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High performance and lightweight Animation/Tween framework for Java 8+
There is a newer version: 9.2
/*
 * Copyright 2012 Aurelien Ribon
 *
 * 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 dorkbox.tweenengine;

/**
 * The TweenAccessor interface lets you interpolate any attribute from any
 * object. Just implement it as you want and register it to the engine by
 * calling {@link Tween#registerAccessor}.
 * 
 *
 * 
Example
 *
 * The following code snippet presents an example of implementation for tweening
 * a Particle class. This Particle class is supposed to only define a position
 * with an "x" and an "y" fields, and their associated getters and setters.
 * 
 *
 * 
 {@code
 * public class ParticleAccessor implements TweenAccessor {
 *     public static final int X = 1;
 *     public static final int Y = 2;
 *     public static final int XY = 3;
 *
 *     public int getValues(Particle target, int tweenType, float[] returnValues) {
 *         switch (tweenType) {
 *             case X: returnValues[0] = target.getX(); return 1;
 *             case Y: returnValues[0] = target.getY(); return 1;
 *             case XY:
 *                 returnValues[0] = target.getX();
 *                 returnValues[1] = target.getY();
 *                 return 2;
 *             default: assert false; return 0;
 *         }
 *     }
 *
 *     public void setValues(Particle target, int tweenType, float[] newValues) {
 *         switch (tweenType) {
 *             case X: target.setX(newValues[0]); break;
 *             case Y: target.setY(newValues[1]); break;
 *             case XY:
 *                 target.setX(newValues[0]);
 *                 target.setY(newValues[1]);
 *                 break;
 *             default: assert false; break;
 *         }
 *     }
 * }
 * }
 *
 * Once done, you only need to register this TweenAccessor once to be able to
 * use it for every Particle objects in your application:
 * 
 *
 * 
 {@code
 * Tween.registerAccessor(Particle.class, new ParticleAccessor());
 * }
 *
 * And that's all, the Tween Engine can no work with all your particles!
 *
 * @author Aurelien Ribon | http://www.aurelienribon.com/
 */
public
interface TweenAccessor {
    /**
     * Gets one or many values from the target object associated to the
     * given tween type. It is used by the Tween Engine to determine starting
     * values.
     *
     * @param target The target object of the tween.
     * @param tweenType An arbitrary number used to associate an interpolation type for a tween in the TweenAccessor get/setValues() methods
     * @param returnValues An array which should be modified by this method.
     *
     * @return The count of modified slots from the returnValues array.
     */
    int getValues(T target, int tweenType, float[] returnValues);

    /**
     * This method is called by the Tween Engine each time a running tween
     * associated with the current target object has been updated.
     *
     * @param target The target object of the tween.
     * @param tweenType An arbitrary number used to associate an interpolation type for a tween in the TweenAccessor get/setValues() methods
     * @param newValues The new values determined by the Tween Engine.
     */
    void setValues(T target, int tweenType, float[] newValues);
}