CTextBox: add static function to get largest line of passed text

This could be useful eg. for size calculations.

src/gui/widget/textbox.cpp

@@ -887,3 +887,21 @@ int CTextBox::getLines(const std::string& text)
 
 	return count;
 }
+
+int CTextBox::getMaxLineWidth(const std::string& text, Font* font)
+{
+	// if found no linebreak, return pure size only
+	if (text.find('\n', 0) == std::string::npos)
+		return font->getRenderWidth(text.c_str());
+
+	std::stringstream in (text);
+	if (!in)
+		return 0;
+
+	int len = 0;
+	std::string line;
+	while(getline(in, line))
+		len = std::max(len, font->getRenderWidth(line.c_str()));
+
+	return len;
+}

src/gui/widget/textbox.h

@@ -200,7 +200,6 @@ class CTextBox : public sigc::trackable
 
 		inline	bool 	isPainted(void)			{if( frameBuffer == NULL) return (false); else return (true);};
 		inline	CBox	getWindowsPos(void)		{return(m_cFrame);};
-		inline	int	getMaxLineWidth(void)		{return(m_nMaxTextWidth);};
 
 		inline  int     getLinesPerPage(void)		{return m_nLinesPerPage;};
 		inline  int     getPages(void)			{return(m_nNrOfPages);};
@@ -222,6 +221,24 @@ class CTextBox : public sigc::trackable
 		*/
 		int     	getLines(){return(m_nNrOfLines);}
 
+		/**
+		* Returns maximal width of passed text
+		* @param[in]	text
+		* 	@li 	exepts type std::string
+		* @param[in]	font
+		* 	@li 	exepts font type object
+		* 	@return	width of largest line as int
+		* 	@see	getMaxLineWidth(void)
+		*/
+		static int	getMaxLineWidth(const std::string& text, Font* font);
+
+		/**
+		* Returns internal defined maximal line width of an existent CTextBox instance.
+		* 	@return	width of largest line as int
+		* 	@see	static version getMaxLineWidth()
+		*/
+		int		getMaxLineWidth()		{return(m_nMaxTextWidth);}
+
 		inline	void	movePosition(int x, int y)	{m_cFrame.iX = x; m_cFrame.iY = y;};
 		int  getFontTextHeight();
 		inline int	getTextMode()			{return m_nMode;};