com.google.code.appengine.imageio.plugins.jpeg.JPEGQTable Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of appengine-awt Show documentation
The newest version!
/*
 *  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.
 */
/**
 * @author Rustem V. Rafikov
 */
package com.google.code.appengine.imageio.plugins.jpeg;


import org.apache.harmony.x.imageio.internal.nls.Messages;

import com.google.code.appengine.imageio.plugins.jpeg.JPEGQTable;

public class JPEGQTable {

    private final static int SIZE = 64;
    private final static int BASELINE_MAX = 255;
    private final static int MAX = 32767;


    private int[] theTable;

    /*
     * K1 & K2 tables can be found in the JPEG format specification 
     * at http://www.w3.org/Graphics/JPEG/itu-t81.pdf
     */

    private static final int[] K1LumTable = new int[] {
        16,  11,  10,  16,  24,  40,  51,  61,
        12,  12,  14,  19,  26,  58,  60,  55,
        14,  13,  16,  24,  40,  57,  69,  56,
        14,  17,  22,  29,  51,  87,  80,  62,
        18,  22,  37,  56,  68,  109, 103, 77,
        24,  35,  55,  64,  81,  104, 113, 92,
        49,  64,  78,  87,  103, 121, 120, 101,
        72,  92,  95,  98,  112, 100, 103, 99
    };

    private static final int[] K2ChrTable = new int[] {
        17,  18,  24,  47,  99,  99,  99,  99,
        18,  21,  26,  66,  99,  99,  99,  99,
        24,  26,  56,  99,  99,  99,  99,  99,
        47,  66,  99,  99,  99,  99,  99,  99,
        99,  99,  99,  99,  99,  99,  99,  99,
        99,  99,  99,  99,  99,  99,  99,  99,
        99,  99,  99,  99,  99,  99,  99,  99,
        99,  99,  99,  99,  99,  99,  99,  99
    };

    public static final JPEGQTable K1Luminance = new JPEGQTable(K1LumTable);
    public static final JPEGQTable K1Div2Luminance = K1Luminance.getScaledInstance(0.5f, true);
    public static final JPEGQTable K2Chrominance = new JPEGQTable(K2ChrTable);
    public static final JPEGQTable K2Div2Chrominance = K2Chrominance.getScaledInstance(0.5f, true);;


    public JPEGQTable(int[] table) {
        if (table == null) {
            throw new IllegalArgumentException(Messages.getString("imageio.42"));
        }
        if (table.length != SIZE) {
                throw new IllegalArgumentException(Messages.getString("imageio.93", table.length));
        }
        theTable = table.clone();
    }

    public int[] getTable() {
        return theTable.clone();
    }

    public JPEGQTable getScaledInstance(float scaleFactor, boolean forceBaseline) {
        int table[] = new int[SIZE];

        int maxValue = forceBaseline ? BASELINE_MAX : MAX;

        for (int i = 0; i < theTable.length; i++) {
            int rounded = Math.round(theTable[i] * scaleFactor);
            if (rounded < 1) {
                rounded = 1;
            }
            if (rounded > maxValue) {
                rounded = maxValue;
            }
            table[i] = rounded;
        }
        return new JPEGQTable(table);
    }

    @Override
    public String toString() {
    	StringBuilder sb = new StringBuilder();
    	
    	sb.append("JPEGQTable:\n");
    	for (int i = 0; i < 8; i++) {
    		sb.append('\t');
    		for (int j = 0; j < 8; j++) {
    			sb.append(theTable[i*8+j]);
    			sb.append(' ');
    		}
    		sb.append('\n');
    	}
    	
        return sb.toString();
    }
}