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SwipeRefreshMultipleViews / src / com.example.android.swiperefreshmultipleviews /

MultiSwipeRefreshLayout.java

       
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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.swiperefreshmultipleviews;
       
       
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        import android.content.Context;
       
       
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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.util.AttributeSet;
       
       
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        import android.view.View;
       
       
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        import android.widget.AbsListView;
       
       
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        /**
       
       
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        * A descendant of {@link android.support.v4.widget.SwipeRefreshLayout} which supports multiple
       
       
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        * child views triggering a refresh gesture. You set the views which can trigger the gesture via
       
       
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        * {@link #setSwipeableChildren(int...)}, providing it the child ids.
       
       
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        */
       
       
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        public class MultiSwipeRefreshLayout extends SwipeRefreshLayout {
       
       
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        private View[] mSwipeableChildren;
       
       
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        public MultiSwipeRefreshLayout(Context context) {
       
       
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        super(context);
       
       
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        }
       
       
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        public MultiSwipeRefreshLayout(Context context, AttributeSet attrs) {
       
       
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        super(context, attrs);
       
       
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        }
       
       
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        /**
       
       
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        * Set the children which can trigger a refresh by swiping down when they are visible. These
       
       
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        * views need to be a descendant of this view.
       
       
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        */
       
       
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        public void setSwipeableChildren(final int... ids) {
       
       
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        assert ids != null;
       
       
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        // Iterate through the ids and find the Views
       
       
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        mSwipeableChildren = new View[ids.length];
       
       
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        for (int i = 0; i < ids.length; i++) {
       
       
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        mSwipeableChildren[i] = findViewById(ids[i]);
       
       
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        }
       
       
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        }
       
       
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        /**
       
       
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        * This method controls when the swipe-to-refresh gesture is triggered. By returning false here
       
       
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        * we are signifying that the view is in a state where a refresh gesture can start.
       
       
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        *
       
       
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        * <p>As {@link android.support.v4.widget.SwipeRefreshLayout} only supports one direct child by
       
       
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        * default, we need to manually iterate through our swipeable children to see if any are in a
       
       
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        * state to trigger the gesture. If so we return false to start the gesture.
       
       
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        */
       
       
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        @Override
       
       
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        public boolean canChildScrollUp() {
       
       
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        if (mSwipeableChildren != null && mSwipeableChildren.length > 0) {
       
       
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        // Iterate through the scrollable children and check if any of them can not scroll up
       
       
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        for (View view : mSwipeableChildren) {
       
       
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        if (view != null && view.isShown() && !canViewScrollUp(view)) {
       
       
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        // If the view is shown, and can not scroll upwards, return false and start the
       
       
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        // gesture.
       
       
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        return false;
       
       
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        }
       
       
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        }
       
       
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        }
       
       
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        return true;
       
       
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        }
       
       
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        /**
       
       
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        * Utility method to check whether a {@link View} 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 canViewScrollUp(View view) {
       
       
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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(view, -1);
       
       
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        } else {
       
       
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        if (view instanceof AbsListView) {
       
       
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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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        final AbsListView listView = (AbsListView) view;
       
       
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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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        } else {
       
       
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        // For all other view types we just check the getScrollY() value
       
       
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        return view.getScrollY() > 0;
       
       
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        }
       
       
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        }
       
       
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        }
       
       
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        }