design/base/android/support/design/widget/StateListAnimator.java

/*
 * Copyright (C) 2015 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 android.support.design.widget;

import android.util.StateSet;

import java.util.ArrayList;

final class StateListAnimator {

    private final ArrayList<Tuple> mTuples = new ArrayList<>();

    private Tuple mLastMatch = null;
    ValueAnimatorCompat mRunningAnimator = null;

    private final ValueAnimatorCompat.AnimatorListener mAnimationListener
            = new ValueAnimatorCompat.AnimatorListenerAdapter() {
        @Override
        public void onAnimationEnd(ValueAnimatorCompat animator) {
            if (mRunningAnimator == animator) {
                mRunningAnimator = null;
            }
        }
    };

    /**
     * Associates the given Animation with the provided drawable state specs so that it will be run
     * when the View's drawable state matches the specs.
     *
     * @param specs    The drawable state specs to match against
     * @param animator The animator to run when the specs match
     */
    public void addState(int[] specs, ValueAnimatorCompat animator) {
        Tuple tuple = new Tuple(specs, animator);
        animator.addListener(mAnimationListener);
        mTuples.add(tuple);
    }

    /**
     * Called by View
     */
    void setState(int[] state) {
        Tuple match = null;
        final int count = mTuples.size();
        for (int i = 0; i < count; i++) {
            final Tuple tuple = mTuples.get(i);
            if (StateSet.stateSetMatches(tuple.mSpecs, state)) {
                match = tuple;
                break;
            }
        }
        if (match == mLastMatch) {
            return;
        }
        if (mLastMatch != null) {
            cancel();
        }

        mLastMatch = match;

        if (match != null) {
            start(match);
        }
    }

    private void start(Tuple match) {
        mRunningAnimator = match.mAnimator;
        mRunningAnimator.start();
    }

    private void cancel() {
        if (mRunningAnimator != null) {
            mRunningAnimator.cancel();
            mRunningAnimator = null;
        }
    }

    /**
     * If there is an animation running for a recent state change, ends it.
     *
     * <p>This causes the animation to assign the end value(s) to the View.</p>
     */
    public void jumpToCurrentState() {
        if (mRunningAnimator != null) {
            mRunningAnimator.end();
            mRunningAnimator = null;
        }
    }

    static class Tuple {
        final int[] mSpecs;
        final ValueAnimatorCompat mAnimator;

        Tuple(int[] specs, ValueAnimatorCompat animator) {
            mSpecs = specs;
            mAnimator = animator;
        }
    }
}