RelativeLayout 中的视图大小不正确

Question

我在下面有一个 RelativeLayout。其中有一个可扩展的视图和一个显示框架布局。 RevealFrameLayout 与屏幕底部对齐，位于 ExpandableView 下方。当用户点击 fab reveal 动画时，将从 fab 中心开始并显示 reveal frame 布局。

<?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/root"
            android:layout_width="match_parent"
            android:layout_height="match_parent">

<FrameLayout
    android:id="@+id/expandable_frame"
    android:layout_width="match_parent"
    android:layout_height="250dp"
    android:layout_alignParentTop="true"
    android:background="@color/colorPrimary"
    android:elevation="16dp"
    android:fitsSystemWindows="true"
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

    <TextView
        android:id="@+id/app_name_tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|start"
        android:padding="16dp"
        android:text="@string/app_name"
        android:textAppearance="@style/ExtraLargeText"/>

</FrameLayout>

<TextView
    android:id="@+id/error_tv"
    android:layout_width="match_parent"
    android:layout_height="60dp"
    android:layout_below="@id/expandable_frame"
    android:background="@color/mid_grey"
    android:gravity="center"
    android:textColor="@color/error_red"
    android:visibility="invisible"
    tools:text="@string/error_login"
    tools:visibility="visible"/>

<android.support.design.widget.TextInputLayout
    android:id="@+id/username_til"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_below="@id/error_tv"
    android:layout_marginEnd="16dp"
    android:layout_marginStart="16dp">

    <android.support.design.widget.TextInputEditText
        android:id="@+id/username_tiet"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/username"
        android:inputType="text"
        android:lines="1"
        android:nextFocusDown="@+id/password_tiet"/>

</android.support.design.widget.TextInputLayout>

<android.support.design.widget.TextInputLayout
    android:id="@+id/password_til"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_below="@id/username_til"
    android:layout_marginEnd="16dp"
    android:layout_marginStart="16dp">

    <android.support.design.widget.TextInputEditText
        android:id="@id/password_tiet"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/password"
        android:inputType="textPassword"
        android:lines="1"/>

</android.support.design.widget.TextInputLayout>

<FrameLayout
    android:id="@+id/loading_reveal_view"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_below="@id/expandable_frame"
    android:background="@color/colorAccent"
    android:visibility="invisible">

    <com.wang.avi.AVLoadingIndicatorView
        android:id="@+id/loading_animation_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:visibility="invisible"/>

</FrameLayout>

<WebView
    android:id="@+id/web_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_alignParentBottom="true"
    android:layout_below="@id/expandable_frame"
    android:visibility="gone"/>

<android.support.design.widget.FloatingActionButton
    android:id="@+id/login_fab"
    android:layout_width="56dp"
    android:layout_height="56dp"
    android:layout_alignParentBottom="true"
    android:layout_alignParentEnd="true"
    android:layout_margin="16dp"
    android:tint="@android:color/white"
    app:srcCompat="@drawable/ic_ok"/>

</RelativeLayout>

我这样计算晶圆厂中心：

        int cx = mLoginFab.getRight() - mLoginFab.getMeasuredWidth() / 2;
        int cy = mLoginFab.getBottom() - mLoginFab.getMeasuredHeight() / 2;

但我得到的坐标总是低于 fab 的位置。 Reveal Frame Layout 的底部似乎超出了 phone 屏幕边界。

有谁知道这个布局有什么问题以及如何获得实际的 fab 中心坐标？

提前致谢。

Answer 1

尝试 getWidth() 和 getHeight 而不是 getMeasuredWidth 和 getMeasuredHeight。根据 documentation for View:

int getMeasuredWidthAndState ()

Return the full width measurement information for this view as computed by the most recent call to measure(int, int). This result is a bit mask as defined by MEASURED_SIZE_MASK and MEASURED_STATE_TOO_SMALL. This should be used during measurement and layout calculations only. Use getWidth() to see how wide a view is after layout.

重点是我的，这也适用于 getMeasuredWidth 和 getMeasuredHeight。

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