ValueDelegate.gradientColor Unable to continuously refresh

[cjl84914]

bulb.json

{
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  "fr": 25,
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  "op": 1,
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  "h": 500,
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  "assets": [],
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  ],
  "markers": [],
  "props": {}
}

flutter code:

class _Animation extends StatefulWidget {
  @override
  State<_Animation> createState() => _AnimationState();
}

class _AnimationState extends State<_Animation> {
  var timer;
  var colorList = [Colors.red, Colors.orange, Colors.yellow];
  var i = 0;

  @override
  void initState() {
    timer = Timer.periodic(const Duration(seconds: 1), (timer) {
      if (i < colorList.length - 1) {
        i++;
      } else {
        i = 0;
      }
      setState(() {

      });
    });
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Lottie.asset(
      'assets/blub.json',
      delegates: LottieDelegates(
        text: (initialText) => '**$initialText**',
        values: [
          ValueDelegate.color(
            const ['灯泡', '灯泡', '填充 1'],
            value: colorList[i],
          ),
          ValueDelegate.gradientColor(
            const ['灯台', '灯台', 'Gradient Fill 1'],
            value: [Colors.black, Colors.grey],
          ),
          ValueDelegate.gradientColor(
            const ['灯光', '灯光', 'Gradient Fill 2'],
            value: [colorList[i], Colors.white],
          ),
        ],
      ),
    );
  }
}

I used lottie 2.7.0, I try continuously refresh bulb light color, but ValueDelegate.gradientColor not working.

[xvrh]

Can you try using callback instead of value in the delegate. example:

ValueDelegate.gradientColor(
  const ['灯光', '灯光', 'Gradient Fill 2'],
  callback: (_) => [colorList[i], Colors.white],
),

Let me know if it helps.

[cjl84914]

@xvrh I try to replace this code:

ValueDelegate.gradientColor(
  const ['灯光', '灯光', 'Gradient Fill 2'],
  callback: (_) => [colorList[i], Colors.white],
),

but it can not helps.

[xvrh]

It seems there is a bug in the update of the gradient. In the mean time to unblock you, you can set a key in the Lottie widget like this:

  @override
  Widget build(BuildContext context) {
    return Lottie.asset(
      'assets/blub.json',
      key: ValueKey(i),
      delegates: LottieDelegates(
        text: (initialText) => '**$initialText**',
        values: [
          ValueDelegate.color(
            const ['灯泡', '灯泡', '填充 1'],
            value: colorList[i],
          ),
          ValueDelegate.gradientColor(
            const ['灯台', '灯台', 'Gradient Fill 1'],
            value: [Colors.black, Colors.grey],
          ),
          ValueDelegate.gradientColor(
            const ['灯光', '灯光', 'Gradient Fill 2'],
            value: [colorList[i], Colors.white],
          ),
        ],
      ),
    );
  }

[cjl84914]

@xvrh Thank you! It is helpful that set a key.