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( 026 new byte[] { (byte) 0x89, 'P', 'N', 'G', '\r', '\n', 0x1A, '\n', }); 027 028 public static final byte COMPRESSION_TYPE_INFLATE_DEFLATE = 0; 029 public static final byte FILTER_METHOD_ADAPTIVE = 0; 030 031 /* 032 * Background colour Solid background colour to be used when presenting the 033 * image if no better option is available. Gamma and chromaticity Gamma 034 * characteristic of the image with respect to the desired output intensity, 035 * and chromaticity characteristics of the RGB values used in the image. ICC 036 * profile Description of the colour space (in the form of an International 037 * Color Consortium (ICC) profile) to which the samples in the image 038 * conform. Image histogram Estimates of how frequently the image uses each 039 * palette entry. Physical pixel dimensions Intended pixel size and aspect 040 * ratio to be used in presenting the PNG image. Significant bits The number 041 * of bits that are significant in the samples. sRGB colour space A 042 * rendering intent (as defined by the International Color Consortium) and 043 * an indication that the image samples conform to this colour space. 044 * Suggested palette A reduced palette that may be used when the display 045 * device is not capable of displaying the full range of colours in the 046 * image. Textual data Textual information (which may be compressed) 047 * associated with the image. Time The time when the PNG image was last 048 * modified. Transparency Alpha information that allows the reference image 049 * to be reconstructed when the alpha channel is not retained in the PNG 050 * image. 051 */ 052 053 public static final String XMP_KEYWORD = "XML:com.adobe.xmp"; 054 055 /** 056 * Parameter key. Used to indicate the PNG compression level to be used. 057 * 058 * <p>For valid values, see {@link java.util.zip.Deflater}. If no value is specified, it will use 059 * the default compression level.</p> 060 * 061 * @see java.util.zip.Deflater 062 */ 063 public static final String PARAM_KEY_PNG_COMPRESSION_LEVEL = "PNG_COMPRESSION_LEVEL"; 064 065 private PngConstants() { 066 } 067}