提交：修改图片展示逻辑；

lib/widget/state_layout.dart

@@ -62,7 +62,9 @@ class _StateLayoutState extends State<StateLayout> {
       crossAxisAlignment: CrossAxisAlignment.center,
       mainAxisAlignment: MainAxisAlignment.center,
       children: <Widget>[
-        Opacity(
+        Offstage(
+          offstage: widget.img!.isEmpty,
+          child: Opacity(
             opacity: 1,
             child: Container(
               height: 120.0,
@@ -72,7 +74,9 @@ class _StateLayoutState extends State<StateLayout> {
                   image: ImageUtils.getAssetImage(img),
                 ),
               ),
-            )),
+            ),
+          ),
+        ),
         const SizedBox(
           height: 16.0,
         ),