All Downloads are FREE. Search and download functionalities are using the official Maven repository.

org.apache.fop.layoutmgr.BreakingAlgorithm Maven / Gradle / Ivy

There is a newer version: 1.2.2.1-jre17
Show newest version
/*
 * 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: BreakingAlgorithm.java 1805173 2017-08-16 10:50:04Z ssteiner $ */

package org.apache.fop.layoutmgr;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.apache.fop.fo.Constants;

/**
 * The set of nodes is sorted into lines indexed into activeLines.
 * The nodes in each line are linked together in a single linked list by the
 * {@link KnuthNode#next} field. The activeLines array contains a link to the head of
 * the linked list in index 'line*2' and a link to the tail at index 'line*2+1'.
 * 

* The set of active nodes can be traversed by *

 * for (int line = startLine; line < endLine; line++) {
 *     for (KnuthNode node = getNode(line); node != null; node = node.next) {
 *         // Do something with 'node'
 *     }
 * }
 * 
*/ public abstract class BreakingAlgorithm { /** the logger for the class */ protected static final Log log = LogFactory.getLog(BreakingAlgorithm.class); /** Maximum adjustment ration */ protected static final int INFINITE_RATIO = 1000; private static final int MAX_RECOVERY_ATTEMPTS = 5; // constants identifying a subset of the feasible breaks /** All feasible breaks are ok. */ public static final int ALL_BREAKS = 0; /** This forbids hyphenation. */ public static final int NO_FLAGGED_PENALTIES = 1; /** wrap-option = "no-wrap". */ public static final int ONLY_FORCED_BREAKS = 2; /** Holder for symbolic literals for the fitness classes */ static final class FitnessClasses { private FitnessClasses() { } static final int VERY_TIGHT = 0; static final int TIGHT = 1; static final int LOOSE = 2; static final int VERY_LOOSE = 3; static final String[] NAMES = { "VERY TIGHT", "TIGHT", "LOOSE", "VERY LOOSE" }; /** * Figure out the fitness class of this line (tight, loose, * very tight or very loose). * See the section on "More Bells and Whistles" in Knuth's * "Breaking Paragraphs Into Lines". * * @param adjustRatio the adjustment ratio * @return the fitness class */ static int computeFitness(double adjustRatio) { if (adjustRatio < -0.5) { return FitnessClasses.VERY_TIGHT; } else if (adjustRatio <= 0.5) { return FitnessClasses.TIGHT; } else if (adjustRatio <= 1.0) { return FitnessClasses.LOOSE; } else { return FitnessClasses.VERY_LOOSE; } } } // parameters of Knuth's algorithm: /** Demerit for consecutive lines ending at flagged penalties. */ protected int repeatedFlaggedDemerit = KnuthPenalty.FLAGGED_PENALTY; /** Demerit for consecutive lines belonging to incompatible fitness classes . */ protected int incompatibleFitnessDemerit = KnuthPenalty.FLAGGED_PENALTY; /** Maximum number of consecutive lines ending with a flagged penalty. * Only a value >= 1 is a significant limit. */ protected int maxFlaggedPenaltiesCount; /** * The threshold for considering breaks to be acceptable. The adjustment ratio must be * inferior to this threshold. */ private double threshold; /** * The paragraph of KnuthElements. */ protected KnuthSequence par; /** * The width of a line (or height of a column in page-breaking mode). * -1 indicates that the line widths are different for each line. */ protected int lineWidth = -1; /** Force the algorithm to find a set of breakpoints, even if no feasible breakpoints * exist. */ private boolean force; /** If set to true, doesn't ignore break possibilities which are definitely too short. */ protected boolean considerTooShort; /** When in forced mode, the best node leading to a too long line. The line will be * too long anyway, but this one will lead to a paragraph with fewest demerits. */ private KnuthNode lastTooLong; /** When in forced mode, the best node leading to a too short line. The line will be * too short anyway, but this one will lead to a paragraph with fewest demerits. */ private KnuthNode lastTooShort; /** The node to be reactivated if no set of feasible breakpoints can be found for this * paragraph. */ private KnuthNode lastDeactivated; /** Alignment of the paragraph/page. One of EN_START, EN_JUSTIFY, etc. */ protected int alignment; /** Alignment of the paragraph's last line. */ protected int alignmentLast; /** Used to handle the text-indent property (indent the first line of a paragraph). */ protected boolean indentFirstPart; /** * The set of active nodes in ascending line order. For each line l, activeLines[2l] contains a * link to l's first active node, and activeLines[2l+1] a link to l's last active node. The * line number l corresponds to the number of the line ending at the node's breakpoint. */ protected KnuthNode[] activeLines; /** * The number of active nodes. */ protected int activeNodeCount; /** * The lowest available line in the set of active nodes. */ protected int startLine; /** * The highest + 1 available line in the set of active nodes. */ protected int endLine; /** * The total width of all elements handled so far. */ protected int totalWidth; /** * The total stretch of all elements handled so far. */ protected int totalStretch; /** * The total shrink of all elements handled so far. */ protected int totalShrink; /** * Best records. */ protected BestRecords best; private boolean partOverflowRecoveryActivated = true; private KnuthNode lastRecovered; /** * Create a new instance. * * @param align alignment of the paragraph/page. One of {@link Constants#EN_START}, * {@link Constants#EN_JUSTIFY}, {@link Constants#EN_CENTER}, * {@link Constants#EN_END}. * For pages, {@link Constants#EN_BEFORE} and {@link Constants#EN_AFTER} * are mapped to the corresponding inline properties, * {@link Constants#EN_START} and {@link Constants#EN_END}. * @param alignLast alignment of the paragraph's last line * @param first for the text-indent property ({@code true} if the first line * of a paragraph should be indented) * @param partOverflowRecovery {@code true} if too long elements should be moved to * the next line/part * @param maxFlagCount maximum allowed number of consecutive lines ending at a flagged penalty * item */ public BreakingAlgorithm(int align, int alignLast, boolean first, boolean partOverflowRecovery, int maxFlagCount) { this.alignment = align; this.alignmentLast = alignLast; this.indentFirstPart = first; this.partOverflowRecoveryActivated = partOverflowRecovery; this.best = new BestRecords(); this.maxFlaggedPenaltiesCount = maxFlagCount; } /** * Class recording all the informations of a feasible breaking point. */ public class KnuthNode { /** index of the breakpoint represented by this node */ public final int position; /** number of the line ending at this breakpoint */ public final int line; /** fitness class of the line ending at this breakpoint. One of 0, 1, 2, 3. */ public final int fitness; /** accumulated width of the KnuthElements up to after this breakpoint. */ public final int totalWidth; /** accumulated stretchability of the KnuthElements up to after this breakpoint. */ public final int totalStretch; /** accumulated shrinkability of the KnuthElements up to after this breakpoint. */ public final int totalShrink; /** adjustment ratio if the line ends at this breakpoint */ public final double adjustRatio; /** available stretch of the line ending at this breakpoint */ public final int availableShrink; /** available shrink of the line ending at this breakpoint */ public final int availableStretch; /** difference between target and actual line width */ public final int difference; /** minimum total demerits up to this breakpoint */ public double totalDemerits; /** best node for the preceding breakpoint */ public KnuthNode previous; /** next possible node in the same line */ public KnuthNode next; /** * Holds the number of subsequent recovery attempty that are made to get content fit * into a line. */ public int fitRecoveryCounter; /** * Construct node. * @param position an integer * @param line an integer * @param fitness an integer * @param totalWidth an integer * @param totalStretch an integer * @param totalShrink an integer * @param adjustRatio a real number * @param availableShrink an integer * @param availableStretch an integer * @param difference an integer * @param totalDemerits a real number * @param previous a node */ public KnuthNode(int position, int line, int fitness, int totalWidth, int totalStretch, int totalShrink, double adjustRatio, int availableShrink, int availableStretch, int difference, double totalDemerits, KnuthNode previous) { this.position = position; this.line = line; this.fitness = fitness; this.totalWidth = totalWidth; this.totalStretch = totalStretch; this.totalShrink = totalShrink; this.adjustRatio = adjustRatio; this.availableShrink = availableShrink; this.availableStretch = availableStretch; this.difference = difference; this.totalDemerits = totalDemerits; this.previous = previous; } /** {@inheritDoc} */ public String toString() { return ""; } } /** Class that stores, for each fitness class, the best active node that could start * a line of the corresponding fitness ending at the current element. */ protected class BestRecords { private static final double INFINITE_DEMERITS = Double.POSITIVE_INFINITY; private final double[] bestDemerits = new double[4]; private final KnuthNode[] bestNode = new KnuthNode[4]; private final double[] bestAdjust = new double[4]; private final int[] bestDifference = new int[4]; private final int[] bestAvailableShrink = new int[4]; private final int[] bestAvailableStretch = new int[4]; /** Points to the fitness class which currently leads to the best demerits. */ private int bestIndex = -1; /** default constructor */ public BestRecords() { reset(); } /** Registers the new best active node for the given fitness class. * @param demerits the total demerits of the new optimal set of breakpoints * @param node the node starting the line ending at the current element * @param adjust adjustment ratio of the current line * @param availableShrink how much the current line can be shrinked * @param availableStretch how much the current line can be stretched * @param difference difference between the width of the considered line and the * width of the "real" line * @param fitness fitness class of the current line */ public void addRecord(double demerits, KnuthNode node, double adjust, int availableShrink, int availableStretch, int difference, int fitness) { if (demerits > bestDemerits[fitness]) { log.error("New demerits value greater than the old one"); } bestDemerits[fitness] = demerits; bestNode[fitness] = node; bestAdjust[fitness] = adjust; bestAvailableShrink[fitness] = availableShrink; bestAvailableStretch[fitness] = availableStretch; bestDifference[fitness] = difference; if (bestIndex == -1 || demerits < bestDemerits[bestIndex]) { bestIndex = fitness; } } /** @return true if has records (best index not -1) */ public boolean hasRecords() { return (bestIndex != -1); } /** * @param fitness fitness class (0, 1, 2 or 3, i.e. "tight" to "very loose") * @return true if there is a set of feasible breakpoints registered for the * given fitness. */ public boolean notInfiniteDemerits(int fitness) { return (bestDemerits[fitness] != INFINITE_DEMERITS); } /** * @param fitness to use * @return best demerits */ public double getDemerits(int fitness) { return bestDemerits[fitness]; } /** * @param fitness to use * @return best node */ public KnuthNode getNode(int fitness) { return bestNode[fitness]; } /** * @param fitness to use * @return adjustment */ public double getAdjust(int fitness) { return bestAdjust[fitness]; } /** * @param fitness to use * @return available shrink */ public int getAvailableShrink(int fitness) { return bestAvailableShrink[fitness]; } /** * @param fitness to use * @return available stretch */ public int getAvailableStretch(int fitness) { return bestAvailableStretch[fitness]; } /** * @param fitness to use * @return difference */ public int getDifference(int fitness) { return bestDifference[fitness]; } /** @return minimum demerits */ public double getMinDemerits() { if (bestIndex != -1) { return getDemerits(bestIndex); } else { // anyway, this should never happen return INFINITE_DEMERITS; } } /** Reset when a new breakpoint is being considered. */ public void reset() { for (int i = 0; i < 4; i++) { bestDemerits[i] = INFINITE_DEMERITS; // there is no need to reset the other arrays } bestIndex = -1; } } /** * @return the number of times the algorithm should try to move overflowing content to the * next line/page. */ protected int getMaxRecoveryAttempts() { return MAX_RECOVERY_ATTEMPTS; } /** * Controls the behaviour of the algorithm in cases where the first element of a part * overflows a line/page. * @return true if the algorithm should try to send the element to the next line/page. */ protected boolean isPartOverflowRecoveryActivated() { return this.partOverflowRecoveryActivated; } protected KnuthNode getLastTooLong() { return lastTooLong; } /** * Empty method, hook for subclasses. Called before determining the optimal * breakpoints corresponding to a given active node. * @param total number of lines for the active node * @param demerits total demerits of the paragraph for the active node */ public abstract void updateData1(int total, double demerits); /** * Empty method, hook for subclasses. Called when determining the optimal breakpoints * for a given active node. * @param bestActiveNode a node in the chain of best active nodes, corresponding to * one of the optimal breakpoints * @param sequence the corresponding paragraph * @param total the number of lines into which the paragraph will be broken */ public abstract void updateData2(KnuthNode bestActiveNode, KnuthSequence sequence, int total); /** @param lineWidth the line width */ public void setConstantLineWidth(int lineWidth) { this.lineWidth = lineWidth; } /** * @param par the paragraph to break * @param threshold upper bound of the adjustment ratio * @param force {@code true} if a set of breakpoints must be found, even * if there are no feasible ones * @param allowedBreaks the type(s) of breaks allowed. One of {@link #ONLY_FORCED_BREAKS}, * {@link #NO_FLAGGED_PENALTIES} or {@link #ALL_BREAKS}. * * @return the number of effective breaks * @see #findBreakingPoints(KnuthSequence, int, double, boolean, int) */ public int findBreakingPoints(KnuthSequence par, double threshold, boolean force, int allowedBreaks) { return findBreakingPoints(par, 0, threshold, force, allowedBreaks); } /** * Finds an optimal set of breakpoints for the given paragraph. * * @param par the paragraph to break * @param startIndex index of the Knuth element at which the breaking must start * @param threshold upper bound of the adjustment ratio * @param force {@code true} if a set of breakpoints must be found, even * if there are no feasible ones * @param allowedBreaks the type(s) of breaks allowed. One of {@link #ONLY_FORCED_BREAKS}, * {@link #NO_FLAGGED_PENALTIES} or {@link #ALL_BREAKS}. * * @return the number of effective breaks */ public int findBreakingPoints(KnuthSequence par, int startIndex, double threshold, boolean force, int allowedBreaks) { this.par = par; this.threshold = threshold; this.force = force; // initialize the algorithm initialize(); // previous element in the paragraph is a KnuthBox? boolean previousIsBox = false; // index of the first KnuthBox in the sequence, in case of non-centered // alignment. For centered alignment, we need to take into account preceding // penalties+glues used for the filler spaces int previousPosition = startIndex; if (alignment != Constants.EN_CENTER) { int firstBoxIndex = par.getFirstBoxIndex(startIndex); previousPosition = (firstBoxIndex >= par.size()) ? startIndex : firstBoxIndex - 1; } previousPosition = (previousPosition < 0) ? 0 : previousPosition; // create an active node representing the starting point addNode(0, createNode(previousPosition, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, null)); KnuthNode lastForced = getNode(0); if (log.isTraceEnabled()) { log.trace("Looping over " + (par.size() - startIndex) + " elements"); log.trace(par); } // main loop for (int elementIndex = startIndex; elementIndex < par.size(); elementIndex++) { previousIsBox = handleElementAt( elementIndex, previousIsBox, allowedBreaks).isBox(); if (activeNodeCount == 0) { if (handlingFloat()) { return handleFloat(); } if (getIPDdifference() != 0) { return handleIpdChange(); } if (!force) { log.debug("Could not find a set of breaking points " + threshold); return 0; } // lastDeactivated was a "good" break, while lastTooShort and lastTooLong // were "bad" breaks since the beginning; // if it is not the node we just restarted from, lastDeactivated can // replace either lastTooShort or lastTooLong if (lastDeactivated != null && lastDeactivated != lastForced) { replaceLastDeactivated(); } if (lastTooShort == null || lastForced.position == lastTooShort.position) { lastForced = recoverFromOverflow(); } else { lastForced = lastTooShort; this.lastRecovered = null; } elementIndex = restartFrom(lastForced, elementIndex); } } finish(); // there is at least one set of breaking points // select one or more active nodes, removing the others from the list int line = filterActiveNodes(); // for each active node, create a set of breaking points for (int i = startLine; i < endLine; i++) { for (KnuthNode node = getNode(i); node != null; node = node.next) { updateData1(node.line, node.totalDemerits); calculateBreakPoints(node, par, node.line); } } activeLines = null; return line; } /** * obtain ipd difference * @return an integer */ protected int getIPDdifference() { return 0; } /** * handle ipd change * @return an integer */ protected int handleIpdChange() { throw new IllegalStateException(); } /** * Recover from a {@link KnuthNode} leading to a line that is too long. * The default implementation creates a new node corresponding to a break * point after the previous node that led to a line that was too short. * * @param lastTooLong the node that leads to a "too long" line * @return node corresponding to a breakpoint after the previous "too short" line */ protected KnuthNode recoverFromTooLong(KnuthNode lastTooLong) { if (log.isDebugEnabled()) { log.debug("Recovering from too long: " + lastTooLong); } // if lastTooLong would be the very first break in the blockList, and // the first element in the paragraph is not a penalty, add an auxiliary // penalty now to make it possible to create a genuine 'empty' node that // represents a break before the first box/glue if (lastTooLong.previous.previous == null) { ListElement el = (ListElement)this.par.get(0); if (!el.isPenalty()) { this.par.add(0, KnuthPenalty.DUMMY_ZERO_PENALTY); } } // content would overflow, insert empty line/page and try again return createNode( lastTooLong.previous.position, lastTooLong.previous.line + 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, lastTooLong.previous); } /** Initializes the algorithm's variables. */ protected void initialize() { this.totalWidth = 0; this.totalStretch = 0; this.totalShrink = 0; this.lastTooShort = null; this.lastTooLong = null; this.startLine = 0; this.endLine = 0; this.activeLines = new KnuthNode[20]; } /** * Creates a new active node for a feasible breakpoint at the given position. Only * called in forced mode. * * @param position index of the element in the Knuth sequence * @param line number of the line ending at the breakpoint * @param fitness fitness class of the line ending at the breakpoint. One of 0, 1, 2, 3. * @param totalWidth accumulated width of the KnuthElements up to after the breakpoint * @param totalStretch accumulated stretchability of the KnuthElements up to after the * breakpoint * @param totalShrink accumulated shrinkability of the KnuthElements up to after the * breakpoint * @param adjustRatio adjustment ratio if the line ends at this breakpoint * @param availableShrink available stretch of the line ending at this breakpoint * @param availableStretch available shrink of the line ending at this breakpoint * @param difference difference between target and actual line width * @param totalDemerits minimum total demerits up to the breakpoint * @param previous active node for the preceding breakpoint * @return a new node */ protected KnuthNode createNode(int position, int line, int fitness, int totalWidth, int totalStretch, int totalShrink, double adjustRatio, int availableShrink, int availableStretch, int difference, double totalDemerits, KnuthNode previous) { return new KnuthNode(position, line, fitness, totalWidth, totalStretch, totalShrink, adjustRatio, availableShrink, availableStretch, difference, totalDemerits, previous); } /** Creates a new active node for a break from the best active node of the given * fitness class to the element at the given position. * @param position index of the element in the Knuth sequence * @param line number of the line ending at the breakpoint * @param fitness fitness class of the line ending at the breakpoint. One of 0, 1, 2, 3. * @param totalWidth accumulated width of the KnuthElements up to after the breakpoint * @param totalStretch accumulated stretchability of the KnuthElements up to after the * breakpoint * @param totalShrink accumulated shrinkability of the KnuthElements up to after the * breakpoint * @return a new node * @see #createNode(int, int, int, int, int, int, double, int, int, int, double, * org.apache.fop.layoutmgr.BreakingAlgorithm.KnuthNode) * @see BreakingAlgorithm.BestRecords */ protected KnuthNode createNode(int position, int line, int fitness, int totalWidth, int totalStretch, int totalShrink) { return new KnuthNode(position, line, fitness, totalWidth, totalStretch, totalShrink, best.getAdjust(fitness), best.getAvailableShrink(fitness), best.getAvailableStretch(fitness), best.getDifference(fitness), best.getDemerits(fitness), best.getNode(fitness)); } /** * Return the last node that yielded a too short line. * @return the node corresponding to the last too short line */ protected final KnuthNode getLastTooShort() { return this.lastTooShort; } /** * Generic handler for a {@link KnuthElement} at the given {@code position}, * taking into account whether the preceding element was a box, and which * type(s) of breaks are allowed. * Non-overridable. This method simply serves to route the call to one of the * more specific handlers ({@link #handleBox(KnuthBox)}, * {@link #handleGlueAt(KnuthGlue,int,boolean,int)} or * {@link #handlePenaltyAt(KnuthPenalty,int,int)}. The specialized handlers * can be overridden by subclasses to add to or modify the default behavior * for the different types of elements. * * @param position the position index of the element in the paragraph * @param previousIsBox {@code true} if the previous element is a box * @param allowedBreaks the type(s) of breaks allowed; should be one * of {@link #ALL_BREAKS}, {@link #NO_FLAGGED_PENALTIES} * or {@link #ONLY_FORCED_BREAKS} * @return the handled element */ protected final KnuthElement handleElementAt(int position, boolean previousIsBox, int allowedBreaks) { KnuthElement element = getElement(position); if (element.isBox()) { handleBox((KnuthBox) element); } else if (element.isGlue()) { handleGlueAt((KnuthGlue) element, position, previousIsBox, allowedBreaks); } else if (element.isPenalty()) { handlePenaltyAt((KnuthPenalty) element, position, allowedBreaks); } else { throw new IllegalArgumentException( "Unknown KnuthElement type: expecting KnuthBox, KnuthGlue or KnuthPenalty"); } return element; } /** * Handle a {@link KnuthBox}. *
Note: default implementation just adds the box's width * to the total content width. Subclasses that do not keep track * of this themselves, but override this method, should remember * to call {@code super.handleBox(box)} to avoid unwanted side-effects. * * @param box the {@link KnuthBox} to handle */ protected void handleBox(KnuthBox box) { // a KnuthBox object is not a legal line break, // just add the width to the total totalWidth += box.getWidth(); } /** * Handle a {@link KnuthGlue} at the given position, * taking into account the additional parameters. * * @param glue the {@link KnuthGlue} to handle * @param position the position of the glue in the list * @param previousIsBox {@code true} if the preceding element is a box * @param allowedBreaks the type of breaks that are allowed */ protected void handleGlueAt(KnuthGlue glue, int position, boolean previousIsBox, int allowedBreaks) { // a KnuthGlue object is a legal line break // only if the previous object is a KnuthBox // consider these glues according to the value of allowedBreaks if (previousIsBox && !(allowedBreaks == ONLY_FORCED_BREAKS)) { considerLegalBreak(glue, position); } totalWidth += glue.getWidth(); totalStretch += glue.getStretch(); totalShrink += glue.getShrink(); } /** * Handle a {@link KnuthPenalty} at the given position, * taking into account the type of breaks allowed. * * @param penalty the {@link KnuthPenalty} to handle * @param position the position of the penalty in the list * @param allowedBreaks the type of breaks that are allowed */ protected void handlePenaltyAt(KnuthPenalty penalty, int position, int allowedBreaks) { // a KnuthPenalty is a legal line break // only if its penalty is not infinite; // consider all penalties, non-flagged penalties or non-forcing penalties // according to the value of allowedBreaks if (((penalty.getPenalty() < KnuthElement.INFINITE) && (!(allowedBreaks == NO_FLAGGED_PENALTIES) || !penalty.isPenaltyFlagged()) && (!(allowedBreaks == ONLY_FORCED_BREAKS) || penalty.isForcedBreak()))) { considerLegalBreak(penalty, position); } } /** * Replace the last too-long or too-short node by the last deactivated * node, if applicable. */ protected final void replaceLastDeactivated() { if (lastDeactivated.adjustRatio > 0) { //last deactivated was too short lastTooShort = lastDeactivated; } else { //last deactivated was too long or exactly the right width lastTooLong = lastDeactivated; } } /** * Recover from an overflow condition. * * @return the new {@code lastForced} node */ protected KnuthNode recoverFromOverflow() { KnuthNode lastForced; if (isPartOverflowRecoveryActivated()) { if (lastRecovered == null) { lastRecovered = lastTooLong; if (log.isDebugEnabled()) { log.debug("Recovery point: " + lastRecovered); } } KnuthNode node = recoverFromTooLong(lastTooLong); lastForced = node; node.fitRecoveryCounter = lastTooLong.previous.fitRecoveryCounter + 1; if (log.isDebugEnabled()) { log.debug("first part doesn't fit into line, recovering: " + node.fitRecoveryCounter); } if (node.fitRecoveryCounter > getMaxRecoveryAttempts()) { while (lastForced.fitRecoveryCounter > 0 && lastForced.previous != null) { lastForced = lastForced.previous; lastDeactivated = lastForced.previous; } lastForced = lastRecovered; lastRecovered = null; startLine = lastForced.line; endLine = lastForced.line; log.debug("rolled back..."); } } else { lastForced = lastTooLong; } return lastForced; } /** * Restart from the given node at the given index. * * @param restartingNode the {@link KnuthNode} to restart from * @param currentIndex the current position index * @return the index of the restart point */ protected int restartFrom(KnuthNode restartingNode, int currentIndex) { if (log.isDebugEnabled()) { log.debug("Restarting at node " + restartingNode); } restartingNode.totalDemerits = 0; addNode(restartingNode.line, restartingNode); startLine = restartingNode.line; endLine = startLine + 1; totalWidth = restartingNode.totalWidth; totalStretch = restartingNode.totalStretch; totalShrink = restartingNode.totalShrink; lastTooShort = null; lastTooLong = null; // the width, stretch and shrink already include the width, // stretch and shrink of the suppressed glues; // advance in the sequence in order to avoid taking into account // these elements twice int restartingIndex = restartingNode.position; while (restartingIndex + 1 < par.size() && !(getElement(restartingIndex + 1).isBox())) { restartingIndex++; } return restartingIndex; } /** * Determines if the given breakpoint is a feasible breakpoint. That is, if a decent * line may be built between one of the currently active nodes and this breakpoint. * @param element the paragraph's element to consider * @param elementIdx the element's index inside the paragraph */ protected void considerLegalBreak(KnuthElement element, int elementIdx) { if (log.isTraceEnabled()) { log.trace("considerLegalBreak() at " + elementIdx + " (" + totalWidth + "+" + totalStretch + "-" + totalShrink + "), parts/lines: " + startLine + "-" + endLine); log.trace("\tCurrent active node list: " + activeNodeCount + " " + this.toString("\t")); } lastDeactivated = null; lastTooLong = null; for (int line = startLine; line < endLine; line++) { for (KnuthNode node = getNode(line); node != null; node = node.next) { if (node.position == elementIdx) { continue; } int difference = computeDifference(node, element, elementIdx); if (!elementCanEndLine(element, endLine, difference)) { log.trace("Skipping legal break"); break; } double r = computeAdjustmentRatio(node, difference); int availableShrink = totalShrink - node.totalShrink; int availableStretch = totalStretch - node.totalStretch; if (log.isTraceEnabled()) { log.trace("\tr=" + r + " difference=" + difference); log.trace("\tline=" + line); } if (element.isForcedBreak() && handlingFloat()) { disableFloatHandling(); // so that we do not create a float edge position later } // The line would be too long. if (r < -1 || element.isForcedBreak() || handlingFloat()) { deactivateNode(node, line); } int fitnessClass = FitnessClasses.computeFitness(r); double demerits = computeDemerits(node, element, fitnessClass, r); // The line is within the available shrink and the threshold. if (r >= -1 && r <= threshold) { activateNode(node, difference, r, demerits, fitnessClass, availableShrink, availableStretch); } // The line is way too short/long, but we are in forcing mode, so a node is // calculated and stored in lastValidNode. if (force && (r <= -1 || r > threshold)) { forceNode(node, line, elementIdx, difference, r, demerits, fitnessClass, availableShrink, availableStretch); } } addBreaks(line, elementIdx); } } /** * Check if the given {@link KnuthElement} can end the line with the given * number. * @param element the element * @param line the line number * @param difference an integer * @return {@code true} if the element can end the line */ protected boolean elementCanEndLine(KnuthElement element, int line, int difference) { return (!element.isPenalty() || element.getPenalty() < KnuthElement.INFINITE); } /** * Force the given {@link KnuthNode}, and register it. * * @param node the node * @param line the line number * @param elementIdx the position index of the element * @param difference the difference between content-length and available width * @param r the adjustment ratio * @param demerits demerits produced by the node * @param fitnessClass the fitness class * @param availableShrink the available amount of shrink * @param availableStretch tha available amount of stretch */ protected void forceNode(KnuthNode node, int line, int elementIdx, int difference, double r, double demerits, int fitnessClass, int availableShrink, int availableStretch) { int newWidth = totalWidth; int newStretch = totalStretch; int newShrink = totalShrink; // add the width, stretch and shrink of glue elements after // the break // this does not affect the dimension of the line / page, only // the values stored in the node; these would be as if the break // was just before the next box element, thus ignoring glues and // penalties between the "real" break and the following box for (int i = elementIdx; i < par.size(); i++) { KnuthElement tempElement = getElement(i); if (tempElement.isBox()) { break; } else if (tempElement.isGlue()) { newWidth += tempElement.getWidth(); newStretch += tempElement.getStretch(); newShrink += tempElement.getShrink(); } else if (tempElement.isForcedBreak() && i != elementIdx) { break; } } createForcedNodes(node, line, elementIdx, difference, r, demerits, fitnessClass, availableShrink, availableStretch, newWidth, newStretch, newShrink); } protected void createForcedNodes(KnuthNode node, int line, int elementIdx, int difference, double r, double demerits, int fitnessClass, int availableShrink, int availableStretch, int newWidth, int newStretch, int newShrink) { if (r <= -1) { log.debug("Considering tooLong, demerits=" + demerits); if (lastTooLong == null || demerits < lastTooLong.totalDemerits) { lastTooLong = createNode(elementIdx, line + 1, fitnessClass, newWidth, newStretch, newShrink, r, availableShrink, availableStretch, difference, demerits, node); if (log.isTraceEnabled()) { log.trace("Picking tooLong " + lastTooLong); } } } else { if (lastTooShort == null || demerits <= lastTooShort.totalDemerits) { if (considerTooShort) { // consider possibilities which are too short best.addRecord(demerits, node, r, availableShrink, availableStretch, difference, fitnessClass); } lastTooShort = createNode(elementIdx, line + 1, fitnessClass, newWidth, newStretch, newShrink, r, availableShrink, availableStretch, difference, demerits, node); if (log.isTraceEnabled()) { log.trace("Picking tooShort " + lastTooShort); } } } } /** * Activate the given node. Will result in the given {@link KnuthNode} * being registered as a feasible breakpoint, if the {@code demerits} are better * than that of the best node registered for the given {@code fitnessClass}. * * @param node the node * @param difference the difference between content-length and available width * @param r the adjustment ratio * @param demerits demerits produced by the node * @param fitnessClass the fitness class * @param availableShrink the available amount of shrink * @param availableStretch the available amount of stretch */ protected void activateNode(KnuthNode node, int difference, double r, double demerits, int fitnessClass, int availableShrink, int availableStretch) { if (log.isTraceEnabled()) { log.trace("\tDemerits=" + demerits); log.trace("\tFitness class=" + FitnessClasses.NAMES[fitnessClass]); } if (demerits < best.getDemerits(fitnessClass)) { // updates best demerits data best.addRecord(demerits, node, r, availableShrink, availableStretch, difference, fitnessClass); lastTooShort = null; } } /** * Deactivate the given node * * @param node the node * @param line the line number */ protected void deactivateNode(KnuthNode node, int line) { // Deactivate node... if (log.isTraceEnabled()) { log.trace("Removing " + node); } removeNode(line, node); // ... and remember it, if it was a good candidate lastDeactivated = compareNodes(lastDeactivated, node); } /** * Adds new active nodes for breaks at the given element. * @param line number of the previous line; this element will end line number (line+1) * @param elementIdx the element's index */ private void addBreaks(int line, int elementIdx) { if (!best.hasRecords()) { return; } int newWidth = totalWidth; int newStretch = totalStretch; int newShrink = totalShrink; // add the width, stretch and shrink of glue elements after // the break // this does not affect the dimension of the line / page, only // the values stored in the node; these would be as if the break // was just before the next box element, thus ignoring glues and // penalties between the "real" break and the following box for (int i = elementIdx; i < par.size(); i++) { KnuthElement tempElement = getElement(i); if (tempElement.isBox()) { break; } else if (tempElement.isGlue()) { newWidth += tempElement.getWidth(); newStretch += tempElement.getStretch(); newShrink += tempElement.getShrink(); } else if (tempElement.isForcedBreak() && i != elementIdx) { break; } } // add nodes to the active nodes list double minimumDemerits = best.getMinDemerits() + incompatibleFitnessDemerit; for (int i = 0; i <= 3; i++) { if (best.notInfiniteDemerits(i) && best.getDemerits(i) <= minimumDemerits) { // the nodes in activeList must be ordered // by line number and position; if (log.isTraceEnabled()) { log.trace("\tInsert new break in list of " + activeNodeCount + " from fitness class " + FitnessClasses.NAMES[i]); } KnuthNode newNode = createNode(elementIdx, line + 1, i, newWidth, newStretch, newShrink); addNode(line + 1, newNode); } } best.reset(); } /** * Return the difference between the natural width of a line that would be made * between the given active node and the given element, and the available width of the * real line. * @param activeNode node for the previous breakpoint * @param element currently considered breakpoint * @param elementIndex index of the element that is considered as a breakpoint * @return The difference in width. Positive numbers mean extra space in the line, * negative number that the line overflows. */ protected int computeDifference(KnuthNode activeNode, KnuthElement element, int elementIndex) { // compute the adjustment ratio int actualWidth = totalWidth - activeNode.totalWidth; if (element.isPenalty()) { actualWidth += element.getWidth(); } return getLineWidth() - actualWidth; } /** * Return the adjustment ratio needed to make up for the difference. A ratio of *
    *
  • 0 means that the break has the exact right width
  • *
  • >= -1 && < 0 means that the break is wider than the line, * but within the minimim values of the glues.
  • *
  • >0 && < 1 means that the break is smaller than the line width, * but within the maximum values of the glues.
  • *
  • > 1 means that the break is too small to make up for the glues.
  • *
* @param activeNode the currently active node * @param difference the difference between content-length and available width * @return The adjustment ratio. */ protected double computeAdjustmentRatio(KnuthNode activeNode, int difference) { // compute the adjustment ratio if (difference > 0) { int maxAdjustment = totalStretch - activeNode.totalStretch; if (maxAdjustment > 0) { return (double) difference / maxAdjustment; } else { return INFINITE_RATIO; } } else if (difference < 0) { int maxAdjustment = totalShrink - activeNode.totalShrink; if (maxAdjustment > 0) { return (double) difference / maxAdjustment; } else { return -INFINITE_RATIO; } } else { return 0; } } /** * Computes the demerits of the current breaking (that is, up to the given element), * if the next-to-last chosen breakpoint is the given active node. This adds to the * total demerits of the given active node, the demerits of a line starting at this * node and ending at the given element. * @param activeNode considered preceding line break * @param element considered current line break * @param fitnessClass fitness of the current line * @param r adjustment ratio for the current line * @return the demerit of the current line */ protected double computeDemerits(KnuthNode activeNode, KnuthElement element, int fitnessClass, double r) { double demerits = 0; // compute demerits double f = Math.abs(r); f = 1 + 100 * f * f * f; if (element.isPenalty()) { double penalty = element.getPenalty(); if (penalty >= 0) { f += penalty; demerits = f * f; } else if (!element.isForcedBreak()) { demerits = f * f - penalty * penalty; } else { demerits = f * f; } } else { demerits = f * f; } if (element.isPenalty() && ((KnuthPenalty) element).isPenaltyFlagged() && getElement(activeNode.position).isPenalty() && ((KnuthPenalty) getElement(activeNode.position)).isPenaltyFlagged()) { // add demerit for consecutive breaks at flagged penalties demerits += repeatedFlaggedDemerit; // there are at least two consecutive lines ending with a flagged penalty; // check if the previous line end with a flagged penalty too, // and if this situation is allowed int flaggedPenaltiesCount = 2; for (KnuthNode prevNode = activeNode.previous; prevNode != null && flaggedPenaltiesCount <= maxFlaggedPenaltiesCount; prevNode = prevNode.previous) { KnuthElement prevElement = getElement(prevNode.position); if (prevElement.isPenalty() && ((KnuthPenalty) prevElement).isPenaltyFlagged()) { // the previous line ends with a flagged penalty too flaggedPenaltiesCount++; } else { // the previous line does not end with a flagged penalty, // exit the loop break; } } if (maxFlaggedPenaltiesCount >= 1 && flaggedPenaltiesCount > maxFlaggedPenaltiesCount) { // add infinite demerits, so this break will not be chosen // unless there isn't any alternative break demerits += BestRecords.INFINITE_DEMERITS; } } if (Math.abs(fitnessClass - activeNode.fitness) > 1) { // add demerit for consecutive breaks // with very different fitness classes demerits += incompatibleFitnessDemerit; } demerits += activeNode.totalDemerits; return demerits; } /** * Hook for subclasses to trigger special behavior after ending the * main loop in {@link #findBreakingPoints(KnuthSequence,int,double,boolean,int)} */ protected void finish() { if (log.isTraceEnabled()) { log.trace("Main loop completed " + activeNodeCount); log.trace("Active nodes=" + toString("")); } } /** * Return the element at index idx in the paragraph. * @param idx index of the element. * @return the element at index idx in the paragraph. */ protected KnuthElement getElement(int idx) { return (KnuthElement) par.get(idx); } /** * Compare two KnuthNodes and return the node with the least demerit. * @param node1 The first knuth node. * @param node2 The other knuth node. * @return the node with the least demerit. */ protected KnuthNode compareNodes(KnuthNode node1, KnuthNode node2) { if (node1 == null || node2.position > node1.position) { return node2; } if (node2.position == node1.position) { if (node2.totalDemerits < node1.totalDemerits) { return node2; } } return node1; } /** * Add a node at the end of the given line's existing active nodes. * If this is the first node in the line, adjust endLine accordingly. * @param line number of the line ending at the node's corresponding breakpoint * @param node the active node to add */ protected void addNode(int line, KnuthNode node) { int headIdx = line * 2; if (headIdx >= activeLines.length) { KnuthNode[] oldList = activeLines; activeLines = new KnuthNode[headIdx + headIdx]; System.arraycopy(oldList, 0, activeLines, 0, oldList.length); } node.next = null; if (activeLines[headIdx + 1] != null) { activeLines[headIdx + 1].next = node; } else { activeLines[headIdx] = node; endLine = line + 1; } activeLines[headIdx + 1] = node; activeNodeCount++; } /** * Remove the given active node registered for the given line. If there are no more active nodes * for this line, adjust the startLine accordingly. * @param line number of the line ending at the node's corresponding breakpoint * @param node the node to deactivate */ protected void removeNode(int line, KnuthNode node) { int headIdx = line * 2; KnuthNode n = getNode(line); if (n != node) { // nodes could be rightly deactivated in a different order KnuthNode prevNode = null; while (n != node) { prevNode = n; n = n.next; } prevNode.next = n.next; if (prevNode.next == null) { activeLines[headIdx + 1] = prevNode; } } else { activeLines[headIdx] = node.next; if (node.next == null) { activeLines[headIdx + 1] = null; } while (startLine < endLine && getNode(startLine) == null) { startLine++; } } activeNodeCount--; } /** * Returns the first active node for the given line. * @param line the line/part number * @return the requested active node */ protected KnuthNode getNode(int line) { return activeLines[line * 2]; } /** * Returns the line/part width of a given line/part. * @param line the line/part number * @return the width/length in millipoints */ protected int getLineWidth(int line) { assert lineWidth >= 0; return this.lineWidth; } /** @return the constant line/part width or -1 if there is no such value */ protected int getLineWidth() { return this.lineWidth; } /** * Creates a string representation of the active nodes. Used for debugging. * @param prepend a string to prepend on each entry * @return the requested string */ public String toString(String prepend) { StringBuffer sb = new StringBuffer(); sb.append("[\n"); for (int i = startLine; i < endLine; i++) { for (KnuthNode node = getNode(i); node != null; node = node.next) { sb.append(prepend).append('\t').append(node).append(",\n"); } } sb.append(prepend).append("]"); return sb.toString(); } /** * Filter active nodes. * @return an integer */ protected abstract int filterActiveNodes(); /** * Determines the set of optimal breakpoints corresponding to the given active node. * @param node the active node * @param par the corresponding paragraph * @param total the number of lines into which the paragraph will be broken */ protected void calculateBreakPoints(KnuthNode node, KnuthSequence par, int total) { KnuthNode bestActiveNode = node; // use bestActiveNode to determine the optimum breakpoints for (int i = node.line; i > 0; i--) { updateData2(bestActiveNode, par, total); bestActiveNode = bestActiveNode.previous; } } /** @return the alignment for normal lines/parts */ public int getAlignment() { return this.alignment; } /** @return the alignment for the last line/part */ public int getAlignmentLast() { return this.alignmentLast; } protected boolean handlingFloat() { return false; } protected int handleFloat() { throw new IllegalStateException(); } protected void disableFloatHandling() { throw new IllegalStateException(); } }




© 2015 - 2024 Weber Informatics LLC | Privacy Policy