Flutter 3.22.0稳定版的MaterialState迁

1. MaterialState及其相关 API已从 Material 库中移出并重命名为WidgetState。

3.22版本以前，MaterialState提供了处理小部件可能具有的多种不同状态的逻辑，例如“悬停”、“聚焦”和“禁用”。由于此功能在 Material 库之外很有用，即对于基础 Widgets 层和 Cupertino，因此决定将其移出 Material。作为移动的一部分，为了避免将来混淆，不同的类MaterialState已重命名为WidgetState。两者的行为相同。

1.1 之间的对应关系

要迁移，请替换MaterialState为WidgetState。

1.2以前的MaterialState代码：

MaterialState selected = MaterialState.selected;

final MaterialStateProperty<Color> backgroundColor;

class _MouseCursor extends MaterialStateMouseCursor{
  const _MouseCursor(this.resolveCallback);

  final MaterialPropertyResolver<MouseCursor?> resolveCallback;

  @override
  MouseCursor resolve(Set<MaterialState> states) => resolveCallback(states) ?? MouseCursor.uncontrolled;
}

BorderSide side = MaterialStateBorderSide.resolveWith((Set<MaterialState> states) {
  if (states.contains(MaterialState.selected)) {
    return const BorderSide(color: Colors.red);
  }
  return null;
});

1.3 迁移后的WidgetState代码：

WidgetState selected = WidgetState.selected;

final WidgetStateProperty<Color> backgroundColor;

class _MouseCursor extends WidgetStateMouseCursor{
  const _MouseCursor(this.resolveCallback);

  final WidgetPropertyResolver<MouseCursor?> resolveCallback;

  @override
  MouseCursor resolve(Set<WidgetState> states) => resolveCallback(states) ?? MouseCursor.uncontrolled;
}

BorderSide side = WidgetStateBorderSide.resolveWith((Set<WidgetState> states) {
  if (states.contains(WidgetState.selected)) {
    return const BorderSide(color: Colors.red);
  }
  return null;
});