TTFDataStream.java
/*
* 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.
*/
package org.apache.fontbox.ttf;
import java.io.Closeable;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.Calendar;
import java.util.TimeZone;
import org.apache.pdfbox.io.RandomAccessRead;
/**
* An abstract class to read a data stream.
*
* @author Ben Litchfield
*/
abstract class TTFDataStream implements Closeable
{
private static final TimeZone TIMEZONE_UTC = TimeZone.getTimeZone("UTC"); // clone before using
TTFDataStream()
{
}
/**
* Read a 16.16 fixed value, where the first 16 bits are the decimal and the last 16 bits are the fraction.
*
* @return A 32 bit value.
* @throws IOException If there is an error reading the data.
*/
public float read32Fixed() throws IOException
{
float retval = readSignedShort();
retval += (readUnsignedShort() / 65536f);
return retval;
}
/**
* Read a fixed length ascii string.
*
* @param length The length of the string to read.
* @return A string of the desired length.
* @throws IOException If there is an error reading the data.
*/
public String readString(int length) throws IOException
{
return readString(length, StandardCharsets.ISO_8859_1);
}
/**
* Read a fixed length string.
*
* @param length The length of the string to read in bytes.
* @param charset The expected character set of the string.
* @return A string of the desired length.
* @throws IOException If there is an error reading the data.
*/
public String readString(int length, Charset charset) throws IOException
{
return new String(read(length), charset);
}
/**
* Read an unsigned byte.
*
* @return An unsigned byte.
* @throws IOException If there is an error reading the data.
*/
public abstract int read() throws IOException;
/**
* Read an unsigned byte.
*
* @return An unsigned byte.
* @throws IOException If there is an error reading the data.
*/
public abstract long readLong() throws IOException;
/**
* Read a signed byte.
*
* @return A signed byte.
* @throws IOException If there is an error reading the data.
*/
public int readSignedByte() throws IOException
{
int signedByte = read();
return signedByte <= 127 ? signedByte : signedByte - 256;
}
/**
* Read an unsigned byte. Similar to {@link #read()}, but throws an exception if EOF is unexpectedly reached.
*
* @return An unsigned byte.
* @throws IOException If there is an error reading the data.
*/
public int readUnsignedByte() throws IOException
{
int unsignedByte = read();
if (unsignedByte == -1)
{
throw new EOFException("premature EOF");
}
return unsignedByte;
}
/**
* Read an unsigned integer.
*
* @return An unsigned integer.
* @throws IOException If there is an error reading the data.
*/
public long readUnsignedInt() throws IOException
{
long byte1 = read();
long byte2 = read();
long byte3 = read();
long byte4 = read();
if (byte4 < 0)
{
throw new EOFException("EOF at " + getCurrentPosition() +
", b1: " + byte1 + ", b2: " + byte2 + ", b3: " + byte3 + ", b4: " + byte4);
}
return (byte1 << 24) + (byte2 << 16) + (byte3 << 8) + byte4;
}
/**
* Read an unsigned short.
*
* @return An unsigned short.
* @throws IOException If there is an error reading the data.
*/
public int readUnsignedShort() throws IOException
{
int b1 = read();
int b2 = read();
if ((b1 | b2) < 0)
{
throw new EOFException("EOF at " + getCurrentPosition() + ", b1: " + b1 + ", b2: " + b2);
}
return (b1 << 8) + b2;
}
/**
* Read an unsigned byte array.
*
* @param length the length of the array to be read
* @return An unsigned byte array.
* @throws IOException If there is an error reading the data.
*/
public int[] readUnsignedByteArray(int length) throws IOException
{
int[] array = new int[length];
for (int i = 0; i < length; i++)
{
array[i] = read();
}
return array;
}
/**
* Read an unsigned short array.
*
* @param length The length of the array to read.
* @return An unsigned short array.
* @throws IOException If there is an error reading the data.
*/
public int[] readUnsignedShortArray(int length) throws IOException
{
int[] array = new int[length];
for (int i = 0; i < length; i++)
{
array[i] = readUnsignedShort();
}
return array;
}
/**
* Read a signed short.
*
* @return A signed short.
* @throws IOException If there is an error reading the data.
*/
public short readSignedShort() throws IOException
{
return (short) readUnsignedShort();
}
/**
* Read an eight byte international date.
*
* @return A signed short.
* @throws IOException If there is an error reading the data.
*/
public Calendar readInternationalDate() throws IOException
{
long secondsSince1904 = readLong();
Calendar cal = Calendar.getInstance((TimeZone) TIMEZONE_UTC.clone());
cal.set(1904, 0, 1, 0, 0, 0);
cal.set(Calendar.MILLISECOND, 0);
long millisFor1904 = cal.getTimeInMillis();
millisFor1904 += (secondsSince1904 * 1000);
cal.setTimeInMillis(millisFor1904);
return cal;
}
/**
* Reads a tag, an array of four uint8s used to identify a script, language system, feature,
* or baseline.
*/
public String readTag() throws IOException
{
return new String(read(4), StandardCharsets.US_ASCII);
}
/**
* Seek into the datasource.
*
* @param pos The position to seek to.
* @throws IOException If there is an error seeking to that position.
*/
public abstract void seek(long pos) throws IOException;
/**
* Read a specific number of bytes from the stream.
*
* @param numberOfBytes The number of bytes to read.
* @return The byte buffer.
* @throws IOException If there is an error while reading.
*/
public byte[] read(int numberOfBytes) throws IOException
{
byte[] data = new byte[numberOfBytes];
int amountRead = 0;
int totalAmountRead = 0;
// read at most numberOfBytes bytes from the stream.
while (totalAmountRead < numberOfBytes
&& (amountRead = read(data, totalAmountRead, numberOfBytes - totalAmountRead)) != -1)
{
totalAmountRead += amountRead;
}
if (totalAmountRead == numberOfBytes)
{
return data;
}
else
{
throw new IOException("Unexpected end of TTF stream reached");
}
}
/**
* @see java.io.InputStream#read(byte[], int, int )
*
* @param b The buffer to write to.
* @param off The offset into the buffer.
* @param len The length into the buffer.
*
* @return The number of bytes read, or -1 at the end of the stream
*
* @throws IOException If there is an error reading from the stream.
*/
public abstract int read(byte[] b, int off, int len) throws IOException;
/**
* Creates a view from current position to {@code pos + length}.
* It can be faster than {@code read(length)} if you only need a few bytes.
* {@code SubView.close()} should never close {@code TTFDataStream.this}, only itself.
*
* @return A view or null (caller can use {@link #read} instead). Please close() the result
*/
public RandomAccessRead createSubView(long length)
{
return null;
}
/**
* Get the current position in the stream.
*
* @return The current position in the stream.
* @throws IOException If an error occurs while reading the stream.
*/
public abstract long getCurrentPosition() throws IOException;
/**
* This will get the original data file that was used for this stream.
*
* @return The data that was read from.
* @throws IOException If there is an issue reading the data.
*/
public abstract InputStream getOriginalData() throws IOException;
/**
* This will get the original data size that was used for this stream.
*
* @return The size of the original data.
*/
public abstract long getOriginalDataSize();
}