OAC-Swing/src/main/java/org/openautonomousconnection/oacswing/animated/AnimationPath.java

/* Author: Maple
 *  Jan. 24 2026
 *  */

package org.openautonomousconnection.oacswing.animated;

import lombok.Getter;
import lombok.Setter;

import java.awt.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;

public class AnimationPath extends ArrayList<KeyFrame> {
    @Getter @Setter
    private int inbetweens;

    private int animationIterator = 0;

    private int subFrameIterator = 0;

    public AnimationPath(int inbetweens, Collection<KeyFrame> keyFrames) {
        this.addAll(keyFrames);
        this.inbetweens = inbetweens;
    }

    public AnimationPath(int inbetweens, KeyFrame... keyFrames) {
        this.addAll(Arrays.stream(keyFrames).toList());
        this.inbetweens = inbetweens;
    }

    public AnimationPath(int inbetweens) {
        this.inbetweens = inbetweens;
    }
    /**
     * Get next keyframe according to current path iterator, depending on the current frame without increasing the animation iterators
     * @return next keyframe in order, depending on the current frame
     */
    public KeyFrame peekNext() {
        int tempSubIterator = this.subFrameIterator, tempAnimationIterator = this.animationIterator;

        if(tempSubIterator >= this.inbetweens) {
            tempSubIterator = 0;
            tempAnimationIterator++;
        }

        if(tempAnimationIterator >= this.size())
            return null;

        tempSubIterator++;

        KeyFrame current = this.get(tempAnimationIterator);

        KeyFrame next = this.getNextInOrder();

        return getKeyFrame(current, next, tempSubIterator);
    }

    /**
     * Get next keyframe according to current path iterator, depending on the current frame, and increase the animation iterators
     * @return next keyframe in order, depending on the current frame
     */
    public KeyFrame getNext() {
        if(this.subFrameIterator >= this.inbetweens) {
            this.subFrameIterator = 0;
            this.animationIterator++;
        }

        if(this.animationIterator >= this.size())
            return null;

        this.subFrameIterator++;

        KeyFrame current = this.get(this.animationIterator);

        KeyFrame next = this.getNextInOrder();

        return getKeyFrame(current, next, this.subFrameIterator);
    }

    private KeyFrame getKeyFrame(KeyFrame current, KeyFrame next, int subIterator) {
        // How far the transition should be finished

        double transition = this.linear(subIterator);

        KeyFrame.PathMethod method;

        // Translate EASE_IN_AND_OUT to its respective currently relevant counterpart

        //TODO: non-linear keyframes can't behandled this way. This just makes it bug around

        if(transition < 0.5)
            method = current.pathMethod().equals(KeyFrame.PathMethod.EASE_IN_AND_OUT) ?
                    KeyFrame.PathMethod.EASE_OUT : current.pathMethod();
        else
            method = next.pathMethod().equals(KeyFrame.PathMethod.EASE_IN_AND_OUT) ?
                KeyFrame.PathMethod.EASE_OUT : next.pathMethod();

        // Else-case would be linear, which doesn't change anything

        if(method.equals(KeyFrame.PathMethod.EASE_IN))
            transition = this.easeIn(subIterator);

        else if(method.equals(KeyFrame.PathMethod.EASE_OUT))
            transition = this.easeOut(subIterator);

        return inBetween(current, next, transition, method);
    }


    /**
     * Get next keyframe according to current path iterator, not depending on the current frame
     * @return next keyframe in order, not depending on the current frame
     */
    public KeyFrame getNextInOrder() {
        int i = this.animationIterator + 1;

        if(i >= this.size())
            i--;

        return this.get(i);
    }

    /**
     * @return true if there are any more frames coming
     */
    public boolean anyMore() {
        return this.animationIterator + 1 < this.size();
    }

    /**
     * Reset animation path iterator to start
     */
    public void reset() {
        this.subFrameIterator = 0;
        this.animationIterator = 0;
    }

    /**
     * Utility method needed to get in-betweens
     * @param point point to multiply
     * @param scalar scalar to multiply with
     * @return scalar product point
     */
    private static Point multiply(Point point, double scalar) {
        int x = Math.toIntExact(Math.round(point.x * scalar));
        int y = Math.toIntExact(Math.round(point.y * scalar));

        return new Point(x, y);
    }


    /**
     * Add two points together; also needed for in-betweens
     * @param point augend
     * @param addend addend
     * @return sum of both points
     */
    private static Point add(Point point, Point addend) {
        return new Point(point.x + addend.x, point.y + addend.y);
    }

    /**
     * Subtracts one point from another; also needed for in-betweens
     * @param point minuend
     * @param subtrahend subtrahend
     * @return sum of both points
     */
    private static Point subtract(Point point, Point subtrahend) {
        return new Point(point.x - subtrahend.x, point.y - subtrahend.y);
    }

    /**
     * Find in-between with given scalar
     * @param kf1 first frame
     * @param kf2 next frame
     * @param scalar factor (ideally between 0 and 1, representing 0% transition to 100% transition)
     * @return in-between frame
     */
    private static KeyFrame inBetween(KeyFrame kf1, KeyFrame kf2, double scalar, KeyFrame.PathMethod method) {
        // position

        Point difference = subtract(kf2.position(), kf1.position());

        Point pos = add(kf1.position(), multiply(difference, scalar));

        // scale

        int width, height;

        int dW = kf2.width() - kf1.width();
        int dH = kf2.height() - kf1.height();

        width = Math.toIntExact(Math.round(kf1.width() + dW * scalar));

        height = Math.toIntExact(Math.round(kf1.height() + dH * scalar));

        return new KeyFrame(pos, width, height, method);
    }

    @Override
    public AnimationPath clone() {
        return new AnimationPath(this.inbetweens, new ArrayList<>(this));
    }

    private double linear(int subIterator) {
        return (double) subIterator/2 / this.inbetweens;
    }

    private double easeIn(int subIterator) {
        return this.linear(subIterator/2) * this.linear(subIterator/2);
    }

    public double easeOut(int subIterator) {
        return Math.sqrt(this.linear(subIterator*2));
    }
}