Android StaggeredGrid 加下拉刷新功能 PullToRefresh

浏览数：109 / 时间：2015年06月11日

https://github.com/etsy/AndroidStaggeredGrid 用的github上面提供瀑布流，继承于abslistview，回收机制不错，并且提供了OnScrollListener来监听滑动时间。

然后想加一个下拉刷新功能，下面分享一下研究的最终结果。

Java代码：

package com.xxx.waterfall;

import android.annotation.TargetApi;
import android.content.Context;
import android.os.Build.VERSION;
import android.os.Build.VERSION_CODES;
import android.os.Bundle;
import android.util.AttributeSet;
import android.view.View;

import com.handmark.pulltorefresh.library.OverscrollHelper;
import com.handmark.pulltorefresh.library.PullToRefreshBase;
import com.handmark.pulltorefresh.library.R;

public class PullToRefreshStaggeredGridView extends PullToRefreshBase<StaggeredGridView> {

    private static final OnRefreshListener<StaggeredGridView> defaultOnRefreshListener = new OnRefreshListener<StaggeredGridView>() {

        @Override
        public void onRefresh(PullToRefreshBase<StaggeredGridView> refreshView) {

        }

    };

    public PullToRefreshStaggeredGridView(Context context) {
        super(context);

        /**
         * Added so that by default, Pull-to-Refresh refreshes the page
         */
        setOnRefreshListener(defaultOnRefreshListener);
    }

    public PullToRefreshStaggeredGridView(Context context, AttributeSet attrs) {
        super(context, attrs);

        /**
         * Added so that by default, Pull-to-Refresh refreshes the page
         */
        setOnRefreshListener(defaultOnRefreshListener);
    }

    public PullToRefreshStaggeredGridView(Context context, Mode mode) {
        super(context, mode);

        /**
         * Added so that by default, Pull-to-Refresh refreshes the page
         */
        setOnRefreshListener(defaultOnRefreshListener);
    }

    public PullToRefreshStaggeredGridView(Context context, Mode mode, AnimationStyle style) {
        super(context, mode, style);

        /**
         * Added so that by default, Pull-to-Refresh refreshes the page
         */
        setOnRefreshListener(defaultOnRefreshListener);
    }

    @Override
    public final Orientation getPullToRefreshScrollDirection() {
        return Orientation.VERTICAL;
    }

    @Override
    protected StaggeredGridView createRefreshableView(Context context, AttributeSet attrs) {
        StaggeredGridView gridView;

        if (VERSION.SDK_INT >= VERSION_CODES.GINGERBREAD) {
            gridView = new InternalStaggeredGridViewSDK9(context, attrs);
        } else {
            gridView = new StaggeredGridView(context, attrs);
        }

        gridView.setId(R.id.gridview);
        return gridView;
    }

    @Override
    protected boolean isReadyForPullStart() {
        boolean result = false;
        View v = getRefreshableView().getChildAt(0);
        if (getRefreshableView().getFirstVisiblePosition() == 0) {
            if (v != null) {
                // getTop() and getBottom() are relative to the ListView,
                // so if getTop() is negative, it is not fully visible
                boolean isTopFullyVisible = v.getTop() >= 0;

                result = isTopFullyVisible;
            }
        }
        return result;
    }

    @Override
    protected boolean isReadyForPullEnd() {
        boolean result = false;
        int last = getRefreshableView().getChildCount() - 1;
        View v = getRefreshableView().getChildAt(last);

        int firstVisiblePosition = getRefreshableView().getFirstVisiblePosition();
        int visibleItemCount = getRefreshableView().getChildCount();
        int itemCount = getRefreshableView().getAdapter().getCount();
        if (firstVisiblePosition + visibleItemCount >= itemCount) {
            if (v != null) {
                boolean isLastFullyVisible = v.getBottom() <= getRefreshableView().getHeight();

                result = isLastFullyVisible;
            }
        }
        return result;
    }

    @Override
    protected void onPtrRestoreInstanceState(Bundle savedInstanceState) {
        super.onPtrRestoreInstanceState(savedInstanceState);
    }

    @Override
    protected void onPtrSaveInstanceState(Bundle saveState) {
        super.onPtrSaveInstanceState(saveState);
    }

    @TargetApi(9)
    final class InternalStaggeredGridViewSDK9 extends StaggeredGridView {
        // WebView doesn‘t always scroll back to it‘s edge so we add some
        // fuzziness
        static final int OVERSCROLL_FUZZY_THRESHOLD = 2;

        // WebView seems quite reluctant to overscroll so we use the scale
        // factor to scale it‘s value
        static final float OVERSCROLL_SCALE_FACTOR = 1.5f;

        public InternalStaggeredGridViewSDK9(Context context, AttributeSet attrs) {
            super(context, attrs);
        }

        @Override
        protected boolean overScrollBy(int deltaX, int deltaY, int scrollX, int scrollY, int scrollRangeX, int scrollRangeY, int maxOverScrollX, int maxOverScrollY, boolean isTouchEvent) {

            final boolean returnValue = super.overScrollBy(deltaX, deltaY, scrollX, scrollY, scrollRangeX, scrollRangeY, maxOverScrollX, maxOverScrollY, isTouchEvent);
// Does all of the hard work...
            OverscrollHelper.overScrollBy(PullToRefreshStaggeredGridView.this, deltaX, scrollX, deltaY, getScrollRange(), isTouchEvent);

            return returnValue;
        }

        /**
         * Taken from the AOSP ScrollView source
         */
        private int getScrollRange() {
            int scrollRange = 0;
            if (getChildCount() > 0) {
                View child = getChildAt(0);
                scrollRange = Math.max(0, child.getHeight() - (getHeight() - getPaddingBottom() - getPaddingTop()));
            }
            return scrollRange;
        }

    }
}

XML代码：

    <com.xxx.waterfall.PullToRefreshStaggeredGridView
        android:id="@+id/HomePullToRefreshStaggerdGridView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@null"
        android:cacheColorHint="#00000000"
        android:fadingEdge="none"
        android:overScrollMode="never"
        android:scrollbars="none"
        app:column_count="2"
        app:item_margin="2dp"
        ptr:ptrMode="both" >
    </com.xxx.waterfall.PullToRefreshStaggeredGridView>

Java Activity:

package com.xxx.activity;
 
import com.handmark.pulltorefresh.library.PullToRefreshBase;
import com.handmark.pulltorefresh.library.PullToRefreshBase.Mode;
import com.handmark.pulltorefresh.library.PullToRefreshBase.OnRefreshListener;
import com.handmark.pulltorefresh.library.PullToRefreshBase.OnRefreshListener2;

public class HomeFragment extends DFFragment implements OnRefreshListener<StaggeredGridView>, AbsListView.OnScrollListener {
 
    /**下来刷新**/
    private PullToRefreshStaggeredGridView mPullToRefreshStaggerdGridView;
    private StaggeredGridView gv  
 
    private void initView() {
        mPullToRefreshStaggerdGridView = (PullToRefreshStaggeredGridView) parentView.findViewById(R.id.HomePullToRefreshStaggerdGridView);
         
        mPullToRefreshStaggerdGridView.setMode(Mode.PULL_FROM_END);
        mPullToRefreshStaggerdGridView.setOnRefreshListener(new OnRefreshListener<StaggeredGridView>() {

            @Override
            public void onRefresh(PullToRefreshBase<StaggeredGridView> refreshView) { 
　　　　　　　　//刷新

            }
        });mPullToRefreshStaggerdGridView.setMode(Mode.BOTH);
        mPullToRefreshStaggerdGridView.setOnRefreshListener(listener);
        gv=mPullToRefreshStaggerdGridView.getRefreshableView(); 
         Gv.setAdapter(waterfallAdapter);
        Gv.setOnScrollListener(this);
    }

    @Override
    public void onScrollStateChanged(final AbsListView view, final int scrollState) {
    }

    @Override
    public void onScroll(final AbsListView view, final int firstVisibleItem, final int visibleItemCount, final int totalItemCount) {
        if (!mHasRequestedMore) {
            int lastInScreen = firstVisibleItem + visibleItemCount;
            if (lastInScreen >= totalItemCount) {
                 //加载事件
                onLoadMoreItems();
            }
        }
    }

    private boolean mHasRequestedMore;

    private void onLoadMoreItems() {
        //加载事件。。。
        mHasRequestedMore = false;
    }

     
}