AndroidUI系列--在DecorView层解决RecyclerView和ScrollView的滑动冲突

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滑动冲突，这个是作安卓的必经之坑。最开始的ListView和ScollView冲突，或者ListView嵌套ListView滑动冲突，再或者ListView和ViewPager的滑动冲突，再或者是GraidView等可滑动控件互相嵌套的冲突。解决方案呢，有很多。比如在onTouchEvent中拦截事件。又或者自定义ListView，修改onMesure测量，使它在测量时获得最大的宽高，这样可以让它不滑动。全部展示，当然作为在android摸爬滚打了这么久的程序猿，这些坑都应该踩过了，而且网上一大堆解决方案，不得不说，这就是开源的好处啊，想着谷歌巴巴把kotlin扶上位了，我们这些苦逼的程序猿，那就只有跟着大部队走了。没办法呀~夹缝里生存。

View的绘制流程，Activity–phonewindow–decorview–contentview，如下图

我们平时在Activity的setContentView就是在ContentViews作文章。那么我们的冲突就是在这里，在ContentView里设置了一个activity_main.xml,为什么会有滑动冲突呢，那是因为recyclerview和scollview都设置在了activity_main.xml。那么换个角度，如果把recyclerview加在contentviews和activity_main.xml布局平级。那么是不是就不存在滑动冲突了呢，想到就来试试。
首先自定义一个view，用来弹窗。

package com.example.administrator.bounceview;import android.animation.ValueAnimator;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.view.View;/*** Created by ShuWen on 2017/5/23.*/public class BounceView extends View {private int mArcMaxHeight;//弹窗最高距离private int mArcHeight;//记录变换过程的距离private Paint mPaint;//画笔private Path mPath = new Path();//绘制动画弧度private BounceAnimatorListener animatorListener;//动画开始的监听回调private Status status = Status.NONE;//记录动画的状态public enum Status{//没动，上升，下降NONE,STATUS_UP,STATUS_DOWN}public BounceView(Context context) {super(context);init();}public BounceView(Context context, AttributeSet attrs) {super(context, attrs);init();}public BounceView(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);init();}//初始化private void init() {mPaint = new Paint();mPaint.setColor(Color.WHITE);mPaint.setAntiAlias(true);mPaint.setStyle(Paint.Style.FILL);mArcMaxHeight = getResources().getDimensionPixelOffset(R.dimen.m_maxarcheight);}//上升的动画public void show(){status = Status.STATUS_UP;if (animatorListener != null){this.postDelayed(new Runnable() {@Overridepublic void run() {animatorListener.showContent();}},600);}ValueAnimator animator = ValueAnimator.ofInt(0,mArcMaxHeight);animator.setDuration(700);animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {@Overridepublic void onAnimationUpdate(ValueAnimator valueAnimator) {mArcHeight = (int) valueAnimator.getAnimatedValue();if (mArcHeight == mArcMaxHeight){bounce();}invalidate();}});animator.start();}//下降的动画private void bounce() {status = Status.STATUS_DOWN;ValueAnimator valueAnimator = ValueAnimator.ofInt(mArcMaxHeight,0);valueAnimator.setDuration(600);valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {@Overridepublic void onAnimationUpdate(ValueAnimator valueAnimator) {mArcHeight = (int) valueAnimator.getAnimatedValue();invalidate();}});valueAnimator.start();}@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);int currentY = 0;switch (status){case NONE:currentY = 0;break;case STATUS_UP:currentY = (int) (getHeight()*(1 - (float)(mArcHeight/mArcMaxHeight))+mArcMaxHeight);break;case STATUS_DOWN:currentY = mArcMaxHeight;break;}mPath.reset();mPath.moveTo(0,currentY);mPath.quadTo(getWidth()/2,currentY - mArcHeight,getWidth(),currentY);mPath.lineTo(getWidth(),getHeight());mPath.lineTo(0,getHeight());mPath.close();canvas.drawPath(mPath,mPaint);}public void setAnimatorListener(BounceAnimatorListener animatorListener){this.animatorListener = animatorListener;}public interface BounceAnimatorListener{void showContent();}
}

上升过程中，绘制动画，使用ValueAnimator在回调里进行更新界面，调用invalidate()。中间使用到了二阶贝塞尔曲线，关于贝塞尔其实很简单的，在网上一搜，当然就有了。

那么在创建一个类，用来加载BounceVeiw。

package com.example.administrator.bounceview;import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.widget.FrameLayout;/*** Created by ShuWen on 2017/5/23.*/public class BounceMenu {private RecyclerView recyclerView;private BounceView bounceView;private ViewGroup parentVG;private View rootView;private BounceMenu(View view, int resId, final MyAdapter myAdapter) {parentVG = findParentVG(view);rootView = LayoutInflater.from(view.getContext()).inflate(resId,null,false);recyclerView = (RecyclerView) rootView.findViewById(R.id.recyclerview);bounceView = (BounceView) rootView.findViewById(R.id.bounceview);recyclerView.setLayoutManager(new LinearLayoutManager(view.getContext()));bounceView.setAnimatorListener(new BounceView.BounceAnimatorListener() {@Overridepublic void showContent() {recyclerView.setVisibility(View.VISIBLE);recyclerView.setAdapter(myAdapter);recyclerView.scheduleLayoutAnimation();}});}public static BounceMenu makeBounce(View view, int resId, final MyAdapter myAdapter){return new BounceMenu(view, resId, myAdapter);}public void show(){if (rootView != null){parentVG.removeView(rootView);}ViewGroup.LayoutParams layoutParams = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);parentVG.addView(rootView,layoutParams);bounceView.show();}private ViewGroup findParentVG(View view) {do {if (view instanceof FrameLayout){//找到decorview的根布局if (view.getId() == android.R.id.content){return (ViewGroup) view;}}if (view != null){ViewParent viewParent = view.getParent();view = viewParent instanceof View? (View) viewParent :null;}}while (view!= null);return null;}
}

在这里面，传入需要添加recylerview的跟布局，通过这个根布局获得decorview的contentviews这个布局，然后在这个布局上添加recyclerview。这样就是与activity_main同级，不会有滑动冲突。在bounceview的监听里，添加recyclerview的动画。
那么再来看看MianAcicity的代码：

package com.example.administrator.bounceview;import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.TextView;import java.util.ArrayList;
import java.util.List;public class MainActivity extends AppCompatActivity {private MyAdapter myAdapter;private List<String> stringList;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);stringList = new ArrayList<>();for (int i = 0; i < 20; i++) {stringList.add("阿西吧"+i);}myAdapter = new MyAdapter(this,stringList) {@Overrideprotected int ItemLayoutId() {return R.layout.item;}@Overrideprotected void onBindHolder(MyViewHolder myViewHolder, int position) {TextView textView = myViewHolder.getTextView(R.id.text);textView.setText(stringList.get(position));}};}public void click(View view){BounceMenu bounceMenu = BounceMenu.makeBounce(findViewById(R.id.activity_main),R.layout.bounce_view_layout,myAdapter);bounceMenu.show();}
}

调用就是相当的简单了。同时还有炫酷的动画，何乐而不为呢。接下来所有代码都贴出来。
activity_main的xml布局。使用ScrollView，展示主要数据。在每一项的点击事件，触发弹窗，recyclerview。

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:tools="http://schemas.android.com/tools"android:id="@+id/activity_main"android:layout_width="match_parent"android:layout_height="match_parent"tools:context="com.example.administrator.bounceview.MainActivity"><ScrollView
        android:layout_width="match_parent"android:layout_height="match_parent"android:background="#465"><LinearLayout
            android:orientation="vertical"android:layout_width="match_parent"android:layout_height="match_parent"><TextView
                android:layout_width="match_parent"android:layout_height="100dp"android:gravity="center"android:textSize="20sp"android:onClick="click"android:text="你滑动啊"/><View
                android:layout_width="match_parent"android:layout_height="1dp"android:background="#fff"></View><TextView
                android:layout_width="match_parent"android:layout_height="100dp"android:gravity="center"android:textSize="20sp"android:onClick="click"android:text="你滑动啊"/><View
                android:layout_width="match_parent"android:layout_height="1dp"android:background="#fff"></View><TextView
                android:layout_width="match_parent"android:layout_height="100dp"android:gravity="center"android:onClick="click"android:textSize="20sp"android:text="你滑动啊"/><View
                android:layout_width="match_parent"android:layout_height="1dp"android:background="#fff"></View><TextView
                android:layout_width="match_parent"android:layout_height="100dp"android:gravity="center"android:textSize="20sp"android:onClick="click"android:text="你滑动啊"/><View
                android:layout_width="match_parent"android:layout_height="1dp"android:background="#fff"></View><TextView
                android:layout_width="match_parent"android:layout_height="100dp"android:gravity="center"android:textSize="20sp"android:onClick="click"android:text="你滑动啊"/><View
                android:layout_width="match_parent"android:layout_height="1dp"android:background="#fff"></View><TextView
                android:layout_width="match_parent"android:layout_height="100dp"android:gravity="center"android:textSize="20sp"android:onClick="click"android:text="你滑动啊"/><View
                android:layout_width="match_parent"android:layout_height="1dp"android:background="#fff"></View><TextView
                android:layout_width="match_parent"android:layout_height="100dp"android:gravity="center"android:textSize="20sp"android:onClick="click"android:text="你滑动啊"/><View
                android:layout_width="match_parent"android:layout_height="1dp"android:background="#fff"></View> <TextView
            android:layout_width="match_parent"android:layout_height="100dp"android:gravity="center"android:textSize="20sp"android:onClick="click"android:text="你滑动啊"/><View
                android:layout_width="match_parent"android:layout_height="1dp"android:background="#fff"></View><TextView
                android:layout_width="match_parent"android:layout_height="100dp"android:gravity="center"android:textSize="20sp"android:onClick="click"android:text="你滑动啊"/><View
                android:layout_width="match_parent"android:layout_height="1dp"android:background="#fff"></View></LinearLayout></ScrollView></RelativeLayout>

那么再看看弹窗的xml。

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:layout_height="match_parent"><RelativeLayout
        android:layout_width="match_parent"android:layout_height="290dp"android:layout_gravity="bottom"><com.example.administrator.bounceview.BounceView
            android:id="@+id/bounceview"android:layout_width="match_parent"android:layout_height="wrap_content"/><android.support.v7.widget.RecyclerView
            android:id="@+id/recyclerview"android:layout_width="match_parent"android:layout_height="match_parent"android:clipChildren="false"android:overScrollMode="never"android:layout_alignParentBottom="true"android:layoutAnimation="@anim/bounce_layout"android:layout_marginTop="70dp"></android.support.v7.widget.RecyclerView></RelativeLayout></FrameLayout>

这里就是弹窗了，recyclerview和scrollview同级，不会产生滑动冲突。
这个是解决滑动冲突的一个可行方案，相当不错。如果觉得动画不必要，直接去掉动画，只需要BounceMenu中的一些逻辑就ok了。我会把代码放在git上，有兴趣的朋友可以自己研究研究。

git地址：https://github.com/SingleShu/BounceView

效果图：

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