fix: replace wordwrap with multibyte-safe implementation

The native PHP wordwrap() function does not handle multibyte characters
correctly, causing text with accents, CJK characters, or emojis to be
wrapped at incorrect positions.

This commit introduces mbWordwrap(), a custom implementation that uses
mb_strlen() and mb_substr() to properly handle UTF-8 and multibyte
text wrapping in signature images.

Signed-off-by: Vitor Mattos <[email protected]>

Author: vitormattos

lib/Service/SignatureTextService.php

@@ -230,7 +230,7 @@ public function signerNameImage(
 		$draw->setTextAlignment($align);
 
 		$maxCharsPerLine = $this->splitAndGetLongestHalfLength($text);
-		$wrappedText = wordwrap($text, $maxCharsPerLine, "\n", true);
+		$wrappedText = $this->mbWordwrap($text, $maxCharsPerLine, "\n", true);
 
 		$textMetrics = $image->queryFontMetrics($draw, $wrappedText);
 		$lineCount = substr_count($wrappedText, "\n") + 1;
@@ -300,6 +300,91 @@ private function splitAndGetLongestHalfLength(string $text): int {
 		return !empty($results) ? max($results) : $length;
 	}
 
+	/**
+	 * Multibyte-safe version of wordwrap
+	 *
+	 * @param string $text The text to wrap
+	 * @param int $width The number of characters at which the string will be wrapped
+	 * @param string $break The line break character
+	 * @param bool $cut If true, words longer than $width will be broken
+	 * @return string The wrapped text
+	 */
+	private function mbWordwrap(string $text, int $width, string $break = "\n", bool $cut = false): string {
+		if ($width <= 0) {
+			return $text;
+		}
+
+		$lines = [];
+		$currentLine = '';
+		$currentLength = 0;
+
+		$paragraphs = explode("\n", $text);
+
+		foreach ($paragraphs as $paragraphIndex => $paragraph) {
+			if ($paragraph === '') {
+				if ($currentLength > 0) {
+					$lines[] = $currentLine;
+					$currentLine = '';
+					$currentLength = 0;
+				}
+				$lines[] = '';
+				continue;
+			}
+
+			$words = explode(' ', $paragraph);
+
+			foreach ($words as $word) {
+				$wordLength = mb_strlen($word);
+
+				if ($cut && $wordLength > $width) {
+					if ($currentLength > 0) {
+						$lines[] = $currentLine;
+						$currentLine = '';
+						$currentLength = 0;
+					}
+
+					while ($wordLength > $width) {
+						$lines[] = mb_substr($word, 0, $width);
+						$word = mb_substr($word, $width);
+						$wordLength = mb_strlen($word);
+					}
+
+					if ($wordLength > 0) {
+						$currentLine = $word;
+						$currentLength = $wordLength;
+					}
+					continue;
+				}
+
+				$spaceLength = ($currentLength > 0) ? 1 : 0;
+				if ($currentLength + $spaceLength + $wordLength > $width && $currentLength > 0) {
+					$lines[] = $currentLine;
+					$currentLine = $word;
+					$currentLength = $wordLength;
+				} else {
+					if ($currentLength > 0) {
+						$currentLine .= ' ';
+						$currentLength++;
+					}
+					$currentLine .= $word;
+					$currentLength += $wordLength;
+				}
+			}
+
+			if ($currentLength > 0 && $paragraphIndex < count($paragraphs) - 1) {
+				$lines[] = $currentLine;
+				$currentLine = '';
+				$currentLength = 0;
+			}
+		}
+
+		if ($currentLength > 0) {
+			$lines[] = $currentLine;
+		}
+
+		return implode($break, $lines);
+	}
+
 	public function getDefaultTemplate(): string {
 		$collectMetadata = $this->appConfig->getValueBool(Application::APP_ID, 'collect_metadata', false);
 		if ($collectMetadata) {