[feat] add online presence check before connecting and show offline warning dialog

src/gui/assets/localization/localization.h

@@ -220,6 +220,8 @@ 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"};
+static std::vector<std::string> device_offline = {
+    reinterpret_cast<const char*>(u8"设备离线"), "Device Offline"};
 
 #if _WIN32
 static std::vector<LPCWSTR> exit_program = {L"退出", L"Exit"};

src/gui/panels/recent_connections_panel.cpp

@@ -238,8 +238,14 @@ int Render::ShowRecentConnections() {
       if (ImGui::Button(connect_to_this_connection_button_name.c_str(),
                         ImVec2(recent_connection_button_width,
                                recent_connection_button_height))) {
-        ConnectTo(it.second.remote_id, it.second.password.c_str(),
-                  it.second.remember_password);
+        if (online) {
+          ConnectTo(it.second.remote_id, it.second.password.c_str(),
+                    it.second.remember_password);
+        } else {
+          show_offline_warning_window_ = true;
+          offline_warning_text_ =
+              localization::device_offline[localization_language_index_];
+        }
       }
     }
     ImGui::SetWindowFontScale(1.0f);
@@ -270,6 +276,9 @@ int Render::ShowRecentConnections() {
   if (show_confirm_delete_connection_) {
     ConfirmDeleteConnection();
   }
+  if (show_offline_warning_window_) {
+    OfflineWarningWindow();
+  }
 
   return 0;
 }
@@ -282,7 +291,7 @@ int Render::ConfirmDeleteConnection() {
       ImVec2(io.DisplaySize.x * 0.33f, io.DisplaySize.y * 0.33f));
 
   ImGui::PushStyleVar(ImGuiStyleVar_FrameRounding, 3.0f);
-  ImGui::PushStyleColor(ImGuiCol_WindowBg, ImVec4(1.0, 1.0, 1.0, 1.0));
+  ImGui::PushStyleColor(ImGuiCol_WindowBg, ImVec4(1.0f, 1.0f, 1.0f, 1.0f));
   ImGui::PushStyleVar(ImGuiStyleVar_WindowBorderSize, 1.0f);
   ImGui::PushStyleVar(ImGuiStyleVar_WindowRounding, 6.0f);
 
@@ -327,4 +336,45 @@ int Render::ConfirmDeleteConnection() {
   ImGui::PopStyleVar();
   return 0;
 }
+
+int Render::OfflineWarningWindow() {
+  ImGuiIO& io = ImGui::GetIO();
+  ImGui::SetNextWindowPos(
+      ImVec2(io.DisplaySize.x * 0.33f, io.DisplaySize.y * 0.33f));
+  ImGui::SetNextWindowSize(
+      ImVec2(io.DisplaySize.x * 0.33f, io.DisplaySize.y * 0.33f));
+
+  ImGui::PushStyleVar(ImGuiStyleVar_FrameRounding, 3.0f);
+  ImGui::PushStyleColor(ImGuiCol_WindowBg, ImVec4(1.0f, 1.0f, 1.0f, 1.0f));
+  ImGui::PushStyleVar(ImGuiStyleVar_WindowBorderSize, 1.0f);
+  ImGui::PushStyleVar(ImGuiStyleVar_WindowRounding, 6.0f);
+
+  ImGui::Begin("OfflineWarningWindow", nullptr,
+               ImGuiWindowFlags_NoDecoration | ImGuiWindowFlags_NoMove |
+                   ImGuiWindowFlags_NoSavedSettings);
+  ImGui::PopStyleVar(2);
+  ImGui::PopStyleColor();
+
+  auto window_width = ImGui::GetWindowSize().x;
+  auto window_height = ImGui::GetWindowSize().y;
+
+  ImGui::SetCursorPosX(window_width * 0.43f);
+  ImGui::SetCursorPosY(window_height * 0.67f);
+  ImGui::SetWindowFontScale(0.5f);
+  if (ImGui::Button(localization::ok[localization_language_index_].c_str()) ||
+      ImGui::IsKeyPressed(ImGuiKey_Enter) ||
+      ImGui::IsKeyPressed(ImGuiKey_Escape)) {
+    show_offline_warning_window_ = false;
+  }
+
+  auto text_width = ImGui::CalcTextSize(offline_warning_text_.c_str()).x;
+  ImGui::SetCursorPosX((window_width - text_width) * 0.5f);
+  ImGui::SetCursorPosY(window_height * 0.2f);
+  ImGui::Text("%s", offline_warning_text_.c_str());
+  ImGui::SetWindowFontScale(1.0f);
+
+  ImGui::End();
+  ImGui::PopStyleVar();
+  return 0;
+}
 }  // namespace crossdesk

src/gui/render.h

@@ -257,6 +257,7 @@ class Render {
   int DrawStreamWindow();
   int DrawServerWindow();
   int ConfirmDeleteConnection();
+  int OfflineWarningWindow();
   int NetTrafficStats(std::shared_ptr<SubStreamWindowProperties>& props);
   void DrawConnectionStatusText(
       std::shared_ptr<SubStreamWindowProperties>& props);
@@ -577,9 +578,11 @@ class Render {
   bool is_server_mode_ = false;
   bool reload_recent_connections_ = true;
   bool show_confirm_delete_connection_ = false;
+  bool show_offline_warning_window_ = false;
   bool delete_connection_ = false;
   bool is_tab_bar_hovered_ = false;
   std::string delete_connection_name_ = "";
+  std::string offline_warning_text_ = "";
   bool re_enter_remote_id_ = false;
   double copy_start_time_ = 0;
   SignalStatus signal_status_ = SignalStatus::SignalClosed;
@@ -685,4 +688,4 @@ class Render {
   FileTransferState file_transfer_;
 };
 }  // namespace crossdesk
-#endif
+#endif