CoordinatorLayout和AppBarLayout抬高 [英] CoordinatorLayout and AppBarLayout elevation

问题描述

我创建了一个AppBar布局像这样

I've created an AppBar layout like this

<android.support.design.widget.AppBarLayout
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/appbar_layout"
    android:layout_height="@dimen/app_bar_height"
    android:layout_width="match_parent"
    android:fitsSystemWindows="true"
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
    app:elevation="20dp">

    <android.support.design.widget.CollapsingToolbarLayout...>
</android.support.design.widget.AppBarLayout>

它的工作原理，并在的LinearLayout蒙上了一层阴影：

it works and casts a shadow in the LinearLayout:

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <include layout="@layout/app_bar_large" />
</LinearLayout>

然而，当我把它改成了CoordinatorLayout阴影消失了：

However when I put it into the CoordinatorLayout shadow is gone:

<android.support.design.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <include layout="@layout/app_bar_large" />
</android.support.design.widget.CoordinatorLayout>

我怎样才能让appbar再次显示它的影子？

How can I make appbar to show its shadow again?

推荐答案

这是实际上是一个 Col​​lapsingToolbarLayout 的实施细节，如在该<一个href=\"https://android.googlesource.com/platform/frameworks/support/+/refs/heads/master/design/src/android/support/design/widget/CollapsingToolbarLayout.java#956\"相对=nofollow>来源$ C ​​$ C ：

This is actually an implementation detail of CollapsingToolbarLayout, as seen in the source code:

if (Math.abs(verticalOffset) == scrollRange) {
  // If we have some pinned children, and we're offset to only show those views,
  // we want to be elevate
  ViewCompat.setElevation(layout, layout.getTargetElevation());
} else {
  // Otherwise, we're inline with the content
  ViewCompat.setElevation(layout, 0f);
}

这消除高程时， Col​​lapsingToolbarLayout 正显示出非固定元素 - 默认情况下，它会只有海拔只有当孩子寄托可见

Which removes the elevation when the CollapsingToolbarLayout is showing non-pinned elements - by default, it'll only have elevation when only pinned children are visible.

这篇关于CoordinatorLayout和AppBarLayout抬高的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！