Preserve the insertion point (but not selection) when switching between lines

libaegisub/common/character_count.cpp

@@ -31,35 +31,34 @@ struct utext_deleter {
 };
 using utext_ptr = std::unique_ptr<UText, utext_deleter>;
 
-template<typename Iterator>
+icu::BreakIterator& get_break_iterator(const char *ptr, size_t len) {
-utext_ptr to_utext(Iterator begin, Iterator end) {
+	static std::unique_ptr<icu::BreakIterator> bi;
+	static std::once_flag token;
+	std::call_once(token, [&] {
+		UErrorCode status = U_ZERO_ERROR;
+		bi.reset(BreakIterator::createCharacterInstance(Locale::getDefault(), status));
+		if (U_FAILURE(status)) throw agi::InternalError("Failed to create character iterator", nullptr);
+	});
+
 	UErrorCode err = U_ZERO_ERROR;
-	utext_ptr ret(utext_openUTF8(nullptr, &*begin, end - begin, &err));
+	utext_ptr ut(utext_openUTF8(nullptr, ptr, len, &err));
 	if (U_FAILURE(err)) throw agi::InternalError("Failed to open utext", nullptr);
-	return ret;
+
+	bi->setText(ut.get(), err);
+	if (U_FAILURE(err)) throw agi::InternalError("Failed to set break iterator text", nullptr);
+
+	return *bi;
 }
 
 template <typename Iterator>
 size_t count_in_range(Iterator begin, Iterator end, int mask) {
 	if (begin == end) return 0;
 
-	static std::unique_ptr<icu::BreakIterator> character_bi;
+	auto& character_bi = get_break_iterator(&*begin, end - begin);
-	static std::once_flag token;
-	std::call_once(token, [&] {
-		UErrorCode status = U_ZERO_ERROR;
-		character_bi.reset(BreakIterator::createCharacterInstance(Locale::getDefault(), status));
-		if (U_FAILURE(status)) throw agi::InternalError("Failed to create character iterator", nullptr);
-	});
-
-	UErrorCode err = U_ZERO_ERROR;
-
-	utext_ptr ut = to_utext(begin, end);
-	character_bi->setText(ut.get(), err);
-	if (U_FAILURE(err)) throw agi::InternalError("Failed to set break iterator text", nullptr);
 
 	size_t count = 0;
-	auto pos = character_bi->first();
+	auto pos = character_bi.first();
-	for (auto end = character_bi->next(); end != BreakIterator::DONE; pos = end, end = character_bi->next()) {
+	for (auto end = character_bi.next(); end != BreakIterator::DONE; pos = end, end = character_bi.next()) {
 		if (!mask)
 			++count;
 		else {
@@ -85,25 +84,29 @@ int ignore_mask_to_icu_mask(int mask) {
 }
 
 namespace agi {
-size_t CharacterCount(std::string const& str, int mask) {
+size_t CharacterCount(std::string::const_iterator begin, std::string::const_iterator end, int mask) {
 	mask = ignore_mask_to_icu_mask(mask);
 	size_t characters = 0;
-	auto pos = begin(str);
+	auto pos = begin;
 	do {
-		auto it = std::find(pos, end(str), '{');
+		auto it = std::find(pos, end, '{');
 		characters += count_in_range(pos, it, mask);
-		if (it == end(str)) break;
+		if (it == end) break;
 
-		pos = std::find(pos, end(str), '}');
+		pos = std::find(pos, end, '}');
-		if (pos == end(str)) {
+		if (pos == end) {
 			characters += count_in_range(it, pos, mask);
 			break;
 		}
-	} while (++pos != end(str));
+	} while (++pos != end);
 
 	return characters;
 }
 
+size_t CharacterCount(std::string const& str, int mask) {
+	return CharacterCount(begin(str), end(str), mask);
+}
+
 size_t MaxLineLength(std::string const& text, int mask) {
 	mask = ignore_mask_to_icu_mask(mask);
 	auto tokens = agi::ass::TokenizeDialogueBody(text);
@@ -131,4 +134,16 @@ size_t MaxLineLength(std::string const& text, int mask) {
 
 	return std::max(max_line_length, current_line_length);
 }
+
+size_t IndexOfCharacter(std::string const& str, size_t n) {
+	if (str.empty() || n == 0) return 0;
+	auto& bi = get_break_iterator(&str[0], str.size());
+
+	for (auto pos = bi.first(), end = bi.next(); ; --n, pos = end, end = bi.next()) {
+		if (end == BreakIterator::DONE)
+			return str.size();
+		if (n == 0)
+			return pos;
+	}
+}
 }

libaegisub/include/libaegisub/character_count.h

@@ -25,5 +25,10 @@ namespace agi {
 
 	/// Get the length in characters of the longest line in the given text
 	size_t MaxLineLength(std::string const& text, int ignore_mask);
+	/// Get the total number of characters in the string
 	size_t CharacterCount(std::string const& str, int ignore_mask);
+	size_t CharacterCount(std::string::const_iterator begin, std::string::const_iterator end, int ignore_mask);
+	/// Get index in bytes of the nth character in str, or str.size() if str
+	/// has less than n characters
+	size_t IndexOfCharacter(std::string const& str, size_t n);
 }

src/subs_edit_box.cpp

@@ -342,7 +342,6 @@ void SubsEditBox::UpdateFields(int type, bool repopulate_lists) {
 		if (repopulate_lists) PopulateList(actor_box, &AssDialogue::Actor);
 		actor_box->ChangeValue(to_wx(line->Actor));
 		actor_box->SetStringSelection(to_wx(line->Actor));
-		edit_ctrl->SetTextTo(line->Text);
 	}
 }
 

src/subs_edit_ctrl.cpp

@@ -47,8 +47,9 @@
 
 #include <libaegisub/ass/dialogue_parser.h>
 #include <libaegisub/calltip_provider.h>
-#include <libaegisub/spellchecker.h>
+#include <libaegisub/character_count.h>
 #include <libaegisub/make_unique.h>
+#include <libaegisub/spellchecker.h>
 
 #include <boost/algorithm/string/predicate.hpp>
 #include <boost/algorithm/string/replace.hpp>
@@ -281,9 +282,16 @@ void SubsTextEditCtrl::SetTextTo(std::string const& text) {
 	SetEvtHandlerEnabled(false);
 	Freeze();
 
+	auto insertion_point = GetInsertionPoint();
+	if (insertion_point > line_text.size())
+		line_text = GetTextRaw().data();
+	auto old_pos = agi::CharacterCount(line_text.begin(), line_text.begin() + insertion_point, 0);
 	line_text.clear();
-	SetTextRaw(text.c_str());
+
 	SetSelection(0, 0);
+	SetTextRaw(text.c_str());
+	auto pos = agi::IndexOfCharacter(text, old_pos);
+	SetSelection(pos, pos);
 
 	SetEvtHandlerEnabled(true);
 	Thaw();