From 3a37f1a35f2c06def9bd2c2ab025e8fc53a58db1 Mon Sep 17 00:00:00 2001
From: Vishnu Mohandas <vishnumohandas@gmail.com>
Date: Fri, 24 Apr 2020 23:04:46 +0530
Subject: [PATCH] Extract zoomable image into a separate file

---
 lib/ui/detail_page.dart    | 52 ++--------------------------
 lib/ui/zoomable_image.dart | 70 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+), 50 deletions(-)
 create mode 100644 lib/ui/zoomable_image.dart

diff --git a/lib/ui/detail_page.dart b/lib/ui/detail_page.dart
index 997526404..eada570b7 100644
--- a/lib/ui/detail_page.dart
+++ b/lib/ui/detail_page.dart
@@ -1,12 +1,9 @@
-import 'dart:typed_data';
-
 import 'package:flutter/material.dart';
 import 'package:logger/logger.dart';
 import 'package:myapp/core/lru_map.dart';
 import 'package:myapp/models/photo.dart';
-import 'package:photo_view/photo_view.dart';
+import 'package:myapp/ui/zoomable_image.dart';
 import 'extents_page_view.dart';
-import 'loading_widget.dart';
 import 'package:myapp/utils/share_util.dart';
 
 class DetailPage extends StatefulWidget {
@@ -40,7 +37,7 @@ class _DetailPageState extends State<DetailPage> {
                 return _cachedImages.get(index);
               }
               final image = ZoomableImage(
-                photo: widget.photos[index],
+                widget.photos[index],
                 shouldDisableScroll: (value) {
                   setState(() {
                     _shouldDisableScroll = value;
@@ -77,48 +74,3 @@ class _DetailPageState extends State<DetailPage> {
     );
   }
 }
-
-class ZoomableImage extends StatelessWidget {
-  final Function(bool) shouldDisableScroll;
-
-  const ZoomableImage({
-    Key key,
-    @required this.photo,
-    this.shouldDisableScroll,
-  }) : super(key: key);
-
-  final Photo photo;
-
-  @override
-  Widget build(BuildContext context) {
-    Logger().i("Building " + photo.toString());
-    if (ImageLruCache.getData(photo.generatedId) != null) {
-      return _buildPhotoView(ImageLruCache.getData(photo.generatedId));
-    }
-    return FutureBuilder<Uint8List>(
-      future: photo.getBytes(),
-      builder: (_, snapshot) {
-        if (snapshot.hasData) {
-          return _buildPhotoView(snapshot.data);
-        } else if (snapshot.hasError) {
-          return Text(snapshot.error.toString());
-        } else {
-          return loadWidget;
-        }
-      },
-    );
-  }
-
-  Widget _buildPhotoView(Uint8List imageData) {
-    ValueChanged<PhotoViewScaleState> scaleStateChangedCallback = (value) {
-      if (shouldDisableScroll != null) {
-        shouldDisableScroll(value != PhotoViewScaleState.initial);
-      }
-    };
-    return PhotoView(
-      imageProvider: Image.memory(imageData).image,
-      scaleStateChangedCallback: scaleStateChangedCallback,
-      minScale: PhotoViewComputedScale.contained,
-    );
-  }
-}
diff --git a/lib/ui/zoomable_image.dart b/lib/ui/zoomable_image.dart
new file mode 100644
index 000000000..e2ed656b9
--- /dev/null
+++ b/lib/ui/zoomable_image.dart
@@ -0,0 +1,70 @@
+import 'dart:typed_data';
+
+import 'package:flutter/widgets.dart';
+import 'package:logger/logger.dart';
+import 'package:myapp/core/lru_map.dart';
+import 'package:myapp/models/photo.dart';
+import 'package:myapp/ui/image_widget.dart';
+import 'package:myapp/ui/loading_widget.dart';
+import 'package:photo_view/photo_view.dart';
+
+class WidgetLruCache {
+  static LRUMap<int, Widget> _map = LRUMap(500);
+
+  static Widget get(Photo photo) {
+    return _map.get(photo.generatedId);
+  }
+
+  static void put(Photo photo, Widget data) {
+    _map.put(photo.generatedId, data);
+  }
+}
+
+class ZoomableImage extends StatelessWidget {
+  final Function(bool) shouldDisableScroll;
+
+  const ZoomableImage(
+    this.photo, {
+    Key key,
+    this.shouldDisableScroll,
+  }) : super(key: key);
+
+  final Photo photo;
+
+  @override
+  Widget build(BuildContext context) {
+    Logger().i("Building " + photo.toString());
+    if (WidgetLruCache.get(photo) != null) {
+      return WidgetLruCache.get(photo);
+    }
+    Logger().i("Cache miss " + photo.toString());
+    return FutureBuilder<Uint8List>(
+      future: photo.getBytes(),
+      builder: (_, snapshot) {
+        if (snapshot.hasData) {
+          final photoView = _buildPhotoView(snapshot.data);
+          WidgetLruCache.put(photo, photoView);
+          return photoView;
+        } else if (snapshot.hasError) {
+          return Text(snapshot.error.toString());
+        } else {
+          Logger().i("Loading");
+          return ImageWidget(photo);
+        }
+      },
+    );
+  }
+
+  Widget _buildPhotoView(Uint8List imageData) {
+    ValueChanged<PhotoViewScaleState> scaleStateChangedCallback = (value) {
+      if (shouldDisableScroll != null) {
+        shouldDisableScroll(value != PhotoViewScaleState.initial);
+      }
+    };
+    return PhotoView(
+      imageProvider: Image.memory(imageData).image,
+      scaleStateChangedCallback: scaleStateChangedCallback,
+      minScale: PhotoViewComputedScale.contained,
+    );
+  }
+}