G-API. Common StreamSource. IFD-GAPI small refactoring.

[mpashchenkov]

PR provides common stream_source class which is used for all G-API demos. Implementation is questionable (CMakeLists should have some standards, which i haven't followed. I hope review help me with this).
Also PR contains small refactoring for Interactive Face detection G-API demo:

• Added parseSSD kernel;
• Demo works with ImagesCapture OMZ common class instead of SetInput().

[ivikhrev]

slog is still used in this demo, it should be directly included.

[ivikhrev]

And, it seems, I forgot to include it directly in the smart_classroom_demo_gapi, when modified it. Can you add it here also, please?

[mpashchenkov]

Some files have dependencies with slog.hpp, m b, because this works fine. This include is returned.

[mpashchenkov]

face_inference_results.hpp contains this file for gaze_estimation
and
custom_kernels.hpp for smart_classroom

[mpashchenkov]

@ivikhrev Could the thread will be resolved?

[mpashchenkov]

@fzhar, @ivikhrev Can you give some recommendations about CMakeLists.txt graph? I missed some steps (see to failed Windows build).

[mpashchenkov]

Also i can't fix Win10 red build (some problems with Yolo network isn't part of this PR).

[ivikhrev]

Also i can't fix Win10 red build (some problems with Yolo network isn't part of this PR).

yeah, I also noticed it. @akorobeinikov is going to fix it today.

[ivikhrev]

@fzhar, @ivikhrev Can you give some recommendations about CMakeLists.txt graph? I missed some steps (see to failed Windows build).

@mpashchenkov , yout can't create a library without .cpp file, create src folder and put a cpp file there with
#include <utils_gapi/stream_source.hpp> .

utils folder should be renamed to utils_gapi.

CMakeLists.txt in cpp_gapi/utils_gapi should be the next:

# Copyright (C) 2021 Intel Corporation
# SPDX-License-Identifier: Apache-2.0
#

file(GLOB_RECURSE HEADERS "${CMAKE_CURRENT_SOURCE_DIR}/include/*")
file(GLOB_RECURSE SOURCES "${CMAKE_CURRENT_SOURCE_DIR}/src/*")

source_group("src" FILES ${SOURCES})
source_group("include" FILES ${HEADERS})

add_library(utils_gapi STATIC ${HEADERS} ${SOURCES})
target_include_directories(utils_gapi PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}/include")
target_link_libraries(utils_gapi PRIVATE gflags ${InferenceEngine_LIBRARIES} opencv_core utils)

[vladimir-dudnik]

@mpashchenkov yolo warnings were fixed in #2654, please rebase your branch to develop

[fzhar]

as for windows build - you have many "warning treated as error" warnings. Just check them in the build log and fix them

[mpashchenkov]

@OrestChura, FYI.