fix #279770: fix aligning of lyrics with leading/trailing numbers

The previously used method did not take into account the fact that
width of some characters (e.g. whitespaces) may vary depending on
the surrounding context. This commit corrects leading/trailing parts
widths calculation by making use of TextBlock::xpos() function which
is used also for text cursor placement in text editing mode.

libmscore/lyrics.cpp

@@ -234,38 +234,27 @@ void Lyrics::layout()
       // parse leading verse number and/or punctuation, so we can factor it into layout separately
       //
       bool hasNumber     = false; // _verseNumber;
-      qreal centerAdjust = 0.0;
-      qreal leftAdjust   = 0.0;
 
       // find:
       // 1) string of numbers and non-word characters at start of syllable
       // 2) at least one other character (indicating start of actual lyric)
       // 3) string of non-word characters at end of syllable
       //QRegularExpression leadingPattern("(^[\\d\\W]+)([^\\d\\W]+)");
 
+      const QString text = plainText();
+      QString leading;
+      QString trailing;
+
       if (score()->styleB(Sid::lyricsAlignVerseNumber)) {
-            QString s = plainText();
             QRegularExpression punctuationPattern("(^[\\d\\W]*)([^\\d\\W].*?)([\\d\\W]*$)", QRegularExpression::UseUnicodePropertiesOption);
-            QRegularExpressionMatch punctuationMatch = punctuationPattern.match(s);
+            QRegularExpressionMatch punctuationMatch = punctuationPattern.match(text);
             if (punctuationMatch.hasMatch()) {
                   // leading and trailing punctuation
-                  QString lp = punctuationMatch.captured(1);
-                  QString tp = punctuationMatch.captured(3);
-                  // actual lyric
+                  leading = punctuationMatch.captured(1);
+                  trailing = punctuationMatch.captured(3);
                   //QString actualLyric = punctuationMatch.captured(2);
-                  if (!lp.isEmpty() || !tp.isEmpty()) {
-//                        qDebug("create leading, trailing <%s> -- <%s><%s>", qPrintable(s), qPrintable(lp), qPrintable(tp));
-                        Lyrics leading(*this);
-                        leading.setPlainText(lp);
-                        leading.layout1();
-                        Lyrics trailing(*this);
-                        trailing.setPlainText(tp);
-                        trailing.layout1();
-                        leftAdjust = leading.width();
-                        centerAdjust = leading.width() - trailing.width();
-                        if (!lp.isEmpty() && lp[0].isDigit())
-                              hasNumber = true;
-                        }
+                  if (!leading.isEmpty() && leading[0].isDigit())
+                        hasNumber = true;
                   }
             }
 
@@ -293,6 +282,26 @@ void Lyrics::layout()
       qreal x = pos().x();
       TextBase::layout1();
 
+      qreal centerAdjust = 0.0;
+      qreal leftAdjust   = 0.0;
+
+      if (score()->styleB(Sid::lyricsAlignVerseNumber)) {
+            // Calculate leading and trailing parts widths. Lyrics
+            // should have text layout to be able to do it correctly.
+            Q_ASSERT(rows() != 0);
+            if (!leading.isEmpty() || !trailing.isEmpty()) {
+//                   qDebug("create leading, trailing <%s> -- <%s><%s>", qPrintable(text), qPrintable(leading), qPrintable(trailing));
+                  const TextBlock& tb = textBlock(0);
+
+                  const qreal leadingWidth = tb.xpos(leading.length(), this) - tb.boundingRect().x();
+                  const int trailingPos = text.length() - trailing.length();
+                  const qreal trailingWidth = tb.boundingRect().right() - tb.xpos(trailingPos, this);
+
+                  leftAdjust = leadingWidth;
+                  centerAdjust = leadingWidth - trailingWidth;
+                  }
+            }
+
       ChordRest* cr = chordRest();
 
       if (align() & Align::HCENTER) {