Class BufferClient

• Defined in File buffer_client.h

Inheritance Relationships

Base Type

• public tf2_ros::BufferInterface (Class BufferInterface)

Class Documentation

class BufferClient : public tf2_ros::BufferInterface

Action client-based implementation of the tf2_ros::BufferInterface abstract data type.

BufferClient uses actions to coordinate waiting for available transforms.

You can use this class with a tf2_ros::BufferServer and tf2_ros::TransformListener in a separate process.

Public Types

using LookupTransformAction = tf2_msgs::action::LookupTransform

Public Functions

template<typename NodePtr>
inline BufferClient(NodePtr node, const std::string ns, const double &check_frequency = 10.0, const tf2::Duration &timeout_padding = tf2::durationFromSec(2.0))

BufferClient constructor.

Parameters:

• node – The node to add the buffer client to

• ns – The namespace in which to look for a BufferServer

• check_frequency – The frequency in Hz to check whether the BufferServer has completed a request

• timeout_padding – The amount of time to allow passed the desired timeout on the client side for communication lag

virtual ~BufferClient() = default

virtual TF2_ROS_PUBLIC geometry_msgs::msg::TransformStamped lookupTransform (const std::string &target_frame, const std::string &source_frame, const tf2::TimePoint &time, const tf2::Duration timeout=tf2::durationFromSec(0.0)) const override

Get the transform between two frames by frame ID.

If there is a communication failure, timeout, or transformation error, an exception is thrown.

Parameters:

• target_frame – The frame to which data should be transformed

• source_frame – The frame where the data originated

• time – The time at which the value of the transform is desired. (0 will get the latest)

• timeout – How long to block before failing

Throws:

• tf2::TransformException – One of the following

  • tf2::LookupException

  • tf2::ConnectivityException

  • tf2::ExtrapolationException

  • tf2::InvalidArgumentException

• tf2_ros::LookupTransformGoalException – One of the following

  • tf2_ros::GoalRejectedException

  • tf2_ros::GoalAbortedException

  • tf2_ros::GoalCanceledException

  • tf2_ros::UnexpectedResultCodeException

Returns:

The transform between the frames

virtual TF2_ROS_PUBLIC geometry_msgs::msg::TransformStamped lookupTransform (const std::string &target_frame, const tf2::TimePoint &target_time, const std::string &source_frame, const tf2::TimePoint &source_time, const std::string &fixed_frame, const tf2::Duration timeout=tf2::durationFromSec(0.0)) const override

Get the transform between two frames by frame ID assuming fixed frame.

If there is a communication failure, timeout, or transformation error, an exception is thrown.

Parameters:

• target_frame – The frame to which data should be transformed

• target_time – The time to which the data should be transformed. (0 will get the latest)

• source_frame – The frame where the data originated

• source_time – The time at which the source_frame should be evaluated. (0 will get the latest)

• fixed_frame – The frame in which to assume the transform is constant in time.

• timeout – How long to block before failing

Throws:

• tf2::TransformException – One of the following

  • tf2::LookupException

  • tf2::ConnectivityException

  • tf2::ExtrapolationException

  • tf2::InvalidArgumentException

• tf2_ros::LookupTransformGoalException – One of the following

  • tf2_ros::GoalRejectedException

  • tf2_ros::GoalAbortedException

  • tf2_ros::GoalCanceledException

  • tf2_ros::UnexpectedResultCodeException

Returns:

The transform between the frames

virtual TF2_ROS_PUBLIC bool canTransform (const std::string &target_frame, const std::string &source_frame, const tf2::TimePoint &time, const tf2::Duration timeout=tf2::durationFromSec(0.0), std::string *errstr=nullptr) const override

Test if a transform is possible.

Parameters:

• target_frame – The frame into which to transform

• source_frame – The frame from which to transform

• time – The time at which to transform

• timeout – How long to block before failing

• errstr – A pointer to a string which will be filled with why the transform failed, if not NULL

Returns:

True if the transform is possible, false otherwise

virtual TF2_ROS_PUBLIC bool canTransform (const std::string &target_frame, const tf2::TimePoint &target_time, const std::string &source_frame, const tf2::TimePoint &source_time, const std::string &fixed_frame, const tf2::Duration timeout=tf2::durationFromSec(0.0), std::string *errstr=nullptr) const override

Test if a transform is possible.

Parameters:

• target_frame – The frame into which to transform

• target_time – The time into which to transform

• source_frame – The frame from which to transform

• source_time – The time from which to transform

• fixed_frame – The frame in which to treat the transform as constant in time

• timeout – How long to block before failing

• errstr – A pointer to a string which will be filled with why the transform failed, if not NULL

Returns:

True if the transform is possible, false otherwise

inline TF2_ROS_PUBLIC bool waitForServer (const tf2::Duration &timeout=tf2::durationFromSec(0))

Block until the action server is ready to respond to requests.

Parameters:

timeout – Time to wait for the server.

Returns:

True if the server is ready, false otherwise.