add a new helper class text_aligner

include/nana/paint/text_renderer.hpp

@@ -9,7 +9,7 @@ namespace nana
 		class text_renderer
 		{
 		public:
-			typedef graphics & graph_reference;
+			using graph_reference = graphics &;
 			
 			text_renderer(graph_reference graph, align = align::left);
 
@@ -22,6 +22,35 @@ namespace nana
 			graph_reference graph_;
 			align text_align_;
 		};
+
+		/// Draw aligned string
+		class aligner
+		{
+		public:
+			using graph_reference = graphics&;
+
+			/// Constructor
+			/**
+			 * @param graph Reference to a graphics object
+			 * @param text_align Alignment of text
+			 * @param text_align_if_too_long Alignment of text if the pixels of string is larger than text area
+			 */
+			aligner(graph_reference graph, align text_align = align::left);
+			aligner(graph_reference graph, align text_align, align text_align_if_too_long);
+
+			/// Draws a text with specified text alignment.
+			/**
+			 * @param text	Text to draw
+			 * @param pos	Postion where the text to draw
+			 * @param width The width of text area. If the pixels of text is larger than this parameter, it draws ellipsis  
+			 */
+			void draw(const std::string& text, point pos, unsigned width);
+			void draw(const std::wstring& text, point pos, unsigned width);
+		private:
+			graph_reference graph_;
+			align text_align_;
+			align text_align_ex_;
+		};
 	}
 }