001/**
002 * Copyright 2005-2016 The Kuali Foundation
003 *
004 * Licensed under the Educational Community License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.opensource.org/licenses/ecl2.php
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.kuali.rice.kns.util;
017
018/**
019 * This class provides utilities to support the rendering of tables in Kuali without using display tag.
020 * 
021 * Normally, displaytag handles the rendering of Kuali tables on various screens, but
022 * there are situations where displaytag is inadequate for the task (e.g. multiple value lookups).
023 * In particular, display tag does not handle POSTing of forms when switching between pages and sorting.
024 * 
025 */
026public final class TableRenderUtil {
027        
028        private TableRenderUtil() {
029                throw new UnsupportedOperationException("do not call");
030        }
031        
032    /**
033     * Returns the minimum number of pages needed to display a result set of the given page
034     * 
035     * @param resultSize number of results
036     * @param maxRowsPerPage maximum number of rows 
037     * 
038     * @return
039     */
040    public static int computeTotalNumberOfPages(int resultSize, int maxRowsPerPage) {
041        int numPages = resultSize / maxRowsPerPage;
042        if (resultSize % maxRowsPerPage != 0) {
043            // partial page
044            numPages++;
045        }
046        return numPages;
047    }
048    
049    /**
050     * This method computes the list index of the first row of the given page
051     * 
052     * @param pageNumber first page is index 0
053     * @param resultSize the size of the list being rendered
054     * @param maxRowsPerPage max number of rows on a page
055     * @return the index in the result list of the first row of the given page 
056     */
057    public static int computeStartIndexForPage(int pageNumber, int resultSize, int maxRowsPerPage) {
058        if (pageNumber < 0 && pageNumber >= computeTotalNumberOfPages(resultSize, maxRowsPerPage)) {
059            return -1;
060        }
061        return pageNumber * maxRowsPerPage;
062    }
063    
064    /**
065     * This method computes the index of the last row of the given page
066     * 
067     * @param pageNumber first page is index 0
068     * @param resultSize the size of the list being rendered
069     * @param maxRowsPerPage max number of rows on a page
070     * @return the index in the result list of the last row of the given page 
071     */
072    public static int computeLastIndexForPage(int pageNumber, int resultSize, int maxRowsPerPage) {
073        int startIndex = computeStartIndexForPage(pageNumber, resultSize, maxRowsPerPage);
074        if (startIndex == -1) {
075            return -1;
076        }
077        if (startIndex + maxRowsPerPage - 1 < resultSize) {
078            return startIndex + maxRowsPerPage - 1;
079        }
080        // partial page
081        return resultSize - 1;
082   }
083}