[feat] add online status indicators for recent connections

src/gui/assets/localization/localization.h

@@ -216,6 +216,11 @@ static std::vector<std::string> connection_mode_direct = {
     reinterpret_cast<const char*>(u8"直连"), "Direct"};
 static std::vector<std::string> connection_mode_relay = {
     reinterpret_cast<const char*>(u8"中继"), "Relay"};
+static std::vector<std::string> online = {
+    reinterpret_cast<const char*>(u8"在线"), "Online"};
+static std::vector<std::string> offline = {
+    reinterpret_cast<const char*>(u8"离线"), "Offline"};
+
 #if _WIN32
 static std::vector<LPCWSTR> exit_program = {L"退出", L"Exit"};
 #endif

src/gui/device_presence.h

@@ -0,0 +1,36 @@
+/*
+ * @Author: DI JUNKUN
+ * @Date: 2026-02-28
+ * Copyright (c) 2026 by DI JUNKUN, All Rights Reserved.
+ */
+
+#ifndef _DEVICE_PRESENCE_H_
+#define _DEVICE_PRESENCE_H_
+
+#include <mutex>
+#include <string>
+#include <unordered_map>
+
+class DevicePresence {
+ public:
+  void SetOnline(const std::string& device_id, bool online) {
+    std::lock_guard<std::mutex> lock(mutex_);
+    cache_[device_id] = online;
+  }
+
+  bool IsOnline(const std::string& device_id) const {
+    std::lock_guard<std::mutex> lock(mutex_);
+    return cache_.count(device_id) > 0 && cache_.at(device_id);
+  }
+
+  void Clear() {
+    std::lock_guard<std::mutex> lock(mutex_);
+    cache_.clear();
+  }
+
+ private:
+  std::unordered_map<std::string, bool> cache_;
+  mutable std::mutex mutex_;
+};
+
+#endif

src/gui/panels/recent_connections_panel.cpp

@@ -122,6 +122,8 @@ int Render::ShowRecentConnections() {
       it.second.remote_host_name = "unknown";
     }
 
+    bool online = device_presence_.IsOnline(it.second.remote_id);
+
     ImVec2 image_screen_pos = ImVec2(
         ImGui::GetCursorScreenPos().x + recent_connection_image_width * 0.04f,
         ImGui::GetCursorScreenPos().y + recent_connection_image_height * 0.08f);
@@ -133,6 +135,26 @@ int Render::ShowRecentConnections() {
         (ImTextureID)(intptr_t)it.second.texture,
         ImVec2(recent_connection_image_width, recent_connection_image_height));
 
+    ImDrawList* draw_list = ImGui::GetWindowDrawList();
+    ImVec2 circle_pos =
+        ImVec2(image_screen_pos.x + recent_connection_image_width * 0.07f,
+               image_screen_pos.y + recent_connection_image_height * 0.13f);
+    ImU32 fill_color =
+        online ? IM_COL32(0, 255, 0, 255) : IM_COL32(140, 140, 140, 255);
+    ImU32 border_color = IM_COL32(255, 255, 255, 230);
+    draw_list->AddCircleFilled(circle_pos, 6.0f, fill_color);
+    draw_list->AddCircle(circle_pos, 6.0f, border_color, 100, 2.0f);
+    if (ImGui::IsMouseHoveringRect(
+            ImVec2(circle_pos.x - 6.0f, circle_pos.y - 6.0f),
+            ImVec2(circle_pos.x + 6.0f, circle_pos.y + 6.0f))) {
+      ImGui::BeginTooltip();
+      ImGui::SetWindowFontScale(0.5f);
+      ImGui::Text("%s", online ? localization::online[0].c_str()
+                               : localization::offline[0].c_str());
+      ImGui::SetWindowFontScale(1.0f);
+      ImGui::EndTooltip();
+    }
+
     // remote id display button
     {
       ImGui::PushStyleColor(ImGuiCol_Button, ImVec4(0, 0, 0, 0.2f));

src/gui/render.cpp

@@ -810,6 +810,7 @@ int Render::CreateConnectionPeer() {
   params_.on_receive_video_frame = OnReceiveVideoBufferCb;
 
   params_.on_signal_status = OnSignalStatusCb;
+  params_.on_signal_message = OnSignalMessageCb;
   params_.on_connection_status = OnConnectionStatusCb;
   params_.on_net_status_report = OnNetStatusReport;
 
@@ -1593,6 +1594,7 @@ void Render::MainLoop() {
 
     UpdateLabels();
     HandleRecentConnections();
+    HandleConnectionStatusChange();
     HandleStreamWindow();
     HandleServerWindow();
 
@@ -1632,10 +1634,46 @@ void Render::HandleRecentConnections() {
         LOG_INFO("Load recent connection thumbnails");
       }
       reload_recent_connections_ = false;
+
+      recent_connection_ids_.clear();
+      for (const auto& conn : recent_connections_) {
+        recent_connection_ids_.push_back(conn.first);
+      }
+      need_to_send_recent_connections_ = true;
     }
   }
 }
 
+void Render::HandleConnectionStatusChange() {
+  if (signal_connected_ && peer_ && need_to_send_recent_connections_) {
+    if (!recent_connection_ids_.empty()) {
+      nlohmann::json j;
+      j["type"] = "recent_connections_presence";
+      j["user_id"] = client_id_;
+      j["devices"] = nlohmann::json::array();
+      for (const auto& id : recent_connection_ids_) {
+        std::string pure_id = id;
+        size_t pos_y = pure_id.find('Y');
+        size_t pos_n = pure_id.find('N');
+        size_t pos = std::string::npos;
+        if (pos_y != std::string::npos &&
+            (pos_n == std::string::npos || pos_y < pos_n)) {
+          pos = pos_y;
+        } else if (pos_n != std::string::npos) {
+          pos = pos_n;
+        }
+        if (pos != std::string::npos) {
+          pure_id = pure_id.substr(0, pos);
+        }
+        j["devices"].push_back(pure_id);
+      }
+      auto s = j.dump();
+      SendSignalMessage(peer_, s.data(), s.size());
+    }
+  }
+  need_to_send_recent_connections_ = false;
+}
+
 void Render::HandleStreamWindow() {
   if (need_to_create_stream_window_) {
     CreateStreamWindow();

src/gui/render.h

@@ -25,6 +25,7 @@
 #include "IconsFontAwesome6.h"
 #include "config_center.h"
 #include "device_controller_factory.h"
+#include "device_presence.h"
 #include "imgui.h"
 #include "imgui_impl_sdl3.h"
 #include "imgui_impl_sdlrenderer3.h"
@@ -192,6 +193,7 @@ class Render {
   void UpdateLabels();
   void UpdateInteractions();
   void HandleRecentConnections();
+  void HandleConnectionStatusChange();
   void HandleStreamWindow();
   void HandleServerWindow();
   void Cleanup();
@@ -286,6 +288,9 @@ class Render {
   static void OnSignalStatusCb(SignalStatus status, const char* user_id,
                                size_t user_id_size, void* user_data);
 
+  static void OnSignalMessageCb(const char* message, size_t size,
+                                void* user_data);
+
   static void OnConnectionStatusCb(ConnectionStatus status, const char* user_id,
                                    size_t user_id_size, void* user_data);
 
@@ -402,9 +407,12 @@ class Render {
   // recent connections
   std::vector<std::pair<std::string, Thumbnail::RecentConnection>>
       recent_connections_;
+  std::vector<std::string> recent_connection_ids_;
   int recent_connection_image_width_ = 160;
   int recent_connection_image_height_ = 90;
   uint32_t recent_connection_image_save_time_ = 0;
+  DevicePresence device_presence_;
+  bool need_to_send_recent_connections_ = true;
 
   // main window render
   SDL_Window* main_window_ = nullptr;

src/gui/render_callback.cpp

@@ -6,6 +6,7 @@
 #include <fstream>
 #include <limits>
 #include <unordered_map>
+#include <unordered_set>
 
 #include "clipboard.h"
 #include "device_controller.h"
@@ -20,6 +21,47 @@
 
 namespace crossdesk {
 
+void Render::OnSignalMessageCb(const char* message, size_t size,
+                               void* user_data) {
+  Render* render = (Render*)user_data;
+  if (!render || !message || size == 0) {
+    return;
+  }
+  std::string s(message, size);
+  auto j = nlohmann::json::parse(s, nullptr, false);
+  if (j.is_discarded() || !j.contains("type") || !j["type"].is_string()) {
+    return;
+  }
+  std::string type = j["type"].get<std::string>();
+  if (type == "presence") {
+    if (j.contains("devices") && j["devices"].is_array()) {
+      for (auto& dev : j["devices"]) {
+        if (!dev.is_object()) {
+          continue;
+        }
+        if (!dev.contains("id") || !dev["id"].is_string()) {
+          continue;
+        }
+        if (!dev.contains("online") || !dev["online"].is_boolean()) {
+          continue;
+        }
+        std::string id = dev["id"].get<std::string>();
+        bool online = dev["online"].get<bool>();
+        render->device_presence_.SetOnline(id, online);
+      }
+    }
+  } else if (type == "presence_update") {
+    if (j.contains("id") && j["id"].is_string() && j.contains("online") &&
+        j["online"].is_boolean()) {
+      std::string id = j["id"].get<std::string>();
+      bool online = j["online"].get<bool>();
+      if (!id.empty()) {
+        render->device_presence_.SetOnline(id, online);
+      }
+    }
+  }
+}
+
 int Render::SendKeyCommand(int key_code, bool is_down) {
   RemoteAction remote_action;
   remote_action.type = ControlType::keyboard;