thi-ng/umbrella

import { illegalArgs } from "@thi.ng/errors";
import sharp from "sharp";
import type { CompLayerFn, Dim, ImgLayer } from "../api.js";
import { computeSize, ensureSize, positionOrGravity } from "../units.js";

export const imageLayerImpl: CompLayerFn = async (layer, _, ctx) => {
    const {
        type: __,
        buffer,
        gravity,
        path,
        pos,
        ref,
        size,
        unit,
        ...opts
    } = <ImgLayer>layer;
    if (!(path || buffer)) illegalArgs("missing image source");
    const input = sharp(path || buffer);
    const meta = await input.metadata();
    let imgSize: Dim = [meta.width!, meta.height!];
    if (size) imgSize = computeSize(size, imgSize, ref, unit);
    const $pos = positionOrGravity(imgSize, ctx.size, layer);
    if (!size) return { input: path, ...$pos, ...opts };
    ensureSize(meta);
    const { data, info } = await input
        .resize(imgSize[0], imgSize[1], { fit: "fill" })
        .raw()
        .toBuffer({ resolveWithObject: true });
    return {
        input: data,
        raw: {
            width: info.width,
            height: info.height,
            channels: info.channels,
        },
        ...$pos,
        ...opts,
    };
};