handy_window: fix build on Ubuntu 18.04

It has too old GLib - libhandy requires 2.58.

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.1.2
+
+* Fix build on Ubuntu 18.04 with old glib version < 2.58.
+
 ## 0.1.1
 
 * Fix compatibility with the core18-based Flutter snap

README.md

@@ -10,6 +10,8 @@ rounded bottom corners.
 |---|---|
 | <image src="https://raw.githubusercontent.com/canonical/ubuntu-flutter-plugins/main/packages/handy_window/images/handy-window.png" width="430"/> | <image src="https://raw.githubusercontent.com/canonical/ubuntu-flutter-plugins/main/packages/handy_window/images/flutter-window.png" width="400"/> |
 
+**NOTE:** Handy windows are only available on Ubuntu 20.04 (GLib >= 2.58) and later.
+
 ## Usage
 
 Add the dependency to `pubspec.yaml`:

linux/CMakeLists.txt

@@ -28,6 +28,7 @@ if(GLIB_FOUND)
   )
 
   add_subdirectory(libhandy)
+  add_definitions(-DHAVE_LIBHANDY)
   target_link_libraries(${PLUGIN_NAME} PRIVATE handy)
 else()
   message(WARNING "The `handy_window` package requires libglib2.0-0 >= 2.58 available in Ubuntu 20.04 and later. Using normal Flutter window instead.")

linux/handy_window_plugin.cc

@@ -1,5 +1,7 @@
 #include "include/handy_window/handy_window_plugin.h"
 
+#if HAVE_LIBHANDY
+
 #include <flutter_linux/flutter_linux.h>
 #include <gtk/gtk.h>
 #include <handy.h>
@@ -212,3 +214,6 @@ void handy_window_plugin_register_with_registrar(FlPluginRegistrar* registrar) {
   FlView* view = fl_plugin_registrar_get_view(registrar);
   setup_handy_window(view);
 }
+#else
+void handy_window_plugin_register_with_registrar(FlPluginRegistrar*) {}
+#endif

pubspec.yaml

@@ -5,7 +5,7 @@ description: |
 homepage: https://github.com/canonical/ubuntu-flutter-plugins
 repository: https://github.com/canonical/ubuntu-flutter-plugins/tree/main/packages/handy_window
 issue_tracker: https://github.com/canonical/ubuntu-flutter-plugins/issues
-version: 0.1.1
+version: 0.1.2
 
 environment:
   sdk: ">=2.12.0 <3.0.0"