[feat] use SendReliableDataFrame() instead of SendDataFrame()

src/gui/assets/localization/localization.h

@@ -185,6 +185,8 @@ static std::vector<std::string> enable_daemon = {
 static std::vector<std::string> takes_effect_after_restart = {
     reinterpret_cast<const char*>(u8"重启后生效"),
     "Takes effect after restart"};
+static std::vector<std::string> select_file = {
+    reinterpret_cast<const char*>(u8"选择文件"), "Select File"};
 #if _WIN32
 static std::vector<std::string> minimize_to_tray = {
     reinterpret_cast<const char*>(u8"退出时最小化到系统托盘:"),

src/gui/panels/local_peer_panel.cpp

@@ -30,6 +30,7 @@ int Render::LocalWindow() {
   ImGui::SetCursorPos(
       ImVec2(io.DisplaySize.x * 0.045f, io.DisplaySize.y * 0.02f));
 
+  ImGui::SetWindowFontScale(0.9f);
   ImGui::TextColored(
       ImVec4(0.0f, 0.0f, 0.0f, 0.5f), "%s",
       localization::local_desktop[localization_language_index_].c_str());

src/gui/panels/recent_connections_panel.cpp

@@ -26,6 +26,7 @@ int Render::RecentConnectionsWindow() {
   ImGui::SetCursorPos(
       ImVec2(io.DisplaySize.x * 0.045f, io.DisplaySize.y * 0.02f));
 
+  ImGui::SetWindowFontScale(0.9f);
   ImGui::TextColored(
       ImVec4(0.0f, 0.0f, 0.0f, 0.5f), "%s",
       localization::recent_connections[localization_language_index_].c_str());

src/gui/panels/remote_peer_panel.cpp

@@ -31,6 +31,7 @@ int Render::RemoteWindow() {
   ImGui::SetCursorPos(
       ImVec2(io.DisplaySize.x * 0.057f, io.DisplaySize.y * 0.02f));
 
+  ImGui::SetWindowFontScale(0.9f);
   ImGui::TextColored(
       ImVec4(0.0f, 0.0f, 0.0f, 0.5f), "%s",
       localization::remote_desktop[localization_language_index_].c_str());
@@ -189,11 +190,11 @@ int Render::ConnectTo(const std::string& remote_id, const char* password,
         props->params_.user_id = props->local_id_.c_str();
         props->peer_ = CreatePeer(&props->params_);
 
-        props->control_window_width_ = title_bar_height_ * 8.0f;
+        props->control_window_width_ = title_bar_height_ * 9.0f;
         props->control_window_height_ = title_bar_height_ * 1.3f;
         props->control_window_min_width_ = title_bar_height_ * 0.65f;
         props->control_window_min_height_ = title_bar_height_ * 1.3f;
-        props->control_window_max_width_ = title_bar_height_ * 8.0f;
+        props->control_window_max_width_ = title_bar_height_ * 9.0f;
         props->control_window_max_height_ = title_bar_height_ * 6.0f;
 
         if (!props->peer_) {
@@ -206,6 +207,7 @@ int Render::ConnectTo(const std::string& remote_id, const char* password,
         }
         AddAudioStream(props->peer_, props->audio_label_.c_str());
         AddDataStream(props->peer_, props->data_label_.c_str());
+        AddDataStream(props->peer_, props->file_label_.c_str());
 
         props->connection_status_ = ConnectionStatus::Connecting;
 

src/gui/render.cpp

@@ -714,6 +714,7 @@ int Render::CreateConnectionPeer() {
 
     AddAudioStream(peer_, audio_label_.c_str());
     AddDataStream(peer_, data_label_.c_str());
+    AddDataStream(peer_, file_label_.c_str());
     return 0;
   } else {
     return -1;
@@ -1340,8 +1341,8 @@ void Render::MainLoop() {
       remote_action.i.host_name_size = host_name.size();
 
       std::string msg = remote_action.to_json();
-      int ret =
-          SendDataFrame(peer_, msg.data(), msg.size(), data_label_.c_str());
+      int ret = SendReliableDataFrame(peer_, msg.data(), msg.size(),
+                                      data_label_.c_str());
       FreeRemoteAction(remote_action);
       if (0 == ret) {
         need_to_send_host_info_ = false;

src/gui/render.h

@@ -45,6 +45,7 @@ class Render {
     PeerPtr* peer_ = nullptr;
     std::string audio_label_ = "control_audio";
     std::string data_label_ = "control_data";
+    std::string file_label_ = "file";
     std::string local_id_ = "";
     std::string remote_id_ = "";
     bool exit_ = false;
@@ -464,6 +465,7 @@ class Render {
   std::string video_secondary_label_ = "secondary_display";
   std::string audio_label_ = "audio";
   std::string data_label_ = "data";
+  std::string file_label_ = "file";
   Params params_;
   SDL_AudioDeviceID input_dev_;
   SDL_AudioDeviceID output_dev_;

src/gui/render_callback.cpp

@@ -1,7 +1,11 @@
+#include <chrono>
 #include <cmath>
+#include <cstdlib>
+#include <filesystem>
 #include <fstream>
 
 #include "device_controller.h"
+#include "file_transfer.h"
 #include "localization.h"
 #include "platform.h"
 #include "rd_log.h"
@@ -29,8 +33,8 @@ int Render::SendKeyCommand(int key_code, bool is_down) {
       if (props->connection_status_ == ConnectionStatus::Connected) {
         std::string msg = remote_action.to_json();
         if (props->peer_) {
-          SendDataFrame(props->peer_, msg.c_str(), msg.size(),
-                        props->data_label_.c_str());
+          SendReliableDataFrame(props->peer_, msg.c_str(), msg.size(),
+                                props->data_label_.c_str());
         }
       }
     }
@@ -100,8 +104,8 @@ int Render::ProcessMouseEvent(const SDL_Event& event) {
 
       std::string msg = remote_action.to_json();
       if (props->peer_) {
-        SendDataFrame(props->peer_, msg.c_str(), msg.size(),
-                      props->data_label_.c_str());
+        SendReliableDataFrame(props->peer_, msg.c_str(), msg.size(),
+                              props->data_label_.c_str());
       }
     } else if (SDL_EVENT_MOUSE_WHEEL == event.type &&
                last_mouse_event.button.x >= props->stream_render_rect_.x &&
@@ -147,8 +151,8 @@ int Render::ProcessMouseEvent(const SDL_Event& event) {
 
       std::string msg = remote_action.to_json();
       if (props->peer_) {
-        SendDataFrame(props->peer_, msg.c_str(), msg.size(),
-                      props->data_label_.c_str());
+        SendReliableDataFrame(props->peer_, msg.c_str(), msg.size(),
+                              props->data_label_.c_str());
       }
     }
   }
@@ -304,6 +308,12 @@ void Render::OnReceiveDataBufferCb(const char* data, size_t size,
     return;
   }
 
+  // try to parse as file-transfer chunk first
+  static FileReceiver receiver;
+  if (receiver.OnData(data, size)) {
+    return;
+  }
+
   std::string json_str(data, size);
   RemoteAction remote_action;
 
@@ -485,12 +495,12 @@ void Render::OnConnectionStatusCb(ConnectionStatus status, const char* user_id,
         render->need_to_send_host_info_ = true;
         render->start_screen_capturer_ = true;
         render->start_speaker_capturer_ = true;
-#ifdef CROSSDESK_DEBUG
+        // #ifdef CROSSDESK_DEBUG
         render->start_mouse_controller_ = false;
         render->start_keyboard_capturer_ = false;
-#else
+        // #else
         render->start_mouse_controller_ = true;
-#endif
+        // #endif
         if (std::all_of(render->connection_status_.begin(),
                         render->connection_status_.end(), [](const auto& kv) {
                           return kv.first.find("web") != std::string::npos;

src/gui/toolbars/control_bar.cpp

@@ -1,10 +1,29 @@
+#include <filesystem>
+#include <fstream>
+#include <thread>
+#include <vector>
+
+#include "file_transfer.h"
 #include "layout.h"
 #include "localization.h"
 #include "rd_log.h"
 #include "render.h"
+#include "tinyfiledialogs.h"
 
 namespace crossdesk {
 
+std::string OpenFileDialog(std::string title) {
+  const char* path = tinyfd_openFileDialog(title.c_str(),
+                                           "",       // default path
+                                           0,        // number of filters
+                                           nullptr,  // filters
+                                           nullptr,  // filter description
+                                           0         // no multiple selection
+  );
+
+  return path ? path : "";
+}
+
 int CountDigits(int number) {
   if (number == 0) return 1;
   return (int)std::floor(std::log10(std::abs(number))) + 1;
@@ -41,14 +60,14 @@ int Render::ControlBar(std::shared_ptr<SubStreamWindowProperties>& props) {
   if (props->control_bar_expand_) {
     ImGui::SetCursorPosX(props->is_control_bar_in_left_
                              ? props->control_window_width_ * 1.03f
-                             : props->control_window_width_ * 0.2f);
+                             : props->control_window_width_ * 0.17f);
 
     ImDrawList* draw_list = ImGui::GetWindowDrawList();
     if (!props->is_control_bar_in_left_) {
       draw_list->AddLine(
-          ImVec2(ImGui::GetCursorScreenPos().x - button_height * 0.56f,
+          ImVec2(ImGui::GetCursorScreenPos().x - button_height * 0.5f,
                  ImGui::GetCursorScreenPos().y + button_height * 0.2f),
-          ImVec2(ImGui::GetCursorScreenPos().x - button_height * 0.56f,
+          ImVec2(ImGui::GetCursorScreenPos().x - button_height * 0.5f,
                  ImGui::GetCursorScreenPos().y + button_height * 0.8f),
           IM_COL32(178, 178, 178, 255), 2.0f);
     }
@@ -73,8 +92,8 @@ int Render::ControlBar(std::shared_ptr<SubStreamWindowProperties>& props) {
           remote_action.d = i;
           if (props->connection_status_ == ConnectionStatus::Connected) {
             std::string msg = remote_action.to_json();
-            SendDataFrame(props->peer_, msg.c_str(), msg.size(),
-                          props->data_label_.c_str());
+            SendReliableDataFrame(props->peer_, msg.c_str(), msg.size(),
+                                  props->data_label_.c_str());
           }
         }
         props->display_selectable_hovered_ = ImGui::IsWindowHovered();
@@ -154,8 +173,8 @@ int Render::ControlBar(std::shared_ptr<SubStreamWindowProperties>& props) {
         remote_action.type = ControlType::audio_capture;
         remote_action.a = props->audio_capture_button_pressed_;
         std::string msg = remote_action.to_json();
-        SendDataFrame(props->peer_, msg.c_str(), msg.size(),
-                      props->data_label_.c_str());
+        SendReliableDataFrame(props->peer_, msg.c_str(), msg.size(),
+                              props->data_label_.c_str());
       }
     }
 
@@ -175,6 +194,39 @@ int Render::ControlBar(std::shared_ptr<SubStreamWindowProperties>& props) {
           line_thickness);
     }
 
+    ImGui::SameLine();
+    std::string open_folder = ICON_FA_FOLDER_OPEN;
+    if (ImGui::Button(open_folder.c_str(),
+                      ImVec2(button_width, button_height))) {
+      std::string title =
+          localization::select_file[localization_language_index_];
+      std::string path = OpenFileDialog(title);
+      if (!path.empty()) {
+        LOG_INFO("Selected file: {}", path.c_str());
+
+        // Send selected file over file data channel in a background thread.
+        auto peer = props->peer_;
+        std::filesystem::path file_path = std::filesystem::path(path);
+        std::string file_label = file_label_;
+
+        std::thread([peer, file_path, file_label]() {
+          FileSender sender;
+          int ret = sender.SendFile(
+              file_path, file_path.filename().string(),
+              [peer, file_label](const char* buf, size_t sz) -> int {
+                return SendReliableDataFrame(peer, buf, sz, file_label.c_str());
+              });
+
+          if (ret != 0) {
+            LOG_ERROR("FileSender::SendFile failed for [{}], ret={}",
+                      file_path.string().c_str(), ret);
+          } else {
+            LOG_INFO("File send finished: {}", file_path.string().c_str());
+          }
+        }).detach();
+      }
+    }
+
     ImGui::SameLine();
     // net traffic stats button
     bool button_color_style_pushed = false;
@@ -238,9 +290,9 @@ int Render::ControlBar(std::shared_ptr<SubStreamWindowProperties>& props) {
 
     if (props->is_control_bar_in_left_) {
       draw_list->AddLine(
-          ImVec2(ImGui::GetCursorScreenPos().x + button_height * 0.2f,
+          ImVec2(ImGui::GetCursorScreenPos().x + button_height * 0.13f,
                  ImGui::GetCursorScreenPos().y + button_height * 0.2f),
-          ImVec2(ImGui::GetCursorScreenPos().x + button_height * 0.2f,
+          ImVec2(ImGui::GetCursorScreenPos().x + button_height * 0.13f,
                  ImGui::GetCursorScreenPos().y + button_height * 0.8f),
           IM_COL32(178, 178, 178, 255), 2.0f);
     }
@@ -250,7 +302,7 @@ int Render::ControlBar(std::shared_ptr<SubStreamWindowProperties>& props) {
 
   float expand_button_pos_x =
       props->control_bar_expand_ ? (props->is_control_bar_in_left_
-                                        ? props->control_window_width_ * 1.91f
+                                        ? props->control_window_width_ * 1.917f
                                         : props->control_window_width_ * 0.03f)
                                  : (props->is_control_bar_in_left_
                                         ? props->control_window_width_ * 1.02f

src/gui/windows/server_settings_window.cpp

@@ -230,6 +230,7 @@ int Render::SelfHostedServerWindow() {
 
       //   ShowSimpleFileBrowser();
       // }
+
       {
         ImGui::AlignTextToFramePadding();
         if (ImGui::Button(localization::reset_cert_fingerprint

src/tools/file_transfer.cpp

@@ -0,0 +1,286 @@
+#include "file_transfer.h"
+
+#include <atomic>
+#include <chrono>
+
+#include "rd_log.h"
+
+namespace crossdesk {
+
+namespace {
+std::atomic<uint32_t> g_next_file_id{1};
+constexpr uint32_t kFileChunkMagic = 0x4A4E544D;  // 'JNTM'
+}  // namespace
+
+uint32_t FileSender::NextFileId() { return g_next_file_id.fetch_add(1); }
+
+int FileSender::SendFile(const std::filesystem::path& path,
+                         const std::string& label, const SendFunc& send,
+                         std::size_t chunk_size) {
+  if (!send) {
+    LOG_ERROR("FileSender::SendFile: send function is empty");
+    return -1;
+  }
+
+  std::error_code ec;
+  if (!std::filesystem::exists(path, ec) ||
+      !std::filesystem::is_regular_file(path, ec)) {
+    LOG_ERROR("FileSender::SendFile: file [{}] not found or not regular",
+              path.string().c_str());
+    return -1;
+  }
+
+  uint64_t total_size = std::filesystem::file_size(path, ec);
+  if (ec) {
+    LOG_ERROR("FileSender::SendFile: failed to get size of [{}]: {}",
+              path.string().c_str(), ec.message().c_str());
+    return -1;
+  }
+
+  std::ifstream ifs(path, std::ios::binary);
+  if (!ifs.is_open()) {
+    LOG_ERROR("FileSender::SendFile: failed to open [{}]",
+              path.string().c_str());
+    return -1;
+  }
+
+  const uint32_t file_id = NextFileId();
+  uint64_t offset = 0;
+  bool is_first = true;
+  std::string file_name = label.empty() ? path.filename().string() : label;
+
+  std::vector<char> buffer;
+  buffer.resize(chunk_size);
+
+  while (ifs && offset < total_size) {
+    uint64_t remaining = total_size - offset;
+    uint32_t to_read =
+        static_cast<uint32_t>(std::min<uint64_t>(remaining, chunk_size));
+
+    ifs.read(buffer.data(), static_cast<std::streamsize>(to_read));
+    std::streamsize bytes_read = ifs.gcount();
+    if (bytes_read <= 0) {
+      break;
+    }
+
+    bool is_last = (offset + static_cast<uint64_t>(bytes_read) >= total_size);
+    const std::string* name_ptr = is_first ? &file_name : nullptr;
+
+    std::vector<char> chunk = BuildChunk(
+        file_id, offset, total_size, buffer.data(),
+        static_cast<uint32_t>(bytes_read), name_ptr, is_first, is_last);
+
+    int ret = send(chunk.data(), chunk.size());
+    if (ret != 0) {
+      LOG_ERROR("FileSender::SendFile: send failed for [{}], ret={}",
+                path.string().c_str(), ret);
+      return ret;
+    }
+
+    offset += static_cast<uint64_t>(bytes_read);
+    is_first = false;
+  }
+
+  return 0;
+}
+
+std::vector<char> FileSender::BuildChunk(uint32_t file_id, uint64_t offset,
+                                         uint64_t total_size, const char* data,
+                                         uint32_t data_size,
+                                         const std::string* file_name,
+                                         bool is_first, bool is_last) {
+  FileChunkHeader header{};
+  header.magic = kFileChunkMagic;
+  header.file_id = file_id;
+  header.offset = offset;
+  header.total_size = total_size;
+  header.chunk_size = data_size;
+  header.name_len =
+      (file_name && is_first) ? static_cast<uint16_t>(file_name->size()) : 0;
+  header.flags = 0;
+  if (is_first) header.flags |= 0x01;
+  if (is_last) header.flags |= 0x02;
+
+  std::size_t total_size_bytes =
+      sizeof(FileChunkHeader) + header.name_len + header.chunk_size;
+
+  std::vector<char> buffer;
+  buffer.resize(total_size_bytes);
+
+  std::size_t offset_bytes = 0;
+  memcpy(buffer.data() + offset_bytes, &header, sizeof(FileChunkHeader));
+  offset_bytes += sizeof(FileChunkHeader);
+
+  if (header.name_len > 0 && file_name) {
+    memcpy(buffer.data() + offset_bytes, file_name->data(), header.name_len);
+    offset_bytes += header.name_len;
+  }
+
+  if (header.chunk_size > 0 && data) {
+    memcpy(buffer.data() + offset_bytes, data, header.chunk_size);
+  }
+
+  return buffer;
+}
+
+// ---------- FileReceiver ----------
+
+FileReceiver::FileReceiver() : output_dir_(GetDefaultDesktopPath()) {}
+
+FileReceiver::FileReceiver(const std::filesystem::path& output_dir)
+    : output_dir_(output_dir) {
+  std::error_code ec;
+  if (!output_dir_.empty()) {
+    std::filesystem::create_directories(output_dir_, ec);
+    if (ec) {
+      LOG_ERROR("FileReceiver: failed to create output dir [{}]: {}",
+                output_dir_.string().c_str(), ec.message().c_str());
+    }
+  }
+}
+
+std::filesystem::path FileReceiver::GetDefaultDesktopPath() {
+#ifdef _WIN32
+  const char* home_env = std::getenv("USERPROFILE");
+#else
+  const char* home_env = std::getenv("HOME");
+#endif
+  if (!home_env) {
+    return std::filesystem::path{};
+  }
+
+  std::filesystem::path desktop_path =
+      std::filesystem::path(home_env) / "Desktop";
+
+  std::error_code ec;
+  std::filesystem::create_directories(desktop_path, ec);
+  if (ec) {
+    LOG_ERROR("FileReceiver: failed to create desktop directory [{}]: {}",
+              desktop_path.string().c_str(), ec.message().c_str());
+  }
+
+  return desktop_path;
+}
+
+bool FileReceiver::OnData(const char* data, size_t size) {
+  if (!data || size < sizeof(FileChunkHeader)) {
+    LOG_ERROR("FileReceiver::OnData: invalid buffer");
+    return false;
+  }
+
+  FileChunkHeader header{};
+  memcpy(&header, data, sizeof(FileChunkHeader));
+
+  if (header.magic != kFileChunkMagic) {
+    return false;
+  }
+
+  std::size_t header_and_name =
+      sizeof(FileChunkHeader) + static_cast<std::size_t>(header.name_len);
+  if (size < header_and_name ||
+      size < header_and_name + static_cast<std::size_t>(header.chunk_size)) {
+    LOG_ERROR("FileReceiver::OnData: buffer too small for header + payload");
+    return false;
+  }
+
+  const char* name_ptr = data + sizeof(FileChunkHeader);
+  std::string file_name;
+  const std::string* file_name_ptr = nullptr;
+  if (header.name_len > 0) {
+    file_name.assign(name_ptr,
+                     name_ptr + static_cast<std::size_t>(header.name_len));
+    file_name_ptr = &file_name;
+  }
+
+  const char* payload = data + header_and_name;
+  std::size_t payload_size =
+      static_cast<std::size_t>(header.chunk_size);  // may be 0
+
+  return HandleChunk(header, payload, payload_size, file_name_ptr);
+}
+
+bool FileReceiver::HandleChunk(const FileChunkHeader& header,
+                               const char* payload, size_t payload_size,
+                               const std::string* file_name) {
+  auto it = contexts_.find(header.file_id);
+  if (it == contexts_.end()) {
+    // new file context must start with first chunk.
+    if ((header.flags & 0x01) == 0) {
+      LOG_ERROR("FileReceiver: received non-first chunk for unknown file_id={}",
+                header.file_id);
+      return false;
+    }
+
+    FileContext ctx;
+    ctx.total_size = header.total_size;
+
+    std::string filename;
+    if (file_name && !file_name->empty()) {
+      filename = *file_name;
+    } else {
+      filename = "received_" + std::to_string(header.file_id);
+    }
+
+    ctx.file_name = filename;
+
+    std::filesystem::path save_path = output_dir_.empty()
+                                          ? std::filesystem::path(filename)
+                                          : output_dir_ / filename;
+
+    // if file exists, append timestamp.
+    std::error_code ec;
+    if (std::filesystem::exists(save_path, ec)) {
+      auto now = std::chrono::system_clock::now();
+      auto ts = std::chrono::duration_cast<std::chrono::milliseconds>(
+                    now.time_since_epoch())
+                    .count();
+      save_path = save_path.parent_path() /
+                  (save_path.stem().string() + "_" + std::to_string(ts) +
+                   save_path.extension().string());
+    }
+
+    ctx.ofs.open(save_path, std::ios::binary | std::ios::trunc);
+    if (!ctx.ofs.is_open()) {
+      LOG_ERROR("FileReceiver: failed to open [{}] for writing",
+                save_path.string().c_str());
+      return false;
+    }
+
+    contexts_.emplace(header.file_id, std::move(ctx));
+    it = contexts_.find(header.file_id);
+  }
+
+  FileContext& ctx = it->second;
+
+  if (payload_size > 0 && payload) {
+    ctx.ofs.seekp(static_cast<std::streamoff>(header.offset), std::ios::beg);
+    ctx.ofs.write(payload, static_cast<std::streamsize>(payload_size));
+    if (!ctx.ofs.good()) {
+      LOG_ERROR("FileReceiver: write failed for file_id={}", header.file_id);
+      return false;
+    }
+    ctx.received += static_cast<uint64_t>(payload_size);
+  }
+
+  bool is_last = (header.flags & 0x02) != 0;
+  if (is_last || ctx.received >= ctx.total_size) {
+    ctx.ofs.close();
+
+    std::filesystem::path saved_path =
+        output_dir_.empty() ? std::filesystem::path(ctx.file_name)
+                            : output_dir_ / ctx.file_name;
+
+    LOG_INFO("FileReceiver: file received complete, file_id={}, size={}",
+             header.file_id, ctx.received);
+
+    if (on_file_complete_) {
+      on_file_complete_(saved_path);
+    }
+
+    contexts_.erase(header.file_id);
+  }
+
+  return true;
+}
+
+}  // namespace crossdesk

src/tools/file_transfer.h

@@ -0,0 +1,99 @@
+/*
+ * @Author: DI JUNKUN
+ * @Date: 2025-12-18
+ * Copyright (c) 2025 by DI JUNKUN, All Rights Reserved.
+ */
+
+#ifndef _FILE_TRANSFER_H_
+#define _FILE_TRANSFER_H_
+
+#include <cstdint>
+#include <filesystem>
+#include <fstream>
+#include <functional>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+namespace crossdesk {
+
+#pragma pack(push, 1)
+struct FileChunkHeader {
+  uint32_t magic;       // magic to identify file-transfer chunks
+  uint32_t file_id;     // unique id per file transfer
+  uint64_t offset;      // offset in file
+  uint64_t total_size;  // total file size
+  uint32_t chunk_size;  // payload size in this chunk
+  uint16_t name_len;    // filename length (bytes), only set on first chunk
+  uint8_t flags;        // bit0: is_first, bit1: is_last, others reserved
+};
+#pragma pack(pop)
+
+class FileSender {
+ public:
+  using SendFunc = std::function<int(const char* data, size_t size)>;
+
+ public:
+  FileSender() = default;
+
+  // generate a new file id
+  static uint32_t NextFileId();
+
+  // synchronously send a file using the provided send function.
+  // `path`  : full path to the local file.
+  // `label` : logical filename to send (usually path.filename()).
+  // `send`  : callback that pushes one encoded chunk into the data channel.
+  // Return 0 on success, <0 on error.
+  int SendFile(const std::filesystem::path& path, const std::string& label,
+               const SendFunc& send, std::size_t chunk_size = 64 * 1024);
+
+  // build a single encoded chunk buffer according to FileChunkHeader protocol.
+  static std::vector<char> BuildChunk(uint32_t file_id, uint64_t offset,
+                                      uint64_t total_size, const char* data,
+                                      uint32_t data_size,
+                                      const std::string* file_name,
+                                      bool is_first, bool is_last);
+};
+
+class FileReceiver {
+ public:
+  struct FileContext {
+    std::string file_name;
+    uint64_t total_size = 0;
+    uint64_t received = 0;
+    std::ofstream ofs;
+  };
+
+  using OnFileComplete =
+      std::function<void(const std::filesystem::path& saved_path)>;
+
+ public:
+  // save to default desktop directory.
+  FileReceiver();
+
+  // save to a specified directory.
+  explicit FileReceiver(const std::filesystem::path& output_dir);
+
+  // process one received data buffer (one chunk).
+  // return true if parsed and processed successfully, false otherwise.
+  bool OnData(const char* data, size_t size);
+
+  void SetOnFileComplete(OnFileComplete cb) { on_file_complete_ = cb; }
+
+  const std::filesystem::path& OutputDir() const { return output_dir_; }
+
+ private:
+  static std::filesystem::path GetDefaultDesktopPath();
+
+  bool HandleChunk(const FileChunkHeader& header, const char* payload,
+                   size_t payload_size, const std::string* file_name);
+
+ private:
+  std::filesystem::path output_dir_;
+  std::unordered_map<uint32_t, FileContext> contexts_;
+  OnFileComplete on_file_complete_ = nullptr;
+};
+
+}  // namespace crossdesk
+
+#endif

xmake.lua

@@ -33,6 +33,7 @@ add_requires("imgui v1.92.1-docking", {configs = {sdl3 = true, sdl3_renderer = t
 add_requires("openssl3 3.3.2", {system = false})
 add_requires("nlohmann_json 3.11.3")
 add_requires("cpp-httplib v0.26.0", {configs = {ssl = true}})
+add_requires("tinyfiledialogs 3.15.1")
 
 if is_os("windows") then
     add_requires("libyuv", "miniaudio 0.11.21")
@@ -168,13 +169,19 @@ target("version_checker")
     add_files("src/version_checker/*.cpp")
     add_includedirs("src/version_checker", {public = true})
 
+target("tools")
+    set_kind("object")
+    add_deps("rd_log")
+    add_files("src/tools/*.cpp")
+    add_includedirs("src/tools", {public = true})
+
 target("gui")
     set_kind("object")
-    add_packages("libyuv")
+    add_packages("libyuv", "tinyfiledialogs")
     add_defines("CROSSDESK_VERSION=\"" .. (get_config("CROSSDESK_VERSION") or "Unknown") .. "\"")
     add_deps("rd_log", "common", "assets", "config_center", "minirtc", 
         "path_manager", "screen_capturer", "speaker_capturer", 
-        "device_controller", "thumbnail", "version_checker")
+        "device_controller", "thumbnail", "version_checker", "tools")
     add_files("src/gui/*.cpp", "src/gui/panels/*.cpp", "src/gui/toolbars/*.cpp",
         "src/gui/windows/*.cpp")
     add_includedirs("src/gui", "src/gui/panels", "src/gui/toolbars",