Initial commit

lib/widgets/blur_hash.dart

@@ -0,0 +1,91 @@
+// SPDX-FileCopyrightText: 2019-Present Christian Kußowski
+// SPDX-FileCopyrightText: 2019-Present Contributors to FluffyChat
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import 'package:blurhash_dart/blurhash_dart.dart' as b;
+import 'package:flutter/foundation.dart';
+import 'package:image/image.dart' as image;
+import 'package:material_ui/material_ui.dart';
+
+class BlurHash extends StatefulWidget {
+  final double width;
+  final double height;
+  final String blurhash;
+  final BoxFit fit;
+
+  const BlurHash({
+    super.key,
+    String? blurhash,
+    required this.width,
+    required this.height,
+    this.fit = BoxFit.cover,
+  }) : blurhash = blurhash ?? 'LEHV6nWB2yk8pyo0adR*.7kCMdnj';
+
+  @override
+  State<BlurHash> createState() => _BlurHashState();
+}
+
+class _BlurHashState extends State<BlurHash> {
+  Uint8List? _data;
+
+  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 {
+    if (_data != null) return _data!;
+    final ratio = widget.width / widget.height;
+    var width = 32;
+    var height = 32;
+    if (ratio > 1.0) {
+      height = (width / ratio).round();
+    } else {
+      width = (height * ratio).round();
+    }
+
+    return _data ??= await compute(
+      getBlurhashData,
+      BlurhashData(hsh: widget.blurhash, w: width, h: height),
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return FutureBuilder<Uint8List?>(
+      future: _computeBlurhashData(),
+      initialData: _data,
+      builder: (context, snapshot) {
+        final data = snapshot.data;
+        if (data == null) {
+          return Container(
+            width: widget.width,
+            height: widget.height,
+            color: Theme.of(context).colorScheme.onInverseSurface,
+          );
+        }
+        return Image.memory(
+          data,
+          fit: widget.fit,
+          width: widget.width,
+          height: widget.height,
+        );
+      },
+    );
+  }
+}
+
+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};
+}