特别注意,如果要是

android:layout_alignTop="@id/bind_decode_item_layout"

android:layout_centerHorizontal="true" 生效
必须要设置兄弟元素android:layout_centerInParent="true"



<?xml version="1.0" encoding="utf-8"?>
<com.whoop.mobile.trace.view.BindDecodeItemLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <RelativeLayout
        android:id="@+id/bind_decode_item_layout"
        android:layout_width="180dp"
        android:layout_height="220dp"
        android:layout_centerInParent="true"
        android:gravity="center" >

        <ImageView
            android:id="@+id/bind_decode_item_layout_diagram"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:scaleType="centerCrop"
            android:src="@drawable/bind_decode_item" />

        <TextView
            android:id="@+id/bind_decode_item_layout_qrcode"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:layout_marginBottom="10dp"
            android:ellipsize="end"
            android:gravity="center_horizontal"
            android:singleLine="true"
            android:textColor="@color/black"
            android:textSize="15sp" />
    </RelativeLayout>

    <ImageButton
        android:id="@+id/bind_decode_item_layout_btnDelete"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:layout_marginTop="-25dp"
        android:layout_alignTop="@id/bind_decode_item_layout"
        android:layout_centerHorizontal="true"
        android:scaleType="centerCrop"
        android:src="@drawable/activity_sale_duplicate_icon" />

</com.whoop.mobile.trace.view.BindDecodeItemLayout>