org.apache.xmlgraphics.image.loader.impl.AbstractImagePreloader Maven / Gradle / Ivy
/*
* 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.
*/
/* $Id: AbstractImagePreloader.java 750418 2009-03-05 11:03:54Z vhennebert $ */
package org.apache.xmlgraphics.image.loader.impl;
import java.io.IOException;
import java.util.Arrays;
import javax.imageio.stream.ImageInputStream;
import org.apache.xmlgraphics.image.loader.spi.ImagePreloader;
/**
* Abstract base class for image preloaders. It provides helper methods for often-used tasks.
*/
public abstract class AbstractImagePreloader implements ImagePreloader {
/**
* Allows to read an image header (usually just a magic number). The InputStream is reset
* to the position before the header was read.
* @param in the ImageInputStream to read from
* @param size the size of the header
* @return the loaded header
* @throws IOException if an I/O error occurs while reading the header
*/
protected byte[] getHeader(ImageInputStream in, int size)
throws IOException {
byte[] header = new byte[size];
long startPos = in.getStreamPosition();
int read = in.read(header);
if (read < size) {
Arrays.fill(header, (byte)0);
}
in.seek(startPos); //Seek back to start position
return header;
}
/** {@inheritDoc} */
public int getPriority() {
return DEFAULT_PRIORITY;
}
}