add support for linux.

CMakeLists.txt

@@ -12,10 +12,16 @@ target_include_directories(tray
 
 if(UNIX AND NOT APPLE)
     find_package(PkgConfig REQUIRED)
-    pkg_check_modules(APPINDICATOR REQUIRED appindicator3-0.1)
+    message(STATUS "To install appindicator3[ayatana-appindicator3-0.1],  sudo apt install libayatana-appindicator3-dev")
+    pkg_check_modules(APPINDICATOR REQUIRED       ayatana-appindicator3-0.1)
     target_compile_options(tray PRIVATE ${APPINDICATOR_CFLAGS})
     target_link_libraries(tray PRIVATE ${APPINDICATOR_LIBRARIES})
     target_link_directories(tray PRIVATE ${APPINDICATOR_LIBRARY_DIRS})
+
+    pkg_check_modules(GTK REQUIRED     gtk+-3.0)
+    target_compile_options(tray PRIVATE ${GTK_CFLAGS})
+    target_link_libraries(tray PRIVATE ${GTK_LIBRARIES})
+    target_link_directories(tray PRIVATE ${GTK_LIBRARY_DIRS})
 elseif(APPLE)
     target_link_libraries(tray PRIVATE "-framework Cocoa")
 endif()

example/example_pp.cpp

 #include "tray/tray.h"
+#include <filesystem>
 #include <stdlib.h>
 
 int main() {
   trays::Menu m;
   m.text_ = "Open work dir";
-  m.on_click_ = [](auto) { system("start ."); };
-  trays::Tray t{"icon.ico", {m}};
+  m.on_click_ = [](auto) { system("open ."); };
+
+  // absolute path for linux.
+  // linux: png, svg
+  std::string icon_name = "icon.png";
+  auto icon_path =std::filesystem::current_path() / icon_name;
+  trays::Tray t{icon_path.string(), {m}};
   //   t.add(m);
   t.run();
 }
\ No newline at end of file

include/tray/platform/linux.h

 #include <gtk/gtk.h>
-#include <libappindicator/app-indicator.h>
+#include <libayatana-appindicator/app-indicator.h>
 
 #define TRAY_APPINDICATOR_ID "tray-id"
 
@@ -38,7 +38,7 @@ static GtkMenuShell *_tray_menu(struct tray_menu *m) {
   return menu;
 }
 
-static int tray_init(struct tray *tray) {
+  int tray_init(struct tray *tray) {
   if (gtk_init_check(0, NULL) == FALSE) {
     return -1;
   }
@@ -49,16 +49,16 @@ static int tray_init(struct tray *tray) {
   return 0;
 }
 
-static int tray_loop(int blocking) {
+  int tray_loop(int blocking) {
   gtk_main_iteration_do(blocking);
   return loop_result;
 }
 
-static void tray_update(struct tray *tray) {
+  void tray_update(struct tray *tray) {
   app_indicator_set_icon(indicator, tray->icon);
   // GTK is all about reference counting, so previous menu should be destroyed
   // here
   app_indicator_set_menu(indicator, GTK_MENU(_tray_menu(tray->menu)));
 }
 
-static void tray_exit() { loop_result = -1; }
+  void tray_exit() { loop_result = -1; }
\ No newline at end of file

include/tray/platform/tray_impl.h

 #include "tray/tray_raw.h"
-#if defined(TRAY_APPINDICATOR)
+#if defined(__linux__)
 #include "linux.h"
-#elif defined(TRAY_APPKIT)
+#elif defined(TARGET_OS_MAC)
 #include "macos.h"
 #elif defined(_WIN32)
 #include "windows.h"