fix checkbox check color no valid bug

example/lib/main.dart

       /// The following are optional parameters.
       themeColor: Colors.green, // the title color and bottom color
       padding: 1.0, // item padding
-      dividerColor: Colors.deepOrange, // divider color
+      dividerColor: Colors.grey, // divider color
       disableColor: Colors.grey.shade300, // the check box disable color
       itemRadio: 0.88, // the content item radio
       maxSelected: 8, // max picker image count
       sortDelegate: SortDelegate
           .common, // default is common ,or you make custom delegate to sort your gallery
       checkBoxBuilderDelegate:
-          DefaultCheckBoxBuilderDelegate(), // default is DefaultCheckBoxBuilderDelegate ,or you make custom delegate to create checkbox
+          DefaultCheckBoxBuilderDelegate(
+            activeColor: Colors.white,
+            unselectedColor: Colors.white,
+          ), // default is DefaultCheckBoxBuilderDelegate ,or you make custom delegate to create checkbox
     );
 
     if (imgList == null) {

lib/src/delegate/checkbox_builder_delegate.dart

         value: checked,
         onChanged: (bool check) {},
         activeColor: activeColor,
-        checkColor: unselectedColor,
+        checkColor: Colors.red,
         title: Text(
           i18nProvider.getSelectedOptionsText(options),
           textAlign: TextAlign.end,

lib/src/ui/page/photo_preview_page.dart

 
 class BigPhotoImage extends StatefulWidget {
   final ImageEntity imageEntity;
+  final Widget loadingWidget;
 
-  const BigPhotoImage({Key key, this.imageEntity}) : super(key: key);
+  const BigPhotoImage({
+    Key key,
+    this.imageEntity,
+    this.loadingWidget,
+  }) : super(key: key);
 
   @override
   _BigPhotoImageState createState() => _BigPhotoImageState();
 
 class _BigPhotoImageState extends State<BigPhotoImage>
     with AutomaticKeepAliveClientMixin {
+
+  Widget get loadingWidget{
+    return widget.loadingWidget ?? Container();
+  }
+
   @override
   Widget build(BuildContext context) {
     var width = MediaQuery.of(context).size.width;
             height: double.infinity,
           );
         }
-        return Container();
+        return loadingWidget;
       },
     );
   }

lib/src/ui/widget/check_tile_copy.dart

     final Widget control = Checkbox(
       value: value,
       onChanged: onChanged,
+      checkColor: checkColor,
       activeColor: activeColor,
       materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
     );