ui: adapt scroll target value in code single file mode as workaround when view scrolls below last line

src/lib_gui/qt/element/QtCodeArea.cpp

@@ -274,8 +274,7 @@ void QtCodeArea::lineNumberAreaPaintEvent(QPaintEvent *event)
 
 int QtCodeArea::lineNumberDigits() const
 {
-	int max = qMax(1, int(getStartLineNumber()) + blockCount());
-	return utility::digits(max);
+	return utility::digits(getEndLineNumber());
 }
 
 int QtCodeArea::lineNumberAreaWidth() const

src/lib_gui/qt/element/QtCodeField.cpp

@@ -130,6 +130,11 @@ uint QtCodeField::getEndLineNumber() const
 	return m_startLineNumber + blockCount() - 1;
 }
 
+int QtCodeField::totalLineHeight() const
+{
+	return blockBoundingRect(firstVisibleBlock()).height() * blockCount();
+}
+
 std::string QtCodeField::getCode() const
 {
 	return m_code;

src/lib_gui/qt/element/QtCodeField.h

@@ -35,6 +35,8 @@ public:
 	uint getStartLineNumber() const;
 	uint getEndLineNumber() const;
 
+	int totalLineHeight() const;
+
 	std::string getCode() const;
 
 	std::shared_ptr<SourceLocationFile> getSourceLocationFile() const;

src/lib_gui/qt/element/QtCodeFileSingle.cpp

@@ -195,6 +195,19 @@ bool QtCodeFileSingle::requestScroll(
 	double percentA = double(lineNumber - 1) / m_area->getEndLineNumber();
 	double percentB = endLineNumber ? double(endLineNumber - 1) / m_area->getEndLineNumber() : 0.0f;
 
+	// fix percentages wrong when code area is scrollable beyond last line due to some unknown bug
+	{
+		int totalHeight = m_area->sizeHint().height();
+		int totalLineHeight = m_area->totalLineHeight();
+
+		if (std::abs(totalHeight - totalLineHeight) > 100)
+		{
+			double factor = totalLineHeight / double(totalHeight);
+			percentA *= factor;
+			percentB *= factor;
+		}
+	}
+
 	ensurePercentVisibleAnimated(percentA, percentB, animated, target);
 
 	m_scrollRequested = true;