quickstep/src/com/android/quickstep/AnimatedFloat.java

/*
 * Copyright (C) 2017 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 com.android.quickstep;

import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.ObjectAnimator;
import android.util.FloatProperty;

/**
 * A mutable float which allows animating the value
 */
public class AnimatedFloat {

    public static FloatProperty<AnimatedFloat> VALUE = new FloatProperty<AnimatedFloat>("value") {
        @Override
        public void setValue(AnimatedFloat obj, float v) {
            obj.updateValue(v);
        }

        @Override
        public Float get(AnimatedFloat obj) {
            return obj.value;
        }
    };

    private final Runnable mUpdateCallback;
    private ObjectAnimator mValueAnimator;

    public float value;

    public AnimatedFloat(Runnable updateCallback) {
        mUpdateCallback = updateCallback;
    }

    public ObjectAnimator animateToValue(float v) {
        cancelAnimation();
        mValueAnimator = ObjectAnimator.ofFloat(this, VALUE, v);
        mValueAnimator.addListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animator) {
                if (mValueAnimator == animator) {
                    mValueAnimator = null;
                }
            }
        });
        return mValueAnimator;
    }

    /**
     * Changes the value and calls the callback.
     * Note that the value can be directly accessed as well to avoid notifying the callback.
     */
    public void updateValue(float v) {
        if (Float.compare(v, value) != 0) {
            value = v;
            mUpdateCallback.run();
        }
    }

    public void cancelAnimation() {
        if (mValueAnimator != null) {
            mValueAnimator.cancel();
        }
    }

    public void finishAnimation() {
        if (mValueAnimator != null && mValueAnimator.isRunning()) {
            mValueAnimator.end();
        }
    }

    public ObjectAnimator getCurrentAnimation() {
        return mValueAnimator;
    }
}