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Images

PNG and JPEG decoding is client-side and pure JS (pngjs, jpeg-js — no native modules). A decoded Image is independent of any X connection; the first time it is drawn it uploads to that server as a 32-bit ARGB pixmap and is cached, so repeated draws cost a single server-side composite.

import { createClient, loadImage } from 'ntk';

const app = await createClient();
const wnd = app.createWindow({ width: 400, height: 300 });
const ctx = wnd.getContext('2d');

const img = await loadImage('photo.jpg');       // path, file URL or Buffer
ctx.drawImage(img, 0, 0);                        // natural size
ctx.drawImage(img, 0, 0, 200, 150);              // scaled (server-side, bilinear)
ctx.drawImage(img, 10, 10, 80, 80, 220, 10, 160, 160); // source crop + scale
wnd.map();

API​

  • loadImage(source) → Promise<Image> — source is a file path, a file URL, or a Buffer/Uint8Array of encoded PNG/JPEG bytes
  • decodeImage(buffer) → Image — synchronous decode of in-memory bytes; the format is sniffed from magic bytes
  • new Image({ width, height, data }) — wrap raw non-premultiplied RGBA pixels (width * height * 4 bytes)

Image​

  • image.width, image.height — pixel dimensions
  • image.data — non-premultiplied RGBA bytes (Buffer)
  • image.picture(app) → Picture — the cached server-side picture for that app's display (uploaded on first call). ctx.drawImage uses this internally; it is public for manual Render compositing
  • image.destroy() / Symbol.dispose — free the server-side copies (safe: the image re-uploads if drawn again). Client-side pixel data stays usable; the server resources are also reclaimed by GC as a fallback (see resource management)

Notes​

  • Alpha is handled correctly: pixels are premultiplied at upload, so translucent PNGs blend with what is underneath (Over composition).
  • Uploads are chunked to respect the server's maximum request length, so large images work over the wire.
  • Drawing the same Image into several windows/pixmaps of one app reuses one upload; using it with several apps (rare) keeps one upload per app.