TransitionManager.beginDelayedTransition 在 activity 第一次加载时没有动画

Question

我正在使用 constraintLayout 和使用 TransitionManager 的动画。

我有以下两种布局

这是我的main_activity.xml

<android.support.constraint.ConstraintLayout
        android:id="@+id/constraintLayout"
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

       <ImageView
            android:id="@+id/image"
            android:layout_width="0dp"
            android:layout_height="160dp"
            android:background="@color/colorPrimary"
            app:layout_constraintTop_toBottomOf="parent"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"/>

    <Button
            android:id="@+id/btn"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layout_constraintTop_toTopOf="parent"
            android:text="Let's start animating"/>
</android.support.constraint.ConstraintLayout>

这是我的 main_activity_alt.xml

<android.support.constraint.ConstraintLayout
        android:id="@+id/constraintLayout"
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        xmlns:app="http://schemas.android.com/apk/res-auto">

      <ImageView
            android:id="@+id/image"
            android:layout_width="0dp"
            android:layout_height="160dp"
            android:background="@color/colorPrimary"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"/>

    <Button
            android:id="@+id/btn"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layout_constraintTop_toTopOf="parent"
            android:text="Let's start animating"/>
</android.support.constraint.ConstraintLayout>

在我的 MainActivity 中，我想为图像设置动画以向上滑动，这将是 main_activity_alt.xml

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

        val constraintSet1 = ConstraintSet()
        constraintSet1.clone(constraintLayout)

        val constraintSet2 = ConstraintSet()
        constraintSet2.clone(this, R.layout.activity_main_alt)

        val transition = ChangeBounds()
        transition.duration = 5000

   val handler = Handler()
        handler.postDelayed({
            TransitionManager.beginDelayedTransition(constraintLayout, transition)
            constraintSet2.applyTo(constraintLayout)
        }, 10)
    }

当上面启动时图像已经显示。 main_activity.xml 应该隐藏起来，main_activity_alt.xml 将是它最后的归宿。

但是，当屏幕加载时它会立即显示 imageview 而没有任何动画

以上我做错了什么？

Answer 1

来自 documentation for beginDelayedTransition:

Calling this method causes TransitionManager to capture current values in the scene root and then post a request to run a transition on the next frame. At that time, the new values in the scene root will be captured and changes will be animated.

您必须等到布局完成后再尝试转换。有多种方法可以做到这一点，但最简单的方法是 post 转换代码如下：

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

    val constraintLayout = findViewById<ConstraintLayout>(R.id.constraintLayout)
    constraintLayout.post {
        val constraintSet1 = ConstraintSet()
        constraintSet1.clone(constraintLayout)
        val constraintSet2 = ConstraintSet()
        constraintSet2.clone(this, R.layout.activity_main2_alt)
        val transition = ChangeBounds()
        transition.duration = 5000
        TransitionManager.beginDelayedTransition(constraintLayout, transition)
        constraintSet2.applyTo(constraintLayout)
    }
}

Answer 2

尝试延迟过渡，这样第一个布局会在过渡开始时膨胀

transition.delay = 300

如果这行不通，请尝试

Handler().postDelayed({do transition here}, 300)

TransitionManager.beginDelayedTransition 在 activity 第一次加载时没有动画

TransitionManager.beginDelayedTransition doesn't animate when activity first loads

android

android-animation

android-constraintlayout

android-transitions