Add app icon for Linux

linux/my_application.cc

@@ -7,6 +7,11 @@
 
 #include "flutter/generated_plugin_registrant.h"
 
+#include <filesystem>
+
+using namespace std;
+using namespace std::filesystem;
+
 struct _MyApplication {
   GtkApplication parent_instance;
   char** dart_entrypoint_arguments;
@@ -20,6 +25,12 @@ static void my_application_activate(GApplication* application) {
   GtkWindow* window =
       GTK_WINDOW(gtk_application_window_new(GTK_APPLICATION(application)));
 
+  // custom icon
+  const string iconFilename = "assets/icon.png";
+  path execDir = canonical(read_symlink("/proc/self/exe")).parent_path();
+  path iconPath = execDir / "data/flutter_assets" / iconFilename;
+  gtk_window_set_icon_from_file(GTK_WINDOW(window), iconPath.c_str(), NULL);
+
   // Use a header bar when running in GNOME as this is the common style used
   // by applications and is the setup most users will be using (e.g. Ubuntu
   // desktop).

pubspec.yaml

@@ -35,6 +35,7 @@ flutter:
   uses-material-design: true
 
   assets:
+    - assets/icon.png
     - assets/userdata-empty.dat
 
 flutter_launcher_icons: