* Return vector of MetaArg instead of MatDesc and fix test with ADL check

* Fix construction of vector

* Change names and tests according to review
Also add GAPI_EXPORTS prefix for two ostream operators

* Add version of descr_of function taking vector of Mat

* Overload descr_of function for cv::Mat

* Add template function instead of copypasting and change tests a little

* GAPI: document GCall's recursive behavior

* Move documentation outside the class

GAPI (fluid): Median blur optimization (#13329)

* GAPI (fluid): Median blur optimization: reference 3x3

* GAPI (fluid): Median blur optimization: CPU dispatcher

* GAPI (fluid): Median blur optimization: manual CV_SIMD

G-API rename GPU backend to OCL backend (#13240)

* renaming draft

* inline namespace instead non-safe define

* more back compatibility

* Updates after review from Dmitry

GAPI (fluid): Erode/Dilate optimization, part 2 (#13319)

* GAPI (fluid): Erode/Dilate optimization: hard-code 3x3 case

* GAPI (fluid): Erode/Dilate optimization: CPU dispatcher

* GAPI (fluid): Erode/Dilate optimization: speed-up 10-15x times with CV_SIMD

* GAPI (fluid): Erode/Dilate optimization: 20-30% speed-up

GAPI (fluid): Erode/Dilate optimization (#13315)

* GAPI (fluid): Erode/Dilate optimization: hard-code 3x3 case

* GAPI (fluid): Erode/Dilate optimization: CPU dispatcher

* GAPI (fluid): Erode/Dilate optimization: speed-up 10-15x times with CV_SIMD

GAPI (fluid): Filter 2D optimization (#13290)

* GAPI (fluid): Filter 2D optimization: speedup 13x if float, 2x if integral

* GAPI (fluid): Filter 2D speedup 8x if output is short/ushort

* GAPI (fluid): Filter 2D speedup 7x if output is uchar

* GAPI (fluid): Filter 2D optimization: fixed compiler warnings

* GAPI (fluid): fix compiler warnings on Mac

* GAPI (fluid): fix compiler warnings on Mac

* GAPI (fluid): fix compiler errors on VS2015

* GAPI (fluid): fix compiler errors on VS2015

* GAPI (fluid): fix compiler errors on VS2015

GAPI (fluid): optimization of Separable filter (#13221)

* GAPI (fluid): Separable filter: performance test

* GAPI (fluid): enable all performance tests

* GAPI: separable filters: alternative code for Sobel

* GAPI (fluid): hide unused old code for Sobel filter

* GAPI (fluid): especial code for Sobel if U8 into S16

* GAPI (fluid): back to old code for Sobel

* GAPI (fluid): run_sepfilter3x3_impl() with CPU dispatcher

* GAPI (fluid): run_sepfilter3x3_impl(): fix compiler warnings

* GAPI (fluid): new engine for separable filters (but Sobel)

* GAPI (fluid): new performance engine for Sobel

* GAPI (fluid): Sepfilters performance: fixed compilation error

* Added caching of agents execution sequence

* Merged linesRead() and nextWindow() methods on FluidAgent in one method

* Added caching of input lines for fluid::View

* Added caching of output lines for fluid::Buffer

* Fixed GAPI_Assert to work in standalone mode

This MR fixes this.

GAPI (fluid): RGB to Lab optimization (#13206)

* GAPI (fluid): BGR2LUV, RGB2Lab: performance test

* GAPI (fluid): BGR2LUV, RGB2Lab: using cv::hal::cvtBGRtoLab

* GAPI (fluid): BGR2LUV, RGB2Lab: hide reference code with #ifdef

GAPI (fluid): RGB to YUV optimization (#13174)

* GAPI (fluid): RGB to YUV: activate performance tests

* GAPI (fluid): speedup 4-8x RGB-to-YUV, 2.5x YUV to RGB with int16 arithmetic

* GAPI (fluid): RGB <--> YUV: fixed compiler warning

* GAPI (fluid): RGB <--> YUV: additional speedup 2-3x times (10-15x over original) via manual CV_SIMD

* GAPI (fluid): RGB <--> YUV: dynamic CV_SIMD dispatching

GAPI (fluid): RGB/BGR to gray: optimization (#13162)

* GAPI (fluid): RGB/BGR to Gray: add performance tests

* GAPI (fluid): RGB/BGR to Gray: speedup 8-12x with manual CV_SIMD

* GAPI (fluid): RGB/BGR to Gray: fix compiler warning

* GAPI (fluid): RGB/BGR to Gray: dynamic dispatching to AVX2

* GAPI (fluid): RGB/BGR to Gray: check R/G/B coefficients

* GAPI (fluid): RGB/BGR to Gray: fixed compilation error (caused by change in master)

* G-API: First steps with tutorial

* G-API Tutorial: First iteration

* G-API port of anisotropic image segmentation tutorial;
* Currently works via OpenCV only;
* Some new kernels have been required.

* G-API Tutorial: added chapters on execution code, inspection, and profiling

* G-API Tutorial: make Fluid kernel headers public

For some reason, these headers were not moved to the public
headers subtree during the initial development. Somehow it even
worked for the existing workloads.

* G-API Tutorial: Fix a couple of issues found during the work

* Introduced Phase & Sqrt kernels, OCV & Fluid versions
* Extended GKernelPackage to allow kernel removal & policies on include()

All the above stuff needs to be tested, tests will be added later

* G-API Tutorial: added chapter on running Fluid backend

* G-API Tutorial: fix a number of issues in the text

* G-API Tutorial - some final updates

- Fixed post-merge issues after Sobel kernel renaming;
- Simplified G-API code a little bit;
- Put a conclusion note in text.

* G-API Tutorial - fix build issues in test/perf targets

Public headers were refactored but tests suites were not updated in time

* G-API Tutorial: Added tests & reference docs on new kernels

* Phase
* Sqrt

* G-API Tutorial: added link to the tutorial from the main module doc

* G-API Tutorial: Added tests on new GKernelPackage functionality

* G-API Tutorial: Extended InRange tests to cover 32F

* G-API Tutorial: Misc fixes

* Avoid building examples when gapi module is not there
* Added a volatile API disclaimer to G-API root documentation page

* G-API Tutorial: Fix perf tests build issue

This change came from master where Fluid kernels are still used
incorrectly.

* G-API Tutorial: Fixed channels support in Sqrt/Phase fluid kernels

Extended tests to cover this case

* G-API Tutorial: Fix text problems found on team review

GAPI (fluid): Sobel 3x3 optimization: CV_SIMD dynamic dispatching (#13133)

* GAPI (fluid): Sobel 3x3: remove template for run_sobel_row()

* GAPI (fluid): Sobel 3x3: dynamic dispatching of CV_SIMD code

* GAPI (fluid): Sobel 3x3 optimization: fixed CV_SIMD dynamic dispatcher

GAPI (fluid): optimization of Sobel 3x3 (#13070)

* GAPI: performance test for Sobel

* GAPI: performance test for Sobel w/FP32 input

* GAPI: Sobel speedup: 2.5x (U8) up to 10x (float)

* GAPI: Sobel 3x3 to support U8 into S16

* GAPI (fluid): Sobel 3x3 speedup: 10% (uchar), 1.5x (float)

* GAPI (fluid): Sobel 3x3 speedup: +10x (uchar), but -20% (float)

* GAPI (fluid): Sobel 3x3 speedup: +10% (float)

* GAPI (fluid): Sobel 3x3 speedup: +15% (float), +10% (uchar)

* GAPI (fluid): Sobel 3x3: address GCC warnings

* GAPI (fluid): Sobel 3x3: separate *.cpp file w/SIMD code

* GAPI (fluid): Sobel 3x3: fixed AVX2 code, AVX2 speedup 20-50% (uchar), 10-20% (float)

* GAPI (fluid): Sobel 3x3: fix CV_SIMD code for AVX2

* GAPI (fluid): Sobel 3x3: refactor

G-API GPU-OpenCL backend (#13008)

* gpu/ocl backend core

* accuracy tests added and adjusted + license headers

* GPU perf. tests added; almost all adjusted to pass

* all tests adjusted and passed - ready for pull request

* missing license headers

* fix warning (workaround RGB2Gray)

* fix c++ magic

* precompiled header

* white spaces

* try to fix warning and blur test

* try to fix Blur perf tests

* more alignments with the latest cpu backend

* more gapi tests refactoring + 1 more UB issue fix + more informative tolerance exceed reports

* white space fix

* try workaround for SumTest

* GAPI_EXPORTS instead CV_EXPORTS

* GAPI: Sobel 3x3 with FP32 input

* GAPI: Sobel 3x3 with FP32 input, v2

G-API: Introduce new `reshape()` API (#12990)

* Moved initFluidUnits, initLineConsumption, calcLatency, calcSkew to separate functions

* Added Fluid::View::allocate method (moved allocation logic from constructor)

* Changed util::zip to util::indexed, utilized collectInputMeta in GFluidExecutable constructor

* Added makeReshape method to FluidExecutable

* Removed m_outputRoi from GFluidExecutable

* Added reshape feature

* Added switch of resize mapper if agent ratio was changed

* Added more TODOs and renamed a function

* G-API reshape(): add missing `override` specifiers

Fix warnings on all platforms

* Renamed Sobel operator GAPI kernel to match with OpenCV naming rules

* Fixed perf tests

* Small refactoring to check CI issue

* Refactored alignment for kernel wrappers in imgproc.hpp

* G-API Fluid basic heterogeneity support: initial upload

* G-API Fluid heterogeneity: address some coding style issues

* G-API Fluid heterogeneity: fix compiler warnings

* G-API Fluid heterogeneity: fix warnings on Windows & ARMv7

* G-API Fluid heterogeneity: finally fix Windows warnings

* G-API Fluid heterogeneity: fix dangling reference problem

Several Resize optimizations count on fetching multiple input lines at
once to do interpolation more efficiently.

At the moment, Fluid backend supports only LPI=1 for Resize kernels.

This patch introduces scheduling support for Resizes with LPI>1 and
covers these cases with new tests.

The support is initially written by Ruslan Garnov.

* 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