chore: Calc blurhash in other thread

lib/widgets/blur_hash.dart

@@ -1,5 +1,4 @@
-import 'dart:typed_data';
-
+import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 
 import 'package:blurhash_dart/blurhash_dart.dart' as b;
@@ -26,16 +25,29 @@ class BlurHash extends StatefulWidget {
 class _BlurHashState extends State<BlurHash> {
   Uint8List? _data;
 
-  Future<Uint8List> getBlurhashData() async {
-    final blurhash = b.BlurHash.decode(widget.blurhash);
-    final img = blurhash.toImage(widget.width.round(), widget.height.round());
-    return _data ??= Uint8List.fromList(image.encodePng(img));
+  static Future<Uint8List> getBlurhashData(
+    BlurhashData blurhashData,
+  ) async {
+    final blurhash = b.BlurHash.decode(blurhashData.hsh);
+    final img = blurhash.toImage(blurhashData.w, blurhashData.h);
+    return Uint8List.fromList(image.encodePng(img));
+  }
+
+  Future<Uint8List?> _computeBlurhashData() async {
+    return _data ??= await compute(
+      getBlurhashData,
+      BlurhashData(
+        hsh: widget.blurhash,
+        w: widget.width.round(),
+        h: widget.height.round(),
+      ),
+    );
   }
 
   @override
   Widget build(BuildContext context) {
-    return FutureBuilder<Uint8List>(
-      future: getBlurhashData(),
+    return FutureBuilder<Uint8List?>(
+      future: _computeBlurhashData(),
       builder: (context, snapshot) {
         final data = snapshot.data;
         if (data == null) {
@@ -55,3 +67,27 @@ class _BlurHashState extends State<BlurHash> {
     );
   }
 }
+
+class BlurhashData {
+  final String hsh;
+  final int w;
+  final int h;
+
+  const BlurhashData({
+    required this.hsh,
+    required this.w,
+    required this.h,
+  });
+
+  factory BlurhashData.fromJson(Map<String, dynamic> json) => BlurhashData(
+        hsh: json['hsh'],
+        w: json['w'],
+        h: json['h'],
+      );
+
+  Map<String, dynamic> toJson() => {
+        'hsh': hsh,
+        'w': w,
+        'h': h,
+      };
+}

lib/widgets/mxc_image.dart

@@ -130,8 +130,13 @@ class _MxcImageState extends State<MxcImage> {
     }
   }
 
+  bool _hasDataFromBeginning = false;
+
   void _tryLoad(_) async {
-    if (_imageData != null) return;
+    if (_imageData != null) {
+      _hasDataFromBeginning = true;
+      return;
+    }
     try {
       await _load();
     } catch (_) {
@@ -160,7 +165,7 @@ class _MxcImageState extends State<MxcImage> {
 
     return Stack(
       children: [
-        if (!hasData) placeholder(context),
+        if (!_hasDataFromBeginning) placeholder(context),
         AnimatedOpacity(
           opacity: hasData ? 1 : 0,
           duration: FluffyThemes.animationDuration,
@@ -171,7 +176,9 @@ class _MxcImageState extends State<MxcImage> {
                   width: widget.width,
                   height: widget.height,
                   fit: widget.fit,
-                  filterQuality: FilterQuality.medium,
+                  filterQuality: widget.isThumbnail
+                      ? FilterQuality.low
+                      : FilterQuality.medium,
                   errorBuilder: (context, __, ___) {
                     _isCached = false;
                     _imageData = null;