/*
* 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.Stack;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.fop.datatypes.LengthBase;
import org.apache.fop.datatypes.PercentBaseContext;
import org.apache.fop.fo.FObj;
/**
* The base class for nearly all LayoutManagers.
* Provides the functionality for merging the {@link LayoutManager}
* and the {@link org.apache.fop.datatypes.PercentBaseContext} interfaces
* into a common base class for all higher LayoutManagers.
*/
public abstract class AbstractBaseLayoutManager
implements LayoutManager, PercentBaseContext {
/** Indicator if this LM generates reference areas. */
protected boolean generatesReferenceArea;
/** Indicator if this LM generates block areas. */
protected boolean generatesBlockArea;
/** The formatting object for this LM. */
protected final FObj fobj;
/**
* logging instance
*/
private static final Log LOG = LogFactory.getLog(AbstractBaseLayoutManager.class);
/**
* Abstract base layout manager.
*/
public AbstractBaseLayoutManager() {
fobj = null;
}
/**
* Abstract base layout manager.
*
* @param fo the formatting object for this layout manager
*/
public AbstractBaseLayoutManager(FObj fo) {
if (fo == null) {
throw new IllegalStateException("Null formatting object found.");
}
this.fobj = fo;
setGeneratesReferenceArea(fo.generatesReferenceAreas());
}
// --------- Property Resolution related functions --------- //
/** {@inheritDoc} */
public int getBaseLength(int lengthBase, FObj fobjx) {
if (fobjx == this.fobj) {
switch (lengthBase) {
case LengthBase.CONTAINING_BLOCK_WIDTH:
return getAncestorBlockAreaIPD();
case LengthBase.CONTAINING_BLOCK_HEIGHT:
return getAncestorBlockAreaBPD();
case LengthBase.PARENT_AREA_WIDTH:
return getParentAreaIPD();
case LengthBase.CONTAINING_REFAREA_WIDTH:
return getReferenceAreaIPD();
default:
LOG.error("Unknown base type for LengthBase:" + lengthBase);
return 0;
}
} else {
LayoutManager lm = getParent();
while (lm != null && fobjx != lm.getFObj()) {
lm = lm.getParent();
}
if (lm != null) {
return lm.getBaseLength(lengthBase, fobjx);
}
}
LOG.error("Cannot find LM to handle given FO for LengthBase. ("
+ fobjx.getContextInfo() + ")");
return 0;
}
/**
* Find the first ancestor area that is a block area
* and returns its IPD.
* @return the ipd of the ancestor block area
*/
protected int getAncestorBlockAreaIPD() {
LayoutManager lm = getParent();
while (lm != null) {
if (lm.getGeneratesBlockArea() && !lm.getGeneratesLineArea()) {
return lm.getContentAreaIPD();
}
lm = lm.getParent();
}
LOG.error("No parent LM found");
return 0;
}
/**
* Find the first ancestor area that is a block area
* and returns its BPD.
* @return the bpd of the ancestor block area
*/
protected int getAncestorBlockAreaBPD() {
LayoutManager lm = getParent();
while (lm != null) {
if (lm.getGeneratesBlockArea() && !lm.getGeneratesLineArea()) {
return lm.getContentAreaBPD();
}
lm = lm.getParent();
}
LOG.error("No parent LM found");
return 0;
}
/**
* Find the parent area and returns its IPD.
* @return the ipd of the parent area
*/
protected int getParentAreaIPD() {
LayoutManager lm = getParent();
if (lm != null) {
return lm.getContentAreaIPD();
}
LOG.error("No parent LM found");
return 0;
}
/**
* Find the parent area and returns its BPD.
* @return the bpd of the parent area
*/
protected int getParentAreaBPD() {
LayoutManager lm = getParent();
if (lm != null) {
return lm.getContentAreaBPD();
}
LOG.error("No parent LM found");
return 0;
}
/**
* Find the first ancestor area that is a reference area
* and returns its IPD.
* @return the ipd of the ancestor reference area
*/
public int getReferenceAreaIPD() {
LayoutManager lm = getParent();
while (lm != null) {
if (lm.getGeneratesReferenceArea()) {
return lm.getContentAreaIPD();
}
lm = lm.getParent();
}
LOG.error("No parent LM found");
return 0;
}
/**
* Find the first ancestor area that is a reference area
* and returns its BPD.
* @return the bpd of the ancestor reference area
*/
protected int getReferenceAreaBPD() {
LayoutManager lm = getParent();
while (lm != null) {
if (lm.getGeneratesReferenceArea()) {
return lm.getContentAreaBPD();
}
lm = lm.getParent();
}
LOG.error("No parent LM found");
return 0;
}
/**
* {@inheritDoc}
* <i>NOTE: Should be overridden by subclasses.
* Default implementation throws an <code>UnsupportedOperationException</code>.</i>
*/
public int getContentAreaIPD() {
throw new UnsupportedOperationException(
"getContentAreaIPD() called when it should have been overridden");
}
/**
* {@inheritDoc}
* <i>NOTE: Should be overridden by subclasses.
* Default implementation throws an <code>UnsupportedOperationException</code>.</i>
*/
public int getContentAreaBPD() {
throw new UnsupportedOperationException(
"getContentAreaBPD() called when it should have been overridden");
}
/** {@inheritDoc} */
public boolean getGeneratesReferenceArea() {
return generatesReferenceArea;
}
/**
* Lets implementing LM set the flag indicating if they
* generate reference areas.
* @param generatesReferenceArea if true the areas generates by this LM are
* reference areas.
*/
protected void setGeneratesReferenceArea(boolean generatesReferenceArea) {
this.generatesReferenceArea = generatesReferenceArea;
}
/** {@inheritDoc} */
public boolean getGeneratesBlockArea() {
return generatesBlockArea;
}
/**
* Lets implementing LM set the flag indicating if they
* generate block areas.
* @param generatesBlockArea if true the areas generates by this LM are block areas.
*/
protected void setGeneratesBlockArea(boolean generatesBlockArea) {
this.generatesBlockArea = generatesBlockArea;
}
/** {@inheritDoc} */
public boolean getGeneratesLineArea() {
return false;
}
/**
* {@inheritDoc}
*/
public FObj getFObj() {
return fobj;
}
/** {@inheritDoc} */
public void reset() {
throw new UnsupportedOperationException("Not implemented");
}
/** {@inheritDoc} */
public boolean isRestartable() {
return false;
}
/** {@inheritDoc} */
public List getNextKnuthElements(LayoutContext context, int alignment, Stack lmStack,
Position positionAtIPDChange, LayoutManager restartAtLM) {
throw new UnsupportedOperationException("Not implemented");
}
public void preserveChildrenAtEndOfLayout() {
}
public void recreateChildrenLMs() {
}
}