org.apache.wicket.extensions.markup.html.image.resource.ThumbnailImageResource.java Source code

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Here is the source code for org.apache.wicket.extensions.markup.html.image.resource.ThumbnailImageResource.java

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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.
 */
package org.apache.wicket.extensions.markup.html.image.resource;

import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;

import javax.imageio.ImageIO;

import org.apache.wicket.WicketRuntimeException;
import org.apache.wicket.request.resource.DynamicImageResource;
import org.apache.wicket.request.resource.IResource;
import org.apache.wicket.response.ByteArrayResponse;
import org.apache.wicket.util.io.IOUtils;
import org.apache.wicket.util.lang.Args;
import org.apache.wicket.util.time.Time;

/**
 * Image resource that dynamically scales the given original resource to a thumbnail. It is scaled
 * either using the given maxSize as width or height, depending on its shape. If both the width and
 * height are less than maxSize, no scaling is performed.
 * 
 * @author Eelco Hillenius
 * @author Eugene Kamenev
 */

public class ThumbnailImageResource extends DynamicImageResource {
    private static final long serialVersionUID = 1L;

    /** the unscaled, original image resource. */
    private final IResource unscaledImageResource;

    /** maximum size (width or height) for resize operation. */
    private final int maxSize;

    /** the cached byte array of the thumbnail. */
    private transient byte[] thumbnail;

    /**
     * Construct.
     * 
     * @param unscaledImageResource
     *            the unscaled, original image resource. Must be not null
     * @param maxSize
     *            maximum size (width or height) for resize operation
     */
    public ThumbnailImageResource(final IResource unscaledImageResource, final int maxSize) {
        Args.notNull(unscaledImageResource, "unscaledImageResource");

        this.unscaledImageResource = unscaledImageResource;
        this.maxSize = maxSize;
    }

    /**
     * @return The image data for this dynamic image
     */
    @Override
    protected byte[] getImageData(final Attributes attributes) {
        if (thumbnail == null) {
            final BufferedImage image = getScaledImageInstance(attributes);
            thumbnail = toImageData(image);
            setLastModifiedTime(Time.now());
        }
        return thumbnail;
    }

    /**
     * get resized image instance.
     * 
     * @param attributes
     * 
     * @return BufferedImage
     */
    protected BufferedImage getScaledImageInstance(final Attributes attributes) {
        InputStream is = null;
        BufferedImage originalImage = null;
        try {
            // read original image
            ByteArrayResponse byteResponse = new ByteArrayResponse();
            Attributes dispatchAttributes = new Attributes(attributes.getRequest(), byteResponse,
                    attributes.getParameters());
            unscaledImageResource.respond(dispatchAttributes);
            is = new ByteArrayInputStream(byteResponse.getBytes());
            originalImage = ImageIO.read(is);
            if (originalImage == null) {
                throw new IOException("Unable to read unscaled image");
            }
        } catch (IOException e) {
            throw new WicketRuntimeException(e);
        } finally {
            IOUtils.closeQuietly(is);
        }

        int originalWidth = originalImage.getWidth();
        int originalHeight = originalImage.getHeight();

        if ((originalWidth > maxSize) || (originalHeight > maxSize)) {
            final int newWidth;
            final int newHeight;

            if (originalWidth > originalHeight) {
                newWidth = maxSize;
                newHeight = (maxSize * originalHeight) / originalWidth;
            } else {
                newWidth = (maxSize * originalWidth) / originalHeight;
                newHeight = maxSize;
            }

            // http://today.java.net/pub/a/today/2007/04/03/perils-of-image-getscaledinstance.html
            BufferedImage dimg = new BufferedImage(newWidth, newHeight, originalImage.getType());
            Graphics2D g = dimg.createGraphics();
            try {
                g.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
                g.drawImage(originalImage, 0, 0, newWidth, newHeight, 0, 0, originalWidth, originalHeight, null);
            } finally {
                g.dispose();
            }

            return dimg;
        }

        // no need for resizing
        return originalImage;
    }

}