Merge branch 'folding' into feature

src/ass_file.cpp

@@ -246,6 +246,39 @@ uint32_t AssFile::AddExtradata(std::string const& key, std::string const& value)
 	return next_extradata_id++; // return old value, then post-increment
 }
 
+void AssFile::SetExtradataValue(AssDialogue& line, std::string const& key, std::string const& value, bool del) {
+	std::vector<uint32_t> id_list = line.ExtradataIds;
+	std::vector<bool> to_erase(id_list.size());
+	bool dirty = false;
+	bool found = false;
+
+	std::vector<ExtradataEntry> entry_list = GetExtradata(id_list);
+	for (int i = entry_list.size() - 1; i >= 0; i--) {
+		if (entry_list[i].key == key) {
+			if (!del && entry_list[i].value == value) {
+				found = true;
+			} else {
+				to_erase[i] = true;
+				dirty = true;
+			}
+		}
+	}
+
+	// The key is already set, we don't need to change anything
+	if (found && !dirty)
+		return;
+
+	for (int i = id_list.size() - 1; i >= 0; i--) {
+		if (to_erase[i])
+			id_list.erase(id_list.begin() + i, id_list.begin() + i + 1);
+	}
+
+	if (!del && !found)
+		id_list.push_back(AddExtradata(key, value));
+
+	line.ExtradataIds = id_list;
+}
+
 namespace {
 struct extradata_id_cmp {
 	bool operator()(ExtradataEntry const& e, uint32_t id) {

src/ass_file.h

@@ -85,7 +85,6 @@ struct ProjectProperties {
 	int active_row = 0;
 	int ar_mode = 0;
 	int video_position = 0;
-	std::vector<LineFold> folds;
 };
 
 class AssFile {
@@ -93,6 +92,8 @@ class AssFile {
 	agi::signal::Signal<int, const AssDialogue*> AnnounceCommit;
 	agi::signal::Signal<int, const AssDialogue*> AnnouncePreCommit;
 	agi::signal::Signal<AssFileCommit> PushState;
+
+	void SetExtradataValue(AssDialogue& line, std::string const& key, std::string const& value, bool del);
 public:
 	/// The lines in the file
 	std::vector<AssInfo> Info;
@@ -144,6 +145,10 @@ public:
 	uint32_t AddExtradata(std::string const& key, std::string const& value);
 	/// Fetch all extradata entries from a list of IDs
 	std::vector<ExtradataEntry> GetExtradata(std::vector<uint32_t> const& id_list) const;
+	/// Set an extradata kex:value pair for a dialogue line, clearing previous values for this key if necessary
+	void SetExtradataValue(AssDialogue& line, std::string const& key, std::string const& value) { SetExtradataValue(line, key, value, false); };
+	/// Delete any extradata values for the given key
+	void DeleteExtradataValue(AssDialogue& line, std::string const& key) { SetExtradataValue(line, key, "", true); };
 	/// Remove unreferenced extradata entries
 	void CleanExtradata();
 
@@ -178,7 +183,7 @@ public:
 		/// Extradata entries were added/modified/removed
 		COMMIT_EXTRADATA   = 0x100,
 		/// Folds were added or removed
-		COMMIT_FOLD        = 0x200,
+		COMMIT_FOLD        = COMMIT_EXTRADATA,
 	};
 
 	DEFINE_SIGNAL_ADDERS(AnnouncePreCommit, AddPreCommitListener)

src/ass_parser.cpp

@@ -24,7 +24,6 @@
 
 #include <libaegisub/ass/uuencode.h>
 #include <libaegisub/make_unique.h>
-#include <libaegisub/split.h>
 #include <libaegisub/util.h>
 
 #include <algorithm>
@@ -40,8 +39,7 @@ class AssParser::HeaderToProperty {
 	using field = boost::variant<
 		std::string ProjectProperties::*,
 		int ProjectProperties::*,
-		double ProjectProperties::*,
+		double ProjectProperties::*
-		std::vector<LineFold> ProjectProperties::*
 	>;
 	std::unordered_map<std::string, field> fields;
 
@@ -60,7 +58,6 @@ public:
 		{"Video Zoom Percent", &ProjectProperties::video_zoom},
 		{"Scroll Position", &ProjectProperties::scroll_position},
 		{"Active Line", &ProjectProperties::active_row},
-		{"Line Folds", &ProjectProperties::folds},
 		{"Video Position", &ProjectProperties::video_position},
 		{"Video AR Mode", &ProjectProperties::ar_mode},
 		{"Video AR Value", &ProjectProperties::ar_value},
@@ -83,29 +80,6 @@ public:
 				void operator()(std::string ProjectProperties::*f) const { obj.*f = value; }
 				void operator()(int ProjectProperties::*f)         const { try_parse(value, &(obj.*f)); }
 				void operator()(double ProjectProperties::*f)      const { try_parse(value, &(obj.*f)); }
-				void operator()(std::vector<LineFold> ProjectProperties::*f) const {
-					std::vector<LineFold> folds;
-
-					for (auto foldstr : agi::Split(value, ',')) {
-						LineFold fold;
-						std::vector<std::string> parsed;
-						agi::Split(parsed, foldstr, ':');
-						if (parsed.size() != 3) {
-							continue;
-						}
-
-						int collapsed;
-						try_parse(parsed[0], &fold.start);
-						try_parse(parsed[1], &fold.end);
-						try_parse(parsed[2], &collapsed);
-						fold.collapsed = !!collapsed;
-
-						if (fold.start >= 0 && fold.end > fold.start) {
-							folds.push_back(fold);
-						}
-					}
-					obj.*f = folds;
-				}
 			} visitor {target->Properties, value};
 			boost::apply_visitor(visitor, it->second);
 			return true;

src/auto4_lua_assfile.cpp

@@ -40,7 +40,6 @@
 #include "ass_karaoke.h"
 #include "ass_style.h"
 #include "compat.h"
-#include "fold_controller.h"
 
 #include <libaegisub/exception.h>
 #include <libaegisub/log.h>
@@ -101,22 +100,6 @@ namespace {
 		return ret;
 	}
 
-	template<typename T>
-	bool get_userdata_field(lua_State *L, const char *name, const char *line_class, T *target, bool required)
-	{
-		lua_getfield(L, -1, name);
-		if (!lua_isuserdata(L, -1)) {
-			if (!required) {
-				lua_pop(L, 1);
-				return false;
-			}
-			throw bad_field("userdata", name, line_class);
-		}
-		*target = *static_cast<T *>(lua_touserdata(L, -1));
-		lua_pop(L, 1);
-		return true;
-	}
-
 	using namespace Automation4;
 	template<int (LuaAssFile::*closure)(lua_State *)>
 	int closure_wrapper(lua_State *L)
@@ -198,10 +181,6 @@ namespace Automation4 {
 
 			set_field(L, "text", std::string(dia->Text));
 
-			// preserve the folds
-			*static_cast<FoldInfo*>(lua_newuserdata(L, sizeof(FoldInfo))) = dia->Fold;
-			lua_setfield(L, -2, "_foldinfo");
-
 			// create extradata table
 			lua_newtable(L);
 			for (auto const& ed : ass->GetExtradata(dia->ExtradataIds)) {
@@ -322,9 +301,6 @@ namespace Automation4 {
 			dia->Margin[2] = get_int_field(L, "margin_t", "dialogue");
 			dia->Effect = get_string_field(L, "effect", "dialogue");
 			dia->Text = get_string_field(L, "text", "dialogue");
-			if (!get_userdata_field(L, "_foldinfo", "dialogue", &dia->Fold, false)) {
-				dia->Fold = FoldInfo();
-			}
 
 			std::vector<uint32_t> new_ids;
 

src/base_grid.cpp

@@ -502,7 +502,7 @@ void BaseGrid::OnMouseEvent(wxMouseEvent &event) {
 		CaptureMouse();
 	}
 
-	if (columns[col]->OnMouseEvent(dlg, context, event)) {
+	if (dlg && columns[col]->OnMouseEvent(dlg, context, event)) {
 		return;
 	}
 

src/fold_controller.cpp

@@ -1,4 +1,4 @@
-// Copyright (c) 2022, arch1t3cht <arch1t3cht@gmail.com>>
+// Copyright (c) 2022, arch1t3cht <arch1t3cht@gmail.com>
 //
 // Permission to use, copy, modify, and distribute this software for any
 // purpose with or without fee is hereby granted, provided that the above
@@ -24,9 +24,10 @@
 #include <algorithm>
 #include <unordered_map>
 
-#include <libaegisub/log.h>
+#include <libaegisub/split.h>
+#include <libaegisub/util.h>
 
-static int next_fold_id = 0;
+const char *folds_key = "_aegi_folddata";
 
 FoldController::FoldController(agi::Context *c)
 : context(c)
@@ -35,12 +36,12 @@ FoldController::FoldController(agi::Context *c)
 
 
 bool FoldController::CanAddFold(AssDialogue& start, AssDialogue& end) {
-	if (start.Fold.exists || end.Fold.exists) {
+	if (start.Fold.valid || end.Fold.valid) {
 		return false;
 	}
 	int folddepth = 0;
 	for (auto it = std::next(context->ass->Events.begin(), start.Row); it->Row < end.Row; it++) {
-		if (it->Fold.exists) {
+		if (it->Fold.valid) {
 			folddepth += it->Fold.side ? -1 : 1;
 		}
 		if (folddepth < 0) {
@@ -51,17 +52,24 @@ bool FoldController::CanAddFold(AssDialogue& start, AssDialogue& end) {
 }
 
 void FoldController::RawAddFold(AssDialogue& start, AssDialogue& end, bool collapsed) {
-	int id = next_fold_id++;
+	int id = ++max_fold_id;
+	context->ass->SetExtradataValue(start, folds_key, agi::format("0;%d;%d", int(collapsed), id));
+	context->ass->SetExtradataValue(end, folds_key, agi::format("1;%d;%d", int(collapsed), id));
+}
 
-	start.Fold.exists = true;
+void FoldController::UpdateLineExtradata(AssDialogue &line) {
-	start.Fold.collapsed = collapsed;
+	if (line.Fold.extraExists)
-	start.Fold.id = id;
+		context->ass->SetExtradataValue(line, folds_key, agi::format("%d;%d;%d", int(line.Fold.side), int(line.Fold.collapsed), int(line.Fold.id)));
-	start.Fold.side = false;
+	else
+		context->ass->DeleteExtradataValue(line, folds_key);
+}
 
-	end.Fold.exists = true;
+void FoldController::InvalidateLineFold(AssDialogue &line) {
-	end.Fold.collapsed = collapsed;
+	line.Fold.valid = false;
-	end.Fold.id = id;
+	if (++line.Fold.invalidCount > 100) {
-	end.Fold.side = true;
+		line.Fold.extraExists = false;
+		UpdateLineExtradata(line);
+	}
 }
 
 void FoldController::AddFold(AssDialogue& start, AssDialogue& end, bool collapsed) {
@@ -73,10 +81,11 @@ void FoldController::AddFold(AssDialogue& start, AssDialogue& end, bool collapse
 
 bool FoldController::DoForAllFolds(bool action(AssDialogue& line)) {
 	for (AssDialogue& line : context->ass->Events) {
-		if (line.Fold.exists) {
+		if (line.Fold.valid) {
-			if (action(line)) {
+			bool result = action(line);
+			UpdateLineExtradata(line);
+			if (result)
 				return true;
-			}
 		}
 	}
 	return false;
@@ -84,34 +93,10 @@ bool FoldController::DoForAllFolds(bool action(AssDialogue& line)) {
 
 void FoldController::FixFoldsPreCommit(int type, const AssDialogue *single_line) {
 	if ((type & (AssFile::COMMIT_FOLD | AssFile::COMMIT_DIAG_ADDREM | AssFile::COMMIT_ORDER)) || type == AssFile::COMMIT_NEW) {
-		if (type == AssFile::COMMIT_NEW && context->subsController->IsUndoStackEmpty()) {
+		UpdateFoldInfo();
-			// This might be the biggest hack in all of this. We want to hook into the FileOpen signal to
-			// read and apply the folds from the project data, but if we do it naively, this will only happen
-			// after the first commit has been pushed to the undo stack. Thus, if a user uses Ctrl+Z after opening
-			// a file, all folds will be cleared.
-			// Instead, we hook into the first commit which is made after loading a file, right after the undo stack was cleared.
-			DoForAllFolds(FoldController::ActionClearFold);
-			MakeFoldsFromFile();
-		}
-		FixFolds();
 	}
 }
 
-void FoldController::MakeFoldsFromFile() {
-	if (context->ass->Properties.folds.empty()) {
-		return;
-	}
-
-	int numlines = context->ass->Events.size();
-	for (LineFold fold : context->ass->Properties.folds) {
-		if (fold.start >= 0 && fold.start < fold.end && fold.end <= numlines) {
-			auto opener = std::next(context->ass->Events.begin(), fold.start);
-			RawAddFold(*opener, *std::next(opener, fold.end - fold.start), fold.collapsed);
-		}
-	}
-}
-
-
 // For each line in lines, applies action() to the opening delimiter of the innermost fold containing this line.
 // Returns true as soon as any action() call returned true.
 //
@@ -119,17 +104,56 @@ void FoldController::MakeFoldsFromFile() {
 // be followed by a commit.
 bool FoldController::DoForFoldsAt(std::vector<AssDialogue *> const& lines, bool action(AssDialogue& line)) {
 	for (AssDialogue *line : lines) {
-		if (line->Fold.parent != nullptr && !(line->Fold.exists && !line->Fold.side)) {
+		if (line->Fold.parent != nullptr && !(line->Fold.valid && !line->Fold.side)) {
 			line = line->Fold.parent;
 		}
-		if (!line->Fold.visited && action(*line)) {
+		if (!line->Fold.visited) {
-			return true;
+			bool result = action(*line);
+			UpdateLineExtradata(*line);
+			if (result)
+				return true;
 		}
 		line->Fold.visited = true;
 	}
 	return false;
 }
 
+void FoldController::UpdateFoldInfo() {
+	ReadFromExtradata();
+	FixFolds();
+	LinkFolds();
+}
+
+void FoldController::ReadFromExtradata() {
+	max_fold_id = 0;
+
+	for (auto line = context->ass->Events.begin(); line != context->ass->Events.end(); line++) {
+		line->Fold.extraExists = false;
+
+		for (auto const& extra : context->ass->GetExtradata(line->ExtradataIds)) {
+			if (extra.key == folds_key) {
+				std::vector<std::string> fields;
+				agi::Split(fields, extra.value, ';');
+				if (fields.size() != 3)
+					break;
+
+				int side;
+				int collapsed;
+				if (!agi::util::try_parse(fields[0], &side)) break;
+				if (!agi::util::try_parse(fields[1], &collapsed)) break;
+				if (!agi::util::try_parse(fields[2], &line->Fold.id)) break;
+				line->Fold.side = side;
+				line->Fold.collapsed = collapsed;
+
+				line->Fold.extraExists = true;
+				max_fold_id = std::max(max_fold_id, line->Fold.id);
+				break;
+			}
+		}
+		line->Fold.valid = line->Fold.extraExists;
+	}
+}
+
 void FoldController::FixFolds() {
 	// Stack of which folds we've desended into so far
 	std::vector<AssDialogue *> foldStack;
@@ -142,15 +166,28 @@ void FoldController::FixFolds() {
 	// fold data with this ID is skipped and deleted.
 	std::unordered_map<int, bool> completedFolds;
 
+	// Map iteratively applied to all id's.
+	// Once some fold has been completely found, subsequent markers found with the same id will be mapped to this new id.
+	std::unordered_map<int, int> idRemap;
+
 	for (auto line = context->ass->Events.begin(); line != context->ass->Events.end(); line++) {
-		if (line->Fold.exists) {
+		if (line->Fold.extraExists) {
-			if (completedFolds.count(line->Fold.id)) { 	// Duplicate entry
+			bool needs_update = false;
-				line->Fold.exists = false;
+
-				continue;
+			while (idRemap.count(line->Fold.id)) {
+				line->Fold.id = idRemap[line->Fold.id];
+				needs_update = true;
 			}
+
+			if (completedFolds.count(line->Fold.id)) { 	// Duplicate entry - try to start a new one
+				idRemap[line->Fold.id] = ++max_fold_id;
+				line->Fold.id = idRemap[line->Fold.id];
+				needs_update = true;
+			}
+
 			if (!line->Fold.side) {
 				if (foldHeads.count(line->Fold.id)) { 	// Duplicate entry
-					line->Fold.exists = false;
+					InvalidateLineFold(*line);
 				} else {
 					foldHeads[line->Fold.id] = &*line;
 					foldStack.push_back(&*line);
@@ -160,7 +197,7 @@ void FoldController::FixFolds() {
 					// Deactivate it. Because we can, also push it to completedFolds:
 					// If its counterpart appears further below, we can delete it right away.
 					completedFolds[line->Fold.id] = true;
-					line->Fold.exists = false;
+					InvalidateLineFold(*line);
 				} else {
 					// We found a fold. Now we need to see if the stack matches.
 					// We scan our stack for the counterpart of the fold.
@@ -176,12 +213,15 @@ void FoldController::FixFolds() {
 							// Erase all folds further inward
 							for (int j = foldStack.size() - 1; j > i; j--) {
 								completedFolds[foldStack[j]->Fold.id] = true;
-								foldStack[j]->Fold.exists = false;
+								InvalidateLineFold(*foldStack[j]);
 								foldStack.pop_back();
 							}
 
 							// Sync the found fold and pop the stack
-							line->Fold.collapsed = foldStack[i]->Fold.collapsed;
+							if (line->Fold.collapsed != foldStack[i]->Fold.collapsed) {
+								line->Fold.collapsed = foldStack[i]->Fold.collapsed;
+								needs_update = true;
+							}
 							foldStack.pop_back();
 
 							found = true;
@@ -190,25 +230,30 @@ void FoldController::FixFolds() {
 					}
 					if (!found) {
 						completedFolds[line->Fold.id] = true;
-						line->Fold.exists = false;
+						InvalidateLineFold(*line);
 					}
 				}
 			}
+
+			if (needs_update) {
+				UpdateLineExtradata(*line);
+			}
 		}
 	}
 
 	// All remaining lines are invalid
 	for (AssDialogue *line : foldStack) {
-		line->Fold.exists = false;
+		line->Fold.valid = false;
+		if (++line->Fold.invalidCount > 100) {
+			line->Fold.extraExists = false;
+			UpdateLineExtradata(*line);
+		}
 	}
-
-	LinkFolds();
 }
 
 void FoldController::LinkFolds() {
 	std::vector<AssDialogue *> foldStack;
 	AssDialogue *lastVisible = nullptr;
-	context->ass->Properties.folds.clear();
 
 	maxdepth = 0;
 
@@ -217,10 +262,10 @@ void FoldController::LinkFolds() {
 	for (auto line = context->ass->Events.begin(); line != context->ass->Events.end(); line++) {
 		line->Fold.parent = foldStack.empty() ? nullptr : foldStack.back();
 		line->Fold.nextVisible = nullptr;
-		line->Fold.visible = highestFolded > foldStack.size();
+		line->Fold.visible = highestFolded > (int) foldStack.size();
 		line->Fold.visited = false;
 		line->Fold.visibleRow = visibleRow;
-		
+
 		if (line->Fold.visible) {
 			if (lastVisible != nullptr) {
 				lastVisible->Fold.nextVisible = &*line;
@@ -228,26 +273,20 @@ void FoldController::LinkFolds() {
 			lastVisible = &*line;
 			visibleRow++;
 		}
-		if (line->Fold.exists && !line->Fold.side) {
+		if (line->Fold.valid && !line->Fold.side) {
 			foldStack.push_back(&*line);
-			if (!line->Fold.collapsed && highestFolded == foldStack.size()) {
+			if (!line->Fold.collapsed && highestFolded == (int) foldStack.size()) {
 				highestFolded++;
 			}
-			if (foldStack.size() > maxdepth) {
+			if ((int) foldStack.size() > maxdepth) {
 				maxdepth = foldStack.size();
 			}
 		}
-		if (line->Fold.exists && line->Fold.side) {
+		if (line->Fold.valid && line->Fold.side) {
-			context->ass->Properties.folds.push_back(LineFold {
-				foldStack.back()->Row,
-				line->Row,
-				line->Fold.collapsed,
-			});
-
 			line->Fold.counterpart = foldStack.back();
 			(*foldStack.rbegin())->Fold.counterpart = &*line;
 
-			if (highestFolded >= foldStack.size()) {
+			if (highestFolded >= (int) foldStack.size()) {
 				highestFolded = foldStack.size();
 			}
 
@@ -260,9 +299,9 @@ int FoldController::GetMaxDepth() {
 	return maxdepth;
 }
 
-bool FoldController::ActionHasFold(AssDialogue& line) { return line.Fold.exists; }
+bool FoldController::ActionHasFold(AssDialogue& line) { return line.Fold.valid; }
 
-bool FoldController::ActionClearFold(AssDialogue& line) { line.Fold.exists = false; return false; }
+bool FoldController::ActionClearFold(AssDialogue& line) { line.Fold.extraExists = false; line.Fold.valid = false; return false; }
 
 bool FoldController::ActionOpenFold(AssDialogue& line) { line.Fold.collapsed = false; return false; }
 

src/fold_controller.h

@@ -1,4 +1,4 @@
-// Copyright (c) 2022, arch1t3cht <arch1t3cht@gmail.com>>
+// Copyright (c) 2022, arch1t3cht <arch1t3cht@gmail.com>
 //
 // Permission to use, copy, modify, and distribute this software for any
 // purpose with or without fee is hereby granted, provided that the above
@@ -23,6 +23,8 @@
 
 namespace agi { struct Context; }
 
+extern const char *folds_key;
+
 /// We allow hiding ass lines using cascading folds, each of which collapses a contiguous collection of dialogue lines into a single one.
 /// A fold is described by inclusive start and end points of the contiguous set of dialogue line it extends over.
 /// An existing fold can be active (collapsed) or inactive (existing, but not collapsed at the moment)
@@ -30,55 +32,58 @@ namespace agi { struct Context; }
 /// an intersection set not equal to one of the two folds.
 /// Only one fold may be started or ended at any given line.
 
-/// Since we need to track how the folds move when lines are inserted or deleted, we need to represent the fold
+/// In order for folds to be preserved while adding or deleting lines and work nicely with operations like copy/paste,
-/// data as part of the individual AssDialogue lines. Hooking into insertion or deletion calls is not possible
+/// they need to be stored as extradata. Furthermore, in order for the subtitle grid and fold management commands to efficiently
-/// without extensive restructuring, and also wouldn't interact well with undo/redo functionality.
+/// navigate the folds, we cache some information on the fold after each commit.
 ///
-/// Because of this, we store the data defining folds as part of the AssDialogue lines. We use a pre-commit hook
+/// A fold descriptor for a line is an extradata field of the form <direction>;<collapsed>;<id>, where
-/// to fix any format violations after changes are made. Furthermore, to be able to traverse the folds more easily,
+///     direction is 0 if this line starts a fold, and 1 if the line ends one
-/// we compute various metadata and set up pointers between the fold parts.
+///     collapsed is 1 if the fold is collapsed and 0 otherwise
+///     id is a unique id pairing this fold with its counterpart
 
 /// Part of the data for an AssDialogue object, describing folds starting or ending at this line.
 class FoldInfo {
-	// Base data describing the folds:w
+	// Cached, parsed versions of the contents of the extradata entry
 
-	/// Whether a fold starts or ends at the line. All other fields are only valid if this is true.
+	/// Whether there is some extradata entry on folds here
-	bool exists = false;
+	bool extraExists = false;
+	/// Whether a fold starts or ends at the line. The following three fields are only valid if this is true.
+	bool valid = false;
+	/// The id
+	int id = 0;
 	/// Whether the fold is currently collapsed
 	bool collapsed = false;
 	/// False if a fold is started here, true otherwise.
 	bool side = false;
-	/// A unique ID describing the fold. The other end of the fold has a matching ID and the opposite value for side.
+
-	int id = 0;
 
 	// Used in DoForFoldsAt to ensure each line is visited only once
 	bool visited = false;
-
-	// The following is cached data used for making traversing folds more efficient. These are only valid directly after
-	// a commit and shouldn't be changed outside of the pre-commit handler.
-
 	/// Whether the line is currently visible
 	bool visible = true;
 
 	/// If exists is true, this is a pointer to the other line with the given fold id
 	AssDialogue *counterpart = nullptr;
-
 	/// A pointer to the opener of the innermost fold containing the line, if one exists.
 	/// If the line starts a fold, this points to the next bigger fold.
 	AssDialogue *parent = nullptr;
-
 	/// If this line is visible, this points to the next visible line, if one exists
 	AssDialogue *nextVisible = nullptr;
 
+	/// Increased when there's an extradata entry in here that turned out to be invalid.
+	/// Once this hits some threshold, the extradata entry is deleted.
+	/// We don't delete it immediately to allow cut/pasting fold delimiters around.
+	int invalidCount = 0;
+
 	/// The row number where this line would appear in the subtitle grid. That is, the ordinary
 	/// Row value, but with hidden lines skipped.
 	/// Out of all AssDialogue lines with the same visibleRow, only the one with the lowest Row is shown.
-	int visibleRow;
+	int visibleRow = -1;
 
 	friend class FoldController;
 
 public:
-	bool hasFold() const { return exists; }
+	bool hasFold() const { return valid; }
 	bool isFolded() const { return collapsed; }
 	bool isEnd() const { return side; }
 
@@ -95,6 +100,7 @@ class FoldController {
 	agi::Context *context;
 	agi::signal::Connection pre_commit_listener;
 	int maxdepth = 0;
+	int max_fold_id = 0;
 
 	bool CanAddFold(AssDialogue& start, AssDialogue& end);
 
@@ -106,8 +112,6 @@ class FoldController {
 
 	void FixFoldsPreCommit(int type, const AssDialogue *single_line);
 
-	void MakeFoldsFromFile();
-
 	// These are used for the DoForAllFolds action and should not be used as ordinary getters/setters
 
 	static bool ActionHasFold(AssDialogue& line);
@@ -120,10 +124,25 @@ class FoldController {
 
 	static bool ActionToggleFold(AssDialogue& line);
 
+	/// Updates the line's extradata entry from the values in FoldInfo. Used after actions like toggling folds.
+	void UpdateLineExtradata(AssDialogue& line);
+
+	/// Sets valid = false and increases the invalidCounter, deleting the extradata if necessary
+	void InvalidateLineFold(AssDialogue &line);
+
 	/// After lines have been added or deleted, this ensures consistency again. Run with every relevant commit.
+	/// Performs the three actions below in order.
+	void UpdateFoldInfo();
+
+	/// Parses the extradata of all lines and sets the respective lines in the FoldInfo.
+	/// Also deduplicates extradata entries and mangles fold id's when necessary.
+	void ReadFromExtradata();
+
+	/// Ensures consistency by making sure every fold has two delimiters and folds are properly nested.
+	/// Cleans up extradata entries if they've been invalid for long enough.
 	void FixFolds();
 
-	/// If the fold base dataa is valid, sets up all the cached links in the FoldData
+	/// Once the fold base data is valid, sets up all the cached links in the FoldData.
 	void LinkFolds();
 
 public:

src/libresrc/default_menu.json

@@ -93,7 +93,7 @@
         { "command" : "grid/fold/open_all" },
         { "command" : "grid/fold/close_all" },
         { "command" : "grid/fold/clear_all" },
-		{},
+        {},
         { "submenu" : "main/subtitle/sort lines", "text" : "Sort All Lines" },
         { "submenu" : "main/subtitle/sort selected lines", "text" : "Sort Selected Lines" },
         { "command" : "grid/swap" },

src/libresrc/osx/default_menu.json

@@ -96,7 +96,7 @@
         { "command" : "grid/fold/open_all" },
         { "command" : "grid/fold/close_all" },
         { "command" : "grid/fold/clear_all" },
-		{},
+        {},
         { "submenu" : "main/subtitle/sort lines", "text" : "Sort All Lines" },
         { "submenu" : "main/subtitle/sort selected lines", "text" : "Sort Selected Lines" },
         { "command" : "grid/swap" },

src/subtitle_format_ass.cpp

@@ -109,19 +109,6 @@ struct Writer {
 			WriteIfNotZero("Active Line: ", properties.active_row);
 			WriteIfNotZero("Video Position: ", properties.video_position);
 		}
-
-		std::string foldsdata;
-		for (LineFold fold : properties.folds) {
-			if (!foldsdata.empty()) {
-				foldsdata += ",";
-			}
-			foldsdata += std::to_string(fold.start);
-			foldsdata += ":";
-			foldsdata += std::to_string(fold.end);
-			foldsdata += ":";
-			foldsdata += fold.collapsed ? "1" : "0";
-		}
-		WriteIfNotEmpty("Line Folds: ", foldsdata);
 	}
 
 	void WriteIfNotEmpty(const char *key, std::string const& value) {