动画失败断言 Flutter

Question

这个断言一直困扰着我，无论使用哪种代码都会出现这个问题。经过搜索，发现Flutter团队一段时间内还未解决此问题，我们能做些什么呢？

v`I/flutter ( 5598): Another exception was thrown: 
'package:flutter/src/animation/animations.dart': Failed assertion: line 
376 pos 15: 'parent != null': is not true.
I/chatty  ( 5598): uid=10085(com.example.gam3ity_aa) 1.ui identical 21 
lines
I/flutter ( 5598): Another exception was thrown: 
'package:flutter/src/animation/animations.dart': Failed assertion: line 
376 pos 15: 'parent != null': is not true.
I/flutter ( 5598): Another exception was thrown: 
'package:flutter/src/animation/animations.dart': Failed assertion: line 
376 pos 15: 'parent != null': is not true.
I/chatty  ( 5598): uid=10085(com.example.gam3ity_aa) 1.ui identical 10 
lines
I/flutter ( 5598): Another exception was thrown: 
'package:flutter/src/animation/animations.dart': Failed assertion: line 
376 pos 15: 'parent != null': is not true.
I/flutter ( 5598): Another exception was thrown: 
'package:flutter/src/animation/animations.dart': Failed assertion: line 
376 pos 15: 'parent != null': is not true.
I/chatty  ( 5598): uid=10085(com.example.gam3ity_aa) 1.ui identical 8 
lines
I/flutter ( 5598): Another exception was thrown: 
'package:flutter/src/animation/animations.dart': Failed assertion: line 
376 
 pos 15: 'parent != null': is not true.

`

- ahmed osman

---

你的代码中是否创建了任何 AnimationController？如果是，能否展示一下？ - Sander Dalby Larsen

Answer 1

当我意外地使用(parent: null)创建Tween对象时，我遇到了这个问题。

  @override
  void initState() {
    _animation = Tween(begin: 0.0, end: 1.0).animate(CurvedAnimation(
      parent: null, // <---------------- This line should be an AnimationController
      curve: widget.curve,
      reverseCurve: widget.reverseCurve ?? widget.curve,
    ));
    super.initState();
  }

应该是这样的：

  AnimationController _animationController;
  Animation _animation;

  @override
  void initState() {
    _animationController = AnimationController(
        duration: Duration(milliseconds: 500),
        reverseDuration: Duration(milliseconds: 1000),
        vsync: this,
        value: 1.0
    );
    _animation = Tween(begin: 0.0, end: 1.0).animate(CurvedAnimation(
      parent: _animationController,
      curve: widget.curve,
      reverseCurve: widget.reverseCurve ?? widget.curve,
    ));
    super.initState();
  }

- BananaNeil