Correctly link against GStreamer

Video is still not being displayed, for some reason

CMakeLists.txt

@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.2)
 
-project(QGroundControl LANGUAGES CXX)
+project(QGroundControl LANGUAGES C CXX)
 
 set_property(CACHE CMAKE_BUILD_TYPE PROPERTY STRINGS "Debug;Release;RelWithDebInfo;MinSizeRel;Coverage")
 
@@ -58,6 +58,16 @@ if (CCACHE AND CCACHE_PROGRAM AND NOT DEFINED ENV{CCACHE_DISABLE})
 	set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE "${CCACHE_PROGRAM}")
 endif()
 
+
+#=============================================================================
+# GStreamer
+#
+find_package(PkgConfig)
+pkg_check_modules(GST
+    gstreamer-1.0>=1.14
+    gstreamer-video-1.0>=1.14
+)
+
 #=============================================================================
 # Qt5
 #
@@ -73,6 +83,7 @@ find_package(Qt5 ${QT_VERSION}
 		Positioning
 		Quick
 		QuickWidgets
+		OpenGL
 		Sql
 		Svg
 		Test

src/VideoStreaming/CMakeLists.txt

@@ -1,7 +1,10 @@
+if (GST_FOUND)
+    include_directories(
+        ${GST_INCLUDE_DIRS}
+        gstqtvideosink/utils/
+        )
 
-set(EXTRA_SRC)
+    set(EXTRA_SRC
-if(VIDEO)
-	list(APPEND EXTRA_SRC
         gstqtvideosink/delegates/basedelegate.cpp
         gstqtvideosink/delegates/qtquick2videosinkdelegate.cpp
         gstqtvideosink/delegates/qtvideosinkdelegate.cpp
@@ -13,6 +16,7 @@ if(VIDEO)
         gstqtvideosink/gstqtvideosinkbase.cpp
         gstqtvideosink/gstqtvideosinkplugin.cpp
         gstqtvideosink/gstqwidgetvideosink.cpp
+        gstqtvideosink/gstqtvideosinkmarshal.c
         gstqtvideosink/painters/genericsurfacepainter.cpp
         gstqtvideosink/painters/openglsurfacepainter.cpp
         gstqtvideosink/painters/videomaterial.cpp
@@ -20,22 +24,23 @@ if(VIDEO)
         gstqtvideosink/utils/bufferformat.cpp
         gstqtvideosink/utils/utils.cpp
     )
-endif()
 
-add_library(VideoStreaming
+    add_library(VideoStreaming
         VideoItem.cc
         VideoReceiver.cc
         VideoStreaming.cc
         VideoSurface.cc
         SubtitleWriter.cc
         ${EXTRA_SRC}
-)
+    )
 
-target_link_libraries(VideoStreaming
+    target_link_libraries(VideoStreaming
         PUBLIC
             qgc
-
             Qt5::Multimedia
-)
+            Qt5::OpenGL
+            ${GST_LIBRARIES}
+    )
 
-target_include_directories(VideoStreaming INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})
+    target_include_directories(VideoStreaming INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})
+endif()