Flutter: animate text color

Question

I am trying to animate some text in my flutter app so that each word's color changes, one after the other - kind of like in karaoke:

I've been looking at packages like animated_text_kit but so far have not found a ready-made solution for this. Maybe there is one out there?

If not, how might I go about making this animation? Making a custom animation for animated_text_kit maybe?

Ideally the amount of time each word is highlighted would depend on the length of the word, too.

Edit: here is what I am trying so far - not the intended effect though.

  Widget textAnimated() {
    TextStyle style = TextStyle(
        fontSize: 18,
        height: 3.0,
    return Padding(
        padding: const EdgeInsets.only(left: 10, right: 10, top: 140),
        child: AnimatedTextKit(
          animatedTexts: [
            ColorizeAnimatedText("The quick brown fox jumps over the lazy dog.",
                textStyle: style, colors: [Colors.white, Colors.black])
          ],
        ));
  }

Answer 1

You can use this widget

  MyAnimatedText(
            sentence: "The quick brown fox jumps over the lazy dog.",
          )

MyAnimatedText widget

class MyAnimatedText extends StatefulWidget {
  final String sentence;

  const MyAnimatedText({
    Key? key,
    required this.sentence,
  }) : super(key: key);

  @override
  State<MyAnimatedText> createState() => _MyAnimatedTextState();
}

class _MyAnimatedTextState extends State<MyAnimatedText> {
  late List<String> words = widget.sentence.split(" ").toList();

  late Timer timer;

  int activeIndex = 0;

  @override
  void initState() {
    super.initState();

    timer = Timer.periodic(const Duration(seconds: 1), (timer) {
      activeIndex++;
      if (activeIndex > words.length) activeIndex = 0;
      setState(() {});
    });
  }

  @override
  void dispose() {
    timer.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return RichText(
      text: TextSpan(
        children: () {
          List<InlineSpan> spans = [];
          for (int i = 0; i < words.length; i++) {
            spans.add(TextSpan(
              text: words[i] + " ",
              style: i == activeIndex
                  ? const TextStyle( //highlight style
                      color: Colors.orange,
                      fontSize: 24,
                    )
                  : TextStyle(
                      color: Colors.grey.shade300,
                      fontSize: 24,
                    ),
            ));
          }
          return spans;
        }(),
      ),
    );
  }
}