Function libwebp::WebPEncodeLosslessRGBA

pub fn WebPEncodeLosslessRGBA(
    rgba: &[u8],
    width: u32,
    height: u32,
    stride: u32
) -> Result<WebpBox<[u8]>, WebPSimpleError>

Encodes images pointed to by rgba and returns the WebP binary data.

The ordering of samples in memory is R, G, B, A, R, G, B, A… in scan order (endian-independent).

Compression

This function compresses using the lossless format. Files are usually larger than lossy format, but will not suffer any compression loss.

For lossy compression, you can use the WebPEncodeRGBA family.

Note these functions, like the lossy versions, use the library’s default settings. For lossless this means exact is disabled. RGB values in transparent areas will be modified to improve compression. To avoid this, use WebPEncode() and set WebPConfig::exact to 1.

(The Rust binding does not yet have the corresponding function.)

Errors

Returns Err if data doesn’t contain a valid WebP header.

Panics

Panics when stride is too small or rgba has a wrong size.

Variants

• WebPEncodeLosslessRGBA
• WebPEncodeLosslessBGRA
• WebPEncodeLosslessRGB
• WebPEncodeLosslessBGR

Examples

use libwebp::WebPEncodeLosslessRGBA;

let buf: &[u8] = &[
    255, 255, 255, 255, // white
    255, 0, 0, 255, // red
    0, 255, 0, 255, // green
    0, 0, 255, 255, // blue
];
let data = WebPEncodeLosslessRGBA(buf, 2, 2, 8).unwrap();
assert_eq!(&data[..4], b"RIFF");
assert_eq!(&data[8..12], b"WEBP");