垂直居中时，如何考虑操作栏？

Question

我的居中正确，正如您在查看 content_main.xml 设计选项卡时看到的那样，

但是，当您查看带有操作栏的 activity_main.xml 设计时，虽然它仍然在应用程序中居中，但它并没有在空白处居中，这是我更喜欢的。关于如何考虑操作栏的任何建议？如果可能，最好在 XML 中。

这是我的 XML

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              xmlns:app="http://schemas.android.com/apk/res-auto"
              xmlns:tools="http://schemas.android.com/tools"
              android:id="@+id/voting_layout"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:paddingBottom="@dimen/activity_vertical_margin"
              android:paddingLeft="@dimen/activity_horizontal_margin"
              android:paddingRight="@dimen/activity_horizontal_margin"
              android:paddingTop="@dimen/activity_vertical_margin"
              android:orientation="vertical"
              android:layout_gravity="fill_vertical|center"
              android:configChanges="orientation|screenSize"
              android:screenOrientation="nosensor"
              tools:context="com.gesslar.threshvote.MainActivity"
              android:background="@color/colorFaded"
              app:layout_behavior="@string/appbar_scrolling_view_behavior"
              tools:showIn="@layout/activity_main">

        <TextView android:id="@+id/textStatusMessage"
                  android:textColor="@color/colorText"
                  android:textAppearance="?android:attr/textAppearanceLarge"
                  android:layout_width="match_parent"
                  android:layout_height="wrap_content"
                  android:gravity="center" />

        <ImageButton android:id="@+id/buttonVote"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
                     android:clickable="false"
                     android:src="@drawable/ic_vote_button_image"
                     android:paddingBottom="@dimen/activity_vertical_margin"
                     android:paddingLeft="@dimen/activity_horizontal_margin"
                     android:paddingRight="@dimen/activity_horizontal_margin"
                     android:paddingTop="@dimen/activity_vertical_margin"
                     android:background="@android:color/transparent"
                     android:scaleType="fitCenter"
                     android:onClick="onVotePressed"
                     android:layout_gravity="center_horizontal|center_vertical"
                     android:adjustViewBounds="true"
                     android:contentDescription="@string/desc_vote_button" />

        <TextSwitcher android:id="@+id/textCountdown"
                      android:gravity="center"
                      android:layout_gravity="center_horizontal"
                      android:textColor="@color/colorText"
                      android:textAppearance="?android:attr/textAppearanceLarge"
                      android:textSize="@dimen/countdown"
                      android:includeFontPadding="false"
                      android:layout_width="match_parent"
                      android:layout_height="wrap_content" />

        <ProgressBar android:id="@+id/loadingBar"
                     style="@style/Widget.AppCompat.ProgressBar"
                     android:layout_gravity="end"
                     android:layout_width="fill_parent"
                     android:layout_height="wrap_content"
                     android:visibility="invisible"
                     android:indeterminate="true"/>
    </LinearLayout>

Answer 1

那个 xml 对我有用：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/voting_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_gravity="fill_vertical|center"
    android:background="@color/colorFaded"
    android:configChanges="orientation|screenSize"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:screenOrientation="nosensor"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.gesslar.threshvote.MainActivity"
    tools:showIn="@layout/activity_main">

    <TextView
        android:id="@+id/textStatusMessage"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:textColor="@color/colorText" />

    <ImageButton
        android:id="@+id/buttonVote"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:adjustViewBounds="true"
        android:background="@android:color/transparent"
        android:clickable="false"
        android:contentDescription="@string/desc_vote_button"
        android:onClick="onVotePressed"
        android:paddingBottom="@dimen/activity_vertical_margin"
        android:paddingLeft="@dimen/activity_horizontal_margin"
        android:paddingRight="@dimen/activity_horizontal_margin"
        android:paddingTop="@dimen/activity_vertical_margin"
        android:scaleType="fitCenter"
        android:src="@drawable/ic_vote_button_image" />

    <TextSwitcher
        android:id="@+id/textCountdown"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_above="@id/buttonVote"
        android:layout_gravity="center_horizontal"
        android:gravity="center"
        android:includeFontPadding="false"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:textColor="@color/colorText"
        android:textSize="@dimen/countdown" />

    <ProgressBar
        android:id="@+id/loadingBar"
        style="@style/Widget.AppCompat.ProgressBar"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_above="@id/textCountdown"
        android:layout_gravity="end"
        android:indeterminate="true"
        android:visibility="invisible" />
</RelativeLayout>

但您需要在设备或模拟器上运行它。 Android Studio 预览显示错误。关键行是app:layout_behavior="@string/appbar_scrolling_view_behavior"

编辑
您还需要使用RelativeLayout - 它支持良好的父母居中。在 LinearLayout 中，只有当您的 ImageView 为 match_parent 时，您才能将图像居中。