api, ipc: add signal for when a plugin is activated or deactivated

plugins/single_plugins/ipc-rules.cpp

@@ -146,6 +146,7 @@ class ipc_rules_t : public wf::plugin_interface_t, public wf::per_output_tracker
         wf::get_core().connect(&on_kbfocus_changed);
         wf::get_core().connect(&on_title_changed);
         wf::get_core().connect(&on_app_id_changed);
+        wf::get_core().connect(&on_plugin_activation_changed);
         init_output_tracking();
     }
 
@@ -372,11 +373,16 @@ class ipc_rules_t : public wf::plugin_interface_t, public wf::per_output_tracker
         nlohmann::json event;
         event["event"] = event_name;
         event["view"]  = view_to_json(view);
+        send_event_to_subscribes(event, event_name);
+    }
+
+    void send_event_to_subscribes(const nlohmann::json& data, const std::string& event_name)
+    {
         for (auto& [client, events] : clients)
         {
             if (events.empty() || events.count(event_name))
             {
-                client->send_json(event);
+                client->send_json(data);
             }
         }
     }
@@ -427,6 +433,17 @@ class ipc_rules_t : public wf::plugin_interface_t, public wf::per_output_tracker
         send_view_to_subscribes(ev->view, "view-app-id-changed");
     };
 
+    wf::signal::connection_t<wf::output_plugin_activated_changed_signal> on_plugin_activation_changed =
+        [=] (wf::output_plugin_activated_changed_signal *ev)
+    {
+        nlohmann::json data;
+        data["event"]  = "plugin-activation-state-changed";
+        data["plugin"] = ev->plugin_name;
+        data["state"]  = ev->activated;
+        data["output"] = ev->output ? (int)ev->output->get_id() : -1;
+        send_event_to_subscribes(data, data["event"]);
+    };
+
     std::string get_view_type(wayfire_view view)
     {
         if (view->role == wf::VIEW_ROLE_TOPLEVEL)

src/api/wayfire/plugin.hpp

@@ -108,7 +108,7 @@ class plugin_interface_t
 using wayfire_plugin_load_func = wf::plugin_interface_t * (*)();
 
 /** The version of Wayfire's API/ABI */
-constexpr uint32_t WAYFIRE_API_ABI_VERSION = 2023'11'23;
+constexpr uint32_t WAYFIRE_API_ABI_VERSION = 2024'02'16;
 
 /**
  * Each plugin must also provide a function which returns the Wayfire API/ABI

src/api/wayfire/signal-definitions.hpp

@@ -1,7 +1,6 @@
 #ifndef SIGNAL_DEFINITIONS_HPP
 #define SIGNAL_DEFINITIONS_HPP
 
-#include "wayfire/object.hpp"
 #include "wayfire/view.hpp"
 #include "wayfire/output.hpp"
 
@@ -263,6 +262,22 @@ struct output_gain_focus_signal
     wf::output_t *output;
 };
 
+/**
+ * on: output, core
+ * when: When an output activates or deactivates. Note that not all plugin actions are reflected with this
+ *   signal. A plugin activates on an output usually if it (temporarily) changes the way Wayfire works like
+ *   Expo, Scale, Vswitch. One-shot actions like command or wsets do not send this signal.
+ */
+struct output_plugin_activated_changed_signal
+{
+    // The output on which the plugin was activated. May be NULL if the plugin works globally.
+    wf::output_t *output;
+    // The name of the plugin.
+    std::string plugin_name;
+    // Whether the plugin was activated (true) or deactivated (false).
+    bool activated;
+};
+
 /* ----------------------------------------------------------------------------/
  * Output rendering signals (see also wayfire/workspace-stream.hpp)
  * -------------------------------------------------------------------------- */

src/output/output.cpp

@@ -292,6 +292,13 @@ bool wf::output_impl_t::activate_plugin(wf::plugin_activation_data_t *owner, uin
     } else
     {
         LOGD("output ", handle->name, ": activate plugin ", owner->name);
+
+        wf::output_plugin_activated_changed_signal data;
+        data.output = this;
+        data.plugin_name = owner->name;
+        data.activated   = true;
+        this->emit(&data);
+        wf::get_core().emit(&data);
     }
 
     active_plugins.insert(owner);
@@ -312,7 +319,12 @@ bool wf::output_impl_t::deactivate_plugin(wf::plugin_activation_data_t *owner)
 
     if (active_plugins.count(owner) == 0)
     {
-        active_plugins.erase(owner);
+        wf::output_plugin_activated_changed_signal data;
+        data.output = this;
+        data.plugin_name = owner->name;
+        data.activated   = false;
+        this->emit(&data);
+        wf::get_core().emit(&data);
         return true;
     }