A simple JNI wrapper for libwebp.
Feature support:
- Simple decoding API
- Advanced decoding API (RGBA output only)
- Simple encoding API
- Advanced encoding API
All functions are implemented under the WebPDecode and WebPEncode static classes.
You will need JDK 9+, Gradle, CMake, and libwebp installed on your system.
To build, run ./gradlew build. The library will be built to build/libs/.
Since this library uses native code, the produced archive is platform-specific.
Example to read an input file with ImageIO, and encode it to WebP:
BufferedImage image = ImageIO.read(new File("input.jpeg"));
byte[] imageBytes = new byte[image.getWidth() * image.getHeight() * 3];
int imageBytesIndex = 0;
for(int y = 0; y < image.getHeight(); y++) {
for(int x = 0; x < image.getWidth(); x++) {
int rgb = image.getRGB(x, y);
imageBytes[imageBytesIndex++] = (byte) (rgb >> 16 & 255); //R
imageBytes[imageBytesIndex++] = (byte) (rgb >> 8 & 255); //G
imageBytes[imageBytesIndex++] = (byte) (rgb & 255); //B
}
}
byte[] encodedImageBytes = WebPEncode.encodeRGB(imageBytes, image.getWidth(), image.getHeight(), image.getWidth() * 3, 80);
Files.write(Path.of("output.webp"), encodedImageBytes);Example to decode a WebP file with the advanced decoding API, flip it, and re-encode it at low quality:
byte[] originalImageBytes = Files.readAllBytes(Path.of("input.webp"));
WebPDecodedData data = WebPDecode.decode(originalImageBytes,
new WebPDecoderOptions.Builder()
.setFlip(true)
.build(),
WebPColorSpace.RGBA);
byte[] newImageBytes = WebPEncode.encodeRGBA(data.getBytes(), data.getWidth(), data.getHeight(), data.getWidth() * 4, 10);
Files.write(Path.of("output.webp"), newImageBytes);