feat: theme logo (#15268)

* feat: theme logo

Signed-off-by: fufesou <linlong1266@gmail.com>

* perf(flutter): cache theme logo asset resolution

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

---------

Signed-off-by: fufesou <linlong1266@gmail.com>
Co-authored-by: RustDesk <71636191+rustdesk@users.noreply.github.com>
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

flutter/lib/common.dart

@@ -3713,14 +3713,54 @@ Widget loadPowered(BuildContext context) {
   ).marginOnly(top: 6);
 }
 
-// max 300 x 60
+const _kDefaultLogoAsset = 'assets/logo.png';
-Widget loadLogo() {
+const _kLightLogoAsset = 'assets/logo_light.png';
-  return FutureBuilder<ByteData>(
+const _kDarkLogoAsset = 'assets/logo_dark.png';
-      future: rootBundle.load('assets/logo.png'),
+
-      builder: (BuildContext context, AsyncSnapshot<ByteData> snapshot) {
+List<String> _logoAssetCandidatesForBrightness(Brightness brightness) {
-        if (snapshot.hasData) {
+  return brightness == Brightness.dark
+      ? [_kDarkLogoAsset, _kDefaultLogoAsset]
+      : [_kLightLogoAsset, _kDefaultLogoAsset];
+}
+
+Future<String?> _resolveLogoAsset(Brightness brightness) async {
+  for (final asset in _logoAssetCandidatesForBrightness(brightness)) {
+    try {
+      await rootBundle.load(asset);
+      return asset;
+    } on FlutterError {
+      continue;
+    }
+  }
+  return null;
+}
+
+class _Logo extends StatefulWidget {
+  const _Logo();
+
+  @override
+  State<_Logo> createState() => _LogoState();
+}
+
+class _LogoState extends State<_Logo> {
+  final Map<Brightness, Future<String?>> _logoFutures = {};
+
+  Future<String?> _logoFutureFor(Brightness brightness) {
+    return _logoFutures.putIfAbsent(
+      brightness,
+      () => _resolveLogoAsset(brightness),
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return FutureBuilder<String?>(
+      future: _logoFutureFor(Theme.of(context).brightness),
+      builder: (BuildContext context, AsyncSnapshot<String?> snapshot) {
+        final asset = snapshot.data;
+        if (asset != null) {
           final image = Image.asset(
-            'assets/logo.png',
+            asset,
             fit: BoxFit.contain,
             errorBuilder: (ctx, error, stackTrace) {
               return Container();
@@ -3732,9 +3772,14 @@ Widget loadLogo() {
           ).marginOnly(left: 12, right: 12, top: 12);
         }
         return const Offstage();
-      });
+      },
+    );
+  }
 }
 
+// max 300 x 60
+Widget loadLogo() => const _Logo();
+
 Widget loadIcon(double size) {
   return Image.asset('assets/icon.png',
       width: size,