[feat] add desktop preview settings and platform placeholders

README.md

@@ -147,6 +147,7 @@ sudo apt install "./crossdesk-linux-amd64-<version>.deb"
 | 视频编码格式 | H.264 / AV1；硬件编解码是否可用取决于平台、硬件与构建选项 |
 | 启用中继服务 | 允许借助 TURN 中继建立连接；P2P 连接失败时先检查此项 |
 | 强制中继连接 | 启用中继服务后可勾选，让连接通过中继建立；关闭中继服务会同时关闭此项 |
+| 保存远程画面预览 | 默认开启，保存远程画面预览；关闭后缩略图区域显示被控端平台，并清除已有预览，保留连接记录和密码 |
 | 被连接时开启隐私屏 | 设置本机被远程连接时是否自动启用隐私屏；会话中可从控制端工具栏切换 |
 | 自托管配置 | 填写服务器地址和信令服务端口，并勾选启用 |
 | 开机自启 / 启用守护进程 | 调整启动与进程守护行为，按界面提示重启后生效 |

README_EN.md

@@ -147,6 +147,7 @@ Open **☰ → Settings** in the top-right corner and click **OK** to save. Conf
 | Video Encode Format | H.264 / AV1; hardware codec availability depends on the platform, device, and build options |
 | Enable TURN Service | Allow relay-assisted connections; check this setting if P2P fails |
 | Force Relay | Require relay connections when TURN is enabled; turning TURN off also disables this option |
+| Save remote screen previews | On by default. When disabled, the thumbnail area shows the remote device’s platform and existing previews are cleared; connection records and passwords are preserved |
 | Privacy screen on connect | Automatically enable privacy when this computer is controlled remotely; the controller can toggle it from the session toolbar |
 | Self-Hosted Config | Set the server address and signaling port, then enable the checkbox |
 | Auto Start / Enable Daemon | Configure startup and process supervision; restart as indicated by the UI |

apps/desktop/src/config_center/config_center.cpp

@@ -125,6 +125,8 @@ int ConfigCenter::Load() {
   enable_daemon_ = ini_->GetBoolValue(section_, "enable_daemon", enable_daemon_);
   enable_privacy_screen_.store(
       ini_->GetBoolValue(section_, "enable_privacy_screen", true));
+  save_remote_previews_.store(
+      ini_->GetBoolValue(section_, "save_remote_previews", true));
   portable_service_prompt_suppressed_ =
       ini_->GetBoolValue(section_, "portable_service_prompt_suppressed",
                         portable_service_prompt_suppressed_);
@@ -214,6 +216,8 @@ int ConfigCenter::Save() {
   ini_->SetBoolValue(section_, "enable_daemon", enable_daemon_);
   ini_->SetBoolValue(section_, "enable_privacy_screen",
                     enable_privacy_screen_.load());
+  ini_->SetBoolValue(section_, "save_remote_previews",
+                    save_remote_previews_.load());
   ini_->SetBoolValue(section_, "portable_service_prompt_suppressed",
                     portable_service_prompt_suppressed_);
 
@@ -344,6 +348,18 @@ int ConfigCenter::SetPrivacyScreen(bool enable_privacy_screen) {
   return 0;
 }
 
+int ConfigCenter::SetSaveRemotePreviews(bool enabled) {
+  if (StoreValues({{"save_remote_previews", enabled ? "true" : "false"}}) != 0) {
+    return -1;
+  }
+  save_remote_previews_.store(enabled);
+  return 0;
+}
+
+bool ConfigCenter::IsSaveRemotePreviews() const {
+  return save_remote_previews_.load();
+}
+
 int ConfigCenter::SetPortableServicePromptSuppressed(bool suppressed) {
   portable_service_prompt_suppressed_ = suppressed;
   ini_->SetBoolValue(section_, "portable_service_prompt_suppressed",

apps/desktop/src/config_center/config_center.h

@@ -46,6 +46,7 @@ class ConfigCenter {
   int SetAutostart(bool enable_autostart);
   int SetDaemon(bool enable_daemon);
   int SetPrivacyScreen(bool enable_privacy_screen);
+  int SetSaveRemotePreviews(bool enabled);
   int SetPortableServicePromptSuppressed(bool suppressed);
   int SetFileTransferSavePath(const std::string& path);
 
@@ -69,6 +70,7 @@ class ConfigCenter {
   bool IsEnableAutostart() const;
   bool IsEnableDaemon() const;
   bool IsEnablePrivacyScreen() const;
+  bool IsSaveRemotePreviews() const;
   bool IsPortableServicePromptSuppressed() const;
   std::string GetFileTransferSavePath() const;
 
@@ -97,6 +99,7 @@ class ConfigCenter {
   bool enable_autostart_ = false;
   bool enable_daemon_ = false;
   std::atomic<bool> enable_privacy_screen_{true};
+  std::atomic<bool> save_remote_previews_{true};
   bool portable_service_prompt_suppressed_ = false;
   std::string file_transfer_save_path_ = "";
 };

apps/desktop/src/gui/application/gui_application.cpp

@@ -1037,6 +1037,9 @@ void GuiApplication::InitializeLogger() { InitLogger(exec_log_path_); }
 
 void GuiApplication::InitializeSettings() {
   settings_.Load();
+  if (thumbnail_->SetSavePreviews(config_center_->IsSaveRemotePreviews()) != 0) {
+    LOG_ERROR("Failed to clear saved remote previews");
+  }
   settings_.LoadRecentConnectionAliases();
   localization_language_index_ =
       localization::detail::ClampLanguageIndex(language_button_value_);
@@ -1240,6 +1243,7 @@ void GuiApplication::ResetSettingsUi() {
   ui_->main->set_self_hosted_enabled(enable_self_hosted_);
   ui_->main->set_autostart_enabled(enable_autostart_);
   ui_->main->set_daemon_enabled(enable_daemon_);
+  ui_->main->set_save_remote_previews(config_center_->IsSaveRemotePreviews());
   ui_->main->set_privacy_on_connect_enabled(
       config_center_->IsEnablePrivacyScreen());
 #ifdef _WIN32
@@ -2334,9 +2338,11 @@ void GuiApplication::SyncMainWindow() {
   }
 
   std::ostringstream signature_builder;
+  signature_builder << config_center_->IsSaveRemotePreviews() << '\n';
   for (const auto& [key, connection] : recent_connections_) {
     signature_builder << key << '\0' << connection.remote_id << '\0'
                       << connection.remote_host_name << '\0'
+                      << static_cast<int>(connection.platform) << '\0'
                       << settings_.RecentConnectionDisplayName(connection)
                       << '\0'
                       << device_presence_cache_.IsOnline(connection.remote_id)
@@ -2351,22 +2357,27 @@ void GuiApplication::SyncMainWindow() {
   std::vector<ui::RecentConnection> model;
   model.reserve(recent_connections_.size());
   for (const auto& [_, connection] : recent_connections_) {
-    ui::RecentConnection item;
+    // Slint-generated scalar fields have no defaults. With no image,
+    // has_thumbnail must remain false so the remote platform is rendered.
+    ui::RecentConnection item{};
     item.remote_id = UiText(connection.remote_id);
     item.host_name = UiText(connection.remote_host_name);
     item.display_name =
         UiText(settings_.RecentConnectionDisplayName(connection));
     item.online = device_presence_cache_.IsOnline(connection.remote_id);
+    item.platform = UiText(HostPlatformName(connection.platform));
     std::vector<unsigned char> rgba;
     int image_width = 0;
     int image_height = 0;
-    if (!connection.image_path.empty() &&
+    if (config_center_->IsSaveRemotePreviews() &&
+        !connection.image_path.empty() &&
         thumbnail_->DecodeImage(connection.image_path, &rgba, &image_width,
                                 &image_height)) {
       slint::SharedPixelBuffer<slint::Rgba8Pixel> pixels(image_width,
                                                          image_height);
       std::memcpy(pixels.begin(), rgba.data(), rgba.size());
       item.thumbnail = slint::Image(std::move(pixels));
+      item.has_thumbnail = true;
     }
     model.push_back(std::move(item));
   }
@@ -3259,6 +3270,13 @@ void GuiApplication::SaveSettingsFromUi() {
   main->set_force_relay_enabled(config_center_->IsForceRelay());
   config_center_->SetAutostart(enable_autostart_);
   config_center_->SetDaemon(enable_daemon_);
+  if (config_center_->SetSaveRemotePreviews(main->get_save_remote_previews()) != 0) {
+    LOG_ERROR("Failed to save remote preview preference");
+  }
+  if (thumbnail_->SetSavePreviews(config_center_->IsSaveRemotePreviews()) != 0) {
+    LOG_ERROR("Failed to clear saved remote previews");
+  }
+  reload_recent_connections_ = true;
 #ifdef _WIN32
   if (!HasActiveSession()) {
     const auto capture_method = static_cast<ScreenCaptureMethod>(

apps/desktop/src/gui/assets/localization/localization_data.h

@@ -79,6 +79,8 @@ struct TranslationRow {
   X(console_setting_files, u8"文件保存目录", "Received file directory", u8"Каталог получаемых файлов") \
   X(console_setting_autostart, u8"登录桌面时自启", "Start at desktop login", u8"Запуск при входе в систему") \
   X(console_setting_daemon, u8"守护进程（无头控制台中不生效）", "Daemon (inactive in headless console)", u8"Фоновый режим (не действует в консоли)") \
+  X(save_remote_previews, u8"保存远程画面预览", "Save remote screen previews", u8"Сохранять превью экрана") \
+  X(unknown_platform, u8"未知平台", "Unknown platform", u8"Неизвестная платформа") \
   X(privacy_screen, u8"隐私屏", "Privacy screen", u8"Приватный экран") \
   X(privacy_enable, u8"开启隐私屏", "Enable privacy screen", u8"Включить приватный экран") \
   X(privacy_disable, u8"关闭隐私屏", "Disable privacy screen", u8"Выключить приватный экран") \

apps/desktop/src/gui/runtime/connection_runtime.cpp

@@ -236,7 +236,8 @@ void GuiRuntime::CloseRemoteSession(std::shared_ptr<RemoteSession> props) {
   std::shared_ptr<std::vector<unsigned char>> frame_snapshot;
   int video_width = 0;
   int video_height = 0;
-  {
+  const bool save_preview = config_center_->IsSaveRemotePreviews();
+  if (save_preview) {
     std::lock_guard<std::mutex> lock(props->video_frame_mutex_);
     frame_snapshot = props->front_frame_;
     video_width = props->video_width_;
@@ -249,7 +250,8 @@ void GuiRuntime::CloseRemoteSession(std::shared_ptr<RemoteSession> props) {
     }
   }
   auto* native_renderer = video_renderer_.get();
-  if ((!frame_snapshot || frame_snapshot->empty()) && native_renderer) {
+  if (save_preview && (!frame_snapshot || frame_snapshot->empty()) &&
+      native_renderer) {
     auto native_snapshot = std::make_shared<std::vector<unsigned char>>();
     if (native_renderer->CopyLatestNv12(props->remote_id_,
                                         native_snapshot.get(), &video_width,
@@ -269,9 +271,14 @@ void GuiRuntime::CloseRemoteSession(std::shared_ptr<RemoteSession> props) {
     std::unique_lock lock(remote_sessions_mutex_);
     peer = std::exchange(props->peer_, nullptr);
   }
+  HostPlatform platform;
+  {
+    std::lock_guard lock(props->remote_version_mutex_);
+    platform = props->recent_platform_;
+  }
   const auto queued_at = std::chrono::steady_clock::now();
   session_cleanup_tasks_[props->remote_id_] = session_cleanup_queue_.PostTask(
-      [props, peer, frame_snapshot, video_width, video_height,
+      [props, peer, frame_snapshot, video_width, video_height, platform,
        thumbnail = thumbnail_, queued_at]() mutable {
         if (peer) {
           LOG_INFO("[{}] Background leave connection [{}]", props->local_id_,
@@ -279,12 +286,16 @@ void GuiRuntime::CloseRemoteSession(std::shared_ptr<RemoteSession> props) {
           LeaveConnection(peer, props->remote_id_.c_str());
           DestroyPeer(&peer);
         }
-        if (thumbnail && frame_snapshot && !frame_snapshot->empty() &&
+        if (thumbnail && props->was_connected_) {
-            video_width > 0 && video_height > 0) {
+          const char* nv12 = frame_snapshot && !frame_snapshot->empty()
-          thumbnail->SaveToThumbnail(
+              ? reinterpret_cast<const char*>(frame_snapshot->data()) : nullptr;
-              reinterpret_cast<char*>(frame_snapshot->data()), video_width,
+          if (thumbnail->SaveToThumbnail(
-              video_height, props->remote_id_, props->remote_host_name_,
+                  nv12, video_width, video_height, props->remote_id_,
-              props->remember_password_ ? props->remote_password_ : "");
+                  props->remote_host_name_,
+                  props->remember_password_ ? props->remote_password_ : "",
+                  platform) != 0) {
+            LOG_ERROR("[{}] Failed to save recent connection", props->remote_id_);
+          }
         }
         const auto elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(
             std::chrono::steady_clock::now() - queued_at).count();

apps/desktop/src/gui/runtime/peer_data_callbacks.cpp

@@ -323,6 +323,7 @@ void PeerEventHandler::OnReceiveDataBuffer(
         std::lock_guard lock(props->remote_version_mutex_);
         props->remote_host_info_received_ = true;
         props->remote_platform_ = remote_action.i.platform;
+        props->recent_platform_ = remote_action.i.platform;
         props->remote_app_version_ = IsValidAppVersion(remote_action.i.app_version)
                                         ? remote_action.i.app_version : "";
       }

apps/desktop/src/gui/runtime/peer_event_handler.cpp

@@ -295,6 +295,7 @@ void PeerEventHandler::OnConnectionStatus(ConnectionStatus status,
           runtime->need_to_create_stream_window_ = true;
         }
         props->connection_established_ = true;
+        props->was_connected_ = true;
         runtime->start_keyboard_capturer_ = true;
         break;
       }
@@ -336,7 +337,8 @@ void PeerEventHandler::OnConnectionStatus(ConnectionStatus status,
           needs_native_snapshot =
               !props->thumbnail_frame_ || props->thumbnail_frame_->empty();
         }
-        if (needs_native_snapshot) {
+        if (needs_native_snapshot &&
+            runtime->config_center_->IsSaveRemotePreviews()) {
           auto* native_renderer = runtime->video_renderer_.get();
           auto snapshot = std::make_shared<std::vector<unsigned char>>();
           if (native_renderer &&

apps/desktop/src/gui/runtime/remote_session.h

@@ -87,6 +87,7 @@ struct RemoteSession {
   bool signal_connected_ = false;
   SignalStatus signal_status_ = SignalStatus::SignalClosed;
   bool connection_established_ = false;
+  std::atomic<bool> was_connected_{false};
   bool rejoin_ = false;
   bool net_traffic_stats_button_pressed_ = false;
   bool enable_mouse_control_ = true;
@@ -130,6 +131,8 @@ struct RemoteSession {
   bool remote_host_info_received_ = false;
   std::string remote_app_version_;
   HostPlatform remote_platform_ = HostPlatform::Unknown;
+  // Retain history metadata after disconnect resets the live capabilities.
+  HostPlatform recent_platform_ = HostPlatform::Unknown;
   bool remote_update_dismissed_ = false;
   bool remote_service_status_received_ = false;
   std::mutex video_settings_mutex_;

apps/desktop/src/gui/ui/main_window.slint

@@ -7,6 +7,8 @@ export struct RecentConnection {
     host-name: string,
     online: bool,
     thumbnail: image,
+    has-thumbnail: bool,
+    platform: string,
 }
 
 export struct ReleaseNoteBlock {
@@ -49,6 +51,8 @@ export global UiStrings {
     in-out property <string> self-hosted: "Self-hosted server";
     in-out property <string> autostart: "Start with system";
     in-out property <string> daemon: "Run in background";
+    in-out property <string> save-remote-previews: "Save remote screen previews";
+    in-out property <string> unknown-platform: "Unknown platform";
     in-out property <string> privacy-on-connect: "Privacy screen on connect";
     in-out property <string> file-save-path: "File save path";
     in-out property <string> default-desktop: "Desktop";
@@ -306,6 +310,7 @@ export component MainWindow inherits Window {
     in-out property <bool> self-hosted-enabled: false;
     in-out property <bool> autostart-enabled: false;
     in-out property <bool> daemon-enabled: false;
+    in-out property <bool> save-remote-previews: true;
     // Show the preference on every platform; only adapted hosts can change it.
     in property <bool> privacy-setting-available: false;
     in-out property <bool> privacy-on-connect-enabled: true;
@@ -864,13 +869,37 @@ export component MainWindow inherits Window {
                         private property <length> toolbar-width: 79px;
                         private property <length> toolbar-right-padding: 3px;
 
-                        Image {
+                        Rectangle {
                             x: 7px;
                             y: 7px;
                             width: connection-card.content-width;
                             height: 84px;
-                            source: connection.thumbnail;
+                            background: connection.platform == "windows" ? @linear-gradient(135deg, #1f61b3, #337ac4) :
-                            image-fit: cover;
+                                connection.platform == "macos" ? @linear-gradient(135deg, #6e4aad, #8c63c4) :
+                                connection.platform == "linux" ? @linear-gradient(135deg, #a14f14, #ba631f) :
+                                connection.platform == "ios" ? @linear-gradient(135deg, #146e66, #1f8278) :
+                                @linear-gradient(135deg, #596675, #737d8c);
+                            if connection.has-thumbnail: Image {
+                                width: parent.width;
+                                height: parent.height;
+                                source: connection.thumbnail;
+                                image-fit: cover;
+                            }
+                            if !connection.has-thumbnail: Text {
+                                x: 8px;
+                                width: parent.width - 16px;
+                                height: parent.height;
+                                text: connection.platform == "windows" ? "Windows" :
+                                    connection.platform == "macos" ? "macOS" :
+                                    connection.platform == "linux" ? "Linux" :
+                                    connection.platform == "ios" ? "iOS" : UiStrings.unknown-platform;
+                                color: white;
+                                font-size: 20px;
+                                font-weight: 600;
+                                horizontal-alignment: center;
+                                vertical-alignment: center;
+                                overflow: elide;
+                            }
                         }
                         Rectangle {
                             x: 7px;
@@ -1513,6 +1542,11 @@ export component MainWindow inherits Window {
                         Text { x: 8px; y: 3px; width: root.compact-language ? 145px : 212px; height: 24px; text: UiStrings.force-relay; color: root.turn-enabled ? #202124 : #8b8f95; font-size: ImGuiFontStyle.body; overflow: elide; vertical-alignment: center; }
                         ImGuiCheckBox { x: root.compact-language ? 157px : 224px; y: 3px; checked <=> root.force-relay-enabled; enabled: root.turn-enabled && !root.settings-session-active; }
                     }
+                    Rectangle {
+                        height: 30px;
+                        Text { x: 8px; y: 3px; width: root.compact-language ? 145px : 212px; height: 24px; text: UiStrings.save-remote-previews; font-size: ImGuiFontStyle.body; overflow: elide; vertical-alignment: center; }
+                        ImGuiCheckBox { x: root.compact-language ? 157px : 224px; y: 3px; checked <=> root.save-remote-previews; }
+                    }
                     Rectangle {
                         height: 30px;
                         Text { x: 8px; y: 3px; width: root.compact-language ? 145px : 212px; height: 24px; text: UiStrings.privacy-on-connect; color: root.privacy-setting-available ? #202124 : #8b8f95; font-size: ImGuiFontStyle.body; overflow: elide; vertical-alignment: center; }

apps/desktop/src/gui/ui/ui_localization.h

@@ -65,6 +65,8 @@ inline int ApplyMainWindowStrings(
       Text(localization::self_hosted_server_config[language]));
   strings.set_autostart(Text(localization::enable_autostart[language]));
   strings.set_daemon(Text(localization::enable_daemon[language]));
+  strings.set_save_remote_previews(Text(localization::save_remote_previews[language]));
+  strings.set_unknown_platform(Text(localization::unknown_platform[language]));
   strings.set_privacy_on_connect(Text(localization::privacy_on_connect[language]));
   strings.set_file_save_path(
       Text(localization::file_transfer_save_path[language]));

apps/desktop/src/thumbnail/thumbnail.cpp

@@ -1,11 +1,17 @@
 #include "thumbnail.h"
 
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
 #include <openssl/aes.h>
 #include <openssl/crypto.h>
 #include <openssl/evp.h>
 #include <openssl/rand.h>
 
+#include <algorithm>
 #include <chrono>
+#include <nlohmann/json.hpp>
 #include <fstream>
 #include <iomanip>
 #include <iostream>
@@ -104,116 +110,217 @@ int Thumbnail::SetThumbnailDpiScale(float dpi_scale) {
   return 0;
 }
 
-int Thumbnail::SaveToThumbnail(const char* yuv420p, int width, int height,
+namespace {
+
+bool IsRemoteId(const std::string& id) {
+  return id.size() == 9 &&
+         std::all_of(id.begin(), id.end(),
+                     [](unsigned char c) { return c >= '0' && c <= '9'; });
+}
+
+std::string ConnectionKey(const Thumbnail::RecentConnection& connection) {
+  return connection.remote_id + (connection.remember_password ? "Y" : "N") +
+         connection.remote_host_name +
+         (connection.remember_password ? "@" + connection.password : "");
+}
+
+}  // namespace
+
+bool Thumbnail::WriteRecord(const RecentConnection& connection) {
+  const auto path =
+      std::filesystem::path(save_path_) / (connection.remote_id + ".json");
+  const auto temporary = path.string() + ".tmp";
+  const nlohmann::json record = {
+      {"remote_id", connection.remote_id},
+      {"host_name", connection.remote_host_name},
+      {"password",
+       connection.remember_password
+           ? AES_encrypt(connection.password, aes128_key_, aes128_iv_)
+           : ""},
+      {"platform", HostPlatformName(connection.platform)}};
+  std::ofstream output(temporary, std::ios::binary | std::ios::trunc);
+  output << record.dump();
+  output.close();
+  if (!output) return false;
+  std::error_code error;
+#ifdef _WIN32
+  // Windows rename does not replace an existing destination.
+  if (!MoveFileExW(std::filesystem::path(temporary).c_str(), path.c_str(),
+                   MOVEFILE_REPLACE_EXISTING | MOVEFILE_WRITE_THROUGH)) {
+    std::filesystem::remove(temporary, error);
+    return false;
+  }
+#else
+  std::filesystem::rename(temporary, path, error);
+  if (error) {
+    std::filesystem::remove(temporary, error);
+    return false;
+  }
+#endif
+  return true;
+}
+
+bool Thumbnail::ReadRecord(const std::filesystem::path& path,
+                           RecentConnection* connection) {
+  std::ifstream input(path, std::ios::binary);
+  const auto record = nlohmann::json::parse(input, nullptr, false);
+  if (!record.is_object()) return false;
+  try {
+    connection->remote_id = record.value("remote_id", "");
+    if (!IsRemoteId(connection->remote_id) ||
+        path.stem() != connection->remote_id)
+      return false;
+    connection->remote_host_name = record.value("host_name", "");
+    const auto password = record.value("password", "");
+    connection->remember_password = !password.empty();
+    connection->password =
+        password.empty() ? "" : AES_decrypt(password, aes128_key_, aes128_iv_);
+    connection->platform =
+        ParseHostPlatform(record.value("platform", "unknown"));
+    const auto image = path.parent_path() / (connection->remote_id + ".png");
+    if (save_previews_ && std::filesystem::is_regular_file(image)) {
+      connection->image_path = image;
+    }
+    return true;
+  } catch (const nlohmann::json::exception&) {
+    return false;
+  }
+}
+
+int Thumbnail::SetSavePreviews(bool enabled) {
+  std::lock_guard lock(mutex_);
+  save_previews_ = enabled;
+  if (enabled) return 0;
+  // Migrate legacy filenames before removing their image contents, preserving
+  // credentials, names and recency even when previews have never been enabled.
+  std::vector<std::pair<std::string, RecentConnection>> connections;
+  return LoadThumbnailLocked(connections);
+}
+
+int Thumbnail::SaveToThumbnail(const char* nv12, int width, int height,
                                const std::string& remote_id,
                                const std::string& host_name,
-                               const std::string& password) {
+                               const std::string& password,
-  if (!rgba_buffer_) {
+                               HostPlatform platform) {
-    rgba_buffer_ = new char[thumbnail_width_ * thumbnail_height_ * 4];
+  std::lock_guard lock(mutex_);
-  }
+  // Preserve the existing opt-in via Remember password for recent connections.
+  if (password.empty()) return 0;
+  if (!IsRemoteId(remote_id)) return -1;
+  RecentConnection connection;
+  ReadRecord(std::filesystem::path(save_path_) / (remote_id + ".json"),
+             &connection);
+  connection.remote_id = remote_id;
+  connection.remote_host_name = host_name;
+  connection.password = password;
+  connection.remember_password = true;
+  if (platform != HostPlatform::Unknown) connection.platform = platform;
+  if (!WriteRecord(connection)) return -1;
 
-  if (yuv420p) {
+  const auto image = std::filesystem::path(save_path_) / (remote_id + ".png");
-    ScaleNv12ToABGR((char*)yuv420p, width, height, thumbnail_width_,
+  if (save_previews_ && nv12 && width > 0 && height > 0) {
-                    thumbnail_height_, rgba_buffer_);
+    if (!rgba_buffer_) {
-  } else {
+      rgba_buffer_ = new char[thumbnail_width_ * thumbnail_height_ * 4];
-    // If yuv420p is null, fill the buffer with black pixels
-    std::memset(rgba_buffer_, 0x00, thumbnail_width_ * thumbnail_height_ * 4);
-    for (int i = 0; i < thumbnail_width_ * thumbnail_height_; ++i) {
-      // Set alpha channel to opaque
-      rgba_buffer_[i * 4 + 3] = static_cast<char>(0xFF);
     }
+    ScaleNv12ToABGR(const_cast<char*>(nv12), width, height, thumbnail_width_,
+                    thumbnail_height_, rgba_buffer_);
+    if (!stbi_write_png(image.string().c_str(), thumbnail_width_,
+                        thumbnail_height_, 4, rgba_buffer_,
+                        thumbnail_width_ * 4))
+      return -1;
+  } else if (!save_previews_) {
+    std::error_code error;
+    std::filesystem::remove(image, error);
+    if (error) return -1;
   }
-
-  std::string image_file_name;
-  if (password.empty()) {
-    return 0;
-  } else {
-    // delete the old thumbnail
-    std::string filename_with_remote_id = remote_id;
-    DeleteThumbnail(filename_with_remote_id);
-  }
-
-  std::string cipher_password = AES_encrypt(password, aes128_key_, aes128_iv_);
-  image_file_name = remote_id + 'Y' + host_name + '@' + cipher_password;
-  std::string file_path = save_path_ + image_file_name;
-  stbi_write_png(file_path.data(), thumbnail_width_, thumbnail_height_, 4,
-                 rgba_buffer_, thumbnail_width_ * 4);
-
   return 0;
 }
 
 int Thumbnail::LoadThumbnail(
-    std::vector<std::pair<std::string, Thumbnail::RecentConnection>>&
+    std::vector<std::pair<std::string, RecentConnection>>& recent_connections,
-        recent_connections,
     int* width, int* height) {
-  recent_connections.clear();
+  std::lock_guard lock(mutex_);
   if (width) *width = thumbnail_width_;
   if (height) *height = thumbnail_height_;
+  return LoadThumbnailLocked(recent_connections);
+}
 
-  std::vector<std::filesystem::path> image_paths =
+int Thumbnail::LoadThumbnailLocked(
-      FindThumbnailPath(save_path_);
+    std::vector<std::pair<std::string, RecentConnection>>& recent_connections) {
-
+  recent_connections.clear();
-  if (image_paths.size() == 0) {
+  int result = 0;
-    return -1;
+  std::map<std::string, RecentConnection> records;
-  } else {
+  const auto paths = FindThumbnailPath(save_path_);
-    for (int i = 0; i < image_paths.size(); i++) {
+  for (const auto& path : paths) {
-      // size_t pos1 = image_paths[i].string().find('/') + 1;
+    if (path.extension() != ".json") continue;
-      std::string cipher_image_name = image_paths[i].filename().string();
+    RecentConnection connection;
-      std::string remote_id;
+    if (ReadRecord(path, &connection))
-      std::string cipher_password;
+      records.emplace(connection.remote_id, connection);
-      std::string remote_host_name;
-      std::string password;
-      std::string original_image_name;
-      bool remember_password = false;
-
-      if (cipher_image_name.size() > 9 && 'Y' == cipher_image_name[9] &&
-          cipher_image_name.size() >= 16) {
-        size_t pos_y = cipher_image_name.find('Y');
-        size_t pos_at = cipher_image_name.find('@');
-
-        if (pos_y == std::string::npos || pos_at == std::string::npos ||
-            pos_y >= pos_at) {
-          LOG_ERROR("Invalid filename");
-          continue;
-        }
-
-        remote_id = cipher_image_name.substr(0, pos_y);
-        remote_host_name =
-            cipher_image_name.substr(pos_y + 1, pos_at - pos_y - 1);
-        cipher_password = cipher_image_name.substr(pos_at + 1);
-        password = AES_decrypt(cipher_password, aes128_key_, aes128_iv_);
-        remember_password = true;
-
-        original_image_name = remote_id + 'Y' + remote_host_name + "@" +
-                              password;
-      } else {
-        size_t pos_n = cipher_image_name.find('N');
-        // size_t pos_at = cipher_image_name.find('@');
-
-        if (pos_n == std::string::npos) {
-          LOG_ERROR("Invalid filename");
-          continue;
-        }
-
-        remote_id = cipher_image_name.substr(0, pos_n);
-        remote_host_name = cipher_image_name.substr(pos_n + 1);
-
-        original_image_name = remote_id + 'N' + remote_host_name;
-      }
-
-      std::string image_path = save_path_ + cipher_image_name;
-      Thumbnail::RecentConnection recent_connection;
-      recent_connection.remote_id = remote_id;
-      recent_connection.remote_host_name = remote_host_name;
-      recent_connection.password = password;
-      recent_connection.remember_password = remember_password;
-      recent_connection.image_path = image_path;
-      recent_connections.emplace_back(
-          std::make_pair(original_image_name, recent_connection));
-    }
-    return 0;
   }
-  return 0;
+  for (const auto& path : paths) {
+    const auto filename = path.filename().string();
+    if (filename.size() < 10 || !IsRemoteId(filename.substr(0, 9)) ||
+        (filename[9] != 'Y' && filename[9] != 'N'))
+      continue;
+    const auto remote_id = filename.substr(0, 9);
+    if (!records.count(remote_id)) {
+      RecentConnection connection;
+      connection.remote_id = remote_id;
+      connection.remember_password = filename[9] == 'Y';
+      const auto separator = filename.find('@', 10);
+      if (connection.remember_password && separator == std::string::npos)
+        continue;
+      connection.remote_host_name =
+          filename.substr(10, connection.remember_password ? separator - 10
+                                                           : std::string::npos);
+      if (connection.remember_password) {
+        connection.password = AES_decrypt(filename.substr(separator + 1),
+                                          aes128_key_, aes128_iv_);
+      }
+      if (!WriteRecord(connection)) {
+        result = -1;
+        recent_connections.emplace_back(ConnectionKey(connection), connection);
+        continue;
+      }
+      const auto metadata =
+          std::filesystem::path(save_path_) / (remote_id + ".json");
+      std::filesystem::last_write_time(metadata,
+                                       std::filesystem::last_write_time(path));
+      records.emplace(remote_id, connection);
+    }
+    auto& connection = records.at(remote_id);
+    if (save_previews_ && connection.image_path.empty()) {
+      const auto image =
+          std::filesystem::path(save_path_) / (remote_id + ".png");
+      std::error_code error;
+      std::filesystem::copy_file(
+          path, image, std::filesystem::copy_options::overwrite_existing,
+          error);
+      if (error) {
+        // Keep the original preview available and retry migration next load.
+        connection.image_path = path;
+        result = -1;
+        continue;
+      }
+      connection.image_path = image;
+    }
+    std::error_code error;
+    std::filesystem::remove(path, error);
+    if (error) result = -1;
+  }
+  // Sort by metadata timestamps, unaffected by preview deletion or migration.
+  for (const auto& path : FindThumbnailPath(save_path_)) {
+    if (path.extension() == ".json") {
+      const auto it = records.find(path.stem().string());
+      if (it != records.end()) {
+        recent_connections.emplace_back(ConnectionKey(it->second), it->second);
+      }
+    } else if (!save_previews_ && path.extension() == ".png") {
+      std::error_code error;
+      std::filesystem::remove(path, error);
+      if (error) result = -1;
+    }
+  }
+  return result;
 }
 
 bool Thumbnail::DecodeImage(const std::filesystem::path& image_path,
@@ -242,16 +349,17 @@ bool Thumbnail::DecodeImage(const std::filesystem::path& image_path,
 }
 
 int Thumbnail::DeleteThumbnail(const std::string& filename_keyword) {
+  std::lock_guard lock(mutex_);
+  const auto remote_id = filename_keyword.substr(0, 9);
+  if (!IsRemoteId(remote_id)) return -1;
   for (const auto& entry : std::filesystem::directory_iterator(save_path_)) {
-    if (entry.is_regular_file()) {
+    const auto name = entry.path().filename().string();
-      const std::string filename = entry.path().filename().string();
+    if (entry.is_regular_file() && name.size() > 9 &&
-      std::string id_hostname = filename_keyword.substr(0, filename.find('@'));
+        name.substr(0, 9) == remote_id &&
-      if (filename.find(id_hostname) != std::string::npos) {
+        (name[9] == '.' || name[9] == 'Y' || name[9] == 'N')) {
-        std::filesystem::remove(entry.path());
+      std::filesystem::remove(entry.path());
-      }
     }
   }
-
   return 0;
 }
 
@@ -280,6 +388,7 @@ std::vector<std::filesystem::path> Thumbnail::FindThumbnailPath(
 }
 
 int Thumbnail::DeleteAllFilesInDirectory() {
+  std::lock_guard lock(mutex_);
   if (std::filesystem::exists(save_path_) &&
       std::filesystem::is_directory(save_path_)) {
     for (const auto& entry : std::filesystem::directory_iterator(save_path_)) {

apps/desktop/src/thumbnail/thumbnail.h

@@ -10,9 +10,12 @@
 #include <cstring>
 #include <filesystem>
 #include <map>
+#include <mutex>
 #include <unordered_map>
 #include <vector>
 
+#include "remote_action.h"
+
 namespace crossdesk {
 
 class Thumbnail {
@@ -23,6 +26,7 @@ class Thumbnail {
     std::string remote_host_name;
     std::string password;
     bool remember_password = false;
+    HostPlatform platform = HostPlatform::Unknown;
   };
 
  public:
@@ -34,10 +38,14 @@ class Thumbnail {
  public:
   int SetThumbnailDpiScale(float dpi_scale);
 
-  int SaveToThumbnail(const char* yuv420p, int width, int height,
+  // Serialized with writes so disabling also clears any in-flight preview.
+  int SetSavePreviews(bool enabled);
+
+  int SaveToThumbnail(const char* nv12, int width, int height,
                       const std::string& remote_id,
                       const std::string& host_name,
-                      const std::string& password);
+                      const std::string& password,
+                      HostPlatform platform = HostPlatform::Unknown);
 
   int LoadThumbnail(
       std::vector<std::pair<std::string, Thumbnail::RecentConnection>>&
@@ -69,6 +77,11 @@ class Thumbnail {
   }
 
  private:
+  int LoadThumbnailLocked(
+      std::vector<std::pair<std::string, RecentConnection>>& connections);
+  bool WriteRecord(const RecentConnection& connection);
+  bool ReadRecord(const std::filesystem::path& path, RecentConnection* connection);
+
   std::vector<std::filesystem::path> FindThumbnailPath(
       const std::filesystem::path& directory);
 
@@ -79,6 +92,8 @@ class Thumbnail {
                           unsigned char* iv);
 
  private:
+  std::mutex mutex_;
+  bool save_previews_ = true;
   int thumbnail_width_ = 160;
   int thumbnail_height_ = 90;
   char* rgba_buffer_ = nullptr;

apps/desktop/tests/slint_ui_smoke_test.cpp

@@ -135,12 +135,13 @@ bool ConfigureDocumentationDemo(
       std::cerr << "Missing documentation thumbnail: " << path << '\n';
       return false;
     }
-    crossdesk::ui::RecentConnection connection;
+    crossdesk::ui::RecentConnection connection{};
     connection.remote_id = device.id;
     connection.display_name = device.name;
     connection.host_name = device.name;
     connection.online = true;
     connection.thumbnail = thumbnail;
+    connection.has_thumbnail = true;
     connections.emplace_back(std::move(connection));
   }
   window->set_recent_connections(
@@ -542,7 +543,7 @@ int main() {
   assert(std::string(window->get_remote_id_input()).empty());
 
   std::vector<crossdesk::ui::RecentConnection> connections;
-  crossdesk::ui::RecentConnection connection;
+  crossdesk::ui::RecentConnection connection{};
   connection.remote_id = "987654321";
   connection.display_name = "Office PC";
   connection.host_name = "office-pc";

apps/desktop/xmake/targets.lua

@@ -386,7 +386,7 @@ function setup_targets()
 
     target("thumbnail")
         set_kind("object")
-        add_packages("libyuv", "openssl3")
+        add_packages("libyuv", "openssl3", "nlohmann_json")
         add_deps("rd_log", "desktop_common")
         add_files("apps/desktop/src/thumbnail/*.cpp")
         add_includedirs("apps/desktop/src/thumbnail", {public = true})