1 /* 2 * Copyright 2014 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.example.android.swiperefreshmultipleviews; 18 19 import android.content.Context; 20 import android.support.v4.view.ViewCompat; 21 import android.support.v4.widget.SwipeRefreshLayout; 22 import android.util.AttributeSet; 23 import android.view.View; 24 import android.widget.AbsListView; 25 26 /** 27 * A descendant of {@link android.support.v4.widget.SwipeRefreshLayout} which supports multiple 28 * child views triggering a refresh gesture. You set the views which can trigger the gesture via 29 * {@link #setSwipeableChildren(int...)}, providing it the child ids. 30 */ 31 public class MultiSwipeRefreshLayout extends SwipeRefreshLayout { 32 33 private View[] mSwipeableChildren; 34 35 public MultiSwipeRefreshLayout(Context context) { 36 super(context); 37 } 38 39 public MultiSwipeRefreshLayout(Context context, AttributeSet attrs) { 40 super(context, attrs); 41 } 42 43 /** 44 * Set the children which can trigger a refresh by swiping down when they are visible. These 45 * views need to be a descendant of this view. 46 */ 47 public void setSwipeableChildren(final int... ids) { 48 assert ids != null; 49 50 // Iterate through the ids and find the Views 51 mSwipeableChildren = new View[ids.length]; 52 for (int i = 0; i < ids.length; i++) { 53 mSwipeableChildren[i] = findViewById(ids[i]); 54 } 55 } 56 58 /** 59 * This method controls when the swipe-to-refresh gesture is triggered. By returning false here 60 * we are signifying that the view is in a state where a refresh gesture can start. 61 * 62 * <p>As {@link android.support.v4.widget.SwipeRefreshLayout} only supports one direct child by 63 * default, we need to manually iterate through our swipeable children to see if any are in a 64 * state to trigger the gesture. If so we return false to start the gesture. 65 */ 66 @Override 67 public boolean canChildScrollUp() { 68 if (mSwipeableChildren != null && mSwipeableChildren.length > 0) { 69 // Iterate through the scrollable children and check if any of them can not scroll up 70 for (View view : mSwipeableChildren) { 71 if (view != null && view.isShown() && !canViewScrollUp(view)) { 72 // If the view is shown, and can not scroll upwards, return false and start the 73 // gesture. 74 return false; 75 } 76 } 77 } 78 return true; 79 } 81 83 /** 84 * Utility method to check whether a {@link View} can scroll up from it's current position. 85 * Handles platform version differences, providing backwards compatible functionality where 86 * needed. 87 */ 88 private static boolean canViewScrollUp(View view) { 89 if (android.os.Build.VERSION.SDK_INT >= 14) { 90 // For ICS and above we can call canScrollVertically() to determine this 91 return ViewCompat.canScrollVertically(view, -1); 92 } else { 93 if (view instanceof AbsListView) { 94 // Pre-ICS we need to manually check the first visible item and the child view's top 95 // value 96 final AbsListView listView = (AbsListView) view; 97 return listView.getChildCount() > 0 && 98 (listView.getFirstVisiblePosition() > 0 99 || listView.getChildAt(0).getTop() < listView.getPaddingTop()); 100 } else { 101 // For all other view types we just check the getScrollY() value 102 return view.getScrollY() > 0; 103 } 104 } 105 } 107 }