Replace ObjectAnimator with Transitions API

build.gradle

@@ -17,7 +17,7 @@ buildscript {
   }
 
   dependencies {
-    classpath 'com.android.tools.build:gradle:3.2.0'
+    classpath 'com.android.tools.build:gradle:3.4.0-rc03'
     classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$versions.kotlin"
   }
 }

fluidresizelayout/build.gradle

@@ -30,4 +30,5 @@ android {
 
 dependencies {
   implementation "org.jetbrains.kotlin:kotlin-stdlib:$versions.kotlin"
+  implementation "androidx.constraintlayout:constraintlayout:2.0.0-alpha3"
 }

gradle/wrapper/gradle-wrapper.properties

@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.6-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.1.1-all.zip

sample/build.gradle

@@ -35,14 +35,16 @@ dependencies {
   implementation project(path: ':fluidresizelayout')
 
   implementation "androidx.appcompat:appcompat:$versions.androidx"
+  implementation "androidx.constraintlayout:constraintlayout:2.0.0-alpha3"
+
   implementation "org.jetbrains.kotlin:kotlin-stdlib:$versions.kotlin"
 
   implementation "com.jakewharton.timber:timber:$versions.timber"
   implementation('com.github.JakeWharton:kotterknife:e157638df1') {
     exclude group: 'com.android.support'
   }
-  implementation 'io.reactivex.rxjava2:rxjava:2.1.9'
-  implementation 'io.reactivex.rxjava2:rxandroid:2.0.1'
+  implementation 'io.reactivex.rxjava2:rxjava:2.2.2'
+  implementation 'io.reactivex.rxjava2:rxandroid:2.0.2'
   implementation "com.jakewharton.rxbinding2:rxbinding:$versions.rxBindings"
   implementation "com.jakewharton.rxrelay2:rxrelay:2.0.0"
   implementation 'io.reactivex.rxjava2:rxkotlin:2.2.0'

sample/src/main/java/me/saket/fluidresize/sample/FluidContentResizer.kt

@@ -1,45 +1,40 @@
 package me.saket.fluidresize.sample
 
-import android.animation.ObjectAnimator
-import android.animation.ValueAnimator
 import android.app.Activity
+import android.transition.*
 import android.view.View
-import androidx.interpolator.view.animation.FastOutSlowInInterpolator
+import android.view.ViewGroup
 import me.saket.fluidresize.ActivityViewHolder
 import me.saket.fluidresize.KeyboardVisibilityChanged
 import me.saket.fluidresize.KeyboardVisibilityDetector
 
 object FluidContentResizer {
 
-  private var heightAnimator: ValueAnimator = ObjectAnimator()
-
   fun listen(activity: Activity) {
     val viewHolder = ActivityViewHolder.createFrom(activity)
 
     KeyboardVisibilityDetector.listen(viewHolder) {
       animateHeight(viewHolder, it)
     }
     viewHolder.onDetach {
-      heightAnimator.cancel()
+      viewHolder.contentView.clearAnimation()
+    }
+    viewHolder.contentView.apply {
+      post {
+        setHeight(viewHolder.resizableLayout.height)
+      }
     }
   }
 
   private fun animateHeight(viewHolder: ActivityViewHolder, event: KeyboardVisibilityChanged) {
     val contentView = viewHolder.contentView
     contentView.setHeight(event.contentHeightBeforeResize)
 
-    heightAnimator.cancel()
+    val transition = ChangeBounds()
+    val sceneRoot = contentView.parent as ViewGroup
+    TransitionManager.beginDelayedTransition(sceneRoot, transition)
 
-    // Warning: animating height might not be very performant. Try turning on
-    // "Profile GPI rendering" in developer options and check if the bars stay
-    // under 16ms in your app. Using Transitions API would be more efficient, but
-    // for some reason it skips the first animation and I cannot figure out why.
-    heightAnimator = ObjectAnimator.ofInt(event.contentHeightBeforeResize, event.contentHeight).apply {
-      interpolator = FastOutSlowInInterpolator()
-      duration = 300
-    }
-    heightAnimator.addUpdateListener { contentView.setHeight(it.animatedValue as Int) }
-    heightAnimator.start()
+    contentView.setHeight(event.contentHeight)
   }
 
   private fun View.setHeight(height: Int) {

sample/src/main/java/me/saket/fluidresize/sample/FluidResizeActivity.kt

@@ -2,6 +2,9 @@ package me.saket.fluidresize.sample
 
 import android.os.Bundle
 import androidx.appcompat.app.AppCompatActivity
+import kotlinx.android.synthetic.main.activity_fluid_resize.*
+import me.saket.fluidresize.ActivityViewHolder
+import me.saket.fluidresize.KeyboardVisibilityDetector
 import me.saket.fluidresize.R
 
 class FluidResizeActivity : AppCompatActivity() {
@@ -10,6 +13,20 @@ class FluidResizeActivity : AppCompatActivity() {
     super.onCreate(savedInstanceState)
     setContentView(R.layout.activity_fluid_resize)
 
-    FluidContentResizer.listen(this)
+    val viewHolder = ActivityViewHolder.createFrom(this)
+
+    KeyboardVisibilityDetector.listen(viewHolder) {
+      event ->
+        if (event.contentHeight <= event.contentHeightBeforeResize) {
+            next_button.alpha = 0f
+        } else {
+            next_button.animate()
+                    .alpha(1f)
+                    .setStartDelay(150)
+                    .start()
+        }
+    }
+
+      FluidContentResizer.listen(this)
   }
 }

sample/src/main/res/layout/activity_fluid_resize.xml

@@ -1,14 +1,40 @@
 <?xml version="1.0" encoding="utf-8"?>
-<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
-  xmlns:tools="http://schemas.android.com/tools"
-  android:layout_width="match_parent"
-  android:layout_height="match_parent"
-  android:orientation="vertical">
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:orientation="vertical">
 
-  <EditText
-    android:layout_width="wrap_content"
-    android:layout_height="wrap_content"
-    android:layout_gravity="center"
-    android:text="Sup world?"
-    tools:ignore="HardcodedText" />
-</FrameLayout>
+    <EditText
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintBottom_toBottomOf="parent"
+        android:layout_gravity="center"
+        android:text="Sup world?"
+        tools:ignore="HardcodedText,LabelFor,UnusedAttribute"
+        android:importantForAutofill="no"
+        android:inputType="text" />
+
+    <TextView
+        android:id="@+id/next_button"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintBottom_toBottomOf="parent"
+        android:text="Next"
+        android:textAllCaps="true"
+        android:paddingTop="18dp"
+        android:paddingBottom="18dp"
+        android:textSize="20sp"
+        android:textStyle="bold"
+        android:textAlignment="center"
+        android:background="@android:color/holo_green_light"
+        android:textColor="@android:color/white"
+        />
+
+</androidx.constraintlayout.widget.ConstraintLayout>