Added storage of proper text size with emoji to input field.

ui/widgets/fields/input_field.cpp

@@ -1927,7 +1927,7 @@ bool InputField::hasText() const {
 	return (from.next() != till);
 }
 
-QString InputField::getTextPart(
+InputField::TextPart InputField::getTextPart(
 		int start,
 		int end,
 		TagList &outTagsList,
@@ -1938,7 +1938,7 @@ QString InputField::getTextPart(
 	if (end >= 0 && end <= start) {
 		outTagsChanged = !outTagsList.isEmpty();
 		outTagsList.clear();
-		return QString();
+		return { QString(), 0 };
 	}
 
 	if (start < 0) {
@@ -1967,6 +1967,7 @@ QString InputField::getTextPart(
 	if (!full && end < 0) {
 		end = possibleLength;
 	}
+	auto textSizeWithoutSurrogatePairsCount = document->characterCount() - 1;
 
 	for (auto block = from; block != till;) {
 		for (auto item = block.begin(); !item.atEnd(); ++item) {
@@ -1993,14 +1994,19 @@ QString InputField::getTextPart(
 				}
 			}
 
-			const auto emojiText = [&] {
+			struct EmojiEntry final {
+				QString text;
+				uint8 surrogatePairs = 0;
+			};
+
+			const auto emojiEntry = [&]() -> EmojiEntry {
 				if (format.isImageFormat()) {
 					const auto imageName = format.toImageFormat().name();
 					if (const auto emoji = Emoji::FromUrl(imageName)) {
-						return emoji->text();
+						return { emoji->text(), emoji->surrogatePairs() };
 					}
 				}
-				return format.property(kCustomEmojiText).toString();
+				return { format.property(kCustomEmojiText).toString(), 0 };
 			}();
 			auto text = [&] {
 				const auto result = fragment.text();
@@ -2030,9 +2036,12 @@ QString InputField::getTextPart(
 					if (ch > begin) {
 						result.append(begin, ch - begin);
 					}
-					adjustedLength += (emojiText.size() - 1);
-					if (!emojiText.isEmpty()) {
-						result.append(emojiText);
+					const auto size = emojiEntry.text.size() - 1;
+					adjustedLength += size;
+					if (!emojiEntry.text.isEmpty()) {
+						result.append(emojiEntry.text);
+						textSizeWithoutSurrogatePairsCount += size
+							- emojiEntry.surrogatePairs;
 					}
 					begin = ch + 1;
 				} break;
@@ -2063,7 +2072,7 @@ QString InputField::getTextPart(
 	markdownTagAccumulator.finish();
 
 	outTagsChanged = tagAccumulator.changed();
-	return result;
+	return { result, textSizeWithoutSurrogatePairsCount };
 }
 
 bool InputField::isUndoAvailable() const {
@@ -2457,7 +2466,7 @@ void InputField::handleContentsChanged() {
 	setErrorShown(false);
 
 	auto tagsChanged = false;
-	const auto currentText = getTextPart(
+	const auto [currentText, currentTextSize] = getTextPart(
 		0,
 		-1,
 		_lastTextWithTags.tags,
@@ -2466,6 +2475,7 @@ void InputField::handleContentsChanged() {
 
 	//highlightMarkdown();
 
+	_lastTextSizeWithoutSurrogatePairsCount = currentTextSize;
 	if (tagsChanged || (_lastTextWithTags.text != currentText)) {
 		_lastTextWithTags.text = currentText;
 		const auto weak = MakeWeak(this);
@@ -2640,7 +2650,7 @@ void InputField::setTextWithTags(
 TextWithTags InputField::getTextWithTagsPart(int start, int end) const {
 	auto changed = false;
 	auto result = TextWithTags();
-	result.text = getTextPart(start, end, result.tags, changed);
+	result.text = getTextPart(start, end, result.tags, changed).text;
 	return result;
 }
 
@@ -3988,7 +3998,7 @@ void PrepareFormattingOptimization(not_null<QTextDocument*> document) {
 
 int FieldCharacterCount(not_null<InputField*> field) {
 	// This method counts emoji properly.
-	return field->document()->characterCount() - 1;
+	return field->lastTextSizeWithoutSurrogatePairsCount();
 }
 
 } // namespace Ui

ui/widgets/fields/input_field.h

@@ -241,6 +241,9 @@ public:
 	const QString &getLastText() const {
 		return _lastTextWithTags.text;
 	}
+	[[nodiscard]] int lastTextSizeWithoutSurrogatePairsCount() const {
+		return _lastTextSizeWithoutSurrogatePairsCount;
+	}
 	void setPlaceholder(
 		rpl::producer<QString> placeholder,
 		int afterSymbols = 0);
@@ -380,7 +383,11 @@ private:
 
 	// "start" and "end" are in coordinates of text where emoji are replaced
 	// by ObjectReplacementCharacter. If "end" = -1 means get text till the end.
-	QString getTextPart(
+	struct TextPart final {
+		QString text;
+		int textSizeWithoutSurrogatePairsCount = 0;
+	};
+	TextPart getTextPart(
 		int start,
 		int end,
 		TagList &outTagsList,
@@ -484,6 +491,7 @@ private:
 	TextWithTags _lastTextWithTags;
 	std::vector<MarkdownTag> _lastMarkdownTags;
 	QString _lastPreEditText;
+	int _lastTextSizeWithoutSurrogatePairsCount = 0;
 	std::optional<QString> _inputMethodCommit;
 
 	QMargins _additionalMargins;