org.apache.fop.fo.flow.table.ColumnNumberManager Maven / Gradle / Ivy
/*
* 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: ColumnNumberManager.java 1466146 2013-04-09 17:31:41Z vhennebert $ */
package org.apache.fop.fo.flow.table;
import java.util.BitSet;
import java.util.List;
/**
* Helper class maintaining a record of occupied columns and an index to the next
* non-occupied column.
*/
public class ColumnNumberManager {
private int columnNumber = 1;
/**
* We use the term "index" instead of "number" because, unlike column numbers, it's
* 0-based.
*/
private BitSet usedColumnIndices = new BitSet();
/**
* Returns the number of the column that shall receive the next parsed cell.
*
* @return a column number, 1-based
*/
int getCurrentColumnNumber() {
return columnNumber;
}
/**
* Flags columns start to end as occupied,
* and updates the number of the next available column.
*
* @param start start number, inclusive, 1-based
* @param end end number, inclusive
*/
void signalUsedColumnNumbers(int start, int end) {
for (int i = start - 1; i < end; i++) {
usedColumnIndices.set(i);
}
columnNumber = end + 1;
while (usedColumnIndices.get(columnNumber - 1)) {
columnNumber++;
}
}
/**
* Resets the record of occupied columns, taking into account columns already occupied
* by previous spanning cells, and computes the number of the first free column.
*
* @param pendingSpans List<PendingSpan> of possible spans over the next row
*/
void prepareForNextRow(List pendingSpans) {
usedColumnIndices.clear();
PendingSpan pSpan;
for (int i = 0; i < pendingSpans.size(); i++) {
pSpan = (PendingSpan) pendingSpans.get(i);
if (pSpan != null) {
if (pSpan.decrRowsLeft() == 0) {
pendingSpans.set(i, null);
} else {
usedColumnIndices.set(i);
}
}
}
// Set columnNumber to the first available column
columnNumber = 1;
while (usedColumnIndices.get(columnNumber - 1)) {
columnNumber++;
}
}
/**
* Checks whether a given column-number is already in use
* for the current row.
*
* @param colNr the column-number to check
* @return true if column-number is already occupied
*/
public boolean isColumnNumberUsed(int colNr) {
return usedColumnIndices.get(colNr - 1);
}
}