improved performance and battery usage on older devices

lib/widget/prosemirror/pm_json_view.dart

@@ -1,9 +1,9 @@
-import 'package:cached_network_image/cached_network_image.dart';
 import 'package:collection/collection.dart';
 import 'package:flutter/material.dart';
 
 import '../app_progress_indicator.dart';
 import 'pm_document_view.dart';
+import 'pm_image_view.dart';
 import 'pm_node.dart';
 
 /// Renders raw ProseMirror JSON and memoises the parsed tree across rebuilds.
@@ -31,7 +31,7 @@ class PmJsonView extends StatefulWidget {
 class _PmJsonViewState extends State<PmJsonView> {
   PmNode? _shown;
   PmNode? _pending;
-  List<ImageProvider> _pendingProviders = const [];
+  List<PmImage> _pendingImages = const [];
   bool _precacheStarted = false;
   int _generation = 0;
 
@@ -62,17 +62,17 @@ class _PmJsonViewState extends State<PmJsonView> {
 
   void _parse() {
     final doc = PmNode.fromJson(widget.json);
-    final providers = <ImageProvider>[];
-    _collectProviders(doc, providers);
+    final images = <PmImage>[];
+    _collectImages(doc, images);
     _generation++;
     _precacheStarted = false;
-    if (providers.isEmpty) {
+    if (images.isEmpty) {
       _shown = doc;
       _pending = null;
-      _pendingProviders = const [];
+      _pendingImages = const [];
     } else {
       _pending = doc;
-      _pendingProviders = providers;
+      _pendingImages = images;
     }
   }
 
@@ -82,8 +82,9 @@ class _PmJsonViewState extends State<PmJsonView> {
     _precacheStarted = true;
     final generation = _generation;
     Future.wait([
-          for (final provider in _pendingProviders)
-            precacheImage(provider, context, onError: (_, _) {}),
+          for (final image in _pendingImages)
+            if (PmImageView.inlineProvider(context, image) case final provider?)
+              precacheImage(provider, context, onError: (_, _) {}),
         ])
         .timeout(PmJsonView.precacheTimeout, onTimeout: () => const [])
         .whenComplete(() {
@@ -91,23 +92,16 @@ class _PmJsonViewState extends State<PmJsonView> {
             setState(() {
               _shown = pending;
               _pending = null;
-              _pendingProviders = const [];
+              _pendingImages = const [];
             });
           }
         });
   }
 
-  void _collectProviders(PmNode node, List<ImageProvider> out) {
-    if (node is PmImage) {
-      final bytes = node.bytes;
-      if (bytes != null) {
-        out.add(MemoryImage(bytes));
-      } else if (node.src.startsWith('http')) {
-        out.add(CachedNetworkImageProvider(node.src));
-      }
-    }
+  void _collectImages(PmNode node, List<PmImage> out) {
+    if (node is PmImage) out.add(node);
     for (final child in node.children) {
-      _collectProviders(child, out);
+      _collectImages(child, out);
     }
   }