PullToRefreshScrollView 添加滚动监听
给PullToRefreshScrollView添加滚动监听前,我们需要先知道怎么给ScrollView添加滚动监听。因为ScrollView没有滚动监听事件(setOnScrollChangeListener这个要sdk23不考虑),那只能我们自己来实现。
其实ScrollView有一个对滚动进行监听的方法(onScrollChanged),但是是protected类型的,我们的实现就是围绕这个方法。实现方法很简单,具体代码如下:
public class MyScrollView extends ScrollView { private OnScrollListener listener; public MyScrollView(Context context) { super(context); } public MyScrollView(Context context, AttributeSet attrs) { super(context, attrs); } public void setOnScrollListener(OnScrollListener listener) { this.listener = listener; } @Override protected void onScrollChanged(int l, int t, int oldl, int oldt) { super.onScrollChanged(l, t, oldl, oldt); if(listener!=null) { listener.onScroll(getScrollY()); } } public interface OnScrollListener { void onScroll(int y); } }
这样就实现了对ScrollView的滚动监听,好了,回到重点,怎么去实现PullToRefreshScrollView的滚动监听,还是围绕上面的方法来的,在PullToRefresh库中添加两个类,一个是我们上面写的,另一个将PullToRefreshScrollView中的代码复制一遍,然后将里面所有的ScrollView改为MyScrollView(你自定义的有滚动监听ScrollView类名)就行了。
其中PullToRefreshScrollView2的代码如下:
/******************************************************************************* * Copyright 2011, 2012 Chris Banes. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. *******************************************************************************/ package com.handmark.pulltorefresh.library; import android.annotation.TargetApi; import android.content.Context; import android.os.Build.VERSION; import android.os.Build.VERSION_CODES; import android.util.AttributeSet; import android.util.Log; import android.view.View; import android.widget.ScrollView; public class PullToRefreshScrollView2 extends PullToRefreshBase<MyScrollView> { public PullToRefreshScrollView2(Context context) { super(context); } public PullToRefreshScrollView2(Context context, AttributeSet attrs) { super(context, attrs); } public PullToRefreshScrollView2(Context context, Mode mode) { super(context, mode); } public PullToRefreshScrollView2(Context context, Mode mode, AnimationStyle style) { super(context, mode, style); } @Override public final Orientation getPullToRefreshScrollDirection() { return Orientation.VERTICAL; } @Override protected MyScrollView createRefreshableView(Context context, AttributeSet attrs) { MyScrollView scrollView; if (VERSION.SDK_INT >= VERSION_CODES.GINGERBREAD) { scrollView = new InternalScrollViewSDK9(context, attrs); } else { scrollView = new MyScrollView(context, attrs); } scrollView.setId(R.id.scrollview); return scrollView; } @Override protected boolean isReadyForPullStart() { return mRefreshableView.getScrollY() == 0; } @Override protected boolean isReadyForPullEnd() { View scrollViewChild = mRefreshableView.getChildAt(0); if (null != scrollViewChild) { return mRefreshableView.getScrollY() >= (scrollViewChild.getHeight() - getHeight()); } return false; } @TargetApi(9) final class InternalScrollViewSDK9 extends MyScrollView { public InternalScrollViewSDK9(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(PullToRefreshScrollView2.this, deltaX, scrollX, deltaY, scrollY, 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; } } }
好了, 监听已经写完了,下面是使用代码:
ptrsv2.getRefreshableView().setOnScrollListener(new com.handmark.pulltorefresh.library.MyScrollView.OnScrollListener() { @Override public void onScroll(int y) {
ToastUtil.toastShort("滚动中.."+y);}});