.Buffer(node=node)
-    listener = tf2_ros.TransformListener(buf, node, spin_thread=False)
+    listener = tf2_ros.TransformListener(buf, node, spin_thread=False,
+                                         tf_topic=parsed_args.tf_topic,
+                                         tf_static_topic=parsed_args.tf_static_topic)
     listener  # To quiet a flake8 warning
 
     executor = rclpy.executors.SingleThreadedExecutor()