nextapp.echo.app.AwtImageReference Maven / Gradle / Ivy
/*
* This file is part of the Echo Web Application Framework (hereinafter "Echo").
* Copyright (C) 2002-2009 NextApp, Inc.
*
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (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.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*/
package nextapp.echo.app;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.image.ColorModel;
import java.awt.image.ImageObserver;
import java.awt.image.MemoryImageSource;
import java.awt.image.PixelGrabber;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
/**
* An ImageReference describing an image which may be rendered from a java.awt.Image. Note that the JVM running the
* Echo Application Container will require access to a graphics context for the Java AWT to function.
*
* WARNING: Use of this class is STRONGLY DISCOURAGED unless you specifically need to dynamically
* render or modify image content. Rendering AWT images requires that the image be brought into memory as a bitmap and then
* rendered to a client-compatible format (e.g., PNG). DO NOT use this class unless you absolutely must.
*
* The preferred means of serving images is by using ResourceImageReferences or HttpImageReferences.
*
* @see ResourceImageReference
* @see HttpImageReference
*/
public class AwtImageReference
implements ImageReference {
/** Serial Version UID. */
private static final long serialVersionUID = 20070101L;
private transient Image image;
private String id;
/**
* Default constructor for use only when a class is derived from
* AwtImageReference and the
* getImage() method is overridden.
*/
public AwtImageReference() {
this(null);
}
/**
* Creates an AwtImageReference to the specified
* java.awt.Image.
* Note that changes to the underlying image will not necessarily be
* reflected on the client unless the image-containing property of the
* target component is update.
*
* @param image the java.awt.Image to be displayed.
*/
public AwtImageReference(Image image) {
super();
this.image = image;
id = ApplicationInstance.generateSystemId();
}
/**
* @see java.lang.Object#equals(java.lang.Object)
*/
public boolean equals(Object o) {
if (!(o instanceof AwtImageReference)) {
return false;
}
AwtImageReference that = (AwtImageReference) o;
if (!(this.image == that.image || (this.image != null && this.image.equals(that.image)))) {
return false;
}
return true;
}
/**
* @see nextapp.echo.app.ImageReference#getHeight()
*/
public Extent getHeight() {
if (image == null) {
return null;
}
int height = image.getHeight(null);
if (height > 0) {
return new Extent(height, Extent.PX);
} else {
return null;
}
}
/**
* @see nextapp.echo.app.RenderIdSupport#getRenderId()
*/
public String getRenderId() {
return id;
}
/**
* Retrieves the image. Calls to this method will be minimized such that
* applications may extend this class and override this method such that
* images are created only when they are needed, thereby reducing memory
* usage at the cost of increased processor workload.
* You should also override the getWidth() and
* getHeight() methods.
*/
public Image getImage() {
return image;
}
/**
* @see nextapp.echo.app.ImageReference#getWidth()
*/
public Extent getWidth() {
if (image == null) {
return null;
}
int width = image.getWidth(null);
if (width > 0) {
return new Extent(width, Extent.PX);
} else {
return null;
}
}
/**
* @see java.io.Serializable
*/
private void readObject(ObjectInputStream in)
throws IOException, ClassNotFoundException {
in.defaultReadObject();
int width = in.readInt();
int height = in.readInt();
int[] pixels = (int[]) in.readObject();
if (pixels != null) {
Toolkit toolkit = Toolkit.getDefaultToolkit();
ColorModel colorModel = ColorModel.getRGBdefault();
image = toolkit.createImage(new MemoryImageSource(width, height, colorModel, pixels, 0, width));
}
}
/**
* @see java.io.Serializable
*/
private void writeObject(ObjectOutputStream out)
throws IOException {
out.defaultWriteObject();
int width = image.getWidth(null);
int height = image.getHeight(null);
out.writeInt(width);
out.writeInt(height);
if (image == null) {
out.writeObject(null);
} else {
int[] pixels = new int[width * height];
try {
PixelGrabber pg = new PixelGrabber(image, 0, 0, width, height, pixels, 0, width);
pg.grabPixels();
if ((pg.getStatus() & ImageObserver.ABORT) != 0) {
throw new IOException("Unable to serialize java.awt.image: PixelGrabber aborted.");
}
} catch (InterruptedException ex) {
throw new IOException("Unable to serialize java.awt.Image: PixelGrabber interrupted.");
}
out.writeObject(pixels);
}
}
}