* Make different overloads

* Order python compileStreaming overloads

* Fix compileStreaming bug

* Replace

gin -> descr_of

* Set error message

* Fix review comments

* Use macros for pyopencv_to GMetaArgs
* Use GAPI_PROP_RW
* Not split Prims python stuff

original commit: 5ad6ff23

[G-API] Introduce cv.gin/cv.descr_of for python

* Implement cv.gin/cv.descr_of

* Fix macos build

* Fix gcomputation tests

* Add test

* Add using to a void exceeded length for windows build

* Add using to a void exceeded length for windows build

* Fix comments to review

* Fix comments to review

* Update from latest master

* Avoid graph compilation to obtain in/out info

* Fix indentation

* Fix comments to review

* Avoid using default in switches

* Post output meta for giebackend

[G-API Wrap streaming

* Wrap streaming

* Fix build

* Add comments

* Remove comment

* Fix comments to review

* Add test for python pull overload

[G-API] Export a part of serialization interface

* Initial stub

* Add test on serialization of a custom type

* Namespaces rework

* Fix isSupported in test struct

* Fix clang build and rework namespaces

* Remove redundant header

[G-API] Wrap GIn & GOut

* Wrap GIn & GOut into python

* Remove extra brackets

* Use reinterpret_cast

[G-API] Wrap cv::gapi::mean kernel into python

* Wrap cv::gapi::mean kernel into python

* Fix test

* Implement G-API python bindings

* Fix hdr_parser

* Drop initlization with brackets using regexp

* Handle bracket initilization another way

* Add test for core operations

* Declaration and definition of View constructor now in different files

* Refactor tests

* Remove combine decorator from tests

* Fix comment to review

* Fix test

* Fix comments to review

* Remove GCompilerArgs implementation from python
Co-authored-by: NPinaev <danil.pinaev@intel.com>

G-API Serialization routines

* Serialization backend in tests, initial version

* S11N/00: A Great Rename

- "Serialization" is too long and too error-prone to type,
  so now it is renamed to "s11n" everywhere;
- Same applies to "SRLZ";
- Tests also renamed to start with 'S11N.*' (easier to run);
- Also updated copyright years in new files to 2020.

* S11N/01: Some basic interface segregation

- Moved some details (low-level functions) out of serialization.hpp;
- Introduced I::IStream and I::OStream interfaces;
- Implemented those via the existing [De]SerializationStream classes;
- Moved all operators to use interfaces instead of classes;
- Moved the htonl/ntohl handling out of operators (to the classes).

The implementation didn't change much, it is a subject to the further
refactoring

* S11N/02: Basic operator reorg, basic tests, vector support

- Reorganized operators on atomic types to follow >>/<< model
  (put them closer in the code for the respective types);
- Introduce more operators for basic (scalar) types;
- Drop all vector s11n overloads -- replace with a generic
  (template-based) one;
- Introduced a new test suite where low-level s11n functionality
  is tested (for the basic types).

* S11N/03: Operators reorganization

- Sorted the Opaque types enum by complexity;
- Reorganized the existing operators for basic types, also ordered by
  complexity;
- Organized operators in three groups (Basics, OpenCV, G-API);
- Added a generic serialization for variant<>;
- Reimplemented some of the existing operators (for OpenCV and G-API
  data structures);
- Introduced new operators for cv::gimpl data types. These operators
  (and so, the data structures) are not yet used in the graph
  dump/reconstruction routine, it will be done as a next step.

* S11N/04: The Great Clean-up

- Drop the duplicates of GModel data structures from the
  serialization, serialize the GModel data structures themselve
  instead (hand-written code replaced with operators).
- Also removed usuned code for printing, etc.

* S11N/05: Internal API Clean-up

- Minimize the serialization API to just Streams and Operators;
- Refactor and fix the graph serialization (deconstruction and
  reconstruction) routines, fix data addressing problems there;
- Move the serialization.[ch]pp files to the core G-API library

* S11N/06: Top-level API introduction

- !!!This is likely the most invasive commit in the series!!!
- Introduced a top-level API to serialize and deserialize a GComputation
- Extended the compiler to support both forms of a GComputation:
  an expession based and a deserialized one. This has led to changes in
  the cv::GComputation::Priv and in its dependent components (even the
  transformation tests);
- Had to extend the kernel API (GKernel) with extra information on
  operations (mainly `outMeta`) which was only available for expression
  based graphs. Now the `outMeta` can be taken from kernels too (and for
  the deserialized graphs it is the only way);
- Revisited the internal serialization API, had to expose previously
  hidden entities (like `GSerialized`);
- Extended the serialized graph info with new details (object counter,
  protocol). Added unordered_map generic serialization for that;
- Reworked the very first pipeline test to be "proper"; GREEN now, the rest
  is to be reworked in the next iteration.

* S11N/07: Tests reworked

- Moved the sample pipeline tests w/serialization to
  test the public API (`cv::gapi::serialize`, then
  followed by `cv::gapi::deserialize<>`). All GREEN.
- As a consequence, dropped the "Serialization" test
  backend as no longer necessary.

* S11N/08: Final touches

- Exposed the C++ native data types at Streams level;
- Switched the ByteMemoryIn/OutStreams to store data in `char`
  internally (2x less memory for sample pipelines);
- Fixed and refactored Mat dumping to the stream;
- Renamed S11N pipeline tests to their new meaning.

* linux build fix

* fix RcDesc and int uint warnings

* more Linux build fix

* white space and virtual android error fix (attempt)

* more warnings to be fixed

* android warnings fix attempt

* one more attempt for android build fix

* android warnings one more fix

* return back override

* avoid size_t

* static deserialize

* and how do you like this, elon? anonymous namespace  to fix android warning.

* static inline

* trying to fix standalone build

* mat dims fix

* fix mat r/w for standalone
Co-authored-by: NDmitry Matveev <dmitry.matveev@intel.com>

G-API: Mat's "deownification"

* deowned Mat

* boner

* Removed canDescribe test for own::Mat

* Removed STANDALONE flag for apply() and operator()

* Removed: desc_tests for own::Mat, descr_of for own::Mat.

* Returned: tests, cv::gapi::own::descr_of; fixed alignment; Removed own::Mat's headers

* Removed unused header own/mat.hpp from gbackend.hpp

* G-API: Addressed various documentation issues

- Fixed various typos and missing references;
- Added brief documentaion on G_TYPED_KERNEL and G_COMPOUND_KERNEL macros;
- Briefly described GComputationT<>;
- Briefly described G-API data objects (in a group section).

* G-API: Some clean-ups in doxygen, also a chapter on Render API

* G-API: Expose more graph compilation arguments in the documentation

* G-API: Address documentation review comments

G-API-NG/Streaming: don't require explicit metadata in compileStreaming()

* First probably working version
Hardcode gose to setSource() :)

* Pre final version of move metadata declaration from compileStreaming() to setSource().

* G-API-NG/Streaming: recovered the existing Streaming functionality

- The auto-meta test is disabling since it crashes.
- Restored .gitignore

* G-API-NG/Streaming: Made the meta-less compileStreaming() work

- Works fine even with OpenCV backend;
- Fluid doesn't support such kind of compilation so far - to be fixed

* G-API-NG/Streaming: Fix Fluid to support meta-less compilation

- Introduced a notion of metadata-sensitive passes and slightly
  refactored GCompiler and GFluidBackend to support that
- Fixed a TwoVideoSourcesFail test on streaming

* Add three smoke streaming tests to gapi_streaming_tests.
All three teste run pipeline with two different input sets
1) SmokeTest_Two_Const_Mats test run pipeline with two const Mats
2) SmokeTest_One_Video_One_Const_Scalar test run pipleline with Mat(video source) and const Scalar
3) SmokeTest_One_Video_One_Const_Vector test run pipeline with Mat(video source) and const Vector
 # Please enter the commit message for your changes. Lines starting

* style fix

* Some review stuff

* Some review stuff

* G-API-NG/Streaming: Introduced a Streaming API

Now a GComputation can be compiled in a special "streaming" way
and then "played" on a video stream.

Currently only VideoCapture is supported as an input source.

* G-API-NG/Streaming: added threading & real streaming

* G-API-NG/Streaming: Added tests & docs on Copy kernel

- Added very simple pipeline tests, not all data types are covered yet
  (in fact, only GMat is tested now);
- Started testing non-OCV backends in the streaming mode;
- Added required fixes to Fluid backend, likely it works OK now;
- Added required fixes to OCL backend, and now it is likely broken
- Also added a UMat-based (OCL) version of Copy kernel

* G-API-NG/Streaming: Added own concurrent queue class

- Used only if TBB is not available

* G-API-NG/Streaming: Fixing various issues

- Added missing header to CMakeLists.txt
- Fixed various CI issues and warnings

* G-API-NG/Streaming: Fixed a compile-time GScalar queue deadlock

- GStreamingExecutor blindly created island's input queues for
  compile-time (value-initialized) GScalars which didn't have any
  producers, making island actor threads wait there forever

* G-API-NG/Streaming: Dropped own version of Copy kernel

One was added into master already

* G-API-NG/Streaming: Addressed GArray<T> review comments

- Added tests on mov()
- Removed unnecessary changes in garray.hpp

* G-API-NG/Streaming: Added Doxygen comments to new public APIs

Also fixed some other comments in the code

* G-API-NG/Streaming: Removed debug info, added some comments & renamed vars

* G-API-NG/Streaming: Fixed own-vs-cv abstraction leak

- Now every island is triggered with own:: (instead of cv::)
  data objects as inputs;
- Changes in Fluid backend required to support cv::Mat/Scalar were
  reverted;

* G-API-NG/Streaming: use holds_alternative<> instead of index/index_of test

- Also fixed regression test comments
- Also added metadata check comments for GStreamingCompiled

* G-API-NG/Streaming: Made start()/stop() more robust

- Fixed various possible deadlocks
- Unified the shutdown code
- Added more tests covering different corner cases on start/stop

* G-API-NG/Streaming: Finally fixed Windows crashes

In fact the problem hasn't been Windows-only.
Island thread popped data from queues without preserving the Cmd
objects and without taking the ownership over data acquired so when
islands started to process the data, this data may be already freed.

Linux version worked only by occasion.

* G-API-NG/Streaming: Fixed (I hope so) Windows warnings

* G-API-NG/Streaming: fixed typos in internal comments

- Also added some more explanation on Streaming/OpenCL status

* G-API-NG/Streaming: Added more unit tests on streaming

- Various start()/stop()/setSource() call flow combinations

* G-API-NG/Streaming: Added tests on own concurrent bounded queue

* G-API-NG/Streaming: Added more tests on various data types, + more

- Vector/Scalar passed as input;
- Vector/Scalar passed in-between islands;
- Some more assertions;
- Also fixed a deadlock problem when inputs are mixed (1 constant, 1 stream)

* G-API-NG/Streaming: Added tests on output data types handling

- Vector
- Scalar

* G-API-NG/Streaming: Fixed test issues with IE + Windows warnings

* G-API-NG/Streaming: Decoupled G-API from videoio

- Now the core G-API doesn't use a cv::VideoCapture directly,
  it comes in via an abstract interface;
- Polished a little bit the setSource()/start()/stop() semantics,
  now setSource() is mandatory before ANY call to start().

* G-API-NG/Streaming: Fix STANDALONE build (errors brought by render)

Found using `codespell -q 3 -S ./3rdparty -L activ,amin,ang,atleast,childs,dof,endwhile,halfs,hist,iff,nd,od,uint`

Changed quotes to brackets when including public includes (#14741)

G-API: GComputation doesn't work with output vector<cv::Mat> (#14150)

* Fix bug with gcomputation output vector

* Add test fixture

* Fix comments to review

* Fix alignment

G-API: Doxygen class reference

* G-API Doxygen documentation: covered cv::GComputation

* G-API Doxygen documentation: added sections on compile arguments

* G-API Doxygen documentation: restructuring & more text

* Added new sections (organized API reference into it);
* Documented GCompiled, compile args, backends, etc.

* G-API Doxygen documentation: documented GKernelPackage and added group for meta

* Update G-API code base to 27-Sep-18

Changes mostly improve standalone build support

* G-API code base update 28-09-2018

* Windows/Documentation warnings should be fixed
* Fixed stability issues in Fluid backend
* Fixed precompiled headers issues in G-API source files

* G-API code base update 28-09-18 EOD

* Fixed several static analysis issues
* Fixed issues found when G-API is built in a standalone mode

* G-API Initial code upload

* Update G-API code base to Sep-24-2018

* The majority of OpenCV buildbot problems was addressed

* Update G-API code base to 24-Sep-18 EOD

* G-API code base update 25-Sep-2018

* Linux warnings should be resolved
* Documentation build should become green
* Number of Windows warnings should be reduced

* Update G-API code base to 25-Sep-18 EOD

* ARMv7 build issue should be resolved
* ADE is bumped to latest version and should fix Clang builds for macOS/iOS
* Remaining Windows warnings should be resolved
* New Linux32 / ARMv7 warnings should be resolved

* G-API code base update 25-Sep-2018-EOD2

* Final Windows warnings should be resolved now

* G-API code base update 26-Sep-2018

* Fixed issues with precompiled headers in module and its tests