edu.cornell.mannlib.vitro.webapp.imageprocessor.jai

Class JaiImageProcessor

java.lang.Object

edu.cornell.mannlib.vitro.webapp.imageprocessor.jai.JaiImageProcessor

All Implemented Interfaces:

Application.Component, Application.Module, ImageProcessor

public class JaiImageProcessor
extends Object
implements ImageProcessor

Crop the main image as specified, and scale it to the correct size for a thumbnail. Use the JAI library to read the file because the javax.imageio package doesn't read extended JPEG properly. Use JAI to remove transparency from JPEGs and PNGs, simply by removing the alpha channel. Annoyingly, this will not work with GIFs with transparent pixels. The transforms in the JAI library are buggy, so standard AWT operations do the scaling and cropping. The most obvious problem in the JAI library is the refusal to crop after scaling an image. Scale first to avoid the boundary error that produces black lines along the edge of the image. Use the javax.imagio pacakge to write the thumbnail image as a JPEG file.

Nested Class Summary

Nested classes/interfaces inherited from interface edu.cornell.mannlib.vitro.webapp.modules.imageProcessor.ImageProcessor

ImageProcessor.CropRectangle, ImageProcessor.Dimensions, ImageProcessor.ImageProcessorException

Nested classes/interfaces inherited from interface edu.cornell.mannlib.vitro.webapp.modules.Application.Component

Application.Component.LifecycleState

Field Summary

Fields inherited from interface edu.cornell.mannlib.vitro.webapp.modules.imageProcessor.ImageProcessor

MINIMUM_CROP_SIZE

Constructor Summary

Constructors

Constructor and Description
JaiImageProcessor()

Method Summary

Modifier and Type	Method and Description
InputStream	cropAndScale(InputStream mainImageStream, ImageProcessor.CropRectangle crop, ImageProcessor.Dimensions limits) Crop the main image according to this rectangle, and scale it to the correct size for a thumbnail.
ImageProcessor.Dimensions	getDimensions(InputStream imageStream) How big is the image contained in this stream?
void	shutdown(Application application) This should be called only once, and should be the last call on this Component.
void	startup(Application application, ComponentStartupStatus ss) Prevent Java Advanced Imaging from complaining about the lack of accelerator classes.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

JaiImageProcessor

public JaiImageProcessor()

Method Detail

startup

public void startup(Application application,
                    ComponentStartupStatus ss)

Prevent Java Advanced Imaging from complaining about the lack of accelerator classes.

Specified by:

startup in interface Application.Component

shutdown

public void shutdown(Application application)

Description copied from interface: Application.Component

This should be called only once, and should be the last call on this Component.

Specified by:

shutdown in interface Application.Component

getDimensions

public ImageProcessor.Dimensions getDimensions(InputStream imageStream)
                                        throws ImageProcessor.ImageProcessorException,
                                               IOException

Description copied from interface: ImageProcessor

How big is the image contained in this stream?

Specified by:

getDimensions in interface ImageProcessor

Parameters:

imageStream - The image stream. This method will not close it.

Returns:

The dimensions of the image. Never returns null.

Throws:

ImageProcessor.ImageProcessorException - if the stream does not contain a valid image.

IOException - if the stream cannot be read.

cropAndScale

public InputStream cropAndScale(InputStream mainImageStream,
                                ImageProcessor.CropRectangle crop,
                                ImageProcessor.Dimensions limits)
                         throws ImageProcessor.ImageProcessorException,
                                IOException

Crop the main image according to this rectangle, and scale it to the correct size for a thumbnail.

Specified by:

cropAndScale in interface ImageProcessor

Parameters:

mainImageStream - The image stream. This method will not close it.

crop - x and y determine the upper left corner of the crop area. height and width determine the size of the crop area.

limits - The resulting image will be reduced as necessary to fit within these dimensions.

Returns:

The new image. Client code should close this stream after reading. Never returns null.

Throws:

ImageProcessor.ImageProcessorException - If the image is smaller than the minimum crop size, or if there is another problem cropping the image.

IOException - if the image stream cannot be read.