G-API Graph Compilation Arguments

Compilation arguments: a set of data structures which can be passed to control compilation process. More...

Classes
struct	cv::GCompileArg
	Represents an arbitrary compilation argument. More...
class	cv::gapi::GKernelPackage
	A container class for heterogeneous kernel implementation collections. More...
struct	cv::graph_dump_path
	Ask G-API to dump compiled graph in Graphviz format under the given file name. More...

Typedefs
using	cv::GCompileArgs = std::vector< GCompileArg >
using	cv::gapi::GLookupOrder = std::vector< GBackend >
	Priority list of backends to use during kernel resolution process.

Functions
template<typename... Ts>
GCompileArgs	cv::compile_args (Ts &&...args)
template<typename... KK>
GKernelPackage	cv::gapi::kernels ()
	Create a kernel package object containing kernels specified in variadic template argument.
GLookupOrder	cv::gapi::lookup_order (std::initializer_list< GBackend > &&list)
	Create a backend lookup order – priority list of backends to use during graph compilation process.

Detailed Description

Compilation arguments: a set of data structures which can be passed to control compilation process.

G-API comes with a number of graph compilation options which can be passed to cv::GComputation::apply() or cv::GComputation::compile(). Known compilation options are listed in this page, while extra backends may introduce their own compilation options (G-API transparently accepts everything which can be passed to cv::compile_args(), it depends on underlying backends if an option would be interpreted or not).

For example, if an example computation is executed like this:

    cv::GComputation sobelEdge(cv::GIn(in), cv::GOut(out));
    sobelEdge.apply(input, output);

Extra parameter specifying which kernels to compile with can be passed like this:

    cv::gapi::GKernelPackage kernels = cv::gapi::combine
        (cv::gapi::core::fluid::kernels(),
         cv::gapi::imgproc::fluid::kernels(),
         cv::unite_policy::KEEP);
    sobelEdge.apply(input, output, cv::compile_args(kernels));

Typedef Documentation

using cv::GCompileArgs = typedef std::vector<GCompileArg>

using cv::gapi::GLookupOrder = typedef std::vector<GBackend>

Priority list of backends to use during kernel resolution process.

Priority is descending – the first backend in the list has the top priority, and the last one has the lowest priority.

If there's multiple implementations available for a kernel at the moment of graph compilation, a kernel (and thus a backend) will be selected according to this order (if the parameter is passed).

Default order is not specified (and by default, only CPU(OpenCV) backend is involved in graph compilation).

Function Documentation

template<typename... Ts>

GCompileArgs cv::compile_args

(

Ts &&...

args

)

Wraps a list of arguments (a parameter pack) into a vector of compilation arguments (cv::GCompileArg).

template<typename... KK>

GKernelPackage cv::gapi::kernels

(

)

Create a kernel package object containing kernels specified in variadic template argument.

In G-API, kernel implementations are types. Every backend has its own kernel API (like GAPI_OCV_KERNEL() and GAPI_FLUID_KERNEL()) but all of that APIs define a new type for each kernel implementation.

Use this function to pass kernel implementations (defined in either way) to the system. Example:

    cv::gapi::GKernelPackage pkg = cv::gapi::kernels
        < CustomAdd
        , CustomFilter2D
        , CustomRGB2YUV
        >();

Note that kernels() itself is a function returning object, not a type, so having () at the end is important – it must be a function call.

GLookupOrder cv::gapi::lookup_order ( std::initializer_list< GBackend > &&  list )

inline

Create a backend lookup order – priority list of backends to use during graph compilation process.

See Also

GLookupOrder, G-API Standard backends