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Library for converting various font formats.
There is a newer version: 1.2.22
/*
 * Copyright (C) Maddie Abboud 2016
 *
 * FontVerter is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * FontVerter is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with FontVerter. If not, see .
 */

package org.mabb.fontverter.io;

import org.mabb.fontverter.FontVerterUtils;

import java.io.*;
import java.nio.charset.Charset;

/**
 * Adds special font data type read functionality to data input stream
 * todo split out into woff/otf specific maybe
 */
public class FontDataInputStream extends DataInputStream implements FontDataInput {
    private final SeekableByteArrayInputStream byteInput;
    Charset encoding = FontDataOutputStream.OPEN_TYPE_CHARSET;

    public FontDataInputStream(byte[] data) {
        super(new SeekableByteArrayInputStream(data));
        byteInput = (SeekableByteArrayInputStream) in;
    }

    public long readUnsignedInt() throws IOException {
        long byte1 = read();
        long byte2 = read();
        long byte3 = read();
        long byte4 = read();
        if (byte4 < 0)
            throw new EOFException();
        return (byte1 << 24) + (byte2 << 16) + (byte3 << 8) + (byte4 << 0);
    }

    public String readString(int length) throws IOException {
        byte[] bytes = readBytes(length);

        return new String(bytes, encoding);
    }

    public byte[] readBytes(int length) throws IOException {
        byte[] bytes = new byte[length];
        for (int i = 0; i < bytes.length; i++)
            bytes[i] = (byte) in.read();
        return bytes;
    }

    public void seek(int offset) {
        byteInput.seek(offset);
    }

    // converted from pseduo C like reader code from woff spec
    public int readUIntBase128() throws IOException {
        int accum = 0;
        for (int i = 0; i < 5; i++) {
            int data_byte = readByte();

            if (i == 0 && data_byte == 0x80)
                throw new IOException("No leading 0's");


            if ((accum & 0xFE000000) > 0)
                throw new IOException("UIntBase128 read error If any of top 7 bits are set then << 7 would overflow");

            accum = (accum << 7) | (data_byte & 0x7F);

            // Spin until most significant bit of data byte is false
            if ((data_byte & 0x80) == 0) {
                return accum;
            }
        }

        throw new IOException("UIntBase128 sequence exceeds 5 bytes");
    }

    public float readFixed32() throws IOException {
        float num;
        num = (float) this.readShort();
        num = (float) ((double) num + (double) this.readUnsignedShort() / 65536.0D);
        return num;
    }

    public int getPosition() {
        return byteInput.getPosition();
    }

    public int[] readSplitBits(int numUpperBits) throws IOException {
        int fulByte = read();
        int upper = FontVerterUtils.readUpperBits(fulByte, numUpperBits);
        int lower = FontVerterUtils.readLowerBits(fulByte, 8 - numUpperBits);

        return new int[]{upper, lower};
    }

    public int[] readUnsignedShortArray(int length) throws IOException {
        int[] readArray = new int[length];
        for (int i = 0; i < length; i++)
            readArray[i] = readUnsignedShort();

        return readArray;
    }

    protected static class SeekableByteArrayInputStream extends ByteArrayInputStream {
        public SeekableByteArrayInputStream(byte[] buf) {
            super(buf);
        }

        public void seek(int n) {
            pos = n;
        }

        public int getPosition() {
            return pos;
        }
    }
}