BottomBehavior.java

package com.xiaomai.geek.ui.behavior;

import android.content.Context;
import android.os.Build;
import android.support.design.widget.CoordinatorLayout;
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.ViewGroup;
import android.view.animation.Interpolator;

/**
 * Created by XiaoMai on 2017/4/1 13:42.
 */

public class BottomBehavior extends CoordinatorLayout.Behavior {

    private float viewY;// 控件距离coordinatorLayout底部距离

    private boolean isAnimate;// 动画是否在进行

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

    private static final Interpolator INTERPOLATOR = new FastOutSlowInInterpolator();

    private boolean mIsAnimatingOut = false;

    @Override
    public boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout, View child,
            View directTargetChild, View target, int nestedScrollAxes) {
        return nestedScrollAxes == ViewCompat.SCROLL_AXIS_VERTICAL || super.onStartNestedScroll(
                coordinatorLayout, child, directTargetChild, target, nestedScrollAxes);
    }

    @Override
    public void onNestedScroll(CoordinatorLayout coordinatorLayout, View child, View target,
            int dxConsumed, int dyConsumed, int dxUnconsumed, 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);
        }
    }

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

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

                        public void onAnimationEnd(View view) {
                            mIsAnimatingOut = false;
                            view.setVisibility(View.GONE);
                        }
                    }).start();
        } else {

        }
    }

    // Same animation that FloatingActionButton.Behavior uses to show the FAB
    // when the AppBarLayout enters
    private void animateIn(View button) {
        button.setVisibility(View.VISIBLE);
        if (Build.VERSION.SDK_INT >= 14) {
            ViewCompat.animate(button).translationY(0).setInterpolator(INTERPOLATOR).withLayer()
                    .setListener(null).start();
        } else {

        }
    }

    private int getMarginBottom(View v) {
        int marginBottom = 0;
        final ViewGroup.LayoutParams layoutParams = v.getLayoutParams();
        if (layoutParams instanceof ViewGroup.MarginLayoutParams) {
            marginBottom = ((ViewGroup.MarginLayoutParams) layoutParams).bottomMargin;
        }
        return marginBottom;
    }

}