org.apache.xmlgraphics.image.loader.util.ImageUtil Maven / Gradle / Ivy
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/*
* 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: ImageUtil.java 1681108 2015-05-22 13:26:12Z ssteiner $ */
package org.apache.xmlgraphics.image.loader.util;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.Map;
import java.util.zip.GZIPInputStream;
import javax.imageio.stream.ImageInputStream;
import javax.xml.transform.Source;
import org.apache.xmlgraphics.image.loader.ImageProcessingHints;
import org.apache.xmlgraphics.image.loader.ImageSessionContext;
import org.apache.xmlgraphics.image.loader.ImageSource;
import org.apache.xmlgraphics.io.XmlSourceUtil;
/**
* Helper and convenience methods for working with the image package.
*/
public final class ImageUtil {
private ImageUtil() {
}
/**
* Returns the InputStream of a Source object.
* @param src the Source object
* @return the InputStream (or null if there's not InputStream available)
* @deprecated Please use {@link XmlSourceUtil#getInputStream(Source)} instead.
*/
@Deprecated
public static InputStream getInputStream(Source src) {
return XmlSourceUtil.getInputStream(src);
}
/**
* Returns the ImageInputStream of a Source object.
* @param src the Source object
* @return the ImageInputStream (or null if there's not ImageInputStream available)
*/
public static ImageInputStream getImageInputStream(Source src) {
if (src instanceof ImageSource) {
return ((ImageSource) src).getImageInputStream();
} else {
return null;
}
}
/**
* Returns the InputStream of a Source object. This method throws an IllegalArgumentException
* if there's no InputStream instance available from the Source object.
* @param src the Source object
* @return the InputStream
* @deprecated use {@link XmlSourceUtil#needInputStream(Source)} instead
*/
@Deprecated
public static InputStream needInputStream(Source src) {
return XmlSourceUtil.needInputStream(src);
}
/**
* Returns the ImageInputStream of a Source object. This method throws an
* IllegalArgumentException if there's no ImageInputStream instance available from the
* Source object.
* @param src the Source object
* @return the ImageInputStream
*/
public static ImageInputStream needImageInputStream(Source src) {
if (src instanceof ImageSource) {
ImageSource isrc = (ImageSource) src;
if (isrc.getImageInputStream() == null) {
throw new IllegalArgumentException(
"ImageInputStream is null/cleared on ImageSource");
}
return isrc.getImageInputStream();
} else {
throw new IllegalArgumentException("Source must be an ImageSource");
}
}
/**
* Indicates whether the Source object has an InputStream instance.
* @param src the Source object
* @return true if an InputStream is available
*/
public static boolean hasInputStream(Source src) {
return XmlSourceUtil.hasInputStream(src) || hasImageInputStream(src);
}
/**
* Indicates whether the Source object has a Reader instance.
* @param src the Source object
* @return true if an Reader is available
* @deprecated use {@link XmlSourceUtil#hasReader(Source)} instead
*/
@Deprecated
public static boolean hasReader(Source src) {
return XmlSourceUtil.hasReader(src);
}
/**
* Indicates whether the Source object has an ImageInputStream instance.
* @param src the Source object
* @return true if an ImageInputStream is available
*/
public static boolean hasImageInputStream(Source src) {
return getImageInputStream(src) != null;
}
/**
* Removes any references to InputStreams or Readers from the given Source to prohibit
* accidental/unwanted use by a component further downstream.
* @param src the Source object
* @deprecated use {@link XmlSourceUtil#removeStreams(Source)} instead
*/
@Deprecated
public static void removeStreams(Source src) {
XmlSourceUtil.removeStreams(src);
}
/**
* Closes the InputStreams or ImageInputStreams of Source objects. Any exception occurring
* while closing the stream is ignored.
* @param src the Source object
* @deprecated use {@link XmlSourceUtil#closeQuietly(Source)} instead
*/
@Deprecated
public static void closeQuietly(Source src) {
XmlSourceUtil.closeQuietly(src);
}
/**
* Decorates an ImageInputStream so the flush*() methods are ignored and have no effect.
* The decoration is implemented using a dynamic proxy.
* @param in the ImageInputStream
* @return the decorated ImageInputStream
*/
public static ImageInputStream ignoreFlushing(final ImageInputStream in) {
return (ImageInputStream) Proxy.newProxyInstance(in.getClass().getClassLoader(),
new Class[] {ImageInputStream.class},
new InvocationHandler() {
public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable {
String methodName = method.getName();
//Ignore calls to flush*()
if (!methodName.startsWith("flush")) {
try {
return method.invoke(in, args);
} catch (InvocationTargetException ite) {
throw ite.getCause();
}
} else {
return null;
}
}
});
}
/**
* GZIP header magic number bytes, like found in a gzipped
* files, which are encoded in Intel format (i..e. little indian).
*/
private static final byte[] GZIP_MAGIC = {(byte) 0x1f, (byte) 0x8b};
/**
* Indicates whether an InputStream is GZIP compressed. The InputStream must support
* mark()/reset().
* @param in the InputStream (must return true on markSupported())
* @return true if the InputStream is GZIP compressed
* @throws IOException in case of an I/O error
*/
public static boolean isGZIPCompressed(InputStream in) throws IOException {
if (!in.markSupported()) {
throw new IllegalArgumentException("InputStream must support mark()!");
}
byte[] data = new byte[2];
in.mark(2);
in.read(data);
in.reset();
return ((data[0] == GZIP_MAGIC[0]) && (data[1] == GZIP_MAGIC[1]));
}
/**
* Decorates an InputStream with a BufferedInputStream if it doesn't support mark()/reset().
* @param in the InputStream
* @return the decorated InputStream
*/
public static InputStream decorateMarkSupported(InputStream in) {
if (in.markSupported()) {
return in;
} else {
return new java.io.BufferedInputStream(in);
}
}
/**
* Automatically decorates an InputStream so it is buffered. Furthermore, it makes sure
* it is decorated with a GZIPInputStream if the stream is GZIP compressed.
* @param in the InputStream
* @return the decorated InputStream
* @throws IOException in case of an I/O error
*/
public static InputStream autoDecorateInputStream(InputStream in) throws IOException {
in = decorateMarkSupported(in);
if (isGZIPCompressed(in)) {
return new GZIPInputStream(in);
}
return in;
}
/**
* Creates a new hint Map with values from the FOUserAgent.
* @param session the session context
* @return a Map of hints
*/
public static Map getDefaultHints(ImageSessionContext session) {
java.util.Map hints = new java.util.HashMap();
hints.put(ImageProcessingHints.SOURCE_RESOLUTION,
session.getParentContext().getSourceResolution());
hints.put(ImageProcessingHints.TARGET_RESOLUTION,
session.getTargetResolution());
hints.put(ImageProcessingHints.IMAGE_SESSION_CONTEXT, session);
return hints;
}
private static final String PAGE_INDICATOR = "page=";
/**
* Extracts page index information from a URI. The expected pattern is "page=x" where x is
* a non-negative integer number. The page index must be specified as part of the URI fragment
* and is 1-based, i.e. the first page is 1 but the the method returns a zero-based page
* index.
* An example: http://www.foo.bar/images/scan1.tif#page=4 (The method will return
* 3.)
*
* If no page index information is found in the URI or if the URI cannot be parsed, the
* method returns null.
* @param uri the URI that should be inspected
* @return the page index (0 is the first page) or null if there's no page index information
* in the URI
*/
public static Integer getPageIndexFromURI(String uri) {
if (uri.indexOf('#') < 0) {
return null;
}
try {
URI u = new URI(uri);
String fragment = u.getFragment();
if (fragment != null) {
int pos = fragment.indexOf(PAGE_INDICATOR);
if (pos >= 0) {
pos += PAGE_INDICATOR.length();
StringBuffer sb = new StringBuffer();
while (pos < fragment.length()) {
char c = fragment.charAt(pos);
if (c >= '0' && c <= '9') {
sb.append(c);
} else {
break;
}
pos++;
}
if (sb.length() > 0) {
int pageIndex = Integer.parseInt(sb.toString()) - 1;
pageIndex = Math.max(0, pageIndex);
return pageIndex;
}
}
}
} catch (URISyntaxException e) {
throw new IllegalArgumentException("URI is invalid: "
+ e.getLocalizedMessage());
}
return null;
}
/**
* Extracts page index information from a URI. The expected pattern is "page=x" where x is
* a non-negative integer number. The page index must be specified as part of the URI fragment
* and is 1-based, i.e. the first page is 1 but the the method returns a zero-based page
* index.
* An example: http://www.foo.bar/images/scan1.tif#page=4 (The method will return
* 3.)
*
* If no page index information is found in the URI, the
* method just returns 0 which indicates the first page.
* @param uri the URI that should be inspected
* @return the page index (0 is the first page)
*/
public static int needPageIndexFromURI(String uri) {
Integer res = getPageIndexFromURI(uri);
if (res != null) {
return res;
} else {
return 0;
}
}
}