Add FloatProperties, which contains helpful properties for animating Rects.

Test: atest SystemUITests
Change-Id: I0f6584e1898b75c19e2e27ba2915dcdff42f419b

packages/SystemUI/src/com/android/systemui/util/animation/FloatProperties.kt

@@ -0,0 +1,107 @@
+/*
+ * Copyright (C) 2020 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 com.android.systemui.util.animation
+
+import android.graphics.Rect
+import android.graphics.RectF
+import androidx.dynamicanimation.animation.FloatPropertyCompat
+
+/**
+ * Helpful extra properties to use with the [PhysicsAnimator]. These allow you to animate objects
+ * such as [Rect] and [RectF].
+ *
+ * There are additional, more basic properties available in [DynamicAnimation].
+ */
+class FloatProperties {
+    companion object {
+        /**
+         * Represents the x-coordinate of a [Rect]. Typically used to animate moving a Rect
+         * horizontally.
+         *
+         * This property's getter returns [Rect.left], and its setter uses [Rect.offsetTo], which
+         * sets [Rect.left] to the new value and offsets [Rect.right] so that the width of the Rect
+         * does not change.
+         */
+        @JvmField
+        val RECT_X = object : FloatPropertyCompat<Rect>("RectX") {
+            override fun setValue(rect: Rect?, value: Float) {
+                rect?.offsetTo(value.toInt(), rect.top)
+            }
+
+            override fun getValue(rect: Rect?): Float {
+                return rect?.left?.toFloat() ?: -Float.MAX_VALUE
+            }
+        }
+
+        /**
+         * Represents the y-coordinate of a [Rect]. Typically used to animate moving a Rect
+         * vertically.
+         *
+         * This property's getter returns [Rect.top], and its setter uses [Rect.offsetTo], which
+         * sets [Rect.top] to the new value and offsets [Rect.bottom] so that the height of the Rect
+         * does not change.
+         */
+        @JvmField
+        val RECT_Y = object : FloatPropertyCompat<Rect>("RectY") {
+            override fun setValue(rect: Rect?, value: Float) {
+                rect?.offsetTo(rect.left, value.toInt())
+            }
+
+            override fun getValue(rect: Rect?): Float {
+                return rect?.top?.toFloat() ?: -Float.MAX_VALUE
+            }
+        }
+
+        /**
+         * Represents the x-coordinate of a [RectF]. Typically used to animate moving a RectF
+         * horizontally.
+         *
+         * This property's getter returns [RectF.left], and its setter uses [RectF.offsetTo], which
+         * sets [RectF.left] to the new value and offsets [RectF.right] so that the width of the
+         * RectF does not change.
+         */
+        @JvmField
+        val RECTF_X = object : FloatPropertyCompat<RectF>("RectFX") {
+            override fun setValue(rect: RectF?, value: Float) {
+                rect?.offsetTo(value, rect.top)
+            }
+
+            override fun getValue(rect: RectF?): Float {
+                return rect?.left ?: -Float.MAX_VALUE
+            }
+        }
+
+        /**
+         * Represents the y-coordinate of a [RectF]. Typically used to animate moving a RectF
+         * vertically.
+         *
+         * This property's getter returns [RectF.top], and its setter uses [RectF.offsetTo], which
+         * sets [RectF.top] to the new value and offsets [RectF.bottom] so that the height of the
+         * RectF does not change.
+         */
+        @JvmField
+        val RECTF_Y = object : FloatPropertyCompat<RectF>("RectFY") {
+            override fun setValue(rect: RectF?, value: Float) {
+                rect?.offsetTo(rect.left, value)
+            }
+
+            override fun getValue(rect: RectF?): Float {
+                return rect?.top ?: -Float.MAX_VALUE
+            }
+        }
+    }
+}