#!/usr/bin/env python3
"""
Script: ASCII Art to Image Converter
Description: Extracts ASCII art diagrams from markdown and converts them to PNG images
for clean PDF rendering.
Usage:
python ascii2image.py input.md output.md --img-dir ./images
This script:
1. Finds ASCII art blocks (code blocks containing box-drawing characters)
2. Renders them as PNG images using DejaVu Sans Mono font
3. Outputs modified markdown with image references
"""
import argparse
import hashlib
import re
import sys
from pathlib import Path
try:
from PIL import Image, ImageDraw, ImageFont
except ImportError:
print("Error: Pillow is required. Install with: pip install Pillow")
sys.exit(1)
# Box-drawing characters that indicate ASCII art
BOX_CHARS = set("┌┐└┘├┤┬┴┼─│═║╔╗╚╝╠╣╦╩╬▼▲◄►")
# Font settings
FONT_PATH = "/usr/share/fonts/truetype/dejavu/DejaVuSansMono.ttf"
FONT_SIZE = 14
LINE_HEIGHT = 18
PADDING = 20
BG_COLOR = "#f8f9fa" # Light gray background
TEXT_COLOR = "#1a1a2e" # Dark text
BORDER_COLOR = "#dee2e6" # Border color
def is_ascii_art(text: str) -> bool:
"""Check if text contains ASCII art box-drawing characters."""
return any(char in BOX_CHARS for char in text)
def extract_code_blocks(markdown: str) -> list[tuple[int, int, str, str]]:
"""
Extract code blocks from markdown.
Returns list of (start_pos, end_pos, language, content) tuples.
"""
# Match fenced code blocks: ```language\n...\n```
pattern = r"```(\w*)\n(.*?)```"
blocks = []
for match in re.finditer(pattern, markdown, re.DOTALL):
start = match.start()
end = match.end()
lang = match.group(1)
content = match.group(2)
# Only process blocks that look like ASCII art
if is_ascii_art(content) and lang in ("", "text", "ascii", "diagram"):
blocks.append((start, end, lang, content))
return blocks
def render_ascii_to_image(text: str, output_path: Path) -> bool:
"""Render ASCII art text to a PNG image."""
try:
font = ImageFont.truetype(FONT_PATH, FONT_SIZE)
except OSError:
# Fallback to default font
font = ImageFont.load_default()
lines = text.rstrip().split("\n")
# Calculate image dimensions
max_width = 0
for line in lines:
bbox = font.getbbox(line)
width = bbox[2] - bbox[0] if bbox else len(line) * 8
max_width = max(max_width, width)
img_width = max_width + (PADDING * 2)
img_height = (len(lines) * LINE_HEIGHT) + (PADDING * 2)
# Create image with background
img = Image.new("RGB", (img_width, img_height), BG_COLOR)
draw = ImageDraw.Draw(img)
# Draw border
draw.rectangle(
[1, 1, img_width - 2, img_height - 2],
outline=BORDER_COLOR,
width=1
)
# Draw text
y = PADDING
for line in lines:
draw.text((PADDING, y), line, font=font, fill=TEXT_COLOR)
y += LINE_HEIGHT
# Save image
output_path.parent.mkdir(parents=True, exist_ok=True)
img.save(output_path, "PNG", optimize=True)
return True
def process_markdown(
input_text: str,
img_dir: Path,
base_name: str = "diagram"
) -> tuple[str, int]:
"""
Process markdown, converting ASCII art blocks to images.
Returns (modified_markdown, num_conversions).
"""
blocks = extract_code_blocks(input_text)
if not blocks:
return input_text, 0
# Process blocks in reverse order to preserve positions
result = input_text
converted = 0
for start, end, lang, content in reversed(blocks):
# Generate unique filename based on content hash
content_hash = hashlib.md5(content.encode()).hexdigest()[:8]
img_name = f"{base_name}_{content_hash}.png"
img_path = img_dir / img_name
if render_ascii_to_image(content, img_path):
# Replace code block with image reference
# Use relative path for markdown
rel_path = img_path.name
replacement = f""
result = result[:start] + replacement + result[end:]
converted += 1
return result, converted
def process_file(
input_path: Path,
output_path: Path,
img_dir: Path
) -> int:
"""Process a single markdown file."""
with open(input_path, "r", encoding="utf-8") as f:
content = f.read()
base_name = input_path.stem.replace("-", "_")
processed, num_converted = process_markdown(content, img_dir, base_name)
with open(output_path, "w", encoding="utf-8") as f:
f.write(processed)
return num_converted
def main():
parser = argparse.ArgumentParser(
description="Convert ASCII art in markdown to PNG images"
)
parser.add_argument("input", help="Input markdown file or '-' for stdin")
parser.add_argument("output", help="Output markdown file or '-' for stdout")
parser.add_argument(
"--img-dir",
default="./diagrams",
help="Directory to save generated images (default: ./diagrams)"
)
parser.add_argument(
"--verbose", "-v",
action="store_true",
help="Verbose output"
)
args = parser.parse_args()
img_dir = Path(args.img_dir)
# Read input
if args.input == "-":
content = sys.stdin.read()
base_name = "diagram"
else:
input_path = Path(args.input)
if not input_path.exists():
print(f"Error: Input file not found: {input_path}", file=sys.stderr)
sys.exit(1)
with open(input_path, "r", encoding="utf-8") as f:
content = f.read()
base_name = input_path.stem.replace("-", "_")
# Process
processed, num_converted = process_markdown(content, img_dir, base_name)
# Write output
if args.output == "-":
print(processed)
else:
output_path = Path(args.output)
output_path.parent.mkdir(parents=True, exist_ok=True)
with open(output_path, "w", encoding="utf-8") as f:
f.write(processed)
if args.verbose:
print(f"Converted {num_converted} ASCII art blocks to images", file=sys.stderr)
return 0
if __name__ == "__main__":
sys.exit(main())
