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 * 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
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * See the License for the specific language governing permissions and
 * limitations under the License.

/* $Id: 750418 2009-03-05 11:03:54Z vhennebert $ */

package org.apache.xmlgraphics.image.loader;


import javax.xml.transform.Source;

 * This interface is used to tell the cache which images are used by a session (in FOP that would
 * be a rendering run). Images access within a session get a hard reference so they cannot be
 * discarded. That could increase memory usage but helps with performance because the images
 * don't get unloaded between layout and rendering which would mean that they have to be reloaded.
public interface ImageSessionContext {

     * Returns the session-independent context object which provides configuration information.
     * @return the associated ImageContext instance
    ImageContext getParentContext();

     * Returns the resolution (in dpi) of the target device used when painting images.
     * @return the target resolution (in dpi)
    float getTargetResolution();

     * Attempts to create a Source object from the given URI. If possible this method returns
     * an ImageSource instance which provides the best possible method to access the image.
     * @param uri URI to access
     * @return A {@link javax.xml.transform.Source} object, or null if the URI
     * cannot be resolved.
    Source newSource(String uri);

     * Returns a Source object for a URI. This method is not guaranteed to return an instance.
     * Implementations normally return already created Sources from a pool (normally populated
     * through the {@link #returnSource(String, Source)} method).
     * @param uri the URI of the image
     * @return the Source object to load the image from, or null
    Source getSource(String uri);

     * Returns a Source object for a URI. This method is guaranteed to return a Source object. If
     * the image cannot be found, a {@link FileNotFoundException} is thrown.
     * @param uri the URI of the image
     * @return the Source object to load the image from
     * @throws FileNotFoundException if the image cannot be found
    Source needSource(String uri) throws FileNotFoundException;

     * Returns a Source object to a pool. This is provided in order to reuse a Source object
     * between the preloading and the final loading of an image. Note that not all Source objects
     * can be reused! Non-reusable Sources are discarded.
     * @param uri the URI of the image
     * @param src the Source object belonging to the URI
    void returnSource(String uri, Source src);

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