flutter - PageRouteBuilder的pageBuilder和transitionsBuilder typedef参数的区别

Question

根据official docs pageBuilder 参数用于构建主要路由内容，transitionsBuilder 参数用于构建路由的转换。

所以它们都有不同的工作，但是如果 pageBuilder 用于构建主要路由内容，那么为什么它还在其 typedef RoutePageBuilder 中声明了两个 Animation 参数，也在 transitionBuilder typedef RouteTransitionBuilder 中，有两个 Animation 参数声明为 animation 和 secondaryAnimation。这两个 Animation 之间有什么区别以及我们如何使用它们？

Answer 1

routes.dart 中的文档:

  /// [buildPage] is only called when the route is first built, and rarely
  /// thereafter. In particular, it is not automatically called again when the
  /// route's state changes unless it uses [ModalRoute.of]. For a builder that
  /// is called every time the route's state changes, consider
  /// [buildTransitions]. For widgets that change their behavior when the
  /// route's state changes, consider [ModalRoute.of] to obtain a reference to
  /// the route; this will cause the widget to be rebuilt each time the route
  /// changes state.
  ///
  /// In general, [buildPage] should be used to build the page contents, and
  /// [buildTransitions] for the widgets that change as the page is brought in
  /// and out of view. Avoid using [buildTransitions] for content that never
  /// changes; building such content once from [buildPage] is more efficient.

  /// The [buildTransitions] method, in contrast to [buildPage], is called each
  /// time the [Route]'s state changes (e.g. the value of [canPop]).
  ///
  /// The [buildTransitions] method is typically used to define transitions
  /// that animate the new topmost route's comings and goings. When the
  /// [Navigator] pushes a route on the top of its stack, the new route's
  /// primary [animation] runs from 0.0 to 1.0. When the Navigator pops the
  /// topmost route, e.g. because the use pressed the back button, the
  /// primary animation runs from 1.0 to 0.0.