| /* |
| * 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 org.apache.fop.fo.Constants; |
| import org.apache.fop.fo.properties.KeepProperty; |
| import org.apache.fop.fo.properties.Property; |
| |
| /** |
| * Object representing a keep constraint, corresponding |
| * to the XSL-FO <a href="http://www.w3.org/TR/xsl/#d0e26492">keep properties</a>. |
| */ |
| public final class Keep { |
| |
| /** The integer value for "auto" keep strength. */ |
| private static final int STRENGTH_AUTO = Integer.MIN_VALUE; |
| |
| /** The integer value for "always" keep strength. */ |
| private static final int STRENGTH_ALWAYS = Integer.MAX_VALUE; |
| |
| /** keep auto */ |
| public static final Keep KEEP_AUTO = new Keep(STRENGTH_AUTO, Constants.EN_AUTO); |
| |
| /** keep always */ |
| public static final Keep KEEP_ALWAYS = new Keep(STRENGTH_ALWAYS, Constants.EN_LINE); |
| |
| private int strength; |
| |
| private int context; |
| |
| private Keep(int strength, int context) { |
| this.strength = strength; |
| this.context = context; |
| } |
| |
| private static int getKeepStrength(Property keep) { |
| if (keep.isAuto()) { |
| return STRENGTH_AUTO; |
| } else if (keep.getEnum() == Constants.EN_ALWAYS) { |
| return STRENGTH_ALWAYS; |
| } else { |
| return keep.getNumber().intValue(); |
| } |
| } |
| |
| /** |
| * Obtain a Keep instance corresponding to the given {@link KeepProperty} |
| * |
| * @param keepProperty the {@link KeepProperty} |
| * @return a new instance corresponding to the given property |
| */ |
| public static Keep getKeep(KeepProperty keepProperty) { |
| Keep keep = new Keep(STRENGTH_AUTO, Constants.EN_AUTO); |
| keep.update(keepProperty.getWithinPage(), Constants.EN_PAGE); |
| keep.update(keepProperty.getWithinColumn(), Constants.EN_COLUMN); |
| keep.update(keepProperty.getWithinLine(), Constants.EN_LINE); |
| return keep; |
| } |
| |
| private void update(Property keep, int context) { |
| if (!keep.isAuto()) { |
| this.strength = getKeepStrength(keep); |
| this.context = context; |
| } |
| } |
| |
| /** @return {@code true} if the keep property was specified as "auto" */ |
| public boolean isAuto() { |
| return strength == STRENGTH_AUTO; |
| } |
| |
| /** |
| * Returns the context of this keep. |
| * |
| * @return one of {@link Constants#EN_LINE}, {@link Constants#EN_COLUMN} or |
| * {@link Constants#EN_PAGE} |
| */ |
| public int getContext() { |
| return context; |
| } |
| |
| /** @return the penalty value corresponding to the strength of this Keep */ |
| public int getPenalty() { |
| if (strength == STRENGTH_AUTO) { |
| return 0; |
| } else if (strength == STRENGTH_ALWAYS) { |
| return KnuthElement.INFINITE; |
| } else { |
| return KnuthElement.INFINITE - 1; |
| } |
| } |
| |
| private static int getKeepContextPriority(int context) { |
| switch (context) { |
| case Constants.EN_LINE: return 0; |
| case Constants.EN_COLUMN: return 1; |
| case Constants.EN_PAGE: return 2; |
| case Constants.EN_AUTO: return 3; |
| default: throw new IllegalArgumentException(); |
| } |
| } |
| |
| /** |
| * Compare this Keep instance to another one, and return the |
| * stronger one if the context is the same |
| * |
| * @param other the instance to compare to |
| * @return the winning Keep instance |
| */ |
| public Keep compare(Keep other) { |
| |
| /* check strength "always" first, regardless of priority */ |
| if (this.strength == STRENGTH_ALWAYS |
| && this.strength > other.strength) { |
| return this; |
| } else if (other.strength == STRENGTH_ALWAYS |
| && other.strength > this.strength) { |
| return other; |
| } |
| |
| int pThis = getKeepContextPriority(this.context); |
| int pOther = getKeepContextPriority(other.context); |
| |
| /* equal priority: strongest wins */ |
| if (pThis == pOther) { |
| return (strength >= other.strength) ? this : other; |
| } |
| |
| /* different priority: lowest priority wins */ |
| return (pThis < pOther) ? this : other; |
| } |
| |
| /** {@inheritDoc} */ |
| public String toString() { |
| return (strength == STRENGTH_AUTO) ? "auto" |
| : (strength == STRENGTH_ALWAYS) ? "always" |
| : Integer.toString(strength); |
| } |
| } |