当永恒的软键盘问题遇到Flutter

════════ Exception caught by rendering library ═════════════════════════════════════════════════════
The following assertion was thrown during layout:
A RenderFlex overflowed by 17 pixels on the bottom.

The relevant error-causing widget was: 
  Column file:///Users/chenglei/fataccount/lib/keepAccount/add_keep_account.dart:48:22
The overflowing RenderFlex has an orientation of Axis.vertical.
The edge of the RenderFlex that is overflowing has been marked in the rendering with a yellow and black striped pattern. This is usually caused by the contents being too big for the RenderFlex.

resizeToAvoidBottomInset: false

/// If true the [body] and the scaffold's floating widgets should size
  /// themselves to avoid the onscreen keyboard whose height is defined by the
  /// ambient [MediaQuery]'s [MediaQueryData.viewInsets] `bottom` property.
  ///
  /// For example, if there is an onscreen keyboard displayed above the
  /// scaffold, the body can be resized to avoid overlapping the keyboard, which
  /// prevents widgets inside the body from being obscured by the keyboard.
  ///
  /// Defaults to true.

MediaQueryData.viewInsets

@override
  void didChangeMetrics() {
    super.didChangeMetrics();
    WidgetsBinding.instance.addPostFrameCallback((_) {
      var bottom = MediaQuery.of(context).viewInsets.bottom;
      if (bottom == 0) {
        // 键盘收起来
        setState(() {
          this.height = initHeight;
        });
      } else {
        setState(() {
          this.height = initHeight + bottom;
        });
      }
    });
  }

@override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) {
      initHeight = context.size.height;
    });
  }

final ValueChanged<double> heightChange;
final ValueChanged<double> initHeight;

@override
  Widget build(BuildContext context) {
    return TextField(
      onChanged: (content) {
        _checkHeight(context);
      },
      keyboardType: TextInputType.multiline,
    );
  }


_checkHeight(BuildContext context) {
    if (widget.heightChange != null) {
      widget.heightChange(context.size.height);
    }
  }

/// 检查输入框的高度
/// 使用一个 lastInputHeight 变量来记录上一次的键盘高度
  _checkHeight(height) {
    if (height > lastInputHeight) {
      // 输入框行数多了
      initHeight += (height - lastInputHeight);
      setState(() {
        var shouldHeight = this.height + (height - lastInputHeight);
        this.height = shouldHeight;
      });
    } else {
      initHeight -= (lastInputHeight - height);
      setState(() {
        var shouldHeight = this.height - (lastInputHeight - height);
        this.height = shouldHeight;
      });
    }
    lastInputHeight = height;
  }

context.size.height

(context.findRenderObject() as RenderBox).size.height

MediaQuery.of(context).viewInsets.bottom;