Combine GStreamer GTK4 plugin with API

Ship custom gtk4glsink plugin as part of API insead of normal gstreamer plugin. This avoids gstreamer plugin registry conflicts with gtk3 plugin and allows more customization.

lib/gst/clapper/meson.build

@@ -6,8 +6,14 @@ gstclapper_sources = [
   'gstclapper-g-main-context-signal-dispatcher.c',
   'gstclapper-video-overlay-video-renderer.c',
   'gstclapper-visualization.c',
-]
+  'gstclapper-gtk4-plugin.c',
 
+  'gtk4/gstgtkbasesink.c',
+  'gtk4/gstgtkutils.c',
+  'gtk4/gtkgstbasewidget.c',
+  'gtk4/gstgtkglsink.c',
+  'gtk4/gtkgstglwidget.c',
+]
 gstclapper_headers = [
   'clapper.h',
   'clapper-prelude.h',
@@ -19,20 +25,57 @@ gstclapper_headers = [
   'gstclapper-g-main-context-signal-dispatcher.h',
   'gstclapper-video-overlay-video-renderer.h',
   'gstclapper-visualization.h',
+  'gstclapper-gtk4-plugin.h',
 ]
+gstclapper_defines = [
+  '-DHAVE_CONFIG_H',
+  '-DBUILDING_GST_CLAPPER',
+  '-DGST_USE_UNSTABLE_API',
+  '-DHAVE_GTK_GL',
+  '-DBUILD_FOR_GTK4',
+]
+gtk_deps = [gstgl_dep, gstglproto_dep]
+have_gtk_gl_windowing = false
 
-if not build_gir
-  error('Clapper requires GI bindings to be compiled')
+gtk4_dep = dependency('gtk4', required : true)
+
+if not gtk4_dep.found() or not gtk4_dep.version().version_compare('>=4.0.0')
+  error('GTK4 is missing or is too old')
+endif
+
+if not have_gstgl
+  error('GstGL is missing')
+endif
+
+if gst_gl_have_window_x11 and gst_gl_have_platform_glx
+  gtk_x11_dep = dependency('gtk4-x11', required : false)
+  if gtk_x11_dep.found()
+    gtk_deps += [gtk_x11_dep, gstglx11_dep]
+    have_gtk_gl_windowing = true
+  endif
+endif
+
+if gst_gl_have_window_wayland and gst_gl_have_platform_egl
+  gtk_wayland_dep = dependency('gtk4-wayland', required : false)
+  if gtk_wayland_dep.found()
+    gtk_deps += [gtk_wayland_dep, gstglegl_dep, gstglwayland_dep]
+    have_gtk_gl_windowing = true
+  endif
+endif
+
+if not have_gtk_gl_windowing
+  error('GTK4 widget requires GL windowing')
 endif
 
 gstclapper = library('gstclapper-' + api_version,
   gstclapper_sources,
-  c_args : gst_clapper_args + ['-DBUILDING_GST_CLAPPER'],
+  c_args : gstclapper_defines,
+  link_args : noseh_link_args,
   include_directories : [configinc, libsinc],
   version : libversion,
   install : true,
-  dependencies : [gstbase_dep, gstvideo_dep, gstaudio_dep,
-    gsttag_dep, gstpbutils_dep],
+  dependencies : [gtk4_dep, gstbase_dep, gstvideo_dep, gstaudio_dep,
+    gsttag_dep, gstpbutils_dep, libm] + gtk_deps,
 )
 
 clapper_gir = gnome.generate_gir(gstclapper,