Updated

backend/layout_preview.py

@@ -0,0 +1,131 @@
+import os
+from typing import Dict, Optional
+
+import yaml
+
+
+def create_layout_svg_from_gds(yaml_content: str, output_path: str, pdk_registry, project_dir: str = None) -> str:
+    """Create an SVG preview by placing real public _BB.gds cells from layout YAML."""
+    layout = yaml.safe_load(yaml_content) or {}
+    try:
+        return _create_with_gdstk(layout, output_path, pdk_registry, project_dir)
+    except ImportError as gdstk_error:
+        try:
+            return _create_with_nazca(layout, output_path, pdk_registry, project_dir)
+        except ImportError as nazca_error:
+            raise RuntimeError(
+                "Layout SVG requires GDS geometry support. Install gdstk, or fix nazca dependencies. "
+                f"gdstk import failed: {gdstk_error}. nazca import failed: {nazca_error}"
+            ) from nazca_error
+
+
+def _create_with_gdstk(layout: dict, output_path: str, pdk_registry, project_dir: Optional[str]) -> str:
+    import gdstk
+
+    library = gdstk.Library()
+    cell_cache = {}
+    top = _build_gdstk_cell(gdstk, library, layout, pdk_registry, project_dir, cell_cache)
+    os.makedirs(os.path.dirname(output_path), exist_ok=True)
+    top.write_svg(output_path)
+    return output_path
+
+
+def _build_gdstk_cell(gdstk, library, layout: dict, pdk_registry, project_dir: Optional[str], cell_cache: Dict):
+    cell_name = _safe_cell_name(layout.get("name") or "layout", library)
+    top = library.new_cell(cell_name)
+
+    for instance_name, instance in (layout.get("instances") or {}).items():
+        component = str(instance.get("component") or "")
+        x = _number(instance.get("x"))
+        y = _number(instance.get("y"))
+        rotation = _number(instance.get("rotation")) * 3.141592653589793 / 180
+        child = _resolve_child_cell(gdstk, library, component, pdk_registry, project_dir, cell_cache)
+        if child is None:
+            raise FileNotFoundError(f"Unable to resolve _BB.gds for instance {instance_name}: {component}")
+        top.add(gdstk.Reference(child, origin=(x, y), rotation=rotation))
+
+    return top
+
+
+def _resolve_child_cell(gdstk, library, component: str, pdk_registry, project_dir: Optional[str], cell_cache: Dict):
+    if component in cell_cache:
+        return cell_cache[component]
+
+    local_layout = _load_local_layout(component, project_dir)
+    if local_layout is not None:
+        child = _build_gdstk_cell(gdstk, library, local_layout, pdk_registry, project_dir, cell_cache)
+        cell_cache[component] = child
+        return child
+
+    asset = pdk_registry.resolve(component)
+    if not asset.gds_path:
+        return None
+    child = _import_gds_cell(gdstk, library, asset.gds_path)
+    cell_cache[component] = child
+    return child
+
+
+def _import_gds_cell(gdstk, library, gds_path: str):
+    source = gdstk.read_gds(gds_path)
+    top_cells = source.top_level()
+    if not top_cells:
+        raise ValueError(f"No top-level cell found in {gds_path}")
+    for source_cell in source.cells:
+        if _library_cell_by_name(library, source_cell.name) is None:
+            library.add(source_cell)
+    return top_cells[0]
+
+
+def _create_with_nazca(layout: dict, output_path: str, pdk_registry, project_dir: Optional[str]) -> str:
+    import nazca as nd
+
+    png_path = os.path.splitext(output_path)[0] + ".gds"
+    with nd.Cell(str(layout.get("name") or "layout")) as top:
+        for instance_name, instance in (layout.get("instances") or {}).items():
+            component = str(instance.get("component") or "")
+            asset = pdk_registry.resolve(component)
+            if not asset.gds_path:
+                raise FileNotFoundError(f"Unable to resolve _BB.gds for instance {instance_name}: {component}")
+            loaded = nd.load_gds(asset.gds_path)
+            loaded.put(_number(instance.get("x")), _number(instance.get("y")), _number(instance.get("rotation")))
+    nd.export_gds(top, filename=png_path)
+    raise RuntimeError(
+        "Nazca can build the placed GDS, but SVG preview export requires gdstk in this backend."
+    )
+
+
+def _load_local_layout(component: str, project_dir: Optional[str]) -> Optional[dict]:
+    if not project_dir or "/" in component or "\\" in component or component == "generate_with_forge":
+        return None
+    for ext in (".yml", ".yaml"):
+        path = os.path.join(project_dir, f"{component}{ext}")
+        if os.path.exists(path):
+            with open(path, "r", encoding="utf-8") as file:
+                return yaml.safe_load(file) or {}
+    return None
+
+
+def _safe_cell_name(name, library) -> str:
+    base = "".join(ch if ch.isalnum() or ch in "._$" else "_" for ch in str(name)) or "layout"
+    candidate = base
+    counter = 1
+    while _library_cell_by_name(library, candidate) is not None:
+        counter += 1
+        candidate = f"{base}_{counter}"
+    return candidate
+
+
+def _library_cell_by_name(library, name: str):
+    for cell in library.cells:
+        if cell.name == name:
+            return cell
+    return None
+
+
+def _number(value, default=0.0) -> float:
+    try:
+        if value is None or value == "":
+            return default
+        return float(value)
+    except (TypeError, ValueError):
+        return default