Code To Images

Convert code files to A4-ratio PNG/SVG images with line numbers and syntax highlighting, then merge to PDF

Install

openclaw skills install code-to-images

Code → A4 Images + PDF

Convert source code files into multi-page A4-ratio images (SVG+PNG) then merge into a single PDF, with:

Line numbers (starting from 1)
Syntax highlighting (keywords, registers, macros, numbers, comments)
File name header with page info per sheet
Light theme (white background)
50 lines per page, 14px Cascadia Code font
Final output: one PDF per source file

Prerequisites

Python 3 (tested with 3.14+)
Node.js and @resvg/resvg-js for SVG→PNG conversion
Python packages: img2pdf

npm install -g @resvg/resvg-js
pip install img2pdf

Workflow

1. Get the source code

Ask the user to provide the source code file(s). Save them to the workspace.

2. Generate SVGs + PNGs + PDF (all-in-one)

Run the batch script below. It reads every source code file and for each one:

Splits code into pages (50 lines/page)
Generates SVG for each page (syntax-highlighted, light theme, A4 ratio)
Renders each SVG to PNG via @resvg/resvg-js
Merges all PNG pages into a single PDF via img2pdf

Output structure:

filename.c/
├── code_page_1.svg
├── code_page_1.png
├── code_page_2.svg
├── code_page_2.png
└── ...
filename.c.pdf    ← merged PDF

Python Batch Script

Save as gen_code_pdfs.py and run with python gen_code_pdfs.py:

"""Batch convert code files → images + PDF. One PDF per source file."""
import os, sys, subprocess, json

# === CONFIG ===
FILES = [
    # List source files here, e.g.:
    # 'main.c', 'key.c', 'KEY.h', 'adc.h', 'ADC.c',
    # 'DS1302.c', 'DS1302.h', 'EEPROM.c', 'EEPROM.h',
]
BASE = os.getcwd()
LINES_PER_PAGE = 50

# Colors (light theme)
KW = {'void','char','int','u8','u16','u32','uchar','unsigned',
      'for','if','else','while','switch','case','break','return',
      'static','bit','sbit','xdata','idata','code','interrupt',
      'do','default','continue','struct','typedef','enum','const',
      '#ifndef','#define','#endif','#ifdef','extern'}
RG = {'P0','P1','P2','P3','P4','P5','P6','P7','RST','SCLK','IO','SCK'}
CO = {'keyword':'#d63384','register':'#e8590c','macro':'#099268',
      'number':'#2b8a3e','string':'#099268','comment':'#868e96',
      'var':'#1971c2','text':'#212529'}
BG='#ffffff'; HDR_BG='#f1f3f5'; HDR_BORDER='#dee2e6'
GT_BG='#f8f9fa'; GT_BORDER='#e9ecef'; LN_COLOR='#868e96'

def tokenize(line):
    t,i,n=[],0,len(line)
    while i<n:
        if line[i]=='#':
            j=i
            while j<n and line[j]!='\n': j+=1
            t.append((line[i:j],'macro')); break
        if line[i:i+2]=='//': t.append((line[i:],'comment')); break
        if line[i:i+2]=='/*':
            j=i+2
            while j<n and line[j:j+2]!='*/': j+=1
            if j<n: j+=2
            t.append((line[i:j],'comment')); break
        if line[i]=='"':
            j=i+1
            while j<n and line[j]!='"':
                if line[j]=='\\': j+=1
                j+=1
            if j<n: j+=1
            t.append((line[i:j],'string')); i=j; continue
        if line[i] in ' \t':
            j=i
            while j<n and line[j] in ' \t': j+=1
            t.append((line[i:j],'space')); i=j; continue
        if line[i].isdigit() or (line[i]=='0' and i+1<n and line[i+1] in 'xX'):
            if line[i]=='0'and i+1<n and line[i+1]in'xX': j=i+2
            else: j=i
            while j<n and (line[j].isalnum() or line[j] in '.xXa-fA-F'): j+=1
            t.append((line[i:j],'number')); i=j; continue
        if line[i].isalpha() or line[i]=='_':
            j=i
            while j<n and (line[j].isalnum() or line[j]=='_'): j+=1
            w=line[i:j]
            if w in KW: t.append((w,'keyword'))
            elif w in RG: t.append((w,'register'))
            else: t.append((w,'text'))
            i=j; continue
        t.append((line[i],'text')); i+=1
    if not t: t.append(('','space'))
    return t

def gen_svg_page(pg_lines, start_ln, page_num, total_pages, total_lines, fname):
    lh=24; fs=14; cw=8.4; gutter=56; xc=gutter+16; hh=60; mt=2; mb=4; mw=794
    max_l=max(len(l) for l in pg_lines) if pg_lines else 10
    w=max(mw, xc+max_l*cw+30)
    h=hh+len(pg_lines)*lh+mt+mb+20
    out=[]
    out.append(f'<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 {w} {h}">')
    out.append(f'<style>text{{font-family:"Cascadia Code","Fira Code","JetBrains Mono","Consolas","Courier New",monospace;font-size:{fs}px;}}</style>')
    out.append(f'<rect width="{w}" height="{h}" fill="{BG}"/>')
    out.append(f'<rect x="0" y="0" width="{w}" height="{hh}" fill="{HDR_BG}"/>')
    out.append(f'<line x1="0" y1="{hh}" x2="{w}" y2="{hh}" stroke="{HDR_BORDER}" stroke-width="1.5"/>')
    out.append(f'<text x="20" y="24" fill="#343a40" font-size="16" font-family="Arial,Helvetica,sans-serif" font-weight="700">📄 {fname}</text>')
    out.append(f'<text x="20" y="48" fill="#868e96" font-size="12" font-family="Arial,Helvetica,sans-serif">第 {page_num} 页 · 共 {total_pages} 页 · {total_lines} 行</text>')
    cy=hh+mt
    out.append(f'<rect x="0" y="{hh}" width="{xc-8}" height="{h-hh}" fill="{GT_BG}"/>')
    out.append(f'<line x1="{xc-8}" y1="{hh}" x2="{xc-8}" y2="{h}" stroke="{GT_BORDER}" stroke-width="1"/>')
    for idx,line in enumerate(pg_lines):
        y=cy+idx*lh; ln=start_ln+idx
        out.append(f'<text x="{xc-14}" y="{y+lh//2+4}" fill="{LN_COLOR}" text-anchor="end" font-size="12">{ln}</text>')
        if not line.strip(): continue
        toks=tokenize(line); x=xc
        for val,typ in toks:
            if typ=='space': x+=(val.count(' ')+val.count('\t')*4)*cw
            else:
                c=CO.get(typ,'#212529'); e=val.replace('&','&amp;').replace('<','&lt;').replace('>','&gt;')
                out.append(f'<text x="{x:.1f}" y="{y+lh//2+4}" fill="{c}">{e}</text>')
                x+=len(val)*cw
    out.append(f'<text x="{w//2}" y="{h-8}" text-anchor="middle" fill="#adb5bd" font-size="10" font-family="Arial,Helvetica,sans-serif">- {page_num} -</text>')
    out.append('</svg>')
    return '\n'.join(out)

# === Main loop ===
for fname in FILES:
    src = os.path.join(BASE, fname)
    if not os.path.exists(src):
        print(f'SKIP {fname}'); continue

    with open(src, 'r', encoding='utf-8') as f:
        lines = f.readlines()
    total = len(lines)
    np = (total + LINES_PER_PAGE - 1) // LINES_PER_PAGE
    out_dir = os.path.join(BASE, fname + '_images')
    os.makedirs(out_dir, exist_ok=True)

    # Generate SVGs
    for p in range(1, np + 1):
        s = (p-1)*LINES_PER_PAGE; e = min(s+LINES_PER_PAGE, total)
        svg = gen_svg_page(lines[s:e], s+1, p, np, total, fname)
        with open(os.path.join(out_dir, f'code_page_{p}.svg'), 'w', encoding='utf-8') as f:
            f.write(svg)
    print(f'{fname}: {total} lines, {np} pages -> SVG OK')

    # Convert SVGs to PNGs via node + @resvg/resvg-js
    js = (
        'const fs=require("fs");const{Resvg}=require("@resvg/resvg-js");'
        'const dir=' + json.dumps(out_dir.replace('\\','\\\\')) + ';'
        'for(let p=1;p<=' + str(np) + ';p++){'
        'const s=dir+"\\\\code_page_"+p+".svg";'
        'const pn=dir+"\\\\code_page_"+p+".png";'
        'try{const d=fs.readFileSync(s,"utf8");const r=new Resvg(d,{background:"#ffffff"});'
        'const b=r.render();fs.writeFileSync(pn,b.asPng())}'
        'catch(e){console.log("  ERR:"+p+" "+e.message)}}'
    )
    subprocess.run(['node','-e',js], check=True)
    print(f'{fname}: PNG OK')

    # Merge PNGs into a single PDF via img2pdf
    import img2pdf
    png_files = sorted(
        [os.path.join(out_dir, f) for f in os.listdir(out_dir) if f.endswith('.png')],
        key=lambda x: int(os.path.basename(x).replace('code_page_','').replace('.png',''))
    )
    pdf_path = os.path.join(BASE, fname + '.pdf')
    with open(pdf_path, 'wb') as f:
        f.write(img2pdf.convert(png_files))
    kb = os.path.getsize(pdf_path) // 1024
    print(f'{fname}: PDF -> {pdf_path} ({kb}KB)')

print('\n=== All done! ===')

Customization

Parameter	Default	Description
`LINES_PER_PAGE`	50	Lines per page
`font_size`	14	Base font size (px)
`line_height`	24	Line spacing (px)
`COLOR_*`	—	Tweak colors for theme
`REGS`	`P0..P7`	Register/pin names to highlight

Tips

Always unpack tokens as for val, typ in tokens (not tt, tv) — val = code text, typ = type name for color lookup
SVG viewBox keeps content at 1x; resvg renders at native A4 resolution
If node PNG conversion is slow, break into smaller batches
Keep the _images/ folders (SVG+PNG) for later editing; the PDF is the deliverable