54 lines
1.8 KiB
Java
54 lines
1.8 KiB
Java
/* ====================================================================
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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==================================================================== */
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package org.apache.poi.util;
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public final class PngUtils {
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/**
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* File header for PNG format.
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*/
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private static final byte[] PNG_FILE_HEADER =
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new byte[] { (byte) 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A };
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private PngUtils() {
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// no instances of this class
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}
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/**
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* Checks if the offset matches the PNG header.
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*
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* @param data the data to check.
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* @param offset the offset to check at.
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* @return {@code true} if the offset matches.
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*/
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public static boolean matchesPngHeader(byte[] data, int offset) {
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if (data == null || data.length - offset < PNG_FILE_HEADER.length) {
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return false;
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}
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for (int i = 0; i < PNG_FILE_HEADER.length; i++) {
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if (PNG_FILE_HEADER[i] != data[i + offset]) {
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return false;
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}
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}
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return true;
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}
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}
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