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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.afp.fonts;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;
import java.nio.charset.CodingErrorAction;
/**
* An abstraction that wraps the encoding mechanism for encoding a Unicode character sequence into a
* specified format.
*/
public abstract class CharactersetEncoder {
private final CharsetEncoder encoder;
private CharactersetEncoder(String encoding) {
this.encoder = Charset.forName(encoding).newEncoder();
this.encoder.onUnmappableCharacter(CodingErrorAction.REPLACE);
}
/**
* Tells whether or not this encoder can encode the given character.
*
* @param c the character
* @return true if, and only if, this encoder can encode the given character
* @throws IllegalStateException - If an encoding operation is already in progress
*/
final boolean canEncode(char c) {
return encoder.canEncode(c);
}
/**
* Encodes a character sequence to a byte array.
*
* @param chars the character sequence
* @return the encoded character sequence
* @throws CharacterCodingException if the encoding operation fails
*/
final EncodedChars encode(CharSequence chars) throws CharacterCodingException {
ByteBuffer bb;
// encode method is not thread safe
synchronized (encoder) {
bb = encoder.encode(CharBuffer.wrap(chars));
}
if (bb.hasArray()) {
return getEncodedChars(bb.array(), bb.limit());
} else {
bb.rewind();
byte[] bytes = new byte[bb.remaining()];
bb.get(bytes);
return getEncodedChars(bytes, bytes.length);
}
}
abstract EncodedChars getEncodedChars(byte[] byteArray, int length);
/**
* Encodes <code>chars</code> into a format specified by <code>encoding</code>.
*
* @param chars the character sequence
* @param encoding the encoding type
* @return encoded data
* @throws CharacterCodingException if encoding fails
*/
public static EncodedChars encodeSBCS(CharSequence chars, String encoding)
throws CharacterCodingException {
CharactersetEncoder encoder = CharacterSetType.SINGLE_BYTE.getEncoder(encoding);
return encoder.encode(chars);
}
/**
* The EBCDIC double byte encoder is used for encoding IBM format DBCS (double byte character
* sets) with an EBCDIC code-page. Given a double byte EBCDIC code page and a Unicode character
* sequence it will return its EBCDIC code-point, however, the "Shift In - Shift Out" operators
* are removed from the sequence of bytes. These are only used in Line Data.
*/
static final class EbcdicDoubleByteLineDataEncoder extends CharactersetEncoder {
EbcdicDoubleByteLineDataEncoder(String encoding) {
super(encoding);
}
@Override
EncodedChars getEncodedChars(byte[] byteArray, int length) {
if (byteArray[0] == 0x0E && byteArray[length - 1] == 0x0F) {
return new EncodedChars(byteArray, 1, length - 2, true);
}
return new EncodedChars(byteArray, true);
}
}
/**
* The default encoder is used for encoding IBM format SBCS (single byte character sets), this
* the primary format for most Latin character sets. This can also be used for Unicode double-
* byte character sets (DBCS).
*/
static final class DefaultEncoder extends CharactersetEncoder {
private final boolean isDBCS;
DefaultEncoder(String encoding, boolean isDBCS) {
super(encoding);
this.isDBCS = isDBCS;
}
@Override
EncodedChars getEncodedChars(byte[] byteArray, int length) {
return new EncodedChars(byteArray, isDBCS);
}
}
/**
* A container for encoded character bytes
*/
// CSOFF: FinalClass - disabling "final" modifier so that this class can be mocked
public static class EncodedChars {
private final byte[] bytes;
private final int offset;
private final int length;
private final boolean isDBCS;
private EncodedChars(byte[] bytes, int offset, int length, boolean isDBCS) {
if (offset < 0 || length < 0 || offset + length > bytes.length) {
throw new IllegalArgumentException();
}
this.bytes = bytes;
this.offset = offset;
this.length = length;
this.isDBCS = isDBCS;
}
private EncodedChars(byte[] bytes, boolean isDBCS) {
this(bytes, 0, bytes.length, isDBCS);
}
/**
* write <code>length</code> bytes from <code>offset</code> to the output stream
*
* @param out output to write the bytes to
* @param offset the offset where to write
* @param length the length to write
* @throws IOException if an I/O error occurs
*/
public void writeTo(OutputStream out, int offset, int length) throws IOException {
if (offset < 0 || length < 0 || offset + length > bytes.length) {
throw new IllegalArgumentException();
}
out.write(bytes, this.offset + offset, length);
}
/**
* The number of containing bytes.
*
* @return the length
*/
public int getLength() {
return length;
}
/**
* Indicates whether or not the EncodedChars object wraps double byte characters.
*
* @return true if the wrapped characters are double byte (DBCSs)
*/
public boolean isDBCS() {
return isDBCS;
}
/**
* The bytes
*
* @return the bytes
*/
public byte[] getBytes() {
// return copy just in case
byte[] copy = new byte[bytes.length];
System.arraycopy(bytes, 0, copy, 0, bytes.length);
return copy;
}
}
}
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