Base for all image transport codecs. All codecs have to extend class ImageTransportCodec and implement the pure virtual methods std::string getTransportName() const, encode(const sensor_msgs::Image&, const dynamic_reconfigure::Config&) const and decode(const topic_tools::ShapeShifter&, const dynamic_reconfigure::Config&) const. There are other convenience methods provided, but all of them are based on these implementations. More...

#include <image_transport_codec.h>

Inheritance diagram for image_transport_codecs::ImageTransportCodec:

[legend]

Public Types
typedef boost::shared_ptr< const ImageTransportCodec >	ConstPtr
	Shared pointer to `const ImageTransportCodec`. More...

typedef cras::expected< sensor_msgs::Image, std::string >	DecodeResult
	Result of image decoding. Either a `sensor_msgs::Image` holding the raw message, or error message. More...

typedef cras::expected< cras::ShapeShifter, std::string >	EncodeResult
	Result of image encoding. Either a shapeshifter holding the compressed message, or error message. More...

typedef cras::expected< cras::optional< CompressedImageContent >, std::string >	GetCompressedContentResult
	Result of getting the actual compressed image data. More...

typedef boost::shared_ptr< ImageTransportCodec >	Ptr
	Shared pointer to `ImageTransportCodec`. More...

Public Member Functions
virtual DecodeResult	decode (const topic_tools::ShapeShifter &compressed, const dynamic_reconfigure::Config &config) const =0
	Decode the given compressed image into a raw image. More...

DecodeResult	decode (const topic_tools::ShapeShifter &compressed) const
	Decode the given compressed image into a raw image using the default decompression parameters. More...

DecodeResult	decode (const topic_tools::ShapeShifter &compressed, const XmlRpc::XmlRpcValue &config) const
	Decode the given compressed image into a raw image. More...

DecodeResult	decode (const topic_tools::ShapeShifter &compressed, const ros::NodeHandle &nh, const std::string &param) const
	Decode the given compressed image into a raw image. More...

template<typename Config >
DecodeResult	decode (const topic_tools::ShapeShifter &compressed, const Config &config) const
	Decode the given compressed image into a raw image. More...

virtual EncodeResult	encode (const sensor_msgs::Image &raw, const dynamic_reconfigure::Config &config) const =0
	Encode the given raw image into the given shapeshifter object. More...

EncodeResult	encode (const sensor_msgs::Image &raw) const
	Encode the given raw image into the given shapeshifter object using the default compression parameters. More...

EncodeResult	encode (const sensor_msgs::Image &raw, const XmlRpc::XmlRpcValue &config) const
	Encode the given raw image into the given shapeshifter object. More...

EncodeResult	encode (const sensor_msgs::Image &raw, const ros::NodeHandle &nh, const std::string &param) const
	Encode the given raw image into the given shapeshifter object. More...

template<typename Config >
EncodeResult	encode (const sensor_msgs::Image &raw, const Config &config) const
	Encode the given raw image into the given shapeshifter object. More...

virtual GetCompressedContentResult	getCompressedImageContent (const topic_tools::ShapeShifter &compressed, const std::string &matchFormat) const =0
	Return the part of the encoded message that represents the actual image data (i.e. the part that can be passed to external decoders or saved to a file). If the codec messages have no such meaning, empty result is returned. More...

GetCompressedContentResult	getCompressedImageContent (const topic_tools::ShapeShifter &compressed) const
	Return the part of the encoded message that represents the actual image data (i.e. the part that can be passed to external decoders or saved to a file). If the codec messages have no such meaning, empty result is returned. More...

virtual std::string	getTransportName () const =0
	Get the name of the codec/transport (used e.g. as topic suffix). More...

	ImageTransportCodec (const cras::LogHelperPtr &logHelper)
	Create an instance of the codec. More...

virtual	~ImageTransportCodec ()

Public Member Functions inherited from cras::HasLogger
::cras::LogHelperConstPtr	getCrasLogger () const

	HasLogger (const ::cras::LogHelperPtr &log)

void	setCrasLogger (const ::cras::LogHelperPtr &log)

Additional Inherited Members
Protected Attributes inherited from cras::HasLogger
::cras::LogHelperPtr	log

Detailed Description

Base for all image transport codecs. All codecs have to extend class ImageTransportCodec and implement the pure virtual methods std::string getTransportName() const, encode(const sensor_msgs::Image&, const dynamic_reconfigure::Config&) const and decode(const topic_tools::ShapeShifter&, const dynamic_reconfigure::Config&) const. There are other convenience methods provided, but all of them are based on these implementations.

Each codec should be implemented as a standalone library for direct use, and also as a plugin inheriting from ImageTransportCodecPlugin for generic use via ImageTransportCodecs.

Note: As there is no common superclass for ROS messages and each codec can output compressed messages of different type, the generic interface for the compressed messages is ShapeShifter. The good thing is it offers a really generic way of working with messages. The bad thing is that it does that through (de)serialization of the messages, which might become a bottleneck in high-performance applications. Therefore, if you know the codec in advance, you should directly use the concrete codec and not this generic interface.

Note: The EncodeResult and DecodeResult types used for outputs of the API functions make use of cras::expected, which is an implementation of the proposed std::expected template. Generally, expected can either hold the result (in the expected case), or an error (in the unexpected case). So after getting the encoding/decoding result, you always first have to check it for validity (if (!result) return false). On a valid result, you can call cras::expected::value() to get the expected object. On an invalid result, you can call cras::expected::error() to get the error message.

Note: Throughout this interface, you will see usages of cras::ShapeShifter instead of topic_tools::ShapeShifter. These two are the same API-wise, but cras::ShapeShifter contains a super-important bugfix without which your programs would quickly segfault. Generally, it is not safe to make copies of topic_tools::ShapeShifter (not even returning it from functions!). cras::ShapeShifter makes copying possible. Note that it is safe to pass around references to topic_tools::ShapeShifter (but you can never copy the objects).

Definition at line 81 of file image_transport_codec.h.

Member Typedef Documentation

◆ ConstPtr

typedef boost::shared_ptr<const ImageTransportCodec> image_transport_codecs::ImageTransportCodec::ConstPtr

Shared pointer to const ImageTransportCodec.

Definition at line 88 of file image_transport_codec.h.

◆ DecodeResult

typedef cras::expected<sensor_msgs::Image, std::string> image_transport_codecs::ImageTransportCodec::DecodeResult

Result of image decoding. Either a sensor_msgs::Image holding the raw message, or error message.

Definition at line 95 of file image_transport_codec.h.

◆ EncodeResult

typedef cras::expected<cras::ShapeShifter, std::string> image_transport_codecs::ImageTransportCodec::EncodeResult

Result of image encoding. Either a shapeshifter holding the compressed message, or error message.

Definition at line 92 of file image_transport_codec.h.

◆ GetCompressedContentResult

typedef cras::expected<cras::optional<CompressedImageContent>, std::string> image_transport_codecs::ImageTransportCodec::GetCompressedContentResult

Result of getting the actual compressed image data.

Definition at line 98 of file image_transport_codec.h.

◆ Ptr

typedef boost::shared_ptr<ImageTransportCodec> image_transport_codecs::ImageTransportCodec::Ptr

Shared pointer to ImageTransportCodec.

Definition at line 85 of file image_transport_codec.h.

Constructor & Destructor Documentation

◆ ImageTransportCodec()

image_transport_codecs::ImageTransportCodec::ImageTransportCodec ( const cras::LogHelperPtr & logHelper )

explicit

Create an instance of the codec.

Parameters

[in] logHelper The logger to use for error messages not directly related to the currently processed image.

◆ ~ImageTransportCodec()

virtual image_transport_codecs::ImageTransportCodec::~ImageTransportCodec ( )

virtual

Member Function Documentation

◆ decode() [1/5]

virtual DecodeResult image_transport_codecs::ImageTransportCodec::decode	(	const topic_tools::ShapeShifter &	compressed,
		const dynamic_reconfigure::Config &	config
	)		const

pure virtual

Decode the given compressed image into a raw image.

Parameters

[in]	compressed	The shapeshifter of the compressed image to be decoded.
[in]	config	Config of the decompression (if it has any parameters).

Returns: The decoded raw image (if decoding succeeds), or an error message.

Implemented in image_transport_codecs::CompressedCodec, and image_transport_codecs::CompressedDepthCodec.

◆ decode() [2/5]

DecodeResult image_transport_codecs::ImageTransportCodec::decode ( const topic_tools::ShapeShifter & compressed ) const

Decode the given compressed image into a raw image using the default decompression parameters.

Parameters

[in] compressed The shapeshifter of the compressed image to be decoded.

Returns: The decoded raw image (if decoding succeeds), or an error message.

◆ decode() [3/5]

DecodeResult image_transport_codecs::ImageTransportCodec::decode	(	const topic_tools::ShapeShifter &	compressed,
		const XmlRpc::XmlRpcValue &	config
	)		const

Decode the given compressed image into a raw image.

Parameters

[in]	compressed	The shapeshifter of the compressed image to be decoded.
[in]	config	Config of the decompression (if it has any parameters). Pass a XmlRpc dict.

Returns: The decoded raw image (if decoding succeeds), or an error message.

◆ decode() [4/5]

DecodeResult image_transport_codecs::ImageTransportCodec::decode	(	const topic_tools::ShapeShifter &	compressed,
		const ros::NodeHandle &	nh,
		const std::string &	param
	)		const

Decode the given compressed image into a raw image.

Parameters

[in]	compressed	The shapeshifter of the compressed image to be decoded.
[in]	nh	Node handle to get parameters from.
[in]	param	Name of the parameter from which config of the decompression can be read (if it has any parameters).

Returns: The decoded raw image (if decoding succeeds), or an error message.

◆ decode() [5/5]

template<typename Config >

DecodeResult image_transport_codecs::ImageTransportCodec::decode	(	const topic_tools::ShapeShifter &	compressed,
		const Config &	config
	)		const

inline

Decode the given compressed image into a raw image.

Template Parameters

Config Type of the config object. This should be the generated dynamic_reconfigure interface of the corresponding image_transport subscriber.

Parameters

[in]	compressed	The shapeshifter of the compressed image to be decoded.
[in]	config	Config of the decompression (if it has any parameters).

Returns: The decoded raw image (if decoding succeeds), or an error message.

Definition at line 230 of file image_transport_codec.h.

◆ encode() [1/5]

virtual EncodeResult image_transport_codecs::ImageTransportCodec::encode	(	const sensor_msgs::Image &	raw,
		const dynamic_reconfigure::Config &	config
	)		const

pure virtual

Encode the given raw image into the given shapeshifter object.

Parameters

[in]	raw	The input raw image.
[in]	config	Config of the compression (if it has any parameters).

Returns: The output shapeshifter holding the compressed image message (if encoding succeeds), or an error message.

Implemented in image_transport_codecs::CompressedCodec, and image_transport_codecs::CompressedDepthCodec.

◆ encode() [2/5]

EncodeResult image_transport_codecs::ImageTransportCodec::encode ( const sensor_msgs::Image & raw ) const

Encode the given raw image into the given shapeshifter object using the default compression parameters.

Parameters

[in] raw The input raw image.

Returns: The output shapeshifter holding the compressed image message (if encoding succeeds), or an error message.

◆ encode() [3/5]

EncodeResult image_transport_codecs::ImageTransportCodec::encode	(	const sensor_msgs::Image &	raw,
		const XmlRpc::XmlRpcValue &	config
	)		const

Encode the given raw image into the given shapeshifter object.

Parameters

[in]	raw	The input raw image.
[in]	config	Config of the compression (if it has any parameters). Pass a XmlRpc dict.

Returns: The output shapeshifter holding the compressed image message (if encoding succeeds), or an error message.

◆ encode() [4/5]

EncodeResult image_transport_codecs::ImageTransportCodec::encode	(	const sensor_msgs::Image &	raw,
		const ros::NodeHandle &	nh,
		const std::string &	param
	)		const

Encode the given raw image into the given shapeshifter object.

Parameters

[in]	raw	The input raw image.
[in]	nh	Node handle to get parameters from.
[in]	param	Name of the parameter from which config of the compression can be read (if it has any parameters).

Returns: The output shapeshifter holding the compressed image message (if encoding succeeds), or an error message.

◆ encode() [5/5]

template<typename Config >

EncodeResult image_transport_codecs::ImageTransportCodec::encode	(	const sensor_msgs::Image &	raw,
		const Config &	config
	)		const

inline

Encode the given raw image into the given shapeshifter object.

Template Parameters

Config Type of the config object. This should be the generated dynamic_reconfigure interface of the corresponding image_transport publisher.

Parameters

[in]	raw	The input raw image.
[in]	config	Config of the compression (if it has any parameters).

Returns: The output shapeshifter holding the compressed image message (if encoding succeeds), or an error message.

Definition at line 214 of file image_transport_codec.h.

◆ getCompressedImageContent() [1/2]

virtual GetCompressedContentResult image_transport_codecs::ImageTransportCodec::getCompressedImageContent	(	const topic_tools::ShapeShifter &	compressed,
		const std::string &	matchFormat
	)		const

pure virtual

Return the part of the encoded message that represents the actual image data (i.e. the part that can be passed to external decoders or saved to a file). If the codec messages have no such meaning, empty result is returned.

Parameters

[in]	compressed	The compressed image.
[in]	matchFormat	If nonempty, the image data is only returned if their `format` field would match the given one. The matching should be case-insensitive.

Returns: If it makes sense, the contained image bytes. If not, empty result. If an error occurred, it is reported as the unexpected result.

Implemented in image_transport_codecs::CompressedCodec, and image_transport_codecs::CompressedDepthCodec.

◆ getCompressedImageContent() [2/2]

GetCompressedContentResult image_transport_codecs::ImageTransportCodec::getCompressedImageContent ( const topic_tools::ShapeShifter & compressed ) const

Return the part of the encoded message that represents the actual image data (i.e. the part that can be passed to external decoders or saved to a file). If the codec messages have no such meaning, empty result is returned.

Parameters

[in] compressed The compressed image.

Returns: If it makes sense, the contained image bytes. If not, empty result. If an error occurred, it is reported as the unexpected result.

◆ getTransportName()

virtual std::string image_transport_codecs::ImageTransportCodec::getTransportName ( ) const

pure virtual

Get the name of the codec/transport (used e.g. as topic suffix).

Note: This name has to be unique among all defined codecs.

Returns: The transport name.

Implemented in image_transport_codecs::CompressedCodec, and image_transport_codecs::CompressedDepthCodec.

The documentation for this class was generated from the following file:

image_transport_codec.h

Public Types

Public Member Functions

Additional Inherited Members

Detailed Description

Member Typedef Documentation

◆ ConstPtr

◆ DecodeResult

◆ EncodeResult

◆ GetCompressedContentResult

◆ Ptr

Constructor & Destructor Documentation

◆ ImageTransportCodec()

◆ ~ImageTransportCodec()

Member Function Documentation

◆ decode() [1/5]

◆ decode() [2/5]

◆ decode() [3/5]

◆ decode() [4/5]

◆ decode() [5/5]

◆ encode() [1/5]

◆ encode() [2/5]

◆ encode() [3/5]

◆ encode() [4/5]

◆ encode() [5/5]

◆ getCompressedImageContent() [1/2]

◆ getCompressedImageContent() [2/2]

◆ getTransportName()