fix text color not true in title.

example/lib/main.dart

       /// The following are optional parameters.
       themeColor: Colors.green,
       // the title color and bottom color
+
+      textColor: Colors.white,
+      // text color
       padding: 1.0,
       // item padding
       dividerColor: Colors.grey,
       // i18n provider ,default is chinese. , you can custom I18nProvider or use ENProvider()
       rowCount: 3,
       // item row count
-      textColor: Colors.white,
-      // text color
+
       thumbSize: 150,
       // preview thumb size , default is 64
       sortDelegate: SortDelegate.common,
       checkBoxBuilderDelegate: DefaultCheckBoxBuilderDelegate(
         activeColor: Colors.white,
         unselectedColor: Colors.white,
+        checkColor: Colors.green,
       ),
       // default is DefaultCheckBoxBuilderDelegate ,or you make custom delegate to create checkbox
 

example/lib/preview.dart

   Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(
-        title: Text("预览"),
+        title: Text("Preview"),
       ),
       body: ListView(
         children: list

lib/src/delegate/checkbox_builder_delegate.dart

 class DefaultCheckBoxBuilderDelegate extends CheckBoxBuilderDelegate {
   Color activeColor;
   Color unselectedColor;
+  Color checkColor;
 
   DefaultCheckBoxBuilderDelegate({
     this.activeColor = Colors.white,
     this.unselectedColor = Colors.white,
+    this.checkColor = Colors.black,
   });
 
   @override
         value: checked,
         onChanged: (bool check) {},
         activeColor: activeColor,
-        checkColor: Colors.red,
+        checkColor: checkColor,
         title: Text(
           i18nProvider.getSelectedOptionsText(options),
           textAlign: TextAlign.end,

lib/src/ui/page/photo_main_page.dart

         child: Scaffold(
           appBar: AppBar(
             leading: IconButton(
-              icon: Icon(Icons.close),
+              icon: Icon(
+                Icons.close,
+                color: options.textColor,
+              ),
               onPressed: _cancel,
             ),
             title: Text(
               i18nProvider.getTitleText(options),
+              style: TextStyle(
+                color: options.textColor,
+              ),
             ),
             actions: <Widget>[
               FlatButton(

lib/src/ui/page/photo_preview_page.dart

 
   @override
   Widget build(BuildContext context) {
+    var data = Theme.of(context);
     var textStyle = TextStyle(
       color: options.textColor,
       fontSize: 14.0,
     );
     return Theme(
-      data: Theme.of(context).copyWith(primaryColor: options.themeColor),
+      data: data.copyWith(
+        primaryColor: options.themeColor,
+      ),
       child: Scaffold(
         appBar: AppBar(
           backgroundColor: config.options.themeColor,
+          leading: BackButton(
+            color: options.textColor,
+          ),
           title: StreamBuilder(
             stream: pageStream,
             initialData: widget.initIndex,
             builder: (ctx, snap) => Text(
                   "${snap.data + 1}/${widget.list.length}",
+                  style: TextStyle(
+                    color: options.textColor,
+                  ),
                 ),
           ),
           actions: <Widget>[

pubspec.lock

       name: async
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.2.0"
+    version: "2.1.0"
   boolean_selector:
     dependency: transitive
     description:
   photo_manager:
     dependency: "direct main"
     description:
-      path: "../flutter_photo_manager"
-      relative: true
-    source: path
+      name: photo_manager
+      url: "https://pub.flutter-io.cn"
+    source: hosted
     version: "0.3.4"
   quiver:
     dependency: transitive
       name: quiver
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.0.3"
+    version: "2.0.2"
   sky_engine:
     dependency: transitive
     description: flutter
       name: test_api
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.2.5"
+    version: "0.2.4"
   typed_data:
     dependency: transitive
     description: