add a setting for original image

lib/pages/illust_page.dart

@@ -318,6 +318,10 @@ class _IllustPageState extends State<IllustPage> {
     }
     Widget image;
 
+    var imageUrl = appdata.settings["showOriginalImage"]
+        ? widget.illust.images[index].original
+        : widget.illust.images[index].large;
+
     if (!widget.illust.isUgoira) {
       image = SizedBox(
         width: imageWidth,
@@ -327,8 +331,7 @@ class _IllustPageState extends State<IllustPage> {
           child: Image(
               key: ValueKey(index),
               image: downloadFile == null
-                  ? CachedImageProvider(widget.illust.images[index].large)
-                      as ImageProvider
+                  ? CachedImageProvider(imageUrl) as ImageProvider
                   : FileImage(downloadFile) as ImageProvider,
               width: imageWidth,
               fit: BoxFit.cover,

lib/pages/settings_page.dart

@@ -252,6 +252,16 @@ class _SettingsPageState extends State<SettingsPage> {
                   context.to(() => const ShortcutsSettings());
                 },
               )),
+          buildItem(
+              title: "Display the original image on the details page".tl,
+              action: ToggleSwitch(
+                  checked: appdata.settings['showOriginalImage'],
+                  onChanged: (value) {
+                    setState(() {
+                      appdata.settings['showOriginalImage'] = value;
+                    });
+                    appdata.writeData();
+                  })),
         ],
       ),
     );