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- /*
- * Copyright 2006 The Apache Software Foundation.
- *
- * Licensed 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.render.afp.tools;
-
- import java.io.IOException;
- import java.io.InputStream;
-
- /**
- * A helper class to read structured fields from a MO:DCA document. Each
- * component of a mixed object document is explicitly defined and delimited
- * in the data. This is accomplished through the use of MO:DCA data structures,
- * called structured fields. Structured fields are used to envelop document
- * components and to provide commands and information to applications using
- * the data. Structured fields may contain one or more parameters. Each
- * parameter provides one value from a set of values defined by the architecture.
- * <p/>
- * MO:DCA structured fields consist of two parts: an introducer that identifies
- * the length and type of the structured field, and data that provides the
- * structured field's effect. The data is contained in a set of parameters,
- * which can consist of other data structures and data elements. The maximum
- * length of a structured field is 32767 bytes.
- * <p/>
- */
- public class StructuredFieldReader {
-
- /**
- * The input stream to read
- */
- private InputStream _inputStream = null;
-
- /**
- * The constructor for the StructuredFieldReader
- * @param inputStream the input stream to process
- */
- public StructuredFieldReader(InputStream inputStream) {
-
- _inputStream = inputStream;
-
- }
-
- /**
- * Get the next structured field as identified by the identifer
- * parameter (this must be a valid MO:DCA structured field.
- * @param identifier the three byte identifier
- */
- public byte[] getNext(byte[] identifier) throws IOException {
-
- int bufferPointer = 0;
- byte[] bufferData = new byte[identifier.length + 2];
- for (int x = 0; x < identifier.length; x++) {
- bufferData[x] = (byte) 0;
- }
-
- int c;
- while ((c = _inputStream.read()) > -1) {
-
- bufferData[bufferPointer] = (byte) c;
-
- // Check the last characters in the buffer
- int index = 0;
- boolean found = true;
-
- for (int i = identifier.length - 1; i > -1; i--) {
-
- int p = bufferPointer - index;
- if (p < 0) {
- p = bufferData.length + p;
- }
-
- index++;
-
- if (identifier[i] != bufferData[p]) {
- found = false;
- break;
- }
-
- }
-
- if (found) {
-
- byte[] length = new byte[2];
-
- int a = bufferPointer - identifier.length;
- if (a < 0) {
- a = bufferData.length + a;
- }
-
- int b = bufferPointer - identifier.length - 1;
- if (b < 0) {
- b = bufferData.length + b;
- }
-
- length[0] = bufferData[b];
- length[1] = bufferData[a];
-
- int reclength = ((length[0] & 0xFF) << 8) + (length[1] & 0xFF) - identifier.length -2;
-
- byte[] retval = new byte[reclength];
-
- _inputStream.read(retval, 0, reclength);
-
- return retval;
-
- }
-
- bufferPointer++;
- if (bufferPointer >= bufferData.length) {
- bufferPointer = 0;
- }
-
- }
-
- return new byte[] {
- };
-
- }
-
- }
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