improved thumbnail widget structure

lib/widgets/album/thumbnail.dart

@@ -7,7 +7,7 @@ import 'package:aves/widgets/common/icons.dart';
 import 'package:flutter/material.dart';
 import 'package:transparent_image/transparent_image.dart';
 
-class Thumbnail extends StatefulWidget {
+class Thumbnail extends StatelessWidget {
   final ImageEntry entry;
   final double extent;
   final double devicePixelRatio;
@@ -20,10 +20,71 @@ class Thumbnail extends StatefulWidget {
   }) : super(key: key);
 
   @override
-  ThumbnailState createState() => ThumbnailState();
+  Widget build(BuildContext context) {
+    return Container(
+      decoration: BoxDecoration(
+        border: Border.all(
+          color: Colors.grey.shade700,
+          width: 0.5,
+        ),
+      ),
+      child: Stack(
+        alignment: AlignmentDirectional.bottomStart,
+        children: [
+          ThumbnailImage(
+            entry: entry,
+            extent: extent,
+            devicePixelRatio: devicePixelRatio,
+          ),
+          _buildOverlayIcons(),
+        ],
+      ),
+    );
+  }
+
+  Widget _buildOverlayIcons() {
+    final fontSize = min(14.0, (extent / 8).roundToDouble());
+    final iconSize = fontSize * 2;
+    return DefaultTextStyle(
+      style: TextStyle(
+        color: Colors.grey[200],
+        fontSize: fontSize,
+      ),
+      child: Column(
+        mainAxisAlignment: MainAxisAlignment.end,
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          if (entry.hasGps) GpsIcon(iconSize: iconSize),
+          if (entry.isGif)
+            GifIcon(iconSize: iconSize)
+          else if (entry.isVideo)
+            VideoIcon(
+              entry: entry,
+              iconSize: iconSize,
+            ),
+        ],
+      ),
+    );
+  }
 }
 
-class ThumbnailState extends State<Thumbnail> {
+class ThumbnailImage extends StatefulWidget {
+  final ImageEntry entry;
+  final double extent;
+  final double devicePixelRatio;
+
+  const ThumbnailImage({
+    Key key,
+    @required this.entry,
+    @required this.extent,
+    @required this.devicePixelRatio,
+  }) : super(key: key);
+
+  @override
+  State<StatefulWidget> createState() => ThumbnailImageState();
+}
+
+class ThumbnailImageState extends State<ThumbnailImage> {
   Future<Uint8List> _byteLoader;
   Listenable _entryChangeNotifier;
 
@@ -40,7 +101,7 @@ class ThumbnailState extends State<Thumbnail> {
   }
 
   @override
-  void didUpdateWidget(Thumbnail oldWidget) {
+  void didUpdateWidget(ThumbnailImage oldWidget) {
     super.didUpdateWidget(oldWidget);
     if (widget.extent == oldWidget.extent && uri == oldWidget.entry.uri && widget.entry.width == oldWidget.entry.width && widget.entry.height == oldWidget.entry.height && widget.entry.orientationDegrees == oldWidget.entry.orientationDegrees) return;
     initByteLoader();
@@ -61,84 +122,24 @@ class ThumbnailState extends State<Thumbnail> {
 
   @override
   Widget build(BuildContext context) {
-    final fontSize = min(14.0, (widget.extent / 8).roundToDouble());
+    return FutureBuilder(
-    final iconSize = fontSize * 2;
-    return DefaultTextStyle(
-      style: TextStyle(
-        color: Colors.grey[200],
-        fontSize: fontSize,
-      ),
-      child: Container(
-        decoration: BoxDecoration(
-          border: Border.all(
-            color: Colors.grey.shade700,
-            width: 0.5,
-          ),
-        ),
-        child: FutureBuilder(
         future: _byteLoader,
         builder: (futureContext, AsyncSnapshot<Uint8List> snapshot) {
           final bytes = (snapshot.connectionState == ConnectionState.done && !snapshot.hasError) ? snapshot.data : kTransparentImage;
-              return ThumbnailImage(entry: entry, bytes: bytes, iconSize: iconSize);
+          return bytes.length > 0
-            }),
+              ? Hero(
-      ),
-    );
-  }
-}
-
-class ThumbnailImage extends StatelessWidget {
-  final Uint8List bytes;
-  final ImageEntry entry;
-  final double iconSize;
-
-  const ThumbnailImage({
-    Key key,
-    @required this.bytes,
-    @required this.entry,
-    @required this.iconSize,
-  }) : super(key: key);
-
-  @override
-  Widget build(BuildContext context) {
-    return Stack(
-      alignment: AlignmentDirectional.bottomStart,
-      children: [
-        Hero(
                   tag: entry.uri,
                   child: LayoutBuilder(builder: (context, constraints) {
-            // during hero animation back from a fullscreen image,
-            // the image covers the whole screen (because of the 'fit' prop and the full screen hero constraints)
-            // so we wrap the image to apply better constraints
                     final dim = min(constraints.maxWidth, constraints.maxHeight);
-            return Container(
+                    return Image.memory(
-              alignment: Alignment.center,
-              constraints: BoxConstraints.tight(Size(dim, dim)),
-              child: bytes.length > 0
-                  ? Image.memory(
                       bytes,
                       width: dim,
                       height: dim,
                       fit: BoxFit.cover,
-                    )
-                  : Icon(Icons.error),
                     );
                   }),
-        ),
+                )
-        Column(
+              : Icon(Icons.error);
-          mainAxisAlignment: MainAxisAlignment.end,
+        });
-          crossAxisAlignment: CrossAxisAlignment.start,
-          children: [
-            if (entry.hasGps) GpsIcon(iconSize: iconSize),
-            if (entry.isGif)
-              GifIcon(iconSize: iconSize)
-            else if (entry.isVideo)
-              VideoIcon(
-                entry: entry,
-                iconSize: iconSize,
-              ),
-          ],
-        ),
-      ],
-    );
   }
 }