drake::lcm Namespace Reference

Classes
class	DrakeLcm
	A wrapper around a real LCM instance. More...
class	DrakeLcmBase
	A concrete subclass of DrakeInterface that throws for all functions except the constructor and destructor. More...
class	DrakeLcmInterface
	A pure virtual interface that enables LCM to be mocked. More...
class	DrakeLcmLog
	A LCM interface for logging LCM messages to a file or playing back from a existing log. More...
struct	DrakeLcmParams
	The set of parameters for configuring DrakeLcm. More...
class	DrakeSubscriptionInterface
	A helper class returned by DrakeLcmInterface::Subscribe() that allows for (possibly automatic) unsubscription and/or queue capacity control. More...
class	Subscriber
	Subscribes to and stores a copy of the most recent message on a given channel, for some Message type. More...

Functions
template<typename Message >
void	Publish (DrakeLcmInterface *lcm, const std::string &channel, const Message &message, std::optional< double > time_sec={})
	Publishes an LCM message on channel channel. More...
template<typename Message >
std::shared_ptr< DrakeSubscriptionInterface >	Subscribe (DrakeLcmInterface *lcm, const std::string &channel, std::function< void(const Message &)> handler, std::function< void()> on_error={})
	Subscribes to an LCM channel named channel and decodes messages of type Message. More...
int	LcmHandleSubscriptionsUntil (DrakeLcmInterface *lcm, const std::function< bool(void)> &finished, int timeout_millis=100)
	Convenience function that repeatedly calls lcm->HandleSubscriptions() with a timeout value of timeout_millis, until finished() returns true. More...
template<typename Message >
std::vector< uint8_t >	EncodeLcmMessage (const Message &message)
	Encodes an LCM message to a series of bytes. More...
template<typename Message >
Message	DecodeLcmMessage (const std::vector< uint8_t > &bytes)
	Decodes an LCM message from a series of bytes. More...
template<typename Message >
bool	AreLcmMessagesEqual (const Message &a, const Message &b)
	Compares two LCM messages of the same type to see if they are equal. More...
bool	CompareLcmtDrakeSignalMessages (const lcmt_drake_signal &actual_message, const lcmt_drake_signal &expected_message)
	Compares two drake::lcmt_drake_signal messages are equal. More...

Function Documentation

AreLcmMessagesEqual()

bool drake::lcm::AreLcmMessagesEqual	(	const Message &	a,
		const Message &	b
	)

Compares two LCM messages of the same type to see if they are equal.

CompareLcmtDrakeSignalMessages()

bool drake::lcm::CompareLcmtDrakeSignalMessages	(	const lcmt_drake_signal &	actual_message,
		const lcmt_drake_signal &	expected_message
	)

Compares two drake::lcmt_drake_signal messages are equal.

Parameters

[in]	actual_message	The actual message to be compared against expected_message.
[in]	expected_message	The expected message to be compared against actual message.

Returns

true if actual_message and expected_message are equal.

DecodeLcmMessage()

Message drake::lcm::DecodeLcmMessage

(

const std::vector< uint8_t > &

bytes

)

Decodes an LCM message from a series of bytes.

Exceptions

std::exception

if decoding fails.

EncodeLcmMessage()

std::vector<uint8_t> drake::lcm::EncodeLcmMessage

(

const Message &

message

)

Encodes an LCM message to a series of bytes.

LcmHandleSubscriptionsUntil()

int drake::lcm::LcmHandleSubscriptionsUntil	(	DrakeLcmInterface *	lcm,
		const std::function< bool(void)> &	finished,
		int	timeout_millis = 100
	)

Convenience function that repeatedly calls lcm->HandleSubscriptions() with a timeout value of timeout_millis, until finished() returns true.

Returns the total number of messages handled.

Publish()

void drake::lcm::Publish	(	DrakeLcmInterface *	lcm,
		const std::string &	channel,
		const Message &	message,
		std::optional< double >	time_sec = {}
	)

Publishes an LCM message on channel channel.

Parameters

lcm	The LCM service on which to publish the message. Must not be null.
channel	The channel on which to publish the message. Must not be the empty string.
message	The message to publish.
time_sec	Time in seconds when the publish event occurred. If unknown, use the default value of nullopt.

Subscribe()

std::shared_ptr<DrakeSubscriptionInterface> drake::lcm::Subscribe	(	DrakeLcmInterface *	lcm,
		const std::string &	channel,
		std::function< void(const Message &)>	handler,
		std::function< void()>	on_error = {}
	)

Subscribes to an LCM channel named channel and decodes messages of type Message.

See also drake::lcm::Subscriber for a simple way to passively observe received messages, without the need to write a handler function.

Parameters

lcm	The LCM service on which to subscribe. Must not be null.
channel	The channel on which to subscribe. Must not be the empty string.
handler	The callback when a message is received and decoded without error.
on_error	The callback when a message is received and cannot be decoded; if no error handler is given, an exception is thrown instead.

Returns

the object used to unsubscribe if that is supported, or else nullptr if unsubscribe is not supported. The unsubscribe-on-delete default is false, so that ignoring this result leaves the subscription intact. Refer to the DrakeSubscriptionInterface class overview for details.

Note

Depending on the specific DrakeLcmInterface implementation, the handler might be invoked on a different thread than this function.