NewPipe/app/src/main/java/org/schabi/newpipe/views/AnimatedProgressBar.java

package org.schabi.newpipe.views;

import android.content.Context;
import android.util.AttributeSet;
import android.view.animation.AccelerateDecelerateInterpolator;
import android.view.animation.Animation;
import android.view.animation.Transformation;
import android.widget.ProgressBar;

import androidx.annotation.Nullable;

public final class AnimatedProgressBar extends ProgressBar {
    @Nullable
    private ProgressBarAnimation animation = null;

    public AnimatedProgressBar(final Context context) {
        super(context);
    }

    public AnimatedProgressBar(final Context context, final AttributeSet attrs) {
        super(context, attrs);
    }

    public AnimatedProgressBar(final Context context, final AttributeSet attrs,
                               final int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    public synchronized void setProgressAnimated(final int progress) {
        cancelAnimation();
        animation = new ProgressBarAnimation(this, getProgress(), progress);
        startAnimation(animation);
    }

    private void cancelAnimation() {
        if (animation != null) {
            animation.cancel();
            animation = null;
        }
        clearAnimation();
    }

    private static class ProgressBarAnimation extends Animation {

        private final AnimatedProgressBar progressBar;
        private final float from;
        private final float to;

        ProgressBarAnimation(final AnimatedProgressBar progressBar, final float from,
                             final float to) {
            super();
            this.progressBar = progressBar;
            this.from = from;
            this.to = to;
            setDuration(500);
            setInterpolator(new AccelerateDecelerateInterpolator());
        }

        @Override
        protected void applyTransformation(final float interpolatedTime, final Transformation t) {
            super.applyTransformation(interpolatedTime, t);
            final float value = from + (to - from) * interpolatedTime;
            progressBar.setProgress((int) value);
        }
    }
}