Java Image I/O reader plugin for the XPM image format (version 3).

Requires Java 8 or later.

Overview

XPM is an uncompressed palette color format that expands on the older monochrome XBM. The encoding is ASCII text formatted as a C string array.

XPM is often used for encoding user interface icons. The color palette supports up to four different display types per pixel--monochrome, four-level grayscale, grayscale, and RGB color--which enables a single image to be optimized for each display type. (This reader renders the RGB version by default, but it can render other versions via the use of a custom XPMImageReadParam instance (see examples).

Installation

This plugin is available in Maven Central. Add the following to the <dependencies> section of your pom.xml:

<dependency>
    <groupId>edu.illinois.library</groupId>
    <artifactId>imageio-xpm</artifactId>
    <version>[the version you want]</version>
</dependency>

Usage

Simple

File file = new File("test.xpm");
BufferedImage image = ImageIO.read(file);

Advanced

Iterator<ImageReader> it = ImageIO.getImageReadersByFormatName("XPM");
if (it.hasNext()) {
    ImageReader reader = it.next();
    try {
        ImageInputStream is = new FileImageInputStream(new File("test.xpm"));
        reader.setInput(is);
        BufferedImage image = reader.read(0);
    } finally {
        reader.dispose();
    }
}

More Advanced

import edu.illinois.library.imageio.xpm.XPMImageReadParam;

// ...

Iterator<ImageReader> it = ImageIO.getImageReadersByFormatName("XPM");
if (it.hasNext()) {
    ImageReader reader = it.next();
    try {
        ImageInputStream is = new FileImageInputStream(new File("test.xpm"));
        reader.setInput(is);
        XPMImageReadParam readParam = new XPMImageReadParam();
        readParam.setDisplayType(DisplayType.GRAYSCALE);
        BufferedImage image = reader.read(0, readParam);
    } finally {
        reader.dispose();
    }
}

Test

The basic tests can be run as usual using mvn test. There is also an assortment of test icons included that can be processed and saved to an output directory of your choosing for visual inspection. Enable this via:

$ mvn clean test -DargLine="-DiconOutputPath=/home/myself/icons"

Build

$ mvn clean package

Notes

1. Logging (which is minimal) uses java.util.logging.
2. Only reading support is available--no writing.
3. 16-bit samples are rescaled to 8 bits.
4. The IIOParamController (for progress updates etc.). is not supported.