90 lines
2.8 KiB
Python
90 lines
2.8 KiB
Python
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"""Schemdraw code block renderer.
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Executes Python schemdraw code from a chapter code block and returns SVG.
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Usage in markdown:
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```schemdraw
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import schemdraw
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from schemdraw import elements as e
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with schemdraw.Drawing(show=False) as d:
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d += e.Resistor().right().label('R1')
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```
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"""
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import base64
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import subprocess
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import sys
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import tempfile
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import textwrap
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from pathlib import Path
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def render(code: str, project_dir: Path = None) -> str:
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"""Execute schemdraw code, return inline SVG as HTML <img> tag.
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Args:
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code: Python source code using schemdraw
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project_dir: project root (unused, kept for interface consistency)
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Returns:
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HTML string with inline base64 SVG image
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"""
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# Write code to a temp script and execute, capturing SVG output
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wrapped = textwrap.dedent(code).strip()
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with tempfile.NamedTemporaryFile(
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suffix='.svg', mode='w+', encoding='utf-8', delete=False
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) as tmp:
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svg_path = Path(tmp.name)
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try:
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# Execute the schemdraw code as a subprocess for isolation.
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# The script must produce 'OUTPUT: <svg filename>' on the last line,
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# or we inject a save hook.
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script = _wrap_code(wrapped, str(svg_path))
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result = subprocess.run(
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[sys.executable, '-c', script],
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capture_output=True, text=True, timeout=30,
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)
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if result.returncode != 0:
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return (
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f'<div class="warning">'
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f'Schemdraw error:<pre>{result.stderr[:500] or result.stdout[:500]}</pre>'
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f'</div>'
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)
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# Read the generated SVG
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if svg_path.exists() and svg_path.stat().st_size > 0:
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svg_content = svg_path.read_text(encoding='utf-8')
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b64 = base64.b64encode(svg_content.encode('utf-8')).decode('ascii')
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return (
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f'<figure class="img-sm">'
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f'<img src="data:image/svg+xml;base64,{b64}"'
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f' alt="schemdraw diagram">'
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f'</figure>'
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)
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else:
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return (
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f'<div class="warning">'
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f'Schemdraw ran but produced no SVG output.'
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f'</div>'
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)
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finally:
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if svg_path.exists():
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svg_path.unlink(missing_ok=True)
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def _wrap_code(code: str, svg_path: str) -> str:
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"""Wrap user code to redirect schemdraw output to a file."""
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# schemdraw writes SVG to the 'file' parameter of Drawing().
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# We modify the code to inject file= if missing.
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if "file=" not in code and "Drawing(" in code:
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code = code.replace(
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'Drawing(show=False)',
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f"Drawing(show=False, file=r'{svg_path}')",
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)
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code = code.replace(
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'Drawing()',
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f"Drawing(show=False, file=r'{svg_path}')",
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)
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return code
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