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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 java.util.ListIterator;
-
- import org.apache.fop.traits.MinOptMax;
- import org.apache.fop.util.ListUtil;
-
- /**
- * Utilities for Knuth element lists.
- */
- public final class ElementListUtils {
-
- private ElementListUtils() {
- // Utility class.
- }
-
- /**
- * Removes legal breaks in an element list. A constraint can be specified to limit the
- * range in which the breaks are removed. Legal breaks occuring before at least
- * constraint.opt space is filled will be removed.
- * @param elements the element list
- * @param constraint min/opt/max value to restrict the range in which the breaks are removed.
- * @return true if the opt constraint is bigger than the list contents
- */
- public static boolean removeLegalBreaks(List elements, MinOptMax constraint) {
- return removeLegalBreaks(elements, constraint.opt);
- }
-
- /**
- * Removes legal breaks in an element list. A constraint can be specified to limit the
- * range in which the breaks are removed. Legal breaks occuring before at least
- * constraint space is filled will be removed.
- * @param elements the element list
- * @param constraint value to restrict the range in which the breaks are removed.
- * @return true if the constraint is bigger than the list contents
- */
- public static boolean removeLegalBreaks(List elements, int constraint) {
- int len = 0;
- ListIterator iter = elements.listIterator();
- while (iter.hasNext()) {
- ListElement el = (ListElement)iter.next();
- if (el.isPenalty()) {
- KnuthPenalty penalty = (KnuthPenalty)el;
- //Convert all penalties to break inhibitors
- if (penalty.getPenalty() < KnuthPenalty.INFINITE) {
- iter.set(new KnuthPenalty(penalty.getWidth(), KnuthPenalty.INFINITE,
- penalty.isPenaltyFlagged(), penalty.getPosition(),
- penalty.isAuxiliary()));
- }
- } else if (el.isGlue()) {
- KnuthGlue glue = (KnuthGlue)el;
- len += glue.getWidth();
- iter.previous();
- el = (ListElement)iter.previous();
- iter.next();
- if (el.isBox()) {
- iter.add(new KnuthPenalty(0, KnuthPenalty.INFINITE, false,
- null, false));
- }
- iter.next();
- } else if (el instanceof BreakElement) {
- BreakElement breakEl = (BreakElement)el;
- if (breakEl.getPenaltyValue() < KnuthPenalty.INFINITE) {
- breakEl.setPenaltyValue(KnuthPenalty.INFINITE);
- }
- } else {
- KnuthElement kel = (KnuthElement)el;
- len += kel.getWidth();
- }
- if (len >= constraint) {
- return false;
- }
- }
- return true;
- }
-
- /**
- * Removes legal breaks in an element list. A constraint can be specified to limit the
- * range in which the breaks are removed. Legal breaks within the space specified through the
- * constraint (starting from the end of the element list) will be removed.
- * @param elements the element list
- * @param constraint value to restrict the range in which the breaks are removed.
- * @return true if the constraint is bigger than the list contents
- */
- public static boolean removeLegalBreaksFromEnd(List elements, int constraint) {
- int len = 0;
- ListIterator i = elements.listIterator(elements.size());
- while (i.hasPrevious()) {
- ListElement el = (ListElement)i.previous();
- if (el.isPenalty()) {
- KnuthPenalty penalty = (KnuthPenalty)el;
- //Convert all penalties to break inhibitors
- if (penalty.getPenalty() < KnuthPenalty.INFINITE) {
- i.set(new KnuthPenalty(penalty.getWidth(), KnuthPenalty.INFINITE,
- penalty.isPenaltyFlagged(), penalty.getPosition(),
- penalty.isAuxiliary()));
- }
- } else if (el.isGlue()) {
- KnuthGlue glue = (KnuthGlue)el;
- len += glue.getWidth();
- el = (ListElement)i.previous();
- i.next();
- if (el.isBox()) {
- i.add(new KnuthPenalty(0, KnuthPenalty.INFINITE, false,
- null, false));
- }
- } else if (el.isUnresolvedElement()) {
- if (el instanceof BreakElement) {
- BreakElement breakEl = (BreakElement)el;
- if (breakEl.getPenaltyValue() < KnuthPenalty.INFINITE) {
- breakEl.setPenaltyValue(KnuthPenalty.INFINITE);
- }
- } else if (el instanceof UnresolvedListElementWithLength) {
- UnresolvedListElementWithLength uel = (UnresolvedListElementWithLength)el;
- len += uel.getLength().opt;
- }
- } else {
- KnuthElement kel = (KnuthElement)el;
- len += kel.getWidth();
- }
- if (len >= constraint) {
- return false;
- }
- }
- return true;
- }
-
- /**
- * Calculates the content length of the given element list. Warning: It doesn't take any
- * stretch and shrink possibilities into account.
- * @param elems the element list
- * @param start element at which to start
- * @param end element at which to stop
- * @return the content length
- */
- public static int calcContentLength(List elems, int start, int end) {
- ListIterator iter = elems.listIterator(start);
- int count = end - start + 1;
- int len = 0;
- while (iter.hasNext()) {
- ListElement el = (ListElement)iter.next();
- if (el.isBox()) {
- len += ((KnuthElement)el).getWidth();
- } else if (el.isGlue()) {
- len += ((KnuthElement)el).getWidth();
- } else {
- //log.debug("Ignoring penalty: " + el);
- //ignore penalties
- }
- count--;
- if (count == 0) {
- break;
- }
- }
- return len;
- }
-
- /**
- * Calculates the content length of the given element list. Warning: It doesn't take any
- * stretch and shrink possibilities into account.
- * @param elems the element list
- * @return the content length
- */
- public static int calcContentLength(List elems) {
- return calcContentLength(elems, 0, elems.size() - 1);
- }
-
- /**
- * Indicates whether the given element list ends with a forced break.
- * @param elems the element list
- * @return true if the list ends with a forced break
- */
- public static boolean endsWithForcedBreak(List elems) {
- ListElement last = (ListElement) ListUtil.getLast(elems);
- return last.isForcedBreak();
- }
-
- /**
- * Indicates whether the given element list starts with a forced break.
- * @param elems the element list
- * @return true if the list starts with a forced break
- */
- public static boolean startsWithForcedBreak(List elems) {
- return !elems.isEmpty() && ((ListElement) elems.get(0)).isForcedBreak();
- }
-
- /**
- * Indicates whether the given element list ends with a penalty with a non-infinite penalty
- * value.
- * @param elems the element list
- * @return true if the list ends with a non-infinite penalty
- */
- public static boolean endsWithNonInfinitePenalty(List elems) {
- ListElement last = (ListElement) ListUtil.getLast(elems);
- if (last.isPenalty() && ((KnuthPenalty)last).getPenalty() < KnuthElement.INFINITE) {
- return true;
- } else if (last instanceof BreakElement
- && ((BreakElement)last).getPenaltyValue() < KnuthElement.INFINITE) {
- return true;
- }
- return false;
- }
-
- /**
- * Determines the position of the previous break before the start index on an
- * element list.
- * @param elems the element list
- * @param startIndex the start index
- * @return the position of the previous break, or -1 if there was no previous break
- */
- public static int determinePreviousBreak(List elems, int startIndex) {
- int prevBreak = startIndex - 1;
- while (prevBreak >= 0) {
- KnuthElement el = (KnuthElement)elems.get(prevBreak);
- if (el.isPenalty() && el.getPenalty() < KnuthElement.INFINITE) {
- break;
- }
- prevBreak--;
- }
- return prevBreak;
- }
-
- }
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