City-Lifeline-Cockpit/.scratch/lanhu-cockpit-asset-replacement/research/probe-industry-colors.mjs

// 从行业切图 PNG 取主色（支持全部 5 种扫描线滤波器；RGBA 8bit）
import { readFileSync } from 'node:fs'
import { inflateSync } from 'node:zlib'

function pngColors(file) {
    const buf = readFileSync(file)
    let off = 8
    const idats = []
    let w = 0
    let h = 0
    let colorType = 6
    while (off < buf.length) {
        const len = buf.readUInt32BE(off)
        const type = buf.toString('ascii', off + 4, off + 8)
        if (type === 'IHDR') {
            w = buf.readUInt32BE(off + 8)
            h = buf.readUInt32BE(off + 12)
            colorType = buf[off + 17]
        }
        if (type === 'IDAT') idats.push(buf.slice(off + 8, off + 8 + len))
        off += 12 + len
    }
    const bpp = colorType === 6 ? 4 : colorType === 2 ? 3 : 4
    const raw = inflateSync(Buffer.concat(idats))
    const stride = w * bpp
    const recon = Buffer.alloc(h * stride)
    for (let y = 0; y < h; y += 1) {
        const filter = raw[y * (stride + 1)]
        const row = raw.slice(y * (stride + 1) + 1, y * (stride + 1) + 1 + stride)
        const prev = y > 0 ? recon.slice((y - 1) * stride, y * stride) : Buffer.alloc(stride)
        const cur = recon.slice(y * stride, (y + 1) * stride)
        for (let x = 0; x < stride; x += 1) {
            const a = x >= bpp ? cur[x - bpp] : 0
            const b = prev[x]
            const c = x >= bpp ? prev[x - bpp] : 0
            let val = row[x]
            if (filter === 1) val += a
            else if (filter === 2) val += b
            else if (filter === 3) val += Math.floor((a + b) / 2)
            else if (filter === 4) {
                const p = a + b - c
                const pa = Math.abs(p - a)
                const pb = Math.abs(p - b)
                const pc = Math.abs(p - c)
                val += pa <= pb && pa <= pc ? a : pb <= pc ? b : c
            }
            cur[x] = val & 0xff
        }
    }
    const colors = new Map()
    for (let i = 0; i < recon.length; i += bpp) {
        const alpha = bpp === 4 ? recon[i + 3] : 255
        if (alpha < 128) continue
        const key = `#${[recon[i], recon[i + 1], recon[i + 2]].map((v) => v.toString(16).padStart(2, '0')).join('')}`
        colors.set(key, (colors.get(key) || 0) + 1)
    }
    return [...colors.entries()].sort((a, b) => b[1] - a[1]).slice(0, 5).map(([k, v]) => `${k}×${v}`).join(' ')
}

for (const f of ['industry-gas', 'industry-water', 'industry-drainage', 'manhole']) {
    console.log(`${f}: ${pngColors(`public/cockpit/assets/icons/${f}.png`)}`)
}