FAB使用在CoordinatorLayout的隐藏动画

ScrollAwareFABBehavior.java

package com.support.android.designlibdemo;

import android.content.Context;
import android.os.Build;
import android.support.design.widget.CoordinatorLayout;
import android.support.design.widget.FloatingActionButton;
import android.support.v4.view.ViewCompat;
import android.support.v4.view.ViewPropertyAnimatorListener;
import android.support.v4.view.animation.FastOutSlowInInterpolator;
import android.util.AttributeSet;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.view.animation.Interpolator;

/**
 * Created by Bruce Too
 * On 6/2/15.
 * At 09:14
 * 只需要在 layout 中
 *  app:layout_behavior="com.support.android.designlibdemo.ScrollAwareFABBehavior" 使用就OK
 */

public class ScrollAwareFABBehavior extends FloatingActionButton.Behavior {
    private static final Interpolator INTERPOLATOR = new FastOutSlowInInterpolator();
    private boolean mIsAnimatingOut = false;

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

    /**
     * 滚动开始的监听
     * @param coordinatorLayout
     * @param child 设置了Behavior得子view
     * @param directTargetChild
     * @param target  需要滚动的子view
     * @param nestedScrollAxes 滚动轴方向 SCROLL_AXIS_HORIZONTAL, SCROLL_AXIS_VERTICAL
     * @return
     */
    @Override
    public boolean onStartNestedScroll(final CoordinatorLayout coordinatorLayout, final FloatingActionButton child,
                                       final View directTargetChild, final View target, final int nestedScrollAxes) {
        // Ensure we react to vertical scrolling
        return nestedScrollAxes == ViewCompat.SCROLL_AXIS_VERTICAL
                || super.onStartNestedScroll(coordinatorLayout, child, directTargetChild, target, nestedScrollAxes);
    }

    /**
     * 滚动时的监听
     * 每一个设置了Behavior 并且是 CoordinatorLayout的直接子view都会调用此方法
     * 比如 FloatActionButton,AppBarLayout
     * @param coordinatorLayout	the CoordinatorLayout parent of the view this Behavior is associated with
     * @param child	the child view of the CoordinatorLayout this Behavior is associated with
     * @param target	the descendant view of the CoordinatorLayout performing the nested scroll
     * @param dxConsumed	horizontal pixels consumed by the target's own scrolling operation
     * @param dyConsumed	vertical pixels consumed by the target's own scrolling operation
     * @param dxUnconsumed	horizontal pixels not consumed by the target's own scrolling operation, but requested by the user
     */
    @Override
    public void onNestedScroll(final CoordinatorLayout coordinatorLayout, final FloatingActionButton child,
                               final View target, final int dxConsumed, final int dyConsumed,
                               final int dxUnconsumed, final int dyUnconsumed) {
        super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed);
        if (dyConsumed > 0 && !this.mIsAnimatingOut && child.getVisibility() == View.VISIBLE) {
            // User scrolled down and the FAB is currently visible -> hide the FAB
            animateOut(child);
        } else if (dyConsumed < 0 && child.getVisibility() != View.VISIBLE) {
            // User scrolled up and the FAB is currently not visible -> show the FAB
            animateIn(child);
        }

        /**
         * 如果>=V22.2.1'
         * 可以使用系统预设的动画
         */

//        if (dyConsumed > 0 && child.getVisibility() == View.VISIBLE) {
//            // User scrolled down and the FAB is currently visible -> hide the FAB
//            child.hide();
//        } else if (dyConsumed < 0 && child.getVisibility() != View.VISIBLE) {
//            // User scrolled up and the FAB is currently not visible -> show the FAB
//            child.show();
//        }

    }

    // Same animation that FloatingActionButton.Behavior uses to hide the FAB when the AppBarLayout exits
    private void animateOut(final FloatingActionButton button) {
        if (Build.VERSION.SDK_INT >= 14) {
            ViewCompat.animate(button).scaleX(0.0F).scaleY(0.0F).alpha(0.0F).setInterpolator(INTERPOLATOR).withLayer()
                    .setListener(new ViewPropertyAnimatorListener() {
                        public void onAnimationStart(View view) {
                            ScrollAwareFABBehavior.this.mIsAnimatingOut = true;
                        }

                        public void onAnimationCancel(View view) {
                            ScrollAwareFABBehavior.this.mIsAnimatingOut = false;
                        }

                        public void onAnimationEnd(View view) {
                            ScrollAwareFABBehavior.this.mIsAnimatingOut = false;
                            view.setVisibility(View.GONE);
                        }
                    }).start();
        } else {
            Animation anim = AnimationUtils.loadAnimation(button.getContext(), R.anim.fab_out);
            anim.setInterpolator(INTERPOLATOR);
            anim.setDuration(200L);
            anim.setAnimationListener(new Animation.AnimationListener() {
                public void onAnimationStart(Animation animation) {
                    ScrollAwareFABBehavior.this.mIsAnimatingOut = true;
                }

                public void onAnimationEnd(Animation animation) {
                    ScrollAwareFABBehavior.this.mIsAnimatingOut = false;
                    button.setVisibility(View.GONE);
                }

                @Override
                public void onAnimationRepeat(final Animation animation) {
                }
            });
            button.startAnimation(anim);
        }
    }

    // Same animation that FloatingActionButton.Behavior uses to show the FAB when the AppBarLayout enters
    private void animateIn(FloatingActionButton button) {
        button.setVisibility(View.VISIBLE);
        if (Build.VERSION.SDK_INT >= 14) {
            ViewCompat.animate(button).scaleX(1.0F).scaleY(1.0F).alpha(1.0F)
                    .setInterpolator(INTERPOLATOR).withLayer().setListener(null)
                    .start();
        } else {
            Animation anim = AnimationUtils.loadAnimation(button.getContext(), R.anim.fab_in);
            anim.setDuration(200L);
            anim.setInterpolator(INTERPOLATOR);
            button.startAnimation(anim);
        }
    }
}