新增自适应标题

lib/components/fit_text.dart

@@ -0,0 +1,61 @@
+import "package:flutter/material.dart";
+
+class FitText extends StatefulWidget {
+  const FitText({
+    Key? key,
+    required this.texts,
+    this.style,
+    this.separator = " ",
+  }) : super(key: key);
+  final List<(String, int)> texts;
+  final TextStyle? style;
+  final String separator;
+
+  @override
+  State<FitText> createState() => _FitText();
+}
+
+class _FitText extends State<FitText> {
+  late List<String> texts;
+  late List<double> sizes;
+
+  Size _textSize(String text, TextStyle? style) {
+    final TextPainter textPainter = TextPainter(
+        text: TextSpan(text: text, style: style),
+        maxLines: 1,
+        textDirection: TextDirection.ltr)
+      ..layout(minWidth: 0, maxWidth: double.infinity);
+    return textPainter.size;
+  }
+
+  @override
+  void initState() {
+    super.initState();
+    final tmp = widget.texts.map((e) => e.$2).toSet().toList()
+      ..sort((b, a) => a.compareTo(b));
+    sizes = [];
+    texts = [];
+    for (final i in tmp) {
+      final text = widget.texts
+          .where((e) => e.$2 >= i)
+          .map((e) => e.$1)
+          .join(widget.separator);
+      texts.add(text);
+      sizes.add(_textSize(text, widget.style).width);
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    if (texts.isEmpty) return Container();
+    return LayoutBuilder(builder: (context, constraints) {
+      final double maxWidth = constraints.maxWidth;
+      for (int i = sizes.length - 1; i >= 0; i--) {
+        if (sizes[i] <= maxWidth) {
+          return Text(texts[i], style: widget.style);
+        }
+      }
+      return Text(texts[0], style: widget.style);
+    });
+  }
+}

lib/viewer/single.dart

@@ -12,6 +12,7 @@ import 'package:photo_view/photo_view.dart';
 import 'package:photo_view/photo_view_gallery.dart';
 import '../api/file.dart';
 import '../api/gallery.dart';
+import '../components/fit_text.dart';
 import '../globals.dart';
 
 final _log = Logger("SinglePageViewer");
@@ -191,6 +192,7 @@ class _SinglePageViewer extends State<SinglePageViewer>
 
   Widget _buildTopAppBar(BuildContext context) {
     if (!_showMenu) return Container();
+    final theme = Theme.of(context);
     return Positioned(
         top: 0,
         left: 0,
@@ -201,8 +203,14 @@ class _SinglePageViewer extends State<SinglePageViewer>
                   context.canPop() ? context.pop() : context.go(_back);
                 },
                 icon: const Icon(Icons.close)),
-            title:
+            title: FitText(
-                Text("${_data!.meta.preferredTitle} - ${_pages![_index].name}"),
+                texts: [
+                  (_data!.meta.preferredTitle, 0),
+                  (_pages![_index].name, 1)
+                ],
+                style: theme.appBarTheme.titleTextStyle ??
+                    theme.textTheme.titleLarge,
+                separator: " - "),
             actions: [
               buildThemeModeIcon(context),
               buildMoreVertSettingsButon(context),