从 API 16 开始，控件Gallery已被废弃，此时我们可以用RecyclerView实现类似于ViewPager的横向移动。
效果图：
布局文件很简单就一个RecyclerView:
<?xml version="1.0" encoding="utf-8"?> xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.example.hans.hansrecyclergallery.MainActivity" > android:id="@+id/rv" android:layout_marginTop="200dp" android:layout_width="match_parent" android:layout_height="wrap_content" >
实现方案：
1.继承RecyclerView.Adapter实现onCreateViewHolder方法，初始化itemView的大小和透明度：
@Override public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { ViewHolder holder = super.onCreateViewHolder(parent, viewType); // 设置Item的宽度 holder.getConvertView().setScaleX(mScale); holder.getConvertView().setScaleY(mScale); holder.getConvertView().setAlpha(mAlpha); ViewGroup.LayoutParams lp = holder.getConvertView().getLayoutParams(); lp.width = getItemStdWidth();//每个item所占屏幕的宽度 return holder; }
2.实现onAttachedToRecyclerView(RecyclerView mRecyclerView)方法，
给RecyclerView添加setOnScrollListener监听器，根据RecyclerView滑动的距离实现动画效果:
@Override public void onScrolled(RecyclerView mRecyclerView, int dx, int dy) { //mCurrentItemOffset += dx; mCurrentItemOffset = mRecyclerView.computeHorizontalScrollOffset(); mCurrentItemPos = (int) ((mCurrentItemOffset * 1.0 / getItemStdWidth())+0.1f); mMiddleItemPos = getMiddlePosition(); int offset = (mCurrentItemPos+1)*getItemStdWidth() - mCurrentItemOffset ; float percent = (float) Math.max(Math.abs(offset)*1.0 / getItemStdWidth(), 0.0001); if (mMiddleItemPos > 0) { leftView = mRecyclerView.getLayoutManager().findViewByPosition(mMiddleItemPos - 1); } currentView = mRecyclerView.getLayoutManager().findViewByPosition(mMiddleItemPos); if (mMiddleItemPos < mRecyclerView.getAdapter().getItemCount() - 1) { rightView = mRecyclerView.getLayoutManager().findViewByPosition(mMiddleItemPos + 1); } if (leftView != null) { // y = (1 - mScale)x + mScale leftView.setScaleY(mScale); leftView.setScaleX(mScale); } if (currentView != null) { // y = (mScale - 1)x + 1 currentView.setScaleY((1 - mScale) * percent + mScale); currentView.setScaleX((1 - mScale) * percent + mScale); currentView.setAlpha((1 - mAlpha) * percent + mAlpha); } if (rightView != null) { // y = (1 - mScale)x + mScale rightView.setScaleY((mScale - 1) * percent + 1); rightView.setScaleX((mScale - 1) * percent + 1); rightView.setAlpha((mAlpha - 1) * percent + 1); } super.onScrolled(mRecyclerView, dx, dy); } }); super.onAttachedToRecyclerView(mRecyclerView); }
3.使用LinearSnapHelper，有点类似 ViewPager，LinearSnapHelper 保证了每次滚动完自动滑动到中心的 Item
new LinearSnapHelper().attachToRecyclerView(recyclerView)
注：LinearSnapHelper支持库,需要把Support RecyclerView包更新到24.2.0以上
我们来看看效果吧：
源码地址：
https://github.com/sugarhans/HansRecyclerGallery
到这里就结束啦.
转播
