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- /*
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You 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.
- */
-
- /* $Id$ */
-
- package org.apache.fop.layoutmgr;
-
- import java.util.List;
-
- import org.apache.commons.logging.Log;
- import org.apache.commons.logging.LogFactory;
-
- import org.apache.fop.area.AreaTreeHandler;
- import org.apache.fop.fo.Constants;
- import org.apache.fop.fo.pagination.PageSequence;
- import org.apache.fop.fo.pagination.Region;
- import org.apache.fop.fo.pagination.SimplePageMaster;
-
- /**
- * <p>This class delivers Page instances. It also caches them as necessary.
- * </p>
- * <p>Additional functionality makes sure that surplus instances that are requested by the
- * page breaker are properly discarded, especially in situations where hard breaks cause
- * blank pages. The reason for that: The page breaker sometimes needs to preallocate
- * additional pages since it doesn't know exactly until the end how many pages it really needs.
- * </p>
- */
- public class PageProvider implements Constants {
-
- private Log log = LogFactory.getLog(PageProvider.class);
-
- /** Indices are evaluated relative to the first page in the page-sequence. */
- public static final int RELTO_PAGE_SEQUENCE = 0;
- /** Indices are evaluated relative to the first page in the current element list. */
- public static final int RELTO_CURRENT_ELEMENT_LIST = 1;
-
- private int startPageOfPageSequence;
- private int startPageOfCurrentElementList;
- private int startColumnOfCurrentElementList;
- private List cachedPages = new java.util.ArrayList();
-
- private int lastPageIndex = -1;
- private int indexOfCachedLastPage = -1;
-
- //Cache to optimize getAvailableBPD() calls
- private int lastRequestedIndex = -1;
- private int lastReportedBPD = -1;
-
- /**
- * AreaTreeHandler which activates the PSLM and controls
- * the rendering of its pages.
- */
- private AreaTreeHandler areaTreeHandler;
-
- /**
- * fo:page-sequence formatting object being
- * processed by this class
- */
- private PageSequence pageSeq;
-
- /**
- * Main constructor.
- * @param ath the area tree handler
- * @param ps The page-sequence the provider operates on
- */
- public PageProvider(AreaTreeHandler ath, PageSequence ps) {
- this.areaTreeHandler = ath;
- this.pageSeq = ps;
- this.startPageOfPageSequence = ps.getStartingPageNumber();
- }
-
- /**
- * The page breaker notifies the provider about the page number an element list starts
- * on so it can later retrieve PageViewports relative to this first page.
- * @param startPage the number of the first page for the element list.
- * @param startColumn the starting column number for the element list.
- */
- public void setStartOfNextElementList(int startPage, int startColumn) {
- log.debug("start of the next element list is:"
- + " page=" + startPage + " col=" + startColumn);
- this.startPageOfCurrentElementList = startPage - startPageOfPageSequence + 1;
- this.startColumnOfCurrentElementList = startColumn;
- //Reset Cache
- this.lastRequestedIndex = -1;
- this.lastReportedBPD = -1;
- }
-
- /**
- * Sets the index of the last page. This is done as soon as the position of the last page
- * is known or assumed.
- * @param index the index relative to the first page in the page-sequence
- */
- public void setLastPageIndex(int index) {
- this.lastPageIndex = index;
- }
-
- /**
- * Returns the available BPD for the part/page indicated by the index parameter.
- * The index is the part/page relative to the start of the current element list.
- * This method takes multiple columns into account.
- * @param index zero-based index of the requested part/page
- * @return the available BPD
- */
- public int getAvailableBPD(int index) {
- //Special optimization: There may be many equal calls by the BreakingAlgorithm
- if (this.lastRequestedIndex == index) {
- if (log.isTraceEnabled()) {
- log.trace("getAvailableBPD(" + index + ") -> (cached) " + lastReportedBPD);
- }
- return this.lastReportedBPD;
- }
- int c = index;
- int pageIndex = 0;
- int colIndex = startColumnOfCurrentElementList;
- Page page = getPage(
- false, pageIndex, RELTO_CURRENT_ELEMENT_LIST);
- while (c > 0) {
- colIndex++;
- if (colIndex >= page.getPageViewport().getCurrentSpan().getColumnCount()) {
- colIndex = 0;
- pageIndex++;
- page = getPage(
- false, pageIndex, RELTO_CURRENT_ELEMENT_LIST);
- }
- c--;
- }
- this.lastRequestedIndex = index;
- this.lastReportedBPD = page.getPageViewport().getBodyRegion().getRemainingBPD();
- if (log.isTraceEnabled()) {
- log.trace("getAvailableBPD(" + index + ") -> " + lastReportedBPD);
- }
- return this.lastReportedBPD;
- }
-
- // Wish there were a more elegant way to do this in Java
- private int[] getColIndexAndColCount(int index) {
- int columnCount = 0;
- int colIndex = startColumnOfCurrentElementList + index;
- int pageIndex = -1;
- do {
- colIndex -= columnCount;
- pageIndex++;
- Page page = getPage(false, pageIndex, RELTO_CURRENT_ELEMENT_LIST);
- columnCount = page.getPageViewport().getCurrentSpan().getColumnCount();
- } while (colIndex >= columnCount);
- return new int[] {colIndex, columnCount};
- }
-
- /**
- * Compares the IPD of the given part with the following one.
- *
- * @param index index of the current part
- * @return a negative integer, zero or a positive integer as the current IPD is less
- * than, equal to or greater than the IPD of the following part
- */
- public int compareIPDs(int index) {
- int columnCount = 0;
- int colIndex = startColumnOfCurrentElementList + index;
- int pageIndex = -1;
- Page page;
- do {
- colIndex -= columnCount;
- pageIndex++;
- page = getPage(false, pageIndex, RELTO_CURRENT_ELEMENT_LIST);
- columnCount = page.getPageViewport().getCurrentSpan().getColumnCount();
- } while (colIndex >= columnCount);
- if (colIndex + 1 < columnCount) {
- // Next part is a column on same page => same IPD
- return 0;
- } else {
- Page nextPage = getPage(false, pageIndex + 1, RELTO_CURRENT_ELEMENT_LIST);
- return page.getPageViewport().getBodyRegion().getIPD()
- - nextPage.getPageViewport().getBodyRegion().getIPD();
- }
- }
-
- /**
- * Checks if a break at the passed index would start a new page
- * @param index the index of the element before the break
- * @return {@code true} if the break starts a new page
- */
- boolean startPage(int index) {
- return getColIndexAndColCount(index)[0] == 0;
- }
-
- /**
- * Checks if a break at the passed index would end a page
- * @param index the index of the element before the break
- * @return {@code true} if the break ends a page
- */
- boolean endPage(int index) {
- int[] colIndexAndColCount = getColIndexAndColCount(index);
- return colIndexAndColCount[0] == colIndexAndColCount[1] - 1;
- }
-
- /**
- * Obtain the applicable column-count for the element at the
- * passed index
- * @param index the index of the element
- * @return the number of columns
- */
- int getColumnCount(int index) {
- return getColIndexAndColCount(index)[1];
- }
-
- /**
- * Returns the part index (0<x<partCount) which denotes the first part on the last page
- * generated by the current element list.
- * @param partCount Number of parts determined by the breaking algorithm
- * @return the requested part index
- */
- public int getStartingPartIndexForLastPage(int partCount) {
- int result = 0;
- int idx = 0;
- int pageIndex = 0;
- int colIndex = startColumnOfCurrentElementList;
- Page page = getPage(
- false, pageIndex, RELTO_CURRENT_ELEMENT_LIST);
- while (idx < partCount) {
- if ((colIndex >= page.getPageViewport().getCurrentSpan().getColumnCount())) {
- colIndex = 0;
- pageIndex++;
- page = getPage(
- false, pageIndex, RELTO_CURRENT_ELEMENT_LIST);
- result = idx;
- }
- colIndex++;
- idx++;
- }
- return result;
- }
-
- /**
- * Returns a Page.
- * @param isBlank true if this page is supposed to be blank.
- * @param index Index of the page (see relativeTo)
- * @param relativeTo Defines which value the index parameter should be evaluated relative
- * to. (One of PageProvider.RELTO_*)
- * @return the requested Page
- */
- public Page getPage(boolean isBlank, int index, int relativeTo) {
- if (relativeTo == RELTO_PAGE_SEQUENCE) {
- return getPage(isBlank, index);
- } else if (relativeTo == RELTO_CURRENT_ELEMENT_LIST) {
- int effIndex = startPageOfCurrentElementList + index;
- effIndex += startPageOfPageSequence - 1;
- return getPage(isBlank, effIndex);
- } else {
- throw new IllegalArgumentException(
- "Illegal value for relativeTo: " + relativeTo);
- }
- }
-
- /**
- * Returns a Page.
- * @param isBlank true if the Page should be a blank one
- * @param index the Page's index
- * @return a Page instance
- */
- protected Page getPage(boolean isBlank, int index) {
- boolean isLastPage = (lastPageIndex >= 0) && (index == lastPageIndex);
- if (log.isTraceEnabled()) {
- log.trace("getPage(" + index + " " + (isBlank ? "blank" : "non-blank")
- + (isLastPage ? " <LAST>" : "") + ")");
- }
- int intIndex = index - startPageOfPageSequence;
- if (log.isTraceEnabled()) {
- if (isBlank) {
- log.trace("blank page requested: " + index);
- }
- if (isLastPage) {
- log.trace("last page requested: " + index);
- }
- }
- while (intIndex >= cachedPages.size()) {
- if (log.isTraceEnabled()) {
- log.trace("Caching " + index);
- }
- cacheNextPage(index, isBlank, isLastPage);
- }
- Page page = (Page)cachedPages.get(intIndex);
- boolean replace = false;
- if (page.getPageViewport().isBlank() != isBlank) {
- log.debug("blank condition doesn't match. Replacing PageViewport.");
- replace = true;
- }
- if ((isLastPage && indexOfCachedLastPage != intIndex)
- || (!isLastPage && indexOfCachedLastPage >= 0)) {
- log.debug("last page condition doesn't match. Replacing PageViewport.");
- replace = true;
- indexOfCachedLastPage = (isLastPage ? intIndex : -1);
- }
- if (replace) {
- discardCacheStartingWith(intIndex);
- page = cacheNextPage(index, isBlank, isLastPage);
- }
- return page;
- }
-
- private void discardCacheStartingWith(int index) {
- while (index < cachedPages.size()) {
- this.cachedPages.remove(cachedPages.size() - 1);
- if (!pageSeq.goToPreviousSimplePageMaster()) {
- log.warn("goToPreviousSimplePageMaster() on the first page called!");
- }
- }
- }
-
- private Page cacheNextPage(int index, boolean isBlank, boolean isLastPage) {
- String pageNumberString = pageSeq.makeFormattedPageNumber(index);
- boolean isFirstPage = (startPageOfPageSequence == index);
- SimplePageMaster spm = pageSeq.getNextSimplePageMaster(
- index, isFirstPage, isLastPage, isBlank);
-
- Region body = spm.getRegion(FO_REGION_BODY);
- if (!pageSeq.getMainFlow().getFlowName().equals(body.getRegionName())) {
- // this is fine by the XSL Rec (fo:flow's flow-name can be mapped to
- // any region), but we don't support it yet.
- BlockLevelEventProducer eventProducer = BlockLevelEventProducer.Provider.get(
- pageSeq.getUserAgent().getEventBroadcaster());
- eventProducer.flowNotMappingToRegionBody(this,
- pageSeq.getMainFlow().getFlowName(), spm.getMasterName(), spm.getLocator());
- }
- Page page = new Page(spm, index, pageNumberString, isBlank);
- //Set unique key obtained from the AreaTreeHandler
- page.getPageViewport().setKey(areaTreeHandler.generatePageViewportKey());
- page.getPageViewport().setForeignAttributes(spm.getForeignAttributes());
- cachedPages.add(page);
- return page;
- }
-
- }
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