对com.handmark.pulltorefresh.library下拉扩充瀑布流

转载请声明：http://blog.csdn.net/yoyo_newbie/article/details/48108417

很多人都会和我一样郁闷，这个com.handmark.pulltorefresh.library下拉库唯一遗憾的是没有下拉的RecyclerView瀑布流。

于是本人看了下源码分析，原来对他扩充很简单，只要了解PullToRefreshBase的

isReadyForPullStart，　isReadyForPullEnd这两个方法就可以轻松实现。当然还有个注意的方法就是
getPullToRefreshScrollDirection。这个决定是上下拉还是左右拉。用过
PullToRefreshViewPager的人就知道，是左右拉刷新的，
PullToRefreshListView，
PullToRefreshGridVie等这些是上下啦的。
isReadyForPullStart这个方法是通知当前控件是否能下拉，
isReadyForPullEnd这个方法是通知当前控件是否能上啦。
那么我们只要实现监听某个控件的是否滚动已到头部（完全显示头部）让isReadyForPullStart提供true or false,
是否滚动到末尾（完全显示末尾）提供true or false就可以扩充com.handmark.pulltorefresh.library拖拽刷新事件
下面这个例子是对其扩充一个　２列的瀑布流下拉，居于RecyclerView的。如果你像实现多列，那么你可以对以下的例子自定义修改。通过在com.handmark.pulltorefresh.library的values文件夹的attrs.xml添加属性进行列的属性控制列数，会自定义ｖｉｅｗ的人都知道，就不多说了。
实现如下:
注意，要添加v4包和v7包的RecyclerView
首先在这个库里面的ids.xml添加 <item type="id" name="straggereddGridLayout" />添加后为
<?xml version="1.0" encoding="utf-8"?><resources>    <item type="id" name="gridview" />    <item type="id" name="webview" />    <item type="id" name="scrollview" />        <item type="id" name="straggereddGridLayout" /></resources>
然后直接贴代码到
com.handmark.pulltorefresh.library.extras包下即可

package com.handmark.pulltorefresh.library.extras;import android.content.Context;import android.content.res.TypedArray;import android.support.v4.view.PagerAdapter;import android.support.v4.view.ViewPager;import android.support.v7.widget.RecyclerView;import android.support.v7.widget.StaggeredGridLayoutManager;import android.util.AttributeSet;import android.view.DragEvent;import android.view.View;import com.handmark.pulltorefresh.library.PullToRefreshBase;import com.handmark.pulltorefresh.library.R;import java.util.concurrent.atomic.AtomicIntegerArray;/** * 瀑布流下啦刷新 * Created by sam on 15-8-30. */public class PullToRefreshStaggeredGridLayout extends PullToRefreshBase<RecyclerView> {    public PullToRefreshStaggeredGridLayout(Context context) {        super(context);    }    public PullToRefreshStaggeredGridLayout(Context context, AttributeSet attrs) {        super(context, attrs);    }    @Override    public final Orientation getPullToRefreshScrollDirection() {        return Orientation.VERTICAL;    }    private RecyclerView recyclerView;    private boolean isScrollOnHeader = true;    private boolean isScrollOnFooter = false;    @Override    protected RecyclerView createRefreshableView(Context context, AttributeSet attrs) {        recyclerView = new RecyclerView(context, attrs);        recyclerView.setId(R.id.straggereddGridLayout);        final  StaggeredGridLayoutManager mLayoutManager = new StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL);        recyclerView.setLayoutManager(mLayoutManager);        recyclerView.setOnScrollListener(new RecyclerView.OnScrollListener()            {            int[] lastVisibleItem;            int[] fistVisibleItem;            @Override            public void onScrollStateChanged(RecyclerView recyclerView,                                             int newState) {                    if(null != fistVisibleItem)                    {                        isScrollOnHeader =  0 ==fistVisibleItem[0];                    }                    else                    {                        isScrollOnHeader =true;                    }                    if(null != lastVisibleItem)                    {                        boolean isLast = mLayoutManager.getItemCount() -1  ==lastVisibleItem[0]||mLayoutManager.getItemCount()  ==lastVisibleItem[1]                       || mLayoutManager.getItemCount() -1  ==lastVisibleItem[1]||mLayoutManager.getItemCount()  ==lastVisibleItem[0];                        isScrollOnFooter =   newState == RecyclerView.SCROLL_STATE_IDLE&& isLast ;                    }                    else                    {                        isScrollOnFooter =true;                    }            }            @Override            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {                fistVisibleItem = mLayoutManager.findFirstCompletelyVisibleItemPositions(new int[2]);                lastVisibleItem = mLayoutManager.findLastCompletelyVisibleItemPositions(new int[2]);            }        });        return recyclerView;    }    @Override    protected boolean isReadyForPullStart() {        return isScrollOnHeader;    }    @Override    protected boolean isReadyForPullEnd() {        return isScrollOnFooter;    }}


使用如下
<com.handmark.pulltorefresh.library.extras.PullToRefreshStaggeredGridLayout    xmlns:ptr="http://schemas.android.com/apk/res-auto"    android:id="@+id/lv_index_jiongtu"    android:layout_width="match_parent"    android:layout_height="wrap_content"    ptr:ptrAnimationStyle="rotate"    ptr:ptrHeaderBackground="#00000000"    ptr:ptrHeaderTextColor="#ffffff"    ptr:ptrMode="both"    ptr:ptrOverScroll="false"    ptr:ptrShowIndicator="false"  />

详细就不多说了,至要你会使用RecyclerView即可。。。。。。。