fix asset AspectRatio

lib/photo.dart

   static Widget buildGallery({
     @required BuildContext context,
     double padding = 1,
-    double itemHeight,
-    @required double itemWidth,
     int thumbSize = 180,
+    double itemRadio = 1.0,
     PhotoTheme theme,
     I18nProvider provider = I18nProvider.chinese,
     SortDelegate sortDelegate,
 
     var options = ListOptions(
       padding: padding,
-      itemHeight: itemHeight,
-      itemWidth: itemWidth,
+      itemRadio: itemRadio,
       theme: theme ?? PhotoTheme.fallback(context),
       thumbSize: thumbSize,
       sortDelegate: sortDelegate,

lib/src/entity/options.dart

 
 class ListOptions extends Options {
 
-  final double itemWidth;
-
-  final double itemHeight;
-
   final Axis scrollDirection;
 
   const ListOptions({
-    this.itemHeight = double.infinity,
-    this.itemWidth,
     this.scrollDirection = Axis.horizontal,
+    double itemRadio,
     int maxSelected,
     double padding,
     PhotoTheme theme,
   }) : super(
     maxSelected: maxSelected,
     padding: padding,
+    itemRadio: itemRadio,
     theme: theme,
     thumbSize: thumbSize,
     sortDelegate: sortDelegate,

lib/src/ui/page/photo_list_page.dart

       scrollDirection: options.scrollDirection,
       physics: ClampingScrollPhysics(),
       itemCount: count,
-      itemExtent: options.itemWidth,
       itemBuilder: _buildItem,
     );
   }
           onTap: () => _onItemClick(data, index),
           child: Stack(
             children: <Widget>[
-              ImageItem(
-                entity: data,
-                themeColor: options.theme.primaryColor,
-                size: options.thumbSize,
-                loadingDelegate: options.loadingDelegate,
-                badgeDelegate: options.badgeDelegate,
+              AspectRatio(
+                aspectRatio: options.itemRadio,
+                child: ImageItem(
+                  entity: data,
+                  themeColor: options.theme.primaryColor,
+                  size: options.thumbSize,
+                  loadingDelegate: options.loadingDelegate,
+                  badgeDelegate: options.badgeDelegate,
+                ),
               ),
               _buildMask(containsEntity(data)),
               _buildSelected(data),