001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.imaging.formats.png;
018
019import org.apache.commons.imaging.common.BinaryConstant;
020
021public final class PngConstants {
022
023    public static final int COMPRESSION_DEFLATE_INFLATE = 0;
024
025    public static final BinaryConstant PNG_SIGNATURE = new BinaryConstant(new byte[] { (byte) 0x89, 'P', 'N', 'G', '\r', '\n', 0x1A, '\n', });
026
027    public static final byte COMPRESSION_TYPE_INFLATE_DEFLATE = 0;
028    public static final byte FILTER_METHOD_ADAPTIVE = 0;
029
030    /*
031     * Background color Solid background color to be used when presenting the image if no better option is available. Gamma and chromaticity Gamma
032     * characteristic of the image with respect to the desired output intensity, and chromaticity characteristics of the RGB values used in the image. ICC
033     * profile Description of the color space (in the form of an International Color Consortium (ICC) profile) to which the samples in the image conform. Image
034     * histogram Estimates of how frequently the image uses each palette entry. Physical pixel dimensions Intended pixel size and aspect ratio to be used in
035     * presenting the PNG image. Significant bits The number of bits that are significant in the samples. sRGB color space A rendering intent (as defined by the
036     * International Color Consortium) and an indication that the image samples conform to this color space. Suggested palette A reduced palette that may be
037     * used when the display device is not capable of displaying the full range of colors in the image. Textual data Textual information (which may be
038     * compressed) associated with the image. Time The time when the PNG image was last modified. Transparency Alpha information that allows the reference image
039     * to be reconstructed when the alpha channel is not retained in the PNG image.
040     */
041
042    public static final String XMP_KEYWORD = "XML:com.adobe.xmp";
043
044    /**
045     * Parameter key. Used to indicate the PNG compression level to be used.
046     *
047     * <p>
048     * For valid values, see {@link java.util.zip.Deflater}. If no value is specified, it will use the default compression level.
049     * </p>
050     *
051     * @see java.util.zip.Deflater
052     */
053    public static final String PARAM_KEY_PNG_COMPRESSION_LEVEL = "PNG_COMPRESSION_LEVEL";
054
055    private PngConstants() {
056    }
057}