An Android layout class that supports animating the expansion and collapse of its child views.

I built this because all of the available libraries I tested were missing features or behaving unexpectedly in certain cases (e.g. rotation handling).

This library offloads as much work as possible to the parent layout to ensure that the rendering and size calculations behave as expected. This means that even complex features such as LinearLayout's weight tag are properly supported.

ExpandableLayout supports animating:

• Views with fixed and variable heights:

• "Accordion" expansion (using two expandable layouts)

• RecyclerView items

• Horizontal expansion

Add the Jitpack maven repository if you don't have it yet:

allprojects {
    repositories {
        ...
        maven { url 'https://jitpack.io' }
    }
}

Reference the library from your module's build.gradle:

dependencies {
    [...]
    implementation 'com.github.cachapa:ExpandableLayout:2.9.2'
}

Add ExpandableLayout as a container to the layout or views you want to make expandable:

<net.cachapa.expandablelayout.ExpandableLayout
    android:id="@+id/expandable_layout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:el_duration="1000"
    app:el_expanded="true"
    app:el_parallax="0.5">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="16dp"
        android:text="Fixed height" />

</net.cachapa.expandablelayout.ExpandableLayout>

Also supported are el_duration and el_expanded tags, for specifying the duration of the animation and whether the layout should start expanded, respectively. el_parallax can be set to a value between 0 and 1 to control how the child view is translated during the expansion.

To trigger the animation, simply grab a reference to the ExpandableLayout from your Java code and and call either of expand(), collapse() or toggle().

A full demo of the library is included with the project.

Copyright 2016 Daniel Cachapa.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

Gifs were generated using the following script: https://gist.github.com/cachapa/aa829bfc717fc4f1d52c568d7ae8521e