一、BottomNavigationBehavior

动画效果是会跟着屏幕一起滚动，上滑时向下滚动移除屏幕，下滑向上滚动显示，适用于底部切换部分。
效果图：
iShot2020-08-1722.14.26.gif
如图，底部很好的移除了屏幕，悬浮按钮由于有一定的间距还留有一部分，可以通过修改动画或者单独给悬浮按钮设置一个 Behavior。
BottomNavigationBehavior：

  1. /**
  2.  * Created by chenxz on 2017/11/25.
  3.  * 下滑一起下滑,下滑到屏幕外就不可见了,上滑一起上滑
  4.  */
  6. public class BottomNavigationBehavior extends CoordinatorLayout.Behavior<View> {
  7.     private ObjectAnimator outAnimator, inAnimator;
  9.     public BottomNavigationBehavior(Context context, AttributeSet attrs) {
  10.         super(context, attrs);
  11.     }
  13.     // 垂直滑动
  14.     @Override
  15.     public boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout, View child, View directTargetChild, View target, int nestedScrollAxes) {
  16.         return nestedScrollAxes == ViewCompat.SCROLL_AXIS_VERTICAL;
  17.     }
  19.     @Override
  20.     public void onNestedPreScroll(CoordinatorLayout coordinatorLayout, View child, View target, int dx, int dy, int[] consumed) {
  21.         if (dy > 0) {// 上滑隐藏
  22.             if (outAnimator == null) {
  23.                 outAnimator = ObjectAnimator.ofFloat(child, "translationY", 0, child.getHeight() * 2);
  24.                 outAnimator.setDuration(200);
  25.             }
  26.             if (!outAnimator.isRunning() && child.getTranslationY() <= 0) {
  27.                 outAnimator.start();
  28.             }
  29.         } else if (dy < 0) {// 下滑显示
  30.             if (inAnimator == null) {
  31.                 inAnimator = ObjectAnimator.ofFloat(child, "translationY", child.getHeight() * 2, 0);
  32.                 inAnimator.setDuration(200);
  33.             }
  34.             if (!inAnimator.isRunning() && child.getTranslationY() >= child.getHeight()) {
  35.                 inAnimator.start();
  36.             }
  37.         }
  38.     }
  40. }

使用的 xml 布局：

  1. <?xml version="1.0" encoding="utf-8"?>
  2. <androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
  3.     android:layout_width="match_parent"
  4.     android:layout_height="match_parent"
  5.     xmlns:app="http://schemas.android.com/apk/res-auto">
  7.     <com.google.android.material.appbar.AppBarLayout
  8.         android:layout_width="match_parent"
  9.         android:layout_height="wrap_content">
  10.         <androidx.appcompat.widget.Toolbar
  11.             android:id="@+id/tb_tb_scroll_tb"
  12.             android:layout_width="match_parent"
  13.             android:layout_height="wrap_content"
  14.             app:navigationIcon="@mipmap/ic_navigation_back_white"
  15.             app:title="toolbar滚动"
  16.             app:titleTextColor="@color/white"
  17.             android:background="@color/blue_74D3FF"
  18.            app:layout_scrollFlags="scroll|enterAlways|snap"/>
  20.     </com.google.android.material.appbar.AppBarLayout>
  23.     <include layout="@layout/content_scrolling"/>
  25. <!--   <androidx.core.widget.NestedScrollView-->
  26. <!--       android:layout_width="match_parent"-->
  27. <!--       android:layout_height="match_parent"-->
  28. <!--       app:layout_behavior="com.google.android.material.appbar.AppBarLayout$ScrollingViewBehavior">-->
  29. <!--       <TextView-->
  30. <!--           android:layout_width="wrap_content"-->
  31. <!--           android:layout_height="wrap_content"-->
  32. <!--           android:layout_margin="@dimen/m12"-->
  33. <!--           android:text="@string/large_text" />-->
  34. <!--   </androidx.core.widget.NestedScrollView>-->
  37.     <!--    加个底部滑动隐藏,适用于底部有控件的情况,上滑显示,-->
  39.     <RelativeLayout
  40.         android:layout_width="match_parent"
  41.         android:layout_height="50dp"
  42.         android:layout_gravity="bottom"
  43.         android:background="@color/yellow_FF9B52"
  44.         app:layout_behavior="@string/bottom_navigation_behavior">
  47.     </RelativeLayout>
  49.     <!--    悬浮按钮-->
  50.     <com.google.android.material.floatingactionbutton.FloatingActionButton
  51.         android:id="@+id/fab_tb_scroll_menu"
  52.         android:layout_width="wrap_content"
  53.         android:layout_height="wrap_content"
  54.         android:layout_gravity="end|bottom"
  55.         android:layout_marginEnd="@dimen/m12"
  56.         android:layout_marginBottom="60dp"
  57.         android:src="@drawable/ic_cloud"
  58.         app:layout_behavior="@string/bottom_navigation_behavior"
  59.         />
  62. </androidx.coordinatorlayout.widget.CoordinatorLayout>

strings，将文件放在strings 里，方便以后对 Behavior 修改：

  1. <string name="scale_up_show_behavior">com.kiwilss.xview.design.behavior.ScaleUpShowBehavior</string>
  2.     <string name="bottom_navigation_behavior">com.kiwilss.xview.design.behavior.BottomNavigationBehavior</string>

二、ScaleDownShowBehavior

FAB 行为控制器,下滑直接消失,上滑缩放出现。效果图：
iShot2020-08-1722.22.29.gif
代码：

  1. /**
  2.  * Created by chenxz on 2018/5/13.
  3.  *
  4.  * FAB 行为控制器,下滑直接消失,上滑缩放出现
  5.  */
  6. class ScaleDownShowBehavior : FloatingActionButton.Behavior {
  8.     constructor(context: Context, attrs: AttributeSet) : super(context, attrs)
  10.     override fun onStartNestedScroll(coordinatorLayout: CoordinatorLayout,
  11.                                      child: FloatingActionButton,
  12.                                      directTargetChild: View,
  13.                                      target: View,
  14.                                      axes: Int,
  15.                                      type: Int): Boolean {
  16.         return axes == ViewCompat.SCROLL_AXIS_VERTICAL ||
  17.                 super.onStartNestedScroll(coordinatorLayout, child, directTargetChild, target, axes, type)
  18.     }
  20.     @SuppressLint("RestrictedApi")
  21.     override fun onNestedScroll(coordinatorLayout: CoordinatorLayout, child: FloatingActionButton, target: View, dxConsumed: Int, dyConsumed: Int, dxUnconsumed: Int, dyUnconsumed: Int, type: Int) {
  22.         super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed, type)
  23.         if (dyConsumed > 0 && child.visibility == View.VISIBLE) {
  24.             child.visibility = View.INVISIBLE
  25.         } else if (dyConsumed < 0 && child.visibility != View.VISIBLE) {
  26.             child.show()
  27.         }
  28.     }
  30. }

三、ScaleUpShowBehavior

FloatingActionButton上滑缩小隐藏,上滑放大显示,使用于返回顶部等
效果图：
iShot2020-08-1722.24.39.gif
代码：

  1. /**
  2.  * @author : Lss Administrator
  3.  * @FileName: ScaleUpShowBehavior
  4.  * @e-mail : kiwilss@163.com
  5.  * @time : 2020/8/17
  6.  * @desc : {FloatingActionButton上滑缩小隐藏,上滑放大显示,使用于返回顶部等}
  7.  */
  8. public class ScaleUpShowBehavior extends FloatingActionButton.Behavior {
  10.     public ScaleUpShowBehavior(Context context, AttributeSet attrs) {
  11.         super();
  12.     }
  14.     private boolean isAnimatingOut = false;
  15.     private boolean isShow = true;
  17.     @Override
  18.     public boolean onStartNestedScroll(@NonNull CoordinatorLayout coordinatorLayout,
  19.                                        @NonNull FloatingActionButton child, @NonNull View directTargetChild, @NonNull View target, int axes, int type) {
  20.         return axes == ViewCompat.SCROLL_AXIS_VERTICAL ||
  21.                 super.onStartNestedScroll(coordinatorLayout, child, directTargetChild, target, axes, type);
  22.         //return super.onStartNestedScroll(coordinatorLayout, child, directTargetChild, target, axes, type);
  23.     }
  25.     @Override
  26.     public void onNestedScroll(@NonNull CoordinatorLayout coordinatorLayout, @NonNull FloatingActionButton child, @NonNull View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed, int type, @NonNull int[] consumed) {
  27.         super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed, type, consumed);
  28. //        if (dyConsumed > 0 && dyUnconsumed == 0) {
  29. //            System.out.println("上滑中。。。");
  30. //        }
  31. //        if (dyConsumed == 0 && dyUnconsumed > 0) {
  32. //            System.out.println("到边界了还在上滑。。。");
  33. //        }
  34. //        if (dyConsumed < 0 && dyUnconsumed == 0) {
  35. //            System.out.println("下滑中。。。");
  36. //        }
  37. //        if (dyConsumed == 0 && dyUnconsumed < 0) {
  38. //            System.out.println("到边界了，还在下滑。。。");
  39. //        }
  40.         // 手指上滑，隐藏FAB
  41.         // 手指上滑，隐藏FAB
  42.         if ((dyConsumed > 0 || dyUnconsumed > 0) && !isAnimatingOut && isShow) {
  43.             AnimatorUtil.INSTANCE.scaleHide(child, viewPropertyAnimatorListenerHide);
  44.         } else if (dyConsumed < 0 || dyUnconsumed < 0 && !isAnimatingOut && !isShow) {
  45.             // 手指下滑，显示FAB
  46.             AnimatorUtil.INSTANCE.scaleShow(child,viewPropertyAnimatorListener);
  47.         }
  48.     }
  52.     ViewPropertyAnimatorListener viewPropertyAnimatorListener = new ViewPropertyAnimatorListener() {
  54.         @Override
  55.         public void onAnimationStart(View view) {
  56.             //view.setVisibility(View.VISIBLE);
  57.             isAnimatingOut = true;
  58.         }
  60.         @Override
  61.         public void onAnimationEnd(View view) {
  62.             isAnimatingOut = false;
  63.         }
  65.         @Override
  66.         public void onAnimationCancel(View arg0) {
  67.             isAnimatingOut = false;
  68.         }
  69.     };
  71.     ViewPropertyAnimatorListener viewPropertyAnimatorListenerHide = new ViewPropertyAnimatorListener() {
  73.         @Override
  74.         public void onAnimationStart(View view) {
  75.             isAnimatingOut = true;
  76.         }
  78.         @Override
  79.         public void onAnimationEnd(View view) {
  80.             isAnimatingOut = false;
  81.             //view.setVisibility(View.GONE);
  82.         }
  84.         @Override
  85.         public void onAnimationCancel(View arg0) {
  86.             isAnimatingOut = false;
  87.         }
  88.     };
  89. }

四、ScrollAwareFABBehavior

FAB 上滑移出屏幕， 下滑显示，很想知乎首页，效果图：
iShot2020-08-1722.27.27.gif
代码：

  2. /**
  3.  * Created by chenxz on 2018/5/13.
  4.  *
  5.  * FAB 上滑隐藏 下滑显示
  6.  */
  7. class ScrollAwareFABBehavior : FloatingActionButton.Behavior {
  9.     /**
  10.      * 是否正在动画
  11.      */
  12.     private var isAnimateIng = false
  14.     /**
  15.      * 是否已经显示
  16.      */
  17.     private var isShow = true
  19.     constructor(context: Context, attrs: AttributeSet) : super()
  21.     override fun onStartNestedScroll(coordinatorLayout: CoordinatorLayout,
  22.                                      child: FloatingActionButton,
  23.                                      directTargetChild: View,
  24.                                      target: View,
  25.                                      axes: Int,
  26.                                      type: Int): Boolean {
  27.         return axes == ViewCompat.SCROLL_AXIS_VERTICAL ||
  28.                 super.onStartNestedScroll(coordinatorLayout, child, directTargetChild, target, axes, type)
  29.     }
  31.     override fun onNestedScroll(coordinatorLayout: CoordinatorLayout, child: FloatingActionButton, target: View, dxConsumed: Int, dyConsumed: Int, dxUnconsumed: Int, dyUnconsumed: Int, type: Int) {
  32.         super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed, type)
  33.         // 手指上滑，隐藏FAB
  34.         if ((dyConsumed > 0 || dyUnconsumed > 0) && !isAnimateIng && isShow) {
  35.             AnimatorUtil.translateHide(child, object : StateListener() {
  36.                 override fun onAnimationStart(view: View) {
  37.                     super.onAnimationStart(view)
  38.                     isShow = false
  39.                 }
  40.             })
  41.         } else if (dyConsumed < 0 || dyUnconsumed < 0 && !isAnimateIng && !isShow) {
  42.             // 手指下滑，显示FAB
  43.             AnimatorUtil.translateShow(child, object : StateListener() {
  44.                 override fun onAnimationStart(view: View) {
  45.                     super.onAnimationStart(view)
  46.                     isShow = true
  47.                 }
  48.             })
  49.         }
  50.     }
  53.     internal open inner class StateListener : ViewPropertyAnimatorListener {
  54.         override fun onAnimationStart(view: View) {
  55.             isAnimateIng = true
  56.         }
  58.         override fun onAnimationEnd(view: View) {
  59.             isAnimateIng = false
  60.         }
  62.         override fun onAnimationCancel(view: View) {
  63.             isAnimateIng = false
  64.         }
  65.     }
  67. }