nextapp.echoservlet.image
Class PngEncoder

java.lang.Object
  nextapp.echoservlet.image.PngEncoder

public class PngEncoder

extends java.lang.Object

Encodes a java.awt.Image into PNG format. For more information on the PNG specification, see the W3C PNG page at http://www.w3.org/TR/REC-png.html.

Nested Class Summary

static interface

PngEncoder.Filter An interface for PNG filters.

Field Summary

static PngEncoder.Filter	AVERAGE_FILTER
static PngEncoder.Filter	PAETH_FILTER
static PngEncoder.Filter	SUB_FILTER
static PngEncoder.Filter	UP_FILTER

Constructor Summary

PngEncoder(java.awt.Image image, boolean encodeAlpha, PngEncoder.Filter filter, int compressionLevel)
Creates a PNG encoder for an image.

Method Summary

void	encode(java.io.OutputStream out) Encodes the image.

Methods inherited from class java.lang.Object

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

Field Detail

SUB_FILTER

public static final PngEncoder.Filter SUB_FILTER

UP_FILTER

public static final PngEncoder.Filter UP_FILTER

AVERAGE_FILTER

public static final PngEncoder.Filter AVERAGE_FILTER

PAETH_FILTER

public static final PngEncoder.Filter PAETH_FILTER

Constructor Detail

PngEncoder

public PngEncoder(java.awt.Image image,
                  boolean encodeAlpha,
                  PngEncoder.Filter filter,
                  int compressionLevel)

Creates a PNG encoder for an image.

Parameters:

image - The image to be encoded.

encodeAlpha - True if the image's alpha channel should be encoded.

filter - The filter to be applied to the image data, one of the following values:

• SUB_FILTER
• UP_FILTER
• AVERAGE_FILTER
• PAETH_FILTER

If a null value is specified, no filtering will be performed.

compressionLevel - The deflater compression level that will be used for compressing the image data. Valid values range from 0 to 9. Higher values result in smaller files and therefore decrease network traffic, but require more CPU time to encode. The normal compromise value is 3.

Method Detail

encode

public void encode(java.io.OutputStream out)
            throws java.io.IOException

Encodes the image.

Parameters:

out - An OutputStream to which the encoded image will be written.

Throws:

java.io.IOException - if a problem is encountered writing the output.