Use custom interpolator for predictive back system animations

import android.annotation.Nullable;

import android.graphics.Insets;

import android.util.Log;

import android.view.animation.BackGestureInterpolator;

import android.view.animation.Interpolator;

import android.view.animation.PathInterpolator;

import android.window.BackEvent;

    private static final int POST_COMMIT_DURATION_MS = 200;

    private static final int POST_COMMIT_CANCEL_DURATION_MS = 50;

    private static final float PEEK_FRACTION = 0.1f;

    private static final Interpolator STANDARD_DECELERATE = new PathInterpolator(0f, 0f, 0f, 1f);

    private static final Interpolator BACK_GESTURE = new BackGestureInterpolator();

    private static final Interpolator EMPHASIZED_DECELERATE = new PathInterpolator(

            0.05f, 0.7f, 0.1f, 1f);

    private static final Interpolator STANDARD_ACCELERATE = new PathInterpolator(0.3f, 0f, 1f, 1f);

            float hiddenY = mWindowInsetsAnimationController.getHiddenStateInsets().bottom;

            float shownY = mWindowInsetsAnimationController.getShownStateInsets().bottom;

            float imeHeight = shownY - hiddenY;

            float interpolatedProgress = STANDARD_DECELERATE.getInterpolation(progress);

            float interpolatedProgress = BACK_GESTURE.getInterpolation(progress);

            int newY = (int) (imeHeight - interpolatedProgress * (imeHeight * PEEK_FRACTION));

            mWindowInsetsAnimationController.setInsetsAndAlpha(Insets.of(0, 0, 0, newY), 1f,

                    progress);

/*

 * Copyright (C) 2024 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 android.view.animation;

/**

 * Decelerating interpolator with a very slight acceleration phase at the beginning.

 * @hide

 */

public class BackGestureInterpolator extends PathInterpolator {

    public BackGestureInterpolator() {

        super(0.1f, 0.1f, 0f, 1f);

    }

}

package com.android.wm.shell.animation;

import android.graphics.Path;

import android.view.animation.BackGestureInterpolator;

import android.view.animation.Interpolator;

import android.view.animation.LinearInterpolator;

import android.view.animation.PathInterpolator;

    public static final PathInterpolator DIM_INTERPOLATOR =

            new PathInterpolator(.23f, .87f, .52f, -0.11f);

    /**

     * Use this interpolator for animating progress values coming from the back callback to get

     * the predictive-back-typical decelerate motion.

     *

     * This interpolator is similar to {@link Interpolators#STANDARD_DECELERATE} but has a slight

     * acceleration phase at the start.

     */

    public static final Interpolator BACK_GESTURE = new BackGestureInterpolator();

    // Create the default emphasized interpolator

    private static PathInterpolator createEmphasizedInterpolator() {

        Path path = new Path();

    private val enteringStartOffset =

        context.resources.getDimension(R.dimen.cross_activity_back_entering_start_offset)

    private val gestureInterpolator = Interpolators.STANDARD_DECELERATE

    private val gestureInterpolator = Interpolators.BACK_GESTURE

    private val postCommitInterpolator = Interpolators.FAST_OUT_SLOW_IN

    private val verticalMoveInterpolator: Interpolator = DecelerateInterpolator()

            // in case we're still animating an onBackCancelled event, let's remove the finish-

            // callback from the progress animator to prevent calling finishAnimation() before

            // restarting a new animation

            progressAnimator.removeOnBackCancelledFinishCallback();

            progressAnimator.removeOnBackCancelledFinishCallback()

            startBackAnimation(backMotionEvent)

            progressAnimator.onBackStarted(backMotionEvent) { backEvent: BackEvent ->

    private final PointF mInitialTouchPos = new PointF();

    private final Interpolator mPostAnimationInterpolator = Interpolators.EMPHASIZED;

    private final Interpolator mProgressInterpolator = Interpolators.STANDARD_DECELERATE;

    private final Interpolator mProgressInterpolator = Interpolators.BACK_GESTURE;

    private final Interpolator mVerticalMoveInterpolator = new DecelerateInterpolator();

    private final Matrix mTransformMatrix = new Matrix();