improved performance and battery usage on older devices

lib/widget/prosemirror/pm_image_view.dart

@@ -10,9 +10,33 @@ class PmImageView extends StatelessWidget {
 
   const PmImageView({required this.node, super.key});
 
+  /// Full-resolution source, used for the zoomable fullscreen view.
+  static ImageProvider? sourceProvider(PmImage node) {
+    final bytes = node.bytes;
+    if (bytes != null) return MemoryImage(bytes);
+    if (node.src.startsWith('http')) {
+      return CachedNetworkImageProvider(node.src);
+    }
+    return null;
+  }
+
+  /// Inline images never render wider than the screen, so they are decoded at
+  /// most at its physical width instead of the (often camera-sized) original.
+  /// [PmJsonView] precaches through this too, so both hit the same cache key.
+  static ImageProvider? inlineProvider(BuildContext context, PmImage node) {
+    final source = sourceProvider(node);
+    if (source == null) return null;
+    final width =
+        (MediaQuery.sizeOf(context).width *
+                MediaQuery.devicePixelRatioOf(context))
+            .round();
+    return ResizeImage(source, width: width);
+  }
+
   @override
   Widget build(BuildContext context) {
-    final provider = _imageProvider();
+    final provider = sourceProvider(node);
+    final inline = inlineProvider(context, node);
     return LayoutBuilder(
       builder: (context, constraints) {
         final available = constraints.maxWidth.isFinite
@@ -22,7 +46,13 @@ class PmImageView extends StatelessWidget {
 
         Widget image = ConstrainedBox(
           constraints: BoxConstraints(maxWidth: targetWidth ?? available),
-          child: _imageWidget(context, provider),
+          child: inline == null
+              ? _brokenImage(context)
+              : Image(
+                  image: inline,
+                  errorBuilder: (context, error, stack) =>
+                      _brokenImage(context),
+                ),
         );
 
         final href = node.href;
@@ -43,30 +73,6 @@ class PmImageView extends StatelessWidget {
     );
   }
 
-  ImageProvider? _imageProvider() {
-    if (node.bytes != null) return MemoryImage(node.bytes!);
-    if (node.src.startsWith('http')) {
-      return CachedNetworkImageProvider(node.src);
-    }
-    return null;
-  }
-
-  Widget _imageWidget(BuildContext context, ImageProvider? provider) {
-    if (node.bytes != null) {
-      return Image.memory(
-        node.bytes!,
-        errorBuilder: (context, error, stack) => _brokenImage(context),
-      );
-    }
-    if (node.src.startsWith('http')) {
-      return CachedNetworkImage(
-        imageUrl: node.src,
-        errorWidget: (context, url, error) => _brokenImage(context),
-      );
-    }
-    return _brokenImage(context);
-  }
-
   Widget _brokenImage(BuildContext context) {
     final theme = Theme.of(context);
     return DecoratedBox(

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);
     }
   }