android - 如何将图像视图的中心对齐到视图组的顶部？

Question

如何将图像视图的中心对齐到视图组的顶部？我想将圆形图像（红色圆圈）的中心对齐到视图组（绿色矩形）的顶部

Answer 1

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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">

    <FrameLayout
        android:id="@+id/some_layout"
        android:layout_width="0dp"
        android:layout_height="200dp"
        android:background="#77ff77"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />


    <ImageView
        android:layout_width="56dp"
        android:layout_height="56dp"
        android:layout_marginEnd="8dp"
        android:src="#f00"
        app:layout_constraintBottom_toTopOf="@id/some_layout"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="@id/some_layout" />

</android.support.constraint.ConstraintLayout>

Answer 2

你可以试试这个。

<View
        android:background="@android:color/black"
        android:layout_alignParentBottom="true"
        android:id="@+id/bottomView"
        android:layout_width="match_parent"
        android:layout_height="200dp"/>


    <ImageView
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:layout_marginBottom="-50dp"
        android:layout_above="@+id/bottomView"
        android:layout_alignParentRight="true"
        />