Stateful Layout

Android StatefulLayout

Installation

Add Jitpack:

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

Add the dependency:

dependencies {
  implementation 'com.github.fabernovel:stateful-layout:<Version>'
}

Usage

StatefulLayout allows to create different state for a screen (loading state, content state, missing permission state, etc). States are referenced using an android resource id.

StatefulLayout

StatefulLayout is a view group containing a set of State. Each State must have an id which will be used to display them when needed.

To use it, add a StatefulLayout to a layout and put a State with android:id="@id/stateContent to define the normal content state.

 <com.fabernovel.statefullayout.StatefulLayout
        android:id="@+id/statefulLayout"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:defaultEnterTransition="@anim/fragment_fade_enter"
        app:defaultExitTransition="@anim/fragment_fade_exit"
        app:initialState="@id/stateLoading"
        app:layout_constraintBottom_toTopOf="@id/actions"
        app:layout_constraintTop_toTopOf="parent"
        >
        <com.fabernovel.statefullayout.State
            android:id="@id/stateContent"
            android:layout_width="match_parent"
            android:layout_height="match_parent">
            <!-- your state content -->
        </com.fabernovel.statefullayout.State>
    </com.fabernovel.statefullayout.StatefulLayout>

Default states:

By default, three states are provided:

Loading state: stateLoading: A progress bar in the middle of the screen.
Content state: stateContent The normal content screen
Error state: stateError An error screen with a retry button

To overwrite the view displayed by a default state, there are two ways:

Add a State with the id you want to overwrite inside your StatefulLayout. For example to create a custom error state:

 <com.fabernovel.statefullayout.StatefulLayout
        android:id="@+id/statefulLayout"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:defaultEnterTransition="@anim/fragment_fade_enter"
        app:defaultExitTransition="@anim/fragment_fade_exit"
        app:initialState="@id/stateLoading"
        app:layout_constraintBottom_toTopOf="@id/actions"
        app:layout_constraintTop_toTopOf="parent"
        >
        <com.fabernovel.statefullayout.State
            android:id="@id/stateError"
            android:layout_width="match_parent"
            android:layout_height="match_parent">
            <!-- your error state content -->
        </com.fabernovel.statefullayout.State>
    </com.fabernovel.statefullayout.StatefulLayout>

Pass a layout resource to a StatefulLayout layout view:

app:loadingStateLayout for the loading state.
app:errorStateLayout for the error state.

Custom state:

To add a custom state, add a State inside a StatefulLayout. Warnings:

State can only have one child view
State must have an id.

State's child can be set:

In the layout by set a layout as contentLayout attribute.

<com.fabernovel.statefullayout.State
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:id="@+id/stateCustom"
            app:contentLayout="@layout/state_custom"
            />

In the layout, by adding a view as a child of the state

<com.fabernovel.statefullayout.State
            android:id="@id/stateContent"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:enterTransition="@anim/fragment_open_enter"
            app:exitTransition="@anim/fragment_close_exit"
            >

            <androidx.constraintlayout.widget.ConstraintLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:background="@color/colorAccent"
                >
                <!--CONTENT-->
            </androidx.constraintlayout.widget.ConstraintLayout>
        </com.fabernovel.statefullayout.State>

State can also be added programmatically to a StatefulLayout (they still need to have an id).

You can access a state content view using contentView or requireContentView which check if view is null.

Change the displayed state:

To change the displayed state, call showState(@IdRes id: Int) with your state's id. Default state also have their kotlin extensions for convenience:

showError(onRetryListener: ((View) -> Unit = {})?)
showLoading()
showContent()

Add listeners to state's views

If the state is in a layout, it can be accessed like any other view. To access views from layout that are inflated by the StatefulLayout, the recommended way is to use Android View Binding. (https://developer.android.com/topic/libraries/view-binding) To get a stateView you can use requireStateView(<stateId>) extension.

// ...
val errorStateView = binding.requireStateView(R.id.stateError)       
val errorBinding = StateErrorBinding.bind(errorStateView)

errorBinding.stateErrorRetryButton.setOnClickListener { 
    // do whatever
}

Theme:

The library adds a theme attribute statefulLayoutStyle which take a StatefulLayout style. Extend Widget.Stateful.StatefulLayout and change the following attributes:

StatefulLayout:

Attribute	Definition
loadingStateLayout	A layout reference used to inflate the loading state view. (optional)
errorStateLayout	A layout reference used to inflate the error state view. (optional)
initialState	Id of the initially displayed state. (by default: none)
defaultEnterTransition	Default enter transition. (by default: none)
defaultExitTransition	Default exit transition. (by default: none)

State also have an theme attribute stateStyle and a default style Widget.Stateful.State

Attribute	Definition
enterTransition	Enter transition. (by default: none)
exitTransition	Exit transition. (by default: none)

Animation

By default, no animation are played on state transition. To add your own enter and exit animation:

On a StatefulLayout using defaultEnterTransition and defaultExitTransition. Those transitions will be played on every state change excluding state with their own transitions.
On a State using enterTransition and exitTransition which override the parent StatefulLayout transitions.

Animation can be either an animator resource or an animation resource. To load a state transition programmatically, use the helper class StateTransitions. StateTransitions allow to create a StateTransition from:

An Animator (https://developer.android.com/reference/android/animation/Animator)
An Animation (https://developer.android.com/reference/android/view/animation/Animation)
A resource version of an animator or an animation.
A callback (see MainFragment)

License

ADUtils is released under the Apache 2.0 license. See LICENSE for details.

sjcqs/stateful-layout