自定义Bahavior

通过使用Bahavior，可以实现嵌套滑动的效果。即一个组件的滑动由另一个组件决定、或者有CoordinatorLayout的滑动状态决定。自定义Bahavior需要继承CoordinatorLayout.Behavior<View>，其中在泛型中指定的是应用这个Behavior的View类型。

1、关联Behavior

<android.support.design.widget.FloatingActionButton
       ...
       app:layout_behavior="@string/appbar_scrolling_view_behavior"
       />

或者

       CoordinatorLayout.LayoutParams params = new CoordinatorLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
       params.setBehavior(new AppBarLayout.ScrollingViewBehavior());
       coordinatorLayout.addView(innerContentView,params);

1

2、依赖其他组件

通过以下两个方法，可以实现一个组件的滑动依赖其他组件

   public boolean layoutDependsOn(CoordinatorLayout parent, V child, View dependency) ；
   public void onDependentViewChanged(CoordinatorLayout parent, V child, View dependency) ；

其中child是应用这个Behavior的view，dependency是被依赖的组件，可以在layoutDependsOn()方法中指定被依赖的组件A，当A发生改变时，会调用onDependentViewChanged()方法。

简单实现如下：

public class DependTitleBeahvior extends CoordinatorLayout.Behavior<View> {
   private int toolbarHeight;
   public DependTitleBeahvior(Context context, AttributeSet attrs) {
       super(context, attrs);
       toolbarHeight = getToolbarHeight(context);
   }

   @Override
   public boolean layoutDependsOn(CoordinatorLayout parent, View child, View dependency) {
       return dependency instanceof AppBarLayout;
   }

   @Override
   public boolean onDependentViewChanged(CoordinatorLayout parent, View child, View dependency) {
       if (dependency instanceof AppBarLayout){
           int childHeight=getChildHeight(child);
           float ratio=childHeight*1.0f/toolbarHeight;
           Log.e("onDependentViewChanged","dependency:"+dependency.getY() +",child"+childHeight +",ratio"+ratio);
           child.setTranslationY( -1 * ratio* dependency.getY());
       }
       return true;
   }

   /**
    * 应用Behavior的组件距离底部的高度
    */
   private int getChildHeight(View child) {
       int bottomMargin=0;
       ViewGroup.LayoutParams params=child.getLayoutParams();
       if (params instanceof ViewGroup.MarginLayoutParams){
           bottomMargin=((ViewGroup.MarginLayoutParams) params).bottomMargin;
       }
       return child.getHeight()+bottomMargin;
   }

   /**
    * 被依赖的toolbar的高度
    */
   private int getToolbarHeight(Context context) {
       final TypedArray styledAttributes = context.getTheme().obtainStyledAttributes(
               new int[]{R.attr.actionBarSize});
       int toolbarHeight = (int) styledAttributes.getDimension(0, 0);
       styledAttributes.recycle();
       return toolbarHeight;
   }
}

依赖其他组件

3、依赖CoordinatorLayout的滑动状态

通过以下两个方法，可以实现一个组件的滑动依赖CoordinatorLayout的滑动状态

   public boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout, View child, View directTargetChild, View target, int nestedScrollAxes)
   public void onDependentViewChanged(CoordinatorLayout parent, V child, View dependency) ；

其中，child是应用这个Behavior的view，target引起滚动的view（比如NestScrollView）。dy>0，向上滑动。

public class DependScrollBehavior extends CoordinatorLayout.Behavior<View> {
   
   public DependScrollBehavior(Context context, AttributeSet attrs) {
       super(context, attrs);
   }

   @Override
   public boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout, View child, View directTargetChild, View target, int nestedScrollAxes) {
       return (nestedScrollAxes & ViewCompat.SCROLL_AXIS_VERTICAL)!=0;
   }

   @Override
   public void onNestedPreScroll(CoordinatorLayout coordinatorLayout, View child, View target, int dx, int dy, int[] consumed) {
       int childHeight=getChildHeight(child);
       int childScrolledY= (int) (child.getTranslationY()+dy);
       // 向上滑动 、 滑动的总距离大于 childHeight
       if (dy>0 && childScrolledY>=childHeight){
           childScrolledY=childHeight;
       }
       //  向下滑动 、 滑动的总距离小于 0
       else if (dy<0 &&  childScrolledY<=0){
           childScrolledY=0;
       }
       child.setTranslationY(childScrolledY);
   }

   /**
    * 应用Behavior的组件距离底部的高度
    */
   private int getChildHeight(View child) {
       int bottomMargin=0;
       ViewGroup.LayoutParams params=child.getLayoutParams();
       if (params instanceof ViewGroup.MarginLayoutParams){
           bottomMargin=((ViewGroup.MarginLayoutParams) params).bottomMargin;
       }
       return child.getHeight()+bottomMargin;
   }

}

分析

http://geek.csdn.net/news/detail/59829

http://www.cnblogs.com/soaringEveryday/p/5711545.html

源码看CoordinatorLayout.Behavior原理

CoordinatorLayout高级用法-自定义Behavior