Added androidx.core.view.ViewPropertyAnimator

src/main/java/androidx/core/view/ViewPropertyAnimator.kt

@@ -0,0 +1,93 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * 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.
+ */
+
+package androidx.core.view
+
+import android.animation.Animator
+import android.view.ViewPropertyAnimator
+
+/**
+ * Add an action which will be invoked when the animation has ended.
+ *
+ * @return the [ViewPropertyAnimator] receiver.
+ * @see Animator.end
+ */
+fun ViewPropertyAnimator.doOnEnd(action: (animator: Animator) -> Unit): ViewPropertyAnimator {
+    setListener(onEnd = action)
+    return this
+}
+
+/**
+ * Add an action which will be invoked when the animation has started.
+ *
+ * @return the [ViewPropertyAnimator] receiver.
+ * @see Animator.start
+ */
+fun ViewPropertyAnimator.doOnStart(action: (animator: Animator) -> Unit): ViewPropertyAnimator {
+    setListener(onStart = action)
+    return this
+}
+
+/**
+ * Add an action which will be invoked when the animation has been cancelled.
+ *
+ * @return the [ViewPropertyAnimator] receiver.
+ * @see Animator.cancel
+ */
+fun ViewPropertyAnimator.doOnCancel(action: (animator: Animator) -> Unit): ViewPropertyAnimator {
+    setListener(onCancel = action)
+    return this
+}
+
+/**
+ * Add an action which will be invoked when the animation has repeated.
+ * @return the [ViewPropertyAnimator] receiver.
+ */
+fun ViewPropertyAnimator.doOnRepeat(action: (animator: Animator) -> Unit): ViewPropertyAnimator {
+    setListener(onRepeat = action)
+    return this
+}
+
+/**
+ * Sets the listener to this Animator using the provided actions.
+ * @return the [ViewPropertyAnimator] receiver.
+ */
+fun ViewPropertyAnimator.setListener(
+        onEnd: ((animator: Animator) -> Unit)? = null,
+        onStart: ((animator: Animator) -> Unit)? = null,
+        onRepeat: ((animator: Animator) -> Unit)? = null,
+        onCancel: ((animator: Animator) -> Unit)? = null
+): ViewPropertyAnimator {
+    val listener = object : Animator.AnimatorListener {
+        override fun onAnimationStart(animator: Animator) {
+            onStart?.invoke(animator)
+        }
+
+        override fun onAnimationRepeat(animator: Animator) {
+            onRepeat?.invoke(animator)
+        }
+
+        override fun onAnimationEnd(animator: Animator) {
+            onEnd?.invoke(animator)
+        }
+
+        override fun onAnimationCancel(animator: Animator) {
+            onCancel?.invoke(animator)
+        }
+    }
+    setListener(listener)
+    return this
+}