ScrollAwareFABBehavior.java

package licola.demo.com.huabandemo.Widget;

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.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.Interpolator;

import licola.demo.com.huabandemo.Util.Logger;

/**
 * Created by LiCola on  2016/05/02  15:42
 * 添加给Fab的 Behavior 实现当内容控件向下滑动向下隐藏 向上滑动进入
 */
public class ScrollAwareFABBehavior extends FloatingActionButton.Behavior {
    private static final Interpolator INTERPOLATOR = new FastOutSlowInInterpolator();
    private boolean mIsAnimatingOut = false;//fab是否被 压出 默认false 表示显示

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

    @Override
    public boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout, FloatingActionButton 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, FloatingActionButton child, View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed) {
        super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed);

//        Logger.d("dyConsumed="+dyConsumed+ " mIsAnimatingOut="+mIsAnimatingOut+" Visibility="+child.getVisibility()+" "+" Y="+child.getTranslationY());
        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 && this.mIsAnimatingOut && 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 FloatingActionButton 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) {
                            Logger.d();
                            ScrollAwareFABBehavior.this.mIsAnimatingOut = true;
                        }

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

                        public void onAnimationEnd(View view) {
                            Logger.d();
//                            ScrollAwareFABBehavior.this.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(FloatingActionButton button) {
        button.setVisibility(View.VISIBLE);
        if (Build.VERSION.SDK_INT >= 14) {
            ViewCompat.animate(button).translationY(0)
                    .setInterpolator(INTERPOLATOR).withLayer().setListener(new ViewPropertyAnimatorListener() {
                @Override
                public void onAnimationStart(View view) {
                    Logger.d();
                    ScrollAwareFABBehavior.this.mIsAnimatingOut = false;
                }

                @Override
                public void onAnimationCancel(View view) {
                    Logger.d();
                    ScrollAwareFABBehavior.this.mIsAnimatingOut = true;
                }

                @Override
                public void onAnimationEnd(View view) {
                    Logger.d();
//                    ScrollAwareFABBehavior.this.mIsAnimatingOut = true;
                    view.setVisibility(View.VISIBLE);
                }
            })
                    .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;
    }
}