Magisk/app/src/main/java/com/topjohnwu/magisk/utils/AnimationHelper.java

package com.topjohnwu.magisk.utils;

import android.view.View;
import android.view.animation.Animation;
import android.view.animation.Transformation;
import android.widget.LinearLayout;

public class AnimationHelper {
    public static void expand(final View v) {
        v.measure(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
        final int targetHeight = v.getMeasuredHeight();

        v.getLayoutParams().height = 0;
        v.setVisibility(View.VISIBLE);
        Animation a = new Animation() {
            @Override
            protected void applyTransformation(float interpolatedTime, Transformation t) {
                v.getLayoutParams().height = interpolatedTime == 1
                        ? LinearLayout.LayoutParams.WRAP_CONTENT
                        : (int) (targetHeight * interpolatedTime);
                v.requestLayout();
            }

            @Override
            public boolean willChangeBounds() {
                return true;
            }
        };

        // 1dp/ms
        a.setDuration((int) (targetHeight / v.getContext().getResources().getDisplayMetrics().density));
        v.startAnimation(a);
    }

    public static void collapse(final View v) {
        final int initialHeight = v.getMeasuredHeight();

        Animation a = new Animation() {
            @Override
            protected void applyTransformation(float interpolatedTime, Transformation t) {
                if (interpolatedTime == 1) {
                    v.setVisibility(View.GONE);
                } else {
                    v.getLayoutParams().height = initialHeight - (int) (initialHeight * interpolatedTime);
                    v.requestLayout();
                }
            }

            @Override
            public boolean willChangeBounds() {
                return true;
            }
        };
        // 1dp/ms
        a.setDuration((int) (initialHeight / v.getContext().getResources().getDisplayMetrics().density));
        v.startAnimation(a);
    }
}