Button in Flutter deactivates with a delay?

General
1

I have programmed a page in Flutter. You can use two arrows (elevated buttons) to control which list element should be displayed. If the first element is reached, the left arrow should be hidden. If the last element is reached, the right button should be hidden. This also works to some extent. You can no longer press the button directly, but the color change to gray is delayed, which is particularly annoying if you want to look through a picture gallery, for example. Unfortunately, I can’t figure out why.

import 'package:flutter/material.dart';


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


  @override
  State<ButtonProblem> createState() => _ButtonProblemState();
}


class _ButtonProblemState extends State<ButtonProblem> {
  late int currentIndex;
  late List<int> list;
  @override
  void initState() {
    super.initState();
    //Liste zum durchgehen
    list = [0, 1, 2, 3, 4, 5, 6];
    currentIndex = 0;
  }


  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Button Problem'),
        backgroundColor: Colors.blue,
        foregroundColor: Colors.white,
      ),
      body: Column(children: [
        SizedBox(
          height: 20,
        ),
        Text("currentIndex: ${currentIndex.toString()}"),
        Text("current list item: ${list[currentIndex].toString()}"),
        SizedBox(
          height: 20,
        ),
        Row(
          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
          children: [
            ElevatedButton(
              onPressed: currentIndex > 0 ? () => navigateToPrevious() : null,
              style: ElevatedButton.styleFrom(
                primary: Colors.blue,
                minimumSize: const Size(150, 50),
              ),
              child: const Icon(Icons.arrow_back, color: Colors.white),
            ),
            ElevatedButton(
              onPressed: (currentIndex < list.length - 1)
                  ? () => navigateToNext()
                  : null,
              style: ElevatedButton.styleFrom(
                primary: Colors.blue,
                minimumSize: const Size(150, 50),
              ),
              child: Icon(Icons.arrow_forward, color: Colors.white),
            ),
          ],
        ),
      ]),
    );
  }


  navigateToPrevious() {
    setState(() {
      currentIndex--;
    });
  }


  navigateToNext() {
    setState(() {
      currentIndex++;
    });
  }
}

I have tried to use the IgnorePointer widget, but that also didn’t help.

Would be grateful for any help :slight_smile:

2

It sounds like the issue you’re facing with delayed button color change in your Flutter app is due to the fact that you’re using ElevatedButton.styleFrom() to define the button’s style, and that doesn’t immediately reflect the button’s disabled state. When a button is disabled (i.e., onPressed is null), its style properties (like the background color) should also update accordingly, but there may be a lag in that response with your current setup.

Possible Solutions:

1. Use ButtonStyle for better control:

Instead of ElevatedButton.styleFrom(), you can use ButtonStyle directly to gain more precise control over the button’s appearance, especially for when it’s disabled. This way, the color will instantly change when the button is disabled.

You can update your code as follows:

import 'package:flutter/material.dart';

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

  @override
  State<ButtonProblem> createState() => _ButtonProblemState();
}

class _ButtonProblemState extends State<ButtonProblem> {
  late int currentIndex;
  late List<int> list;

  @override
  void initState() {
    super.initState();
    // List to navigate through
    list = [0, 1, 2, 3, 4, 5, 6];
    currentIndex = 0;
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Button Problem'),
        backgroundColor: Colors.blue,
        foregroundColor: Colors.white,
      ),
      body: Column(
        children: [
          const SizedBox(height: 20),
          Text("Current Index: ${currentIndex.toString()}"),
          Text("Current List Item: ${list[currentIndex].toString()}"),
          const SizedBox(height: 20),
          Row(
            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
            children: [
              ElevatedButton(
                onPressed: currentIndex > 0 ? navigateToPrevious : null,
                style: ButtonStyle(
                  backgroundColor: MaterialStateProperty.resolveWith<Color>(
                    (Set<MaterialState> states) {
                      if (states.contains(MaterialState.disabled)) {
                        return Colors.grey; // Disabled button color
                      }
                      return Colors.blue; // Regular button color
                    },
                  ),
                  minimumSize: MaterialStateProperty.all(const Size(150, 50)),
                ),
                child: const Icon(Icons.arrow_back, color: Colors.white),
              ),
              ElevatedButton(
                onPressed: currentIndex < list.length - 1 ? navigateToNext : null,
                style: ButtonStyle(
                  backgroundColor: MaterialStateProperty.resolveWith<Color>(
                    (Set<MaterialState> states) {
                      if (states.contains(MaterialState.disabled)) {
                        return Colors.grey; // Disabled button color
                      }
                      return Colors.blue; // Regular button color
                    },
                  ),
                  minimumSize: MaterialStateProperty.all(const Size(150, 50)),
                ),
                child: const Icon(Icons.arrow_forward, color: Colors.white),
              ),
            ],
          ),
        ],
      ),
    );
  }

  void navigateToPrevious() {
    setState(() {
      currentIndex--;
    });
  }

  void navigateToNext() {
    setState(() {
      currentIndex++;
    });
  }
}

Key Changes:

  • I used ButtonStyle with MaterialStateProperty.resolveWith<Color> to control the background color of the buttons based on their states (enabled or disabled). This ensures the button color immediately reflects when it’s disabled.
  • You can adjust the colors if you prefer different ones for the disabled state.

2. Consider Using setState to Rebuild Immediately

In some cases, the issue can also be related to the timing of how the UI rebuilds. Using setState as you’re already doing should trigger an immediate rebuild, but you could ensure there’s no delay by confirming that your Flutter version is up to date and using stable or recommended versions for ElevatedButton.

Final Words:

This updated approach should fix the delay in button state changes by directly controlling the button’s color based on its enabled/disabled state using ButtonStyle. Let me know if this works for you or if you need further clarification!