update the painting part name.

Author: nb312

lib/const/page_item_const.dart

@@ -288,8 +288,8 @@ const PAGE_ITEMS = [
     "click": PageName.ASYNC_STREAM_BUILDER,
   },
   {
-    "title": PageName.PAINT_OPACITY,
+    "title": PageName.PAINTING,
     "img": PageImage.FLUTTER_OPEN,
-    "click": PageName.PAINT_OPACITY,
+    "click": PageName.PAINTING,
   },
 ];

lib/const/page_name_const.dart

@@ -63,5 +63,5 @@ class PageName {
   static const INTER_NAV = "Navigator";
   static const ASYNC_FUTURE = "FutureBuilder";
   static const ASYNC_STREAM_BUILDER = "StreamBuilder";
-  static const PAINT_OPACITY = "Opacity";
+  static const PAINTING = "Painting";
 }

lib/main.dart

@@ -76,7 +76,7 @@ class FlutterOpenApp extends StatelessWidget {
         PageName.INTER_NAV: (context) => NavigatorPage(),
         PageName.ASYNC_FUTURE: (context) => FuturePage(),
         PageName.ASYNC_STREAM_BUILDER: (context) => StreamBuilderPage(),
-        PageName.PAINT_OPACITY: (context) => PaintingPage(),
+        PageName.PAINTING: (context) => PaintingPage(),
       },
     );
   }

lib/page/painting/PaintingPage.dart

@@ -117,7 +117,7 @@ class _OpacityState extends State<PaintingPage> {
   Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(
-        title: Text("Hello world"),
+        title: Text(PageName.PAINTING),
       ),
       body: SingleChildScrollView(
         child: Column(