make text preview backend use imagettftext, fixes #8087

lib/private/preview/txt.php

@@ -40,13 +40,17 @@ class TXT extends Provider {
 		imagecolorallocate($image, 255, 255, 255);
 		$textColor = imagecolorallocate($image, 0, 0, 0);
 
+		$fontFile  = __DIR__;
+		$fontFile .= '/../../../core';
+		$fontFile .= '/fonts/OpenSans-Regular.ttf';
+
 		foreach($lines as $index => $line) {
 			$index = $index + 1;
 
 			$x = (int) 1;
-			$y = (int) ($index * $lineSize) - $fontSize;
+			$y = (int) ($index * $lineSize);
 
-			imagestring($image, 1, $x, $y, $line, $textColor);
+			imagettftext($image, $fontSize, 0, $x, $y, $textColor, $fontFile, $line);
 
 			if(($index * $lineSize) >= $maxY) {
 				break;