Cross-platform, single header, super tiny C99 implementation of a system tray icon with a popup menu.

Works well on:

• Linux/Gtk (libappindicator)
• Windows XP or newer (shellapi.h)
• MacOS (Cocoa/AppKit)

There is also a stub implementation that returns errors on attempt to create a tray menu.

Before you can compile tray, you'll need to add an environment definition before the line where you include tray.h.

For Windows:

#include <stdio.h>
#include <string.h>

#define TRAY_WINAPI 1

#include "tray.h"
...

For Linux:

#include <stdio.h>
#include <string.h>

#define TRAY_APPINDICATOR 1

#include "tray.h"
...

For Mac:

#include <stdio.h>
#include <string.h>

#define TRAY_APPKIT 1

#include "tray.h"
...

The included example .c files can be compiled based on your environment.

For example, to compile and run the program on Windows:

$> gcc example_windows.c [Enter]

This will compile and build a.out. To run it:

$> a [Enter]

struct tray tray = {
    .icon = "icon.png",
    .menu = (struct tray_menu[]){{"Toggle me", 0, 0, toggle_cb, NULL},
                                 {"-", 0, 0, NULL, NULL},
                                 {"Quit", 0, 0, quit_cb, NULL},
                                 {NULL, 0, 0, NULL, NULL}},
};

void toggle_cb(struct tray_menu *item) {
	item->checked = !item->checked;
	tray_update(&tray);
}

void quit_cb(struct tray_menu *item) {
  tray_exit();
}

...

tray_init(&tray);
while (tray_loop(1) == 0);
tray_exit();

Tray structure defines an icon and a menu. Menu is a NULL-terminated array of items. Menu item defines menu text, menu checked and disabled (grayed) flags and a callback with some optional context pointer.

struct tray {
  char *icon;
  struct tray_menu *menu;
};

struct tray_menu {
  char *text;
  int disabled;
  int checked;

  void (*cb)(struct tray_menu *);
  void *context;

  struct tray_menu *submenu;
};

• int tray_init(struct tray *) - creates tray icon. Returns -1 if tray icon/menu can't be created.
• void tray_update(struct tray *) - updates tray icon and menu.
• int tray_loop(int blocking) - runs one iteration of the UI loop. Returns -1 if tray_exit() has been called.
• void tray_exit() - terminates UI loop.

All functions are meant to be called from the UI thread only.

Menu arrays must be terminated with a NULL item, e.g. the last item in the array must have text field set to NULL.

• Cross-platform tray icon
• Cross-platform tray popup menu
• Separators in the menu
• Disabled/enabled menu items
• Checked/unchecked menu items
• Nested menus
• Icons for menu items
• Rewrite ObjC code in C using ObjC Runtime (now ObjC code breaks many linters and static analyzers)
• Call GTK code using dlopen/dlsym (to make binaries run safely if Gtk libraries are not available)

This software is distributed under MIT license, so feel free to integrate it in your commercial products.