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/*
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* Copyright 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.example.android.swiperefreshlistfragment;
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import android.content.Context;
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import android.os.Bundle;
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import android.support.v4.app.ListFragment;
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import android.support.v4.view.ViewCompat;
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import android.support.v4.widget.SwipeRefreshLayout;
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import android.view.LayoutInflater;
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import android.view.View;
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import android.view.ViewGroup;
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import android.widget.ListView;
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/**
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* Subclass of {@link android.support.v4.app.ListFragment} which provides automatic support for
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* providing the 'swipe-to-refresh' UX gesture by wrapping the the content view in a
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* {@link android.support.v4.widget.SwipeRefreshLayout}.
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*/
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public class SwipeRefreshListFragment extends ListFragment {
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private SwipeRefreshLayout mSwipeRefreshLayout;
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@Override
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public View onCreateView(LayoutInflater inflater, ViewGroup container,
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Bundle savedInstanceState) {
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// Create the list fragment's content view by calling the super method
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final View listFragmentView = super.onCreateView(inflater, container, savedInstanceState);
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// Now create a SwipeRefreshLayout to wrap the fragment's content view
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mSwipeRefreshLayout = new ListFragmentSwipeRefreshLayout(container.getContext());
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// Add the list fragment's content view to the SwipeRefreshLayout, making sure that it fills
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// the SwipeRefreshLayout
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mSwipeRefreshLayout.addView(listFragmentView,
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ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
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// Make sure that the SwipeRefreshLayout will fill the fragment
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mSwipeRefreshLayout.setLayoutParams(
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new ViewGroup.LayoutParams(
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ViewGroup.LayoutParams.MATCH_PARENT,
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ViewGroup.LayoutParams.MATCH_PARENT));
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// Now return the SwipeRefreshLayout as this fragment's content view
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return mSwipeRefreshLayout;
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}
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/**
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* Set the {@link android.support.v4.widget.SwipeRefreshLayout.OnRefreshListener} to listen for
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* initiated refreshes.
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*
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* @see android.support.v4.widget.SwipeRefreshLayout#setOnRefreshListener(android.support.v4.widget.SwipeRefreshLayout.OnRefreshListener)
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*/
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public void setOnRefreshListener(SwipeRefreshLayout.OnRefreshListener listener) {
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mSwipeRefreshLayout.setOnRefreshListener(listener);
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}
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/**
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* Returns whether the {@link android.support.v4.widget.SwipeRefreshLayout} is currently
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* refreshing or not.
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*
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* @see android.support.v4.widget.SwipeRefreshLayout#isRefreshing()
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*/
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public boolean isRefreshing() {
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return mSwipeRefreshLayout.isRefreshing();
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}
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/**
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* Set whether the {@link android.support.v4.widget.SwipeRefreshLayout} should be displaying
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* that it is refreshing or not.
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*
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* @see android.support.v4.widget.SwipeRefreshLayout#setRefreshing(boolean)
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*/
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public void setRefreshing(boolean refreshing) {
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mSwipeRefreshLayout.setRefreshing(refreshing);
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}
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/**
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* Set the color scheme for the {@link android.support.v4.widget.SwipeRefreshLayout}.
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*
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* @see android.support.v4.widget.SwipeRefreshLayout#setColorScheme(int, int, int, int)
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*/
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public void setColorScheme(int colorRes1, int colorRes2, int colorRes3, int colorRes4) {
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mSwipeRefreshLayout.setColorScheme(colorRes1, colorRes2, colorRes3, colorRes4);
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}
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/**
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* @return the fragment's {@link android.support.v4.widget.SwipeRefreshLayout} widget.
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*/
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public SwipeRefreshLayout getSwipeRefreshLayout() {
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return mSwipeRefreshLayout;
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}
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/**
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* Sub-class of {@link android.support.v4.widget.SwipeRefreshLayout} for use in this
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* {@link android.support.v4.app.ListFragment}. The reason that this is needed is because
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* {@link android.support.v4.widget.SwipeRefreshLayout} only supports a single child, which it
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* expects to be the one which triggers refreshes. In our case the layout's child is the content
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* view returned from
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* {@link android.support.v4.app.ListFragment#onCreateView(android.view.LayoutInflater, android.view.ViewGroup, android.os.Bundle)}
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* which is a {@link android.view.ViewGroup}.
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*
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* <p>To enable 'swipe-to-refresh' support via the {@link android.widget.ListView} we need to
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* override the default behavior and properly signal when a gesture is possible. This is done by
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* overriding {@link #canChildScrollUp()}.
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*/
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private class ListFragmentSwipeRefreshLayout extends SwipeRefreshLayout {
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public ListFragmentSwipeRefreshLayout(Context context) {
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super(context);
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}
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/**
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* As mentioned above, we need to override this method to properly signal when a
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* 'swipe-to-refresh' is possible.
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*
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* @return true if the {@link android.widget.ListView} is visible and can scroll up.
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*/
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@Override
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public boolean canChildScrollUp() {
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final ListView listView = getListView();
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if (listView.getVisibility() == View.VISIBLE) {
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return canListViewScrollUp(listView);
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} else {
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return false;
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}
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}
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}
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/**
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* Utility method to check whether a {@link ListView} can scroll up from it's current position.
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* Handles platform version differences, providing backwards compatible functionality where
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* needed.
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*/
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private static boolean canListViewScrollUp(ListView listView) {
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if (android.os.Build.VERSION.SDK_INT >= 14) {
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// For ICS and above we can call canScrollVertically() to determine this
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return ViewCompat.canScrollVertically(listView, -1);
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} else {
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// Pre-ICS we need to manually check the first visible item and the child view's top
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// value
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return listView.getChildCount() > 0 &&
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(listView.getFirstVisiblePosition() > 0
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|| listView.getChildAt(0).getTop() < listView.getPaddingTop());
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}
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}
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}