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/*
* Copyright 2014 The Android Open Source Project
*
* 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.example.android.swiperefreshlistfragment;
import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.support.v4.view.ViewCompat;
import android.support.v4.widget.SwipeRefreshLayout;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;
/**
* Subclass of {@link android.support.v4.app.ListFragment} which provides automatic support for
* providing the 'swipe-to-refresh' UX gesture by wrapping the the content view in a
* {@link android.support.v4.widget.SwipeRefreshLayout}.
*/
public class SwipeRefreshListFragment extends ListFragment {
private SwipeRefreshLayout mSwipeRefreshLayout;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Create the list fragment's content view by calling the super method
final View listFragmentView = super.onCreateView(inflater, container, savedInstanceState);
// Now create a SwipeRefreshLayout to wrap the fragment's content view
mSwipeRefreshLayout = new ListFragmentSwipeRefreshLayout(container.getContext());
47
// Add the list fragment's content view to the SwipeRefreshLayout, making sure that it fills
// the SwipeRefreshLayout
mSwipeRefreshLayout.addView(listFragmentView,
ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
// Make sure that the SwipeRefreshLayout will fill the fragment
mSwipeRefreshLayout.setLayoutParams(
new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.MATCH_PARENT));
// Now return the SwipeRefreshLayout as this fragment's content view
return mSwipeRefreshLayout;
}
/**
* Set the {@link android.support.v4.widget.SwipeRefreshLayout.OnRefreshListener} to listen for
* initiated refreshes.
*
* @see android.support.v4.widget.SwipeRefreshLayout#setOnRefreshListener(android.support.v4.widget.SwipeRefreshLayout.OnRefreshListener)
*/
public void setOnRefreshListener(SwipeRefreshLayout.OnRefreshListener listener) {
mSwipeRefreshLayout.setOnRefreshListener(listener);
}
/**
* Returns whether the {@link android.support.v4.widget.SwipeRefreshLayout} is currently
* refreshing or not.
*
* @see android.support.v4.widget.SwipeRefreshLayout#isRefreshing()
*/
public boolean isRefreshing() {
return mSwipeRefreshLayout.isRefreshing();
}
/**
* Set whether the {@link android.support.v4.widget.SwipeRefreshLayout} should be displaying
* that it is refreshing or not.
*
* @see android.support.v4.widget.SwipeRefreshLayout#setRefreshing(boolean)
*/
public void setRefreshing(boolean refreshing) {
mSwipeRefreshLayout.setRefreshing(refreshing);
}
/**
* Set the color scheme for the {@link android.support.v4.widget.SwipeRefreshLayout}.
*
* @see android.support.v4.widget.SwipeRefreshLayout#setColorScheme(int, int, int, int)
*/
public void setColorScheme(int colorRes1, int colorRes2, int colorRes3, int colorRes4) {
mSwipeRefreshLayout.setColorScheme(colorRes1, colorRes2, colorRes3, colorRes4);
}
/**
* @return the fragment's {@link android.support.v4.widget.SwipeRefreshLayout} widget.
*/
public SwipeRefreshLayout getSwipeRefreshLayout() {
return mSwipeRefreshLayout;
}
/**
* Sub-class of {@link android.support.v4.widget.SwipeRefreshLayout} for use in this
* {@link android.support.v4.app.ListFragment}. The reason that this is needed is because
* {@link android.support.v4.widget.SwipeRefreshLayout} only supports a single child, which it
* expects to be the one which triggers refreshes. In our case the layout's child is the content
* view returned from
* {@link android.support.v4.app.ListFragment#onCreateView(android.view.LayoutInflater, android.view.ViewGroup, android.os.Bundle)}
* which is a {@link android.view.ViewGroup}.
*
* <p>To enable 'swipe-to-refresh' support via the {@link android.widget.ListView} we need to
* override the default behavior and properly signal when a gesture is possible. This is done by
* overriding {@link #canChildScrollUp()}.
*/
private class ListFragmentSwipeRefreshLayout extends SwipeRefreshLayout {
public ListFragmentSwipeRefreshLayout(Context context) {
super(context);
}
/**
* As mentioned above, we need to override this method to properly signal when a
* 'swipe-to-refresh' is possible.
*
* @return true if the {@link android.widget.ListView} is visible and can scroll up.
*/
@Override
public boolean canChildScrollUp() {
final ListView listView = getListView();
if (listView.getVisibility() == View.VISIBLE) {
return canListViewScrollUp(listView);
} else {
return false;
}
}
}
/**
* Utility method to check whether a {@link ListView} can scroll up from it's current position.
* Handles platform version differences, providing backwards compatible functionality where
* needed.
*/
private static boolean canListViewScrollUp(ListView listView) {
if (android.os.Build.VERSION.SDK_INT >= 14) {
// For ICS and above we can call canScrollVertically() to determine this
return ViewCompat.canScrollVertically(listView, -1);
} else {
// Pre-ICS we need to manually check the first visible item and the child view's top
// value
return listView.getChildCount() > 0 &&
(listView.getFirstVisiblePosition() > 0
|| listView.getChildAt(0).getTop() < listView.getPaddingTop());
}
}
}