因此，我已经在Dart中使用typedef一段时间了，而没有考虑它们的实际含义。因此，例如在这段代码中：
new PageRouteBuilder(
pageBuilder: (BuildContext context, Animation<double> animation1, Animation<double> animation2) => new Test(),
transitionsBuilder: (BuildContext context, Animation<double> animation1, Animation<double> animation2, Widget child) {
return new FadeTransition(
child: child,
opacity: animation1,
);
}
)
该pageBuilder属性需要一个名为的typedef RoutePageBuilder并为transitionsBuilder财产被称为typedef的RouteTransitionsBuilder预期。
在我看来，我只是在为那些具有来自typedef的预定义参数的属性使用函数，但是对此我不确定。
另外，这里实际上输入了哪些参数？因为例如我已经用作Animation<double> animation1参数，但是实际上并没有创建一个new Animation，或者它是吗？如果没有，Animation实际上将作为参数传递什么？
typedef可用于指定我们希望特定功能匹配的功能签名。函数签名由函数的参数（包括其类型）定义。返回类型不是函数签名的一部分。其语法如下。
在您的情况下，PageRouteBuilder采用以下参数：
两种typedef（RouteTransitionsBuilder和RoutePageBuilder）就像（面向对象编程的）接口，用于单个方法。在这种情况下，typedef RoutePageBuilder会强制您将返回一个以上下文和两个Animation作为参数的Widget的函数作为参数传递。
如果需要有关该函数中传递的参数的更多详细信息，可以在flutter的文档中进行检查，例如：
动画→动画驱动路线的过渡和上一条路线的前向过渡的动画。只读，继承
要么
secondaryAnimation→动画在此路线上推入路线的动画。此动画使此路线与推入此路线顶部的路线的入口和出口过渡相协调。只读，继承
PS：如果您浏览颤动代码并到达routes.dart文件，则可以找到记录此部分的注释：
/// Override this method to build the primary content of this route.
///
/// The arguments have the following meanings:
///
/// * `context`: The context in which the route is being built.
/// * [animation]: The animation for this route's transition. When entering,
/// the animation runs forward from 0.0 to 1.0. When exiting, this animation
/// runs backwards from 1.0 to 0.0.
/// * [secondaryAnimation]: The animation for the route being pushed on top of
/// this route. This animation lets this route coordinate with the entrance
/// and exit transition of routes pushed on top of this route.
///
/// This method is called when the route is first built, and rarely
/// thereafter. In particular, it is not called again when the route's state
/// changes. 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.
Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation);
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