Consolidating various interpolators

Change-Id: I9588eee3552001b162a1e8d5ccefcfb44d221880

1 files changed, 90 insertions, 0 deletions

diff --git a/src/com/android/launcher3/anim/Interpolators.java b/src/com/android/launcher3/anim/Interpolators.java
new file mode 100644
index 000000000..8826e64d8
--- /dev/null
+++ b/src/com/android/launcher3/anim/Interpolators.java
@@ -0,0 +1,90 @@
+/*
+ * Copyright (C) 2017 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.launcher3.anim;
+
+import android.view.animation.AccelerateInterpolator;
+import android.view.animation.DecelerateInterpolator;
+import android.view.animation.Interpolator;
+import android.view.animation.LinearInterpolator;
+import android.view.animation.PathInterpolator;
+
+
+/**
+ * Common interpolators used in Launcher
+ */
+public class Interpolators {
+
+    public static final Interpolator LINEAR = new LinearInterpolator();
+
+    public static final Interpolator ACCEL = new AccelerateInterpolator();
+    public static final Interpolator ACCEL_1_5 = new AccelerateInterpolator(1.5f);
+    public static final Interpolator ACCEL_2 = new AccelerateInterpolator(2);
+
+    public static final Interpolator DEACCEL = new DecelerateInterpolator();
+    public static final Interpolator DEACCEL_1_5 = new DecelerateInterpolator(1.5f);
+    public static final Interpolator DEACCEL_2 = new DecelerateInterpolator(2);
+    public static final Interpolator DEACCEL_2_5 = new DecelerateInterpolator(2.5f);
+    public static final Interpolator DEACCEL_3 = new DecelerateInterpolator(3f);
+
+    public static final Interpolator FAST_OUT_SLOW_IN = new PathInterpolator(0.4f, 0f, 0.2f, 1f);
+
+    /**
+     * Inversion of zInterpolate, compounded with an ease-out.
+     */
+    public static final Interpolator ZOOM_IN = new Interpolator() {
+
+        private static final float FOCAL_LENGTH = 0.35f;
+
+        @Override
+        public float getInterpolation(float v) {
+            return DEACCEL_3.getInterpolation(1 - zInterpolate(1 - v));
+        }
+
+        /**
+         * This interpolator emulates the rate at which the perceived scale of an object changes
+         * as its distance from a camera increases. When this interpolator is applied to a scale
+         * animation on a view, it evokes the sense that the object is shrinking due to moving away
+         * from the camera.
+         */
+        private float zInterpolate(float input) {
+            return (1.0f - FOCAL_LENGTH / (FOCAL_LENGTH + input)) /
+                    (1.0f - FOCAL_LENGTH / (FOCAL_LENGTH + 1.0f));
+        }
+    };
+
+    public static final Interpolator SCROLL = new Interpolator() {
+        @Override
+        public float getInterpolation(float t) {
+            t -= 1.0f;
+            return t*t*t*t*t + 1;
+        }
+    };
+
+    public static final Interpolator SCROLL_CUBIC = new Interpolator() {
+        @Override
+        public float getInterpolation(float t) {
+            t -= 1.0f;
+            return t*t*t + 1;
+        }
+    };
+
+    private static final float FAST_FLING_PX_MS = 10;
+
+    public static Interpolator scrollInterpolatorForVelocity(float velocity) {
+        return Math.abs(velocity) > FAST_FLING_PX_MS ? SCROLL : SCROLL_CUBIC;
+    }
+}
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