pdfbox-trunk/fontbox/src/main/java/org/apache/fontbox/ttf/VerticalOriginTable.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.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * A vertical origin 'VORG' table in an OpenType font.
 *
 * The purpose of this table is to improve the efficiency of determining
 * vertical origins in CFF fonts where absent this information the bounding
 * box would have to be extracted from CFF charstring data.
 *
 * This table is strongly recommended by the OpenType CJK Font Guidelines
 * for "CFF OpenType fonts that are used for vertical writing".
 * 
 * This table is specified only in the OpenType specification (1.3 and later).
 * 
 * @author Glenn Adams
 * 
 */
public class VerticalOriginTable extends TTFTable
{
    /**
     * A tag that identifies this table type.
     */
    public static final String TAG = "VORG";
    
    private float version;
    private int defaultVertOriginY;
    private Map<Integer, Integer> origins;

    VerticalOriginTable()
    {
        super();
    }

    /**
     * This will read the required data from the stream.
     * 
     * @param ttf The font that is being read.
     * @param data The stream to read the data from.
     * @throws IOException If there is an error reading the data.
     */
    @Override
    void read(TrueTypeFont ttf, TTFDataStream data) throws IOException
    {
        version = data.read32Fixed();
        defaultVertOriginY = data.readSignedShort();
        int numVertOriginYMetrics = data.readUnsignedShort();
        origins = new ConcurrentHashMap<>(numVertOriginYMetrics);
        for (int i = 0; i < numVertOriginYMetrics; ++i) 
        {
            int g = data.readUnsignedShort();
            int y = data.readSignedShort();
            origins.put(g, y);
        }
        initialized = true;
    }
    
    /**
     * @return Returns the version.
     */
    public float getVersion()
    {
        return version;
    }

    /**
     * Returns the y-coordinate of the vertical origin for the given GID if known,
     * or returns the default value if not specified in table data.
     *
     * @param gid GID
     * @return Returns the y-coordinate of the vertical origin.
     */
    public int getOriginY(int gid)
    {
        if (origins.containsKey(gid))
        {
            return origins.get(gid);
        }
        else
        {
            return defaultVertOriginY;
        }
    }
}
