com.handmark.pulltorefresh.library.PullToRefreshStaggeredGridView.java Source code

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Here is the source code for com.handmark.pulltorefresh.library.PullToRefreshStaggeredGridView.java

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/*******************************************************************************
 * 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.os.Bundle;
import android.support.v4.widget.StaggeredGridView;
import android.util.AttributeSet;
import android.view.View;

public class PullToRefreshStaggeredGridView extends PullToRefreshBase<StaggeredGridView> {

    private static final OnRefreshListener<StaggeredGridView> defaultOnRefreshListener = new OnRefreshListener<StaggeredGridView>() {

        @Override
        public void onRefresh(PullToRefreshBase<StaggeredGridView> refreshView) {
        }

    };

    public PullToRefreshStaggeredGridView(Context context) {
        super(context);

        /**
         * Added so that by default, Pull-to-Refresh refreshes the page
         */
        setOnRefreshListener(defaultOnRefreshListener);
    }

    public PullToRefreshStaggeredGridView(Context context, AttributeSet attrs) {
        super(context, attrs);

        /**
         * Added so that by default, Pull-to-Refresh refreshes the page
         */
        setOnRefreshListener(defaultOnRefreshListener);
    }

    public PullToRefreshStaggeredGridView(Context context, Mode mode) {
        super(context, mode);

        /**
         * Added so that by default, Pull-to-Refresh refreshes the page
         */
        setOnRefreshListener(defaultOnRefreshListener);
    }

    public PullToRefreshStaggeredGridView(Context context, Mode mode, AnimationStyle style) {
        super(context, mode, style);

        /**
         * Added so that by default, Pull-to-Refresh refreshes the page
         */
        setOnRefreshListener(defaultOnRefreshListener);
    }

    @Override
    public final Orientation getPullToRefreshScrollDirection() {
        return Orientation.VERTICAL;
    }

    @Override
    protected StaggeredGridView createRefreshableView(Context context, AttributeSet attrs) {
        StaggeredGridView gridView;

        if (VERSION.SDK_INT >= VERSION_CODES.GINGERBREAD) {
            gridView = new InternalStaggeredGridViewSDK9(context, attrs);
        } else {
            gridView = new StaggeredGridView(context, attrs);
        }

        gridView.setId(R.id.gridview);
        return gridView;
    }

    @Override
    protected boolean isReadyForPullStart() {
        boolean result = false;
        View v = mRefreshableView.getChildAt(0);
        if (mRefreshableView.getFirstPosition() == 0) {
            if (v != null) {
                // getTop() and getBottom() are relative to the ListView, 
                // so if getTop() is negative, it is not fully visible
                boolean isTopFullyVisible = v.getTop() >= 0;

                result = isTopFullyVisible;
            }
        }
        return result;
    }

    @Override
    protected boolean isReadyForPullEnd() {
        boolean result = false;
        int last = mRefreshableView.getChildCount() - 1;
        View v = mRefreshableView.getChildAt(last);

        int firstVisiblePosition = mRefreshableView.getFirstPosition();
        int visibleItemCount = mRefreshableView.getChildCount();
        int itemCount = mRefreshableView.getItemCount();

        if (firstVisiblePosition + visibleItemCount >= itemCount) {
            if (v != null) {
                boolean isLastFullyVisible = v.getBottom() <= mRefreshableView.getHeight();

                result = isLastFullyVisible;
            }
        }
        return result;
    }

    @Override
    protected void onPtrRestoreInstanceState(Bundle savedInstanceState) {
        super.onPtrRestoreInstanceState(savedInstanceState);
    }

    @Override
    protected void onPtrSaveInstanceState(Bundle saveState) {
        super.onPtrSaveInstanceState(saveState);
    }

    @TargetApi(9)
    final class InternalStaggeredGridViewSDK9 extends StaggeredGridView {

        // WebView doesn't always scroll back to it's edge so we add some
        // fuzziness
        static final int OVERSCROLL_FUZZY_THRESHOLD = 2;

        // WebView seems quite reluctant to overscroll so we use the scale
        // factor to scale it's value
        static final float OVERSCROLL_SCALE_FACTOR = 1.5f;

        public InternalStaggeredGridViewSDK9(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(PullToRefreshStaggeredGridView.this, deltaX, scrollX, deltaY, scrollY,
            //               getScrollRange(), OVERSCROLL_FUZZY_THRESHOLD, OVERSCROLL_SCALE_FACTOR, isTouchEvent);

            // Does all of the hard work...
            OverscrollHelper.overScrollBy(PullToRefreshStaggeredGridView.this, deltaX, scrollX, deltaY,
                    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;
        }

    }
}