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MultiStateView.kt
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MultiStateView.kt
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package com.kennyc.view
import android.animation.Animator
import android.animation.AnimatorListenerAdapter
import android.animation.ObjectAnimator
import android.content.Context
import android.os.Parcel
import android.os.Parcelable
import android.util.AttributeSet
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.FrameLayout
import androidx.annotation.LayoutRes
import com.kennyc.multistateview.R
class MultiStateView
@JvmOverloads constructor(context: Context,
attrs: AttributeSet? = null,
defStyle: Int = 0) : FrameLayout(context, attrs, defStyle) {
enum class ViewState {
CONTENT,
LOADING,
ERROR,
EMPTY
}
private var contentView: View? = null
private var loadingView: View? = null
private var errorView: View? = null
private var emptyView: View? = null
var listener: StateListener? = null
var animateLayoutChanges: Boolean = false
var viewState: ViewState = ViewState.CONTENT
set(value) {
val previousField = field
if (value != previousField) {
field = value
setView(previousField)
listener?.onStateChanged(value)
}
}
init {
val inflater = LayoutInflater.from(getContext())
val a = getContext().obtainStyledAttributes(attrs, R.styleable.MultiStateView)
val loadingViewResId = a.getResourceId(R.styleable.MultiStateView_msv_loadingView, -1)
if (loadingViewResId > -1) {
val inflatedLoadingView = inflater.inflate(loadingViewResId, this, false)
loadingView = inflatedLoadingView
addView(inflatedLoadingView, inflatedLoadingView.layoutParams)
}
val emptyViewResId = a.getResourceId(R.styleable.MultiStateView_msv_emptyView, -1)
if (emptyViewResId > -1) {
val inflatedEmptyView = inflater.inflate(emptyViewResId, this, false)
emptyView = inflatedEmptyView
addView(inflatedEmptyView, inflatedEmptyView.layoutParams)
}
val errorViewResId = a.getResourceId(R.styleable.MultiStateView_msv_errorView, -1)
if (errorViewResId > -1) {
val inflatedErrorView = inflater.inflate(errorViewResId, this, false)
errorView = inflatedErrorView
addView(inflatedErrorView, inflatedErrorView.layoutParams)
}
viewState = when (a.getInt(R.styleable.MultiStateView_msv_viewState, VIEW_STATE_CONTENT)) {
VIEW_STATE_ERROR -> ViewState.ERROR
VIEW_STATE_EMPTY -> ViewState.EMPTY
VIEW_STATE_LOADING -> ViewState.LOADING
else -> ViewState.CONTENT
}
animateLayoutChanges = a.getBoolean(R.styleable.MultiStateView_msv_animateViewChanges, false)
a.recycle()
}
/**
* Returns the [View] associated with the [com.kennyc.view.MultiStateView.ViewState]
*
* @param state The [com.kennyc.view.MultiStateView.ViewState] with to return the view for
* @return The [View] associated with the [com.kennyc.view.MultiStateView.ViewState], null if no view is present
*/
fun getView(state: ViewState): View? {
return when (state) {
ViewState.LOADING -> loadingView
ViewState.CONTENT -> contentView
ViewState.EMPTY -> emptyView
ViewState.ERROR -> errorView
}
}
/**
* Sets the view for the given view state
*
* @param view The [View] to use
* @param state The [com.kennyc.view.MultiStateView.ViewState]to set
* @param switchToState If the [com.kennyc.view.MultiStateView.ViewState] should be switched to
*/
fun setViewForState(view: View, state: ViewState, switchToState: Boolean = false) {
when (state) {
ViewState.LOADING -> {
if (loadingView != null) removeView(loadingView)
loadingView = view
addView(view)
}
ViewState.EMPTY -> {
if (emptyView != null) removeView(emptyView)
emptyView = view
addView(view)
}
ViewState.ERROR -> {
if (errorView != null) removeView(errorView)
errorView = view
addView(view)
}
ViewState.CONTENT -> {
if (contentView != null) removeView(contentView)
contentView = view
addView(view)
}
}
if (switchToState) viewState = state
}
/**
* Sets the [View] for the given [com.kennyc.view.MultiStateView.ViewState]
*
* @param layoutRes Layout resource id
* @param state The [com.kennyc.view.MultiStateView.ViewState] to set
* @param switchToState If the [com.kennyc.view.MultiStateView.ViewState] should be switched to
*/
fun setViewForState(@LayoutRes layoutRes: Int, state: ViewState, switchToState: Boolean = false) {
val view = LayoutInflater.from(context).inflate(layoutRes, this, false)
setViewForState(view, state, switchToState)
}
override fun onAttachedToWindow() {
super.onAttachedToWindow()
if (contentView == null) throw IllegalArgumentException("Content view is not defined")
when (viewState) {
ViewState.CONTENT -> setView(ViewState.CONTENT)
else -> contentView?.visibility = View.GONE
}
}
override fun onSaveInstanceState(): Parcelable? {
return when (val superState = super.onSaveInstanceState()) {
null -> superState
else -> SavedState(superState, viewState)
}
}
override fun onRestoreInstanceState(state: Parcelable) {
if (state is SavedState) {
super.onRestoreInstanceState(state.superState)
viewState = state.state
} else {
super.onRestoreInstanceState(state)
}
}
/* All of the addView methods have been overridden so that it can obtain the content view via XML
It is NOT recommended to add views into MultiStateView via the addView methods, but rather use
any of the setViewForState methods to set views for their given ViewState accordingly */
override fun addView(child: View) {
if (isValidContentView(child)) contentView = child
super.addView(child)
}
override fun addView(child: View, index: Int) {
if (isValidContentView(child)) contentView = child
super.addView(child, index)
}
override fun addView(child: View, index: Int, params: ViewGroup.LayoutParams) {
if (isValidContentView(child)) contentView = child
super.addView(child, index, params)
}
override fun addView(child: View, params: ViewGroup.LayoutParams) {
if (isValidContentView(child)) contentView = child
super.addView(child, params)
}
override fun addView(child: View, width: Int, height: Int) {
if (isValidContentView(child)) contentView = child
super.addView(child, width, height)
}
override fun addViewInLayout(child: View, index: Int, params: ViewGroup.LayoutParams): Boolean {
if (isValidContentView(child)) contentView = child
return super.addViewInLayout(child, index, params)
}
override fun addViewInLayout(child: View, index: Int, params: ViewGroup.LayoutParams, preventRequestLayout: Boolean): Boolean {
if (isValidContentView(child)) contentView = child
return super.addViewInLayout(child, index, params, preventRequestLayout)
}
/**
* Checks if the given [View] is valid for the Content View
*
* @param view The [View] to check
* @return
*/
private fun isValidContentView(view: View): Boolean {
return if (contentView != null && contentView !== view) {
false
} else view != loadingView && view != errorView && view != emptyView
}
/**
* Shows the [View] based on the [com.kennyc.view.MultiStateView.ViewState]
*/
private fun setView(previousState: ViewState) {
when (viewState) {
ViewState.LOADING -> {
requireNotNull(loadingView).apply {
contentView?.visibility = View.GONE
errorView?.visibility = View.GONE
emptyView?.visibility = View.GONE
if (animateLayoutChanges) {
animateLayoutChange(getView(previousState))
} else {
visibility = View.VISIBLE
}
}
}
ViewState.EMPTY -> {
requireNotNull(emptyView).apply {
contentView?.visibility = View.GONE
errorView?.visibility = View.GONE
loadingView?.visibility = View.GONE
if (animateLayoutChanges) {
animateLayoutChange(getView(previousState))
} else {
visibility = View.VISIBLE
}
}
}
ViewState.ERROR -> {
requireNotNull(errorView).apply {
contentView?.visibility = View.GONE
loadingView?.visibility = View.GONE
emptyView?.visibility = View.GONE
if (animateLayoutChanges) {
animateLayoutChange(getView(previousState))
} else {
visibility = View.VISIBLE
}
}
}
ViewState.CONTENT -> {
requireNotNull(contentView).apply {
loadingView?.visibility = View.GONE
errorView?.visibility = View.GONE
emptyView?.visibility = View.GONE
if (animateLayoutChanges) {
animateLayoutChange(getView(previousState))
} else {
visibility = View.VISIBLE
}
}
}
}
}
/**
* Animates the layout changes between [ViewState]
*
* @param previousView The view that it was currently on
*/
private fun animateLayoutChange(previousView: View?) {
if (previousView == null) {
requireNotNull(getView(viewState)).visibility = View.VISIBLE
return
}
ObjectAnimator.ofFloat(previousView, "alpha", 1.0f, 0.0f).apply {
duration = 250L
addListener(object : AnimatorListenerAdapter() {
override fun onAnimationStart(animation: Animator?) {
previousView.visibility = View.VISIBLE
}
override fun onAnimationEnd(animation: Animator) {
previousView.visibility = View.GONE
val currentView = requireNotNull(getView(viewState))
currentView.visibility = View.VISIBLE
ObjectAnimator.ofFloat(currentView, "alpha", 0.0f, 1.0f).setDuration(250L).start()
}
})
}.start()
}
interface StateListener {
/**
* Callback for when the [ViewState] has changed
*
* @param viewState The [ViewState] that was switched to
*/
fun onStateChanged(viewState: ViewState)
}
private class SavedState : BaseSavedState {
internal val state: ViewState
constructor(superState: Parcelable, state: ViewState) : super(superState) {
this.state = state
}
constructor(parcel: Parcel) : super(parcel) {
state = parcel.readSerializable() as ViewState
}
override fun writeToParcel(out: Parcel, flags: Int) {
super.writeToParcel(out, flags)
out.writeSerializable(state)
}
companion object {
@JvmField
val CREATOR: Parcelable.Creator<SavedState> = object : Parcelable.Creator<SavedState> {
override fun createFromParcel(`in`: Parcel): SavedState {
return SavedState(`in`)
}
override fun newArray(size: Int): Array<SavedState?> {
return arrayOfNulls(size)
}
}
}
}
}
private const val VIEW_STATE_CONTENT = 0
private const val VIEW_STATE_ERROR = 1
private const val VIEW_STATE_EMPTY = 2
private const val VIEW_STATE_LOADING = 3