mizchi/image

Image codec primitives for MoonBit. Core codecs have no external dependencies except mizchi/zlib; the AVIF js-target MVP uses browser AVIF canvas support or local ffmpeg.

Features

• PNG decode / encode (RGBA8, adaptive row filtering)
• BMP decode / encode
• JPEG baseline decode / encode
• GIF encode (single-frame, indexed palette, binary transparency)
• WebP lossless encode (still image)
• ICO encode (single-image, PNG payload)
• AVIF encode (js target MVP, opaque still image)
• Resize with Nearest / Bilinear / Bicubic interpolation

All decoded images are normalized to ImageData (RGBA8 buffer).

Install

moon add mizchi/image

Usage

// PNG decode → resize → encode
let img = @image.decode_png(png_bytes)
let resized = @image.resize(img, 128, 128, Bilinear)
let out = @image.encode_png(resized)

// JPEG encode (quality defaults to 85)
let jpg = @image.encode_jpeg(resized)

// GIF encode (<= 256 colors, alpha 0/255 only)
let gif = @image.encode_gif(resized)

// WebP lossless encode
let webp = @image.encode_webp(resized)

// ICO encode (single PNG-backed icon, <= 256x256)
let ico = @image.encode_ico(resized)

// AVIF encode (js target MVP, opaque images only)
let avif = @image.encode_avif(resized)

// Stream decode (PNG/BMP auto detect)
let rows : Array[Bytes] = []
let info = @image.decode_image_stream(
  image_bytes,
  on_row=fn(_y, row) { rows.push(row) },
)
inspect((info.format, info.width, info.height))

API

pub fn decode_png(Bytes) -> ImageData raise DecodeError
pub fn decode_png_stream(Bytes, on_row~ : (Int, Bytes) -> Unit) -> IhdrData raise DecodeError
pub fn decode_image_stream(Bytes, on_row~ : (Int, Bytes) -> Unit) -> StreamImageInfo raise DecodeError
pub fn encode_png(ImageData) -> Bytes raise EncodeError
pub fn decode_bmp(Bytes) -> ImageData raise DecodeError
pub fn decode_bmp_stream(Bytes, on_row~ : (Int, Bytes) -> Unit) -> (Int, Int) raise DecodeError
pub fn encode_bmp(ImageData) -> Bytes raise EncodeError
pub fn decode_jpeg(Bytes) -> ImageData raise DecodeError
pub fn encode_jpeg(ImageData, quality? : Int = 85) -> Bytes raise EncodeError
pub fn encode_gif(ImageData) -> Bytes raise EncodeError
pub fn encode_webp(ImageData) -> Bytes raise EncodeError
pub fn encode_ico(ImageData) -> Bytes raise EncodeError
pub fn encode_avif(ImageData) -> Bytes raise EncodeError
pub fn resize(ImageData, Int, Int, ResizeMethod) -> ImageData raise EncodeError

Types

pub(all) struct ImageData { width : Int; height : Int; data : Bytes }
pub(all) enum ResizeMethod { Nearest; Bilinear; Bicubic }

Support

Feature	Decode	Encode	Targets	Notes
PNG	yes	yes	js / native / wasm-gc	RGBA8 normalize, stream decode
BMP	yes	yes	js / native / wasm-gc	decode: 24/32-bit, encode: 32-bit BGRA
JPEG	yes	yes	js / native / wasm-gc	baseline only
GIF	no	yes	js / native / wasm-gc	single-frame, <=256 colors, alpha 0/255 only
WebP	no	yes	js / native / wasm-gc	lossless still-image encoder
ICO	no	yes	js / native / wasm-gc	single PNG payload, <=256x256
AVIF	no	yes	js	opaque images only, requires browser AVIF canvas support or local ffmpeg
Resize	n/a	n/a	js / native / wasm-gc	Nearest / Bilinear / Bicubic

License

Apache-2.0