CODEWITHSUNDEEP
androidandroid-layoutcoordinator-layout
Kata Lune
Kata Lune

Reputation: 451

CoordinatorLayout and AppBarLayout elevation

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>

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>

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>

How can I make appbar to show its shadow again?

enter image description here

Upvotes: 22

Views: 17372

Answers (4)

Mick&#228;el A.
Mick&#228;el A.

Reputation: 9397

The solution is to use app:elevation=0dp to remove the default elevation and set android:translationZ to the elevation you want.

Note : The code below uses the latest AndroidX / Material libraries and might not work if you're using the old support library

<com.google.android.material.appbar.AppBarLayout
    android:layout_height="wrap_content"
    android:layout_width="match_parent"
    android:translationZ="8dp"
    app:elevation="0dp">

    <!--
      * `app:elevation=0dp` disables the default shadow that is automatically added on
      scroll ; other values e.g. `6dp` are ignored despite what the official doc says
      (see below)
      * so instead we're using `android:translationZ` to add a shadow with a custom
      elevation
    -->

The documentation for AppBarLayout # setTargetElevation() states that you can set a custom elevation value using the app:elevation attribute, but it didn't work for me for values greater than 0dp, so I'm using translationZ as a workaround.

Upvotes: 5

w3bshark
w3bshark

Reputation: 2749

setTargetElevation() is now deprecated for AppBarLayout.

The new correct implementation for applying custom elevation to an AppBarLayout based on the state of the layout is to use a StateListAnimator. material-components uses this as you can see here

I've added an example implementation of always showing AppBarLayout elevation here in this gist.

All you need is to 1. create a custom state list animator under /res/animator and 2. set the AppBarLayout's StateListAnimator like so:

appBarLayout.stateListAnimator = AnimatorInflater.loadStateListAnimator(context, R.animator.appbar_always_elevated_state_list_animator)

Upvotes: 1

halfCup
halfCup

Reputation: 91

the reason is above,try this to solve:

appBarLayout.addOnOffsetChangedListener(new AppBarLayout.OnOffsetChangedListener() {
        @Override
        public void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset) {
            //some other code here
            ViewCompat.setElevation(appBarLayout, The Elevation In Px);
        }
    });

Upvotes: 9

ianhanniballake
ianhanniballake

Reputation: 200130

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);
}

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.

Upvotes: 18

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