Jakarta ANT Image Task

Check: If you are using ANT 1.6 or above,the Image task included in it may satisfy your requirement.
I had offered to contribute these Image tasks to ANT 1.7 but have not received any reply yet. I am planning to stop developing and maintaining these tasks since I see no point in maintaining separate internal and external Image tasks.
Moreoever I can concentrate on developing PMIW. If you need some specialized imaging operations (not available in the ANT distribution) let me know.

License: Apache License ( http://www.apache.org)
Download: Source and Binary. You will also need the supporting PMIW library and pjatools.jar from the PJA Toolkit for GIF encoding support.
Technologies: Java2D, ImageIO, Java Advanced Imaging

Description

The structure is very similar to the standard "copy" ANT task. The funcationality is almost same as the jakarta image taglib (currently in the jakarta-taglibs-sandbox), because the underlying library used (PMIW: see below) is the same.
It does image operations on a file or FileSet to a new file or directory. The operations are specified as a set of nested elements. By default, files are only copied if the source file is newer than the destination file, or when the destination file does not exist. However, you can explicitly overwrite files with the overwrite attribute. FileSets are used to select a set of files to copy. To use a <fileset>, the todir attribute must be set.

This Image task generates and transforms images dynamically. It exposes the imaging capability available in Java2D, Java Advanced Imaging, ImageIO, etc., as set of nested elements.

One of the design objectives was to keep it as simple as possible. It does not require the user to have an in-depth knowledge of the underlying imaging APIs. Currently it includes the basic Java2D and Java Advanced Imaging based implementations. The Java2D implementation uses ImageIO if it is available or else defaults to AWT.

Requirements info

This Image Task can use optional software such as Java Advanced Imaging (JAI), ImageIO, etc., other than Java2D.

• Jakarta ANT 1.4 or above.
• Java 1.2 or above.
• Currently the tags use Java2D (with ImageIO or just AWT) OR Java Advanced Imaging API (JAI). JAI or ImageIO support is loaded if the classes are available. Absence of ImageIO and JAI classes will force the usage of the AWT for loading and encoding/ saving. AWT currently supports only the reading of GIF and JPEG files and encoding of JPEG only. Writing GIF is NOT supported by any of the above mentioned libraries. ImageIO may be added separately for Java versions prior to 1.4.
• On a server without a graphics environment (X-Windows or MS Windows), the "java.awt.headless=true" option should be set or a work-around such as loading XVFB or so must be done.
• Since Java2D loads only GIF, JPEG and BMP images, the new ImageIO is used. Hence now it needs: - J2SDK-1.4 and above OR J2SDK-1.2 and above with ImageIO jar OR J2SDK-1.2 and above with JAI jars.
• This Task uses "Poor Man's Imaging Wrapper" (PMIW), a simple imaging wrapper library. This wrapper exposes a very simple interface for imaging operation using Java2D, JAI, etc. It is distributed under the Apache software license and the binary is included in this taglib distribution. The source of PMIW can be obtained from PMIW project home. It was not made part of this library because it is used for other projects such as jakarta image taglibs (in the sandbox), etc.

Currently supported transformations/ operations

The nested elements of the <image> task can be a set of transformations such as: -

• resize -- scale the image by a percentage or to a specified width and height. Thus it supports differential scaling (i.e., scaleX != scaleY)
• grayscale -- convert a color image to grayscale.
• rotate -- rotate the image by some degrees and enlarges it to still accommodate the full image.
• crop -- get a rectangular region specified as a percentage or absolute pixels.
• border -- add a border to the image in the color specified. Color is specified as a number such as 0xff00ff (red) or 0x0000ff(blue).
• overlay -- overlays/ paints a new image specified by a nested <image> tag, on the parent image at a specified point. Transparency effect can be added by specifying a color The pixels with the color will be considered as transparent.
• text -- writes a string/ text on the image in the color and font at a given point.

These elements can be combined and used in any order to get the desired effect. The overlay is useful to add tags like "SOLD", "NEW", etc., to a product image. Text can be used to add copyright information to images. Grayscale and Resize can be used to generate thumbnail images. There are numerous ways to use them in combination. Take a look at the example.

It is possible to refine the set of files that are being operated on. This can be done with the includes, includesfile, excludes, excludesfile and defaultexcludes attributes. With the includes or includesfile attribute you specify the files you want to have included by using patterns. The exclude or excludesfile attribute is used to specify the files you want to have excluded. This is also done with patterns. And finally with the defaultexcludes attribute, you can specify whether you want to use default exclusions or not. See the section on directory based tasks, on how the inclusion/exclusion of files works, and how to write patterns.

This task forms an implicit FileSet and supports all attributes of <fileset> (dir becomes basedir) as well as the nested <include>, <exclude> and <patternset> elements.

You can also use nested file sets for more flexibility, and specify multiple ones to merge together different trees of files.

Parameters

Parameters specified as nested elements

fileset

FileSets are used to select sets of files to copy. To use a fileset, the todir attribute must be set.

Examples

<image todir="processed" overwrite="true" failOnError="true">
    <fileset dir="images" includes="**/a*.jpg"/>
    <text text="Created by Image tasks" color="0x0000ff"/>
    <rotate degrees="30" />
    <overlay src="images/new.gif" x="10%" y="10%"/> 
    <resize width="80%"/>
</image>

This above task operates on all the "jpg" files starting with "a". All the images in this list will be operated with the following operations in the given order: -

1. Paint/ write a string "Created by Image tasks" on the image at the bottom. The color is specified as RGB values in hexadecimal "0x0000ff" (blue)
2. Rotate the image by "30" degrees in the clockwise direction
3. Overlay/paint the "new.gif" on the image at the specified location
4. Resize the whole image to "80%" of its current size
5. The final image is encoded as "JPEG" to a file witht he same file name in the directory "processed"

Planned features

• Specifying pattern based filenames for output files.
• Loading Scalable Vector Graphics (SVG) files using Batik.
• Shape overlay and transformation operations such as "ShapeOverlay", "Circle", "Rectangle", etc.
• Image kernel operations such as "Brightness", "Contrast", "Threshold", "Blur", "Posterize", etc.
• Special operations such as "Tile", "Bevel border", etc.
• Implementations based on Standard Windowing Toolkit (SWT) or similar library that might not have "headless" issues.
• Support for GIF file writing using ACME or similar libraries.

I have just started development on this. But do send me your feedback.