介绍
Interaction behavior plugin for child views of {@link CoordinatorLayout}.
A Behavior implements one or more interactions that a user can take on a child view.
These interactions may include drags, swipes, flings, or any other gestures.
@param < V > The View type that this Behavior operates on
交互行为主要用于CoordinatorLayout的子View。一个Behavior可以在一个字View上实现一个或者多个交互内容。这些交互可能包括拖拽，滑动，滚动或者是其他手势。
参数V代表这个Behavior可以操作的视图类型
类结构
初步实战
关注两个方面：
1、实现child view 监听另外一个child view的状态变化，例如大小、位置、显示状态等
关注layoutDependsOn和onDependentViewChanged方法。
2、实现child view监听CoordinatorLayout内NestedScrollingChild的接口实现类的滑动状态
关注onStartNestedScroll和onNestedPreScroll方法。如上一篇博文中提到的NestedScrollView，而不能使用普通的ScrollView
第一种情况，监听View的状态
位置跟随
布局文件
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/main_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context="mraz.com.coordinatorlayoutdemo.ScrollingActivity">
<TextView
android:id="@+id/depentent"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_gravity="top|left"
android:background="#73ff00"
android:gravity="center"
android:text="depentent"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_gravity="top|right"
android:background="#ffee00"
android:gravity="center"
android:text="auto"
android:textColor="@android:color/holo_red_dark"
app:layout_behavior="mraz.com.coordinatorlayoutdemo.FollowingBehavior" />
</android.support.design.widget.CoordinatorLayout>
Behavior
package mraz.com.coordinatorlayoutdemo;
import android.content.Context;
import android.support.design.widget.CoordinatorLayout;
import android.support.v4.view.ViewCompat;
import android.util.AttributeSet;
import android.view.View;
/**
* Created by Mraz on 2016/8/15.
*/
public class FollowingBehavior extends CoordinatorLayout.Behavior<View> {
public FollowingBehavior(Context context, AttributeSet attrs) {
super(context, attrs);
}
@Override
public boolean layoutDependsOn(CoordinatorLayout parent, View child, View dependency) {
return (dependency.getId() == R.id.depentent);//依赖左边的View
}
@Override
public boolean onDependentViewChanged(CoordinatorLayout parent, View child, View dependency) {
int offsetX = dependency.getTop() - child.getTop();//拿到左边View和右边view的顶部差距
ViewCompat.offsetTopAndBottom(child, offsetX);//移动
return true;
}
}
实际效果
第二种情况，监听滚动状态
CoordinatorLayout实现NestedScrollingParent接口，
NestedScrollView实现NestedScrollingParent， NestedScrollingChild, ScrollingView接口
public class NestedScrollView extends FrameLayout implements NestedScrollingParent,
NestedScrollingChild, ScrollingView说白了就是一个加强的ScrollView，但是实现的这几个接口是怎么回事呢？一个个的看下
NestedScrollingParent
| Interface | Meaning |
|---|---|
| onStartNestedScroll | child执行startNestedScroll方法的时候会调用，返回true代表代表要和child联动 |
| onNestedScrollAccepted | onStartNestedScroll执行完成并返回true之后执行，用于做联动前的准备 |
| onStopNestedScroll | nested scroll结束后执行 |
| onNestedScroll | nested scroll进行中时执行，传递的参数是消耗了和没有消耗的滚动距离 |
| onNestedPreScroll | neseted scroll进行并且target没有消耗滚动时执行，nested scrolling执行dispatchNestedPreScroll后执行该方法 |
| onNestedFling | 请求一个滚动结束后的fling |
| onNestedPreFling | target view没有消耗flinger之前执行 |
| getNestedScrollAxes | 返回NestedScrollingParent的滚动轴 |
NestedScrollingChild
| Interface | Meaning |
|---|---|
| setNestedScrollingEnabled | 设置视图是否可以nested scrolling |
| isNestedScrollingEnabled | 获取当前view是否可以nested scrolling |
| startNestedScroll | 开始执行nested scroll,沿着给点的轴方向，返回true,代表找到了parent |
| stopNestedScroll | 停止nested scroll |
| hasNestedScrollingParent | 判断nested scrolling是否存在parent |
| dispatchNestedScroll | 派发一个滚动给parent |
| dispatchNestedPreScroll | 在没有消耗之前派发给parent，也就是parent有可能会在child之前消耗 |
| dispatchNestedFling | 派发fling给parent |
| dispatchNestedPreFling | 消耗之前派发给parent |
ScrollingView
| Interface | Meaning |
|---|---|
| computeHorizontalScrollRange | 计算横向滚动的范围 |
| computeHorizontalScrollOffset | 计算横向偏移量 |
| computeHorizontalScrollExtent | 计算横向额外距离 |
| computeVerticalScrollRange | 滚动视图的可滚动范围是所有子元素的高度 |
| computeVerticalScrollOffset | 计算垂直方向滚动条的滑块的偏移。此值用来计算滚动条轨迹的滑块的位置 |
| computeVerticalScrollExtent | 计算纵向额外距离 |
关于NestedScrollingParent和NestedScrollingChild，存在两个Helper类
基本上方法和上面的比较类似，不赘述
看实例：
布局文件
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/main_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
android:scrollbars="vertical"
tools:context="mraz.com.coordinatorlayoutdemo.ScrollingActivity">
<android.support.v4.widget.NestedScrollView
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#73ff00"
android:gravity="center"
android:text="depentent"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#73ff00"
android:gravity="center"
android:text="depentent"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#73ff00"
android:gravity="center"
android:text="depentent"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#73ff00"
android:gravity="center"
android:text="depentent"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#73ff00"
android:gravity="center"
android:text="depentent"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#73ff00"
android:gravity="center"
android:text="depentent"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#73ff00"
android:gravity="center"
android:text="depentent"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#73ff00"
android:gravity="center"
android:text="depentent"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#73ff00"
android:gravity="center"
android:text="depentent"
android:textColor="@android:color/black" />
</LinearLayout>
</android.support.v4.widget.NestedScrollView>
<android.support.v4.widget.NestedScrollView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
app:layout_behavior="mraz.com.coordinatorlayoutdemo.MyScrollingBehavior">
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#ff00aa"
android:gravity="center"
android:text="right"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#ff00aa"
android:gravity="center"
android:text="right"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#ff00aa"
android:gravity="center"
android:text="right"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#ff00aa"
android:gravity="center"
android:text="right"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#ff00aa"
android:gravity="center"
android:text="right"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#ff00aa"
android:gravity="center"
android:text="right"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#ff00aa"
android:gravity="center"
android:text="right"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#ff00aa"
android:gravity="center"
android:text="right"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#ff00aa"
android:gravity="center"
android:text="right"
android:textColor="@android:color/black" />
</LinearLayout>
</android.support.v4.widget.NestedScrollView>
<android.support.v4.widget.NestedScrollView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="right"
app:layout_behavior="mraz.com.coordinatorlayoutdemo.MyScrollingBehavior">
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#ffe600"
android:gravity="center"
android:text="right"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#ffe600"
android:gravity="center"
android:text="right"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#ffe600"
android:gravity="center"
android:text="right"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#ffe600"
android:gravity="center"
android:text="right"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#ffe600"
android:gravity="center"
android:text="right"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#ffe600"
android:gravity="center"
android:text="right"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#ffe600"
android:gravity="center"
android:text="right"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#ffe600"
android:gravity="center"
android:text="right"
android:textColor="@android:color/black" />
<TextView
android:layout_width="100dp"
android:layout_height="200dp"
android:layout_gravity="top|left"
android:background="#ffe600"
android:gravity="center"
android:text="right"
android:textColor="@android:color/black" />
</LinearLayout>
</android.support.v4.widget.NestedScrollView>
</android.support.design.widget.CoordinatorLayout>
3条杠杠~
Behavior
package mraz.com.coordinatorlayoutdemo;
import android.content.Context;
import android.support.design.widget.CoordinatorLayout;
import android.support.v4.view.ViewCompat;
import android.support.v4.widget.NestedScrollView;
import android.util.AttributeSet;
import android.view.View;
public class MyScrollingBehavior extends CoordinatorLayout.Behavior {
public MyScrollingBehavior(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;//只对垂直滚动感兴趣
}
@Override
public void onNestedPreScroll(CoordinatorLayout coordinatorLayout, View child, View target, int dx, int dy, int[] consumed) {
super.onNestedPreScroll(coordinatorLayout, child, target, dx, dy, consumed);
int leftScrolled = target.getScrollY();//获取左侧滚动距离
child.setScrollY(leftScrolled);//设置联动
}
@Override
public boolean onNestedPreFling(CoordinatorLayout coordinatorLayout, View child, View target, float velocityX, float velocityY) {
((NestedScrollView) child).fling((int) velocityY);//松手后速度传递下去
return true;
}
}实际效果
备注
参考博客：
http://blog.csdn.net/qibin0506/article/details/50290421