feat: add onViewAttached and onViewDetached methods to ViewDelegate

- Added onViewAttached method to handle view attachment logic
- Added onViewDetached method to handle view detachment logic

Closes #40

Author: DylanCaiCoding

loadingstateview/src/main/java/com/dylanc/loadingstateview/LoadingStateView.kt

@@ -148,12 +148,14 @@ class LoadingStateView @JvmOverloads constructor(
       if (viewType != currentViewType) {
         val view = getView(viewType)
         view.visibility = View.VISIBLE
+        getViewDelegate<ViewDelegate>(viewType)?.onViewAttached(view)
         if (animation != null) {
           animation.onStartHideAnimation(currentView, currentViewType)
           animation.onStartShowAnimation(view, getViewDelegate<ViewDelegate>(viewType)!!.viewType)
         } else {
           currentView.visibility = View.GONE
         }
+        getViewDelegate<ViewDelegate>(currentViewType)?.onViewDetached(view)
         this.currentView = view
       }
     }
@@ -190,10 +192,11 @@ class LoadingStateView @JvmOverloads constructor(
   }
 
   abstract class ViewDelegate(val viewType: Any) {
+    abstract fun onCreateView(inflater: LayoutInflater, parent: ViewGroup): View
+    open fun onViewAttached(view: View) = Unit
+    open fun onViewDetached(view: View) = Unit
     var onReloadListener: OnReloadListener? = null
       internal set
-
-    abstract fun onCreateView(inflater: LayoutInflater, parent: ViewGroup): View
   }
 
   private inner class ContentViewDelegate : LoadingStateView.ViewDelegate(ViewType.CONTENT) {

sample-kotlin/src/main/java/com/dylanc/loadingstateview/sample/kotlin/delegate/LoadingViewDelegate.kt

@@ -30,4 +30,15 @@ class LoadingViewDelegate : LoadingStateView.ViewDelegate(ViewType.LOADING) {
 
   override fun onCreateView(inflater: LayoutInflater, parent: ViewGroup): View =
     inflater.inflate(R.layout.layout_loading, parent, false)
+
+  override fun onViewAttached(view: View) {
+    view.animate().rotationBy(360f)
+      .setDuration(800)
+      .withEndAction { onViewAttached(view) }
+      .start()
+  }
+
+  override fun onViewDetached(view: View) {
+    view.animate().cancel()
+  }
 }

sample-kotlin/src/main/res/drawable/ic_refresh.xml

@@ -0,0 +1,12 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+  android:width="48dp"
+  android:height="48dp"
+  android:tint="#bbbbbb"
+  android:viewportWidth="24"
+  android:viewportHeight="24">
+
+  <path
+    android:fillColor="@android:color/white"
+    android:pathData="M17.65,6.35C16.2,4.9 14.21,4 12,4c-4.42,0 -7.99,3.58 -7.99,8s3.57,8 7.99,8c3.73,0 6.84,-2.55 7.73,-6h-2.08c-0.82,2.33 -3.04,4 -5.65,4 -3.31,0 -6,-2.69 -6,-6s2.69,-6 6,-6c1.66,0 3.14,0.69 4.22,1.78L13,11h7V4l-2.35,2.35z" />
+
+</vector>

sample-kotlin/src/main/res/layout/layout_loading.xml

@@ -4,18 +4,14 @@
   android:layout_width="match_parent"
   android:layout_height="match_parent">
 
-  <ProgressBar
-    android:id="@+id/progress_bar"
-    style="?android:attr/progressBarStyle"
+  <ImageView
+    android:id="@+id/iv_loading"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
-    android:layout_marginStart="8dp"
-    android:layout_marginTop="24dp"
-    android:layout_marginEnd="8dp"
-    android:layout_marginBottom="24dp"
+    android:importantForAccessibility="no"
     app:layout_constraintBottom_toBottomOf="parent"
     app:layout_constraintEnd_toEndOf="parent"
     app:layout_constraintStart_toStartOf="parent"
     app:layout_constraintTop_toTopOf="parent"
-    app:layout_constraintVertical_chainStyle="packed" />
+    app:srcCompat="@drawable/ic_refresh" />
 </androidx.constraintlayout.widget.ConstraintLayout>