build file selector list in a thread

src/chat_gui/file_selector.cpp

@@ -18,6 +18,12 @@ FileSelector::FileSelector(void) {
 	reset();
 }
 
+FileSelector::~FileSelector(void) {
+	if (_future_cache.valid()) {
+		_future_cache.get();
+	}
+}
+
 void FileSelector::requestFile(
 	std::function<bool(std::filesystem::path& path)>&& is_valid,
 	std::function<void(const std::filesystem::path& path)>&& on_choose,
@@ -101,9 +107,32 @@ void FileSelector::render(void) {
 			static const ImU32 dir_bg0_color = ImGui::GetColorU32(ImVec4(0.6, 0.6, 0.1, 0.15));
 			static const ImU32 dir_bg1_color = ImGui::GetColorU32(ImVec4(0.7, 0.7, 0.2, 0.15));
 
-			std::vector<std::filesystem::directory_entry> dirs;
+			bool start_new_collection_task {false};
-			std::vector<std::filesystem::directory_entry> files;
+			if (_future_cache.valid()) {
-			for (auto const& dir_entry : std::filesystem::directory_iterator(current_path)) {
+				if (_future_cache.wait_for(std::chrono::milliseconds(0)) == std::future_status::ready) {
+					// data is ready
+					_current_cache = _future_cache.get();
+
+					// also queue a new one
+					start_new_collection_task = true;
+				}
+			} else {
+				start_new_collection_task = true;
+			}
+
+			// check if cache still current
+			if (_current_cache.has_value() && _current_cache.value().file_path != current_path) {
+				// and drop it if not
+				_current_cache.reset();
+			}
+
+			if (start_new_collection_task) {
+				_future_cache = std::async(std::launch::async, [path = current_path, sorts_specs = ImGui::TableGetSortSpecs()](void) -> CachedData {
+					CachedData cd;
+					cd.file_path = path;
+					auto& dirs = cd.dirs;
+					auto& files = cd.files;
+					for (auto const& dir_entry : std::filesystem::directory_iterator(path)) {
 						if (dir_entry.is_directory()) {
 							dirs.push_back(dir_entry);
 						} else if (dir_entry.is_regular_file()) {
@@ -113,8 +142,7 @@ void FileSelector::render(void) {
 
 					try {
 						// do sorting here
-				// TODO: cache the result (lol)
+						if (sorts_specs != nullptr && sorts_specs->SpecsCount >= 1) {
-				if (ImGuiTableSortSpecs* sorts_specs = ImGui::TableGetSortSpecs(); sorts_specs != nullptr && sorts_specs->SpecsCount >= 1) {
 							switch (static_cast<SortID>(sorts_specs->Specs->ColumnUserID)) {
 								break; case SortID::name:
 									if (sorts_specs->Specs->SortDirection == ImGuiSortDirection_Descending) {
@@ -167,7 +195,20 @@ void FileSelector::render(void) {
 						// we likely saw a file disapear
 					}
 
-			for (auto const& dir_entry : dirs) {
+					return cd;
+				});
+			}
+
+			if (_current_cache.has_value()) {
+				const auto& dirs = _current_cache.value().dirs;
+				const auto& files = _current_cache.value().files;
+
+				// dirs
+				ImGuiListClipper dirs_clipper;
+				dirs_clipper.Begin(dirs.size());
+				while (dirs_clipper.Step()) {
+					for (int row = dirs_clipper.DisplayStart; row < dirs_clipper.DisplayEnd; row++) {
+						const auto& dir_entry = dirs.at(row);
 						if (ImGui::TableNextColumn()) {
 							if (tmp_id & 0x01) {
 								ImGui::TableSetBgColor(ImGuiTableBgTarget_RowBg0, dir_bg0_color);
@@ -201,33 +242,34 @@ void FileSelector::render(void) {
 							ImGui::TextDisabled("%2d.%2d.%2d - %2d:%2d", ltime->tm_mday, ltime->tm_mon + 1, ltime->tm_year + 1900, ltime->tm_hour, ltime->tm_min);
 						}
 					}
+				}
 
 				// files
 				ImGuiListClipper files_clipper;
 				files_clipper.Begin(files.size());
 				while (files_clipper.Step()) {
 					for (int row = files_clipper.DisplayStart; row < files_clipper.DisplayEnd; row++) {
-					const auto& dir_entry = files.at(row);
+						const auto& file_entry = files.at(row);
 						if (ImGui::TableNextColumn()) {
 							ImGui::PushID(tmp_id++);
 							if (ImGui::Selectable("F", false, ImGuiSelectableFlags_SpanAllColumns | ImGuiSelectableFlags_AllowItemOverlap)) {
-							_current_file_path = dir_entry.path();
+								_current_file_path = file_entry.path();
 							}
 							ImGui::PopID();
 						}
 
 						if (ImGui::TableNextColumn()) {
-						ImGui::TextUnformatted(dir_entry.path().filename().generic_u8string().c_str());
+							ImGui::TextUnformatted(file_entry.path().filename().generic_u8string().c_str());
 						}
 
 						if (ImGui::TableNextColumn()) {
-						ImGui::TextDisabled("%s", std::to_string(dir_entry.file_size()).c_str());
+							ImGui::TextDisabled("%s", std::to_string(file_entry.file_size()).c_str());
 						}
 
 						if (ImGui::TableNextColumn()) {
 							const auto file_time_converted = std::chrono::time_point_cast<std::chrono::system_clock::duration>(
-							dir_entry.last_write_time()
+								file_entry.last_write_time()
-							- decltype(dir_entry.last_write_time())::clock::now()
+								- decltype(file_entry.last_write_time())::clock::now()
 								+ std::chrono::system_clock::now()
 							);
 							const auto ctime = std::chrono::system_clock::to_time_t(file_time_converted);
@@ -237,6 +279,15 @@ void FileSelector::render(void) {
 						}
 					}
 				}
+			} else {
+				// render loading placeholder
+				if (ImGui::TableNextColumn()) {
+					ImGui::TextUnformatted("-");
+				}
+				if (ImGui::TableNextColumn()) {
+					ImGui::TextUnformatted("... loading ...");
+				}
+			}
 
 			ImGui::EndTable();
 		}

src/chat_gui/file_selector.hpp

@@ -2,10 +2,20 @@
 
 #include <filesystem>
 #include <functional>
+#include <optional>
+#include <future>
 
 struct FileSelector {
 	std::filesystem::path _current_file_path = std::filesystem::canonical(".") / ""; // add /
 
+	struct CachedData {
+		std::filesystem::path file_path; // can be used to check against current
+		std::vector<std::filesystem::directory_entry> dirs;
+		std::vector<std::filesystem::directory_entry> files;
+	};
+	std::optional<CachedData> _current_cache;
+	std::future<CachedData> _future_cache;
+
 	bool _open_popup {false};
 
 	std::function<bool(std::filesystem::path& path)> _is_valid = [](auto){ return true; };
@@ -16,6 +26,7 @@ struct FileSelector {
 
 	public:
 		FileSelector(void);
+		~FileSelector(void);
 
 		// TODO: supply hints
 		// HACK: until we supply hints, is_valid can modify

src/chat_gui/image_viewer_popup.cpp

@@ -25,7 +25,9 @@ void ImageViewerPopup::render(float) {
 		ImGui::OpenPopup("Image##ImageViewerPopup");
 	}
 
-	if (!ImGui::BeginPopup("Image##ImageViewerPopup", ImGuiWindowFlags_NoDecoration | ImGuiWindowFlags_AlwaysAutoResize)) {
+	// TODO: remplace with modal(?), pop up i limited to viewport in size
+	// or replace with fixed window where the image can be moved
+	if (!ImGui::BeginPopup("Image##ImageViewerPopup", ImGuiWindowFlags_NoDecoration)) {
 		_m = {}; // meh, event on close would be nice, but the reset is cheap
 		_scale = 1.f;
 		return;