动画视图的顶部和底部尺寸

Question

我需要用视图做两件事:

1. 将顶部尺寸移动到窗口的最顶部
2. 将底部尺寸移动到窗口的最底部.

简而言之,我需要视图覆盖100%的父视图.

翻译动画不起作用,因为它移动视图但不会增加大小.

缩放动画有效,但它会拉伸视图的内容,我不希望这样.我想增加可见区域,而不是拉伸内容以适应新的尺寸.

这样做的正确方法是什么？

Answer 1

使用Transitions API可以轻松实现这一点.

使用Transitions API,您不需要编写动画,只需告诉您想要的最终值,Transitions API将负责构建动画.

将此xml作为内容视图(屏幕中心的视图):

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/root"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <View
        android:id="@+id/view"
        android:layout_width="120dp"
        android:layout_height="80dp"
        android:layout_gravity="center"
        android:background="@color/colorAccent" />

</FrameLayout>

在活动中:

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.item)

    val root = findViewById(R.id.root) as ViewGroup
    val view = findViewById(R.id.view)

    view.setOnClickListener {

        // After this line Transitions API would start counting the delta
        // and will take care of creating animations for each view in `root`
        TransitionManager.beginDelayedTransition(root)

        // By default AutoTransition would be applied,
        // but you can provide your transition with the second parameter

        // val transition = AutoTransition()
        // transition.duration = 2000
        // TransitionManager.beginDelayedTransition(root, transition)

        // We are changing size of the view to match parent
        val params = view.layoutParams
        params.height = ViewGroup.LayoutParams.MATCH_PARENT
        params.width = ViewGroup.LayoutParams.MATCH_PARENT

        view.requestLayout()
    }
}

这是输出:

Platform的Transitions API(android.transition.TransitionManager)可从API 19获得,但支持库将功能向后移植到API 14(android.support.transition.TransitionManager).