扩展ViewFlow避免和ViewPager滑动冲突，同时支持无限循环，并完美和CircleFlowIndicator结合
首先，为了避免滑动冲突，我们要继承ViewFlow，重写onInterceptTouchEvent
1 public class MyViewFlow extends ViewFlow { 2 private ViewPager mPager; 3 4 public MyViewFlow(Context context, AttributeSet attrs) { 5 super(context, attrs); 6 } 7 8 9 public void setViewPager(ViewPager viewPager) { 10 mPager = viewPager; 11 } 12 13 @Override 14 public boolean onInterceptTouchEvent(MotionEvent ev) { 15 if (mPager != null) 16 switch (ev.getAction()) { 17 case MotionEvent.ACTION_DOWN: 18 mPager.requestDisallowInterceptTouchEvent(true); 19 break; 20 case MotionEvent.ACTION_UP: 21 mPager.requestDisallowInterceptTouchEvent(false); 22 break; 23 case MotionEvent.ACTION_CANCEL: 24 mPager.requestDisallowInterceptTouchEvent(false); 25 break; 26 case MotionEvent.ACTION_MOVE: 27 mPager.requestDisallowInterceptTouchEvent(true); 28 break; 29 } 30 return super.onInterceptTouchEvent(ev); 31 } 32 }
调用setViewPager指定viewPager后，滑动便不再冲突
接下来，我们实现无限循环滚动
1 public class AdapterBanner extends BaseAdapter { 2 3 private LayoutInflater mInflater; 4 private static final int[] ids = { R.drawable.banner, R.drawable.banner, R.drawable.banner, R.drawable.banner}; 5 6 public AdapterBanner(Context context) { 7 mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 8 } 9 10 @Override 11 public int getCount() { 12 //return ids.length; 13 return Integer.MAX_VALUE;//返回很大的值使得getView中的position不断增大来实现循环 14 } 15 16 @Override 17 public Object getItem(int position) { 18 return position; 19 } 20 21 @Override 22 public long getItemId(int position) { 23 return position; 24 } 25 26 @Override 27 public View getView(int position, View convertView, ViewGroup parent) { 28 if (convertView == null) { 29 convertView = mInflater.inflate(R.layout.item_fr_acmain_nearby_banner, null); 30 } 31 convertView.findViewById(R.id.imgView).setBackgroundResource(ids[position%ids.length]); 32 return convertView; 33 } 34 35 }
关键代码在第13行和31行的红色部分。不过这样实现之后，和CircleFlowIndicator结合使用，会发现程序ANR（无响应），原因是CircleFlowIndicator会调用ViewFlow.getViewCount()来绘制圆点，显然这个数是Integer.MAX_VALUE,圆点数太多了导致ANR，我们需要继续扩展MyViewFlow的getViewCount()。如下。
1 private int mCount; 2 public void setCount(int count){ 3 mCount=count; 4 } 5 @Override 6 public int getViewsCount() { 7 return mCount; 8 }
需要调用MyViewFlow.setCount(int count)指定真实的数目，这样做了之后，发现程序不会ANR了。CircleFlowIndicator绘制的圆点数目也正常。但是会发现，无论怎么滑动，圆点状态都不变化，分析ViewFlow的源码，发现要重写一下onScrollChanged，我们继续扩展MyViewFlow,代码如下。
1 private int mLastIndex; 2 @Override 3 public void setAdapter(Adapter adapter, int initialPosition){ 4 super.setAdapter(adapter,initialPosition); 5 mLastIndex = initialPosition; 6 } 7 8 @Override 9 protected void onScrollChanged(int h, int v, int oldh, int oldv) { 10 //super.onScrollChanged(h, v, oldh, oldv); 11 if (mIndicator != null) { 12 /* 13 * The actual horizontal scroll origin does typically not match the 14 * perceived one. Therefore, we need to calculate the perceived 15 * horizontal scroll origin here, since we use a view buffer. 16 */ 17 int hPerceived = h + (mCurrentAdapterIndex%mCount - mCurrentBufferIndex) 18 * getChildWidth(); 19 20 if(mLastIndex%mCount==mCount-1 && mCurrentAdapterIndex>mLastIndex) { 21 oldh=0; 22 hPerceived = 0; 23 } 24 if(mLastIndex%mCount==0&&mCurrentAdapterIndex<mLastIndex) 25 hPerceived=h+(mCount-1-mCurrentBufferIndex)*getChildWidth(); 26 27 LogUtil.e(Config.MYTAG,"mCurrentAdapterIndex="+mCurrentAdapterIndex); 28 LogUtil.e(Config.MYTAG,"mLastIndex="+mLastIndex); 29 LogUtil.e(Config.MYTAG, "hPerceived=" + hPerceived); 30 31 mIndicator.onScrolled(hPerceived, v, oldh, oldv); 32 33 mLastIndex=mCurrentAdapterIndex; 34 } 35 }
当然，有几个变量mIndicator,mCurrentAdapterIndex，mCurrentBufferIndex是沿用父类ViewFlow的，如果找不到，需要将父类ViewFlow中这些变量改为public即可（虽然从oop角度，这种做法很脏，但很省事，大半夜码文字很累，我很懒）。
至此，大功告成！
整体MyViewFlow代码如下：
package common.control.viewflow; import android.content.Context; import android.support.v4.view.ViewPager; import android.util.AttributeSet; import android.view.MotionEvent; import android.widget.Adapter; import com.xxx.android.main.Config; import common.util.LogUtil; public class MyViewFlow extends ViewFlow { private ViewPager mPager; public MyViewFlow(Context context, AttributeSet attrs) { super(context, attrs); } public void setViewPager(ViewPager viewPager) { mPager = viewPager; } @Override public boolean onInterceptTouchEvent(MotionEvent ev) { if (mPager != null) switch (ev.getAction()) { case MotionEvent.ACTION_DOWN: mPager.requestDisallowInterceptTouchEvent(true); break; case MotionEvent.ACTION_UP: mPager.requestDisallowInterceptTouchEvent(false); break; case MotionEvent.ACTION_CANCEL: mPager.requestDisallowInterceptTouchEvent(false); break; case MotionEvent.ACTION_MOVE: mPager.requestDisallowInterceptTouchEvent(true); break; } return super.onInterceptTouchEvent(ev); } private int mCount; public void setCount(int count){ mCount=count; } @Override public int getViewsCount() { return mCount; } private int mLastIndex; @Override public void setAdapter(Adapter adapter, int initialPosition){ super.setAdapter(adapter,initialPosition); mLastIndex = initialPosition; } @Override protected void onScrollChanged(int h, int v, int oldh, int oldv) { //super.onScrollChanged(h, v, oldh, oldv); if (mIndicator != null) { /* * The actual horizontal scroll origin does typically not match the * perceived one. Therefore, we need to calculate the perceived * horizontal scroll origin here, since we use a view buffer. */ int hPerceived = h + (mCurrentAdapterIndex%mCount - mCurrentBufferIndex) * getChildWidth(); if(mLastIndex%mCount==mCount-1 && mCurrentAdapterIndex>mLastIndex) { oldh=0; hPerceived = 0; } if(mLastIndex%mCount==0&&mCurrentAdapterIndex<mLastIndex) hPerceived=h+(mCount-1-mCurrentBufferIndex)*getChildWidth(); LogUtil.e(Config.MYTAG,"mCurrentAdapterIndex="+mCurrentAdapterIndex); LogUtil.e(Config.MYTAG,"mLastIndex="+mLastIndex); LogUtil.e(Config.MYTAG, "hPerceived=" + hPerceived); mIndicator.onScrolled(hPerceived, v, oldh, oldv); mLastIndex=mCurrentAdapterIndex; } } }
自动播放就不用讲了，网上很多。同学们如果有收获，记得回赞。
本文转自Kai的世界,道法自然博客园博客，原文链接：http://www.cnblogs.com/kaima/p/3999390.html，如需转载请自行联系原作者。
