Fix ExpansionTile properties cannot be updated with setState

[TahaTesser]

fixes ExpansionTile properties aren't updated with setState

Code sample

expand to view the code sample

import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Example(),
    );
  }
}

class Example extends StatefulWidget {
  const Example({super.key});

  @override
  State<Example> createState() => _ExampleState();
}

class _ExampleState extends State<Example> {
  ShapeBorder collapsedShape = const RoundedRectangleBorder(
    borderRadius: BorderRadius.all(Radius.circular(4)),
  );
  Color collapsedTextColor = const Color(0xffffffff);
  Color collapsedBackgroundColor = const Color(0xffff0000);
  Color collapsedIconColor = const Color(0xffffffff);
  ShapeBorder shape = const RoundedRectangleBorder(
    borderRadius: BorderRadius.all(Radius.circular(16)),
  );
  Color backgroundColor = const Color(0xffff0000);
  Color textColor = const Color(0xffffffff);
  Color iconColor = const Color(0xffffffff);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Padding(
          padding: const EdgeInsets.symmetric(horizontal: 16.0),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              ExpansionTile(
                shape: shape,
                backgroundColor: backgroundColor,
                textColor: textColor,
                iconColor: iconColor,
                collapsedShape: collapsedShape,
                collapsedTextColor: collapsedTextColor,
                collapsedBackgroundColor: collapsedBackgroundColor,
                collapsedIconColor: collapsedIconColor,
                title: const Text('Collapsed ExpansionTile'),
                children: const [
                  ListTile(
                    title: Text('Revealed!'),
                  ),
                ],
              ),
              const SizedBox(height: 16),
              ExpansionTile(
                shape: shape,
                backgroundColor: backgroundColor,
                textColor: textColor,
                iconColor: iconColor,
                initiallyExpanded: true,
                title: const Text('Expanded ExpansionTile'),
                children: const [
                  ListTile(
                    title: Text('Revealed!'),
                  ),
                ],
              ),
              const SizedBox(height: 16),
              FilledButton(
                onPressed: () {
                  setState(() {
                    collapsedShape = const RoundedRectangleBorder(
                      borderRadius: BorderRadius.all(Radius.circular(50)),
                    );
                    collapsedTextColor = const Color(0xfff00000);
                    collapsedBackgroundColor = const Color(0xffffff00);
                    collapsedIconColor = const Color(0xfff00000);

                    shape = const RoundedRectangleBorder();
                    backgroundColor = const Color(0xfffff000);
                    textColor = const Color(0xfff00000);
                    iconColor = const Color(0xfff00000);
                  });
                },
                child: const Text('Update properties'),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

Before

before.mov

After

after.mov

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene wiki page, which explains my responsibilities.
• I read and followed the Flutter Style Guide, including Features we expect every widget to implement.
• I signed the CLA.
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is test-exempt.
• All existing and new tests are passing.

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[HansMuller]

This parameter isn't used, but presumably it should be?

[TahaTesser]

Great catch, it should be only expansionTileTheme and themeData fallback

flutter/packages/flutter/lib/src/material/expansion_tile.dart

Lines 686 to 689 in e308722

	?? expansionTileTheme.shape
	?? Border(
	top: BorderSide(color: theme.dividerColor),
	bottom: BorderSide(color: theme.dividerColor),

[HansMuller]

LGTM