Checkpoint before more window sizing work

ui_theme.py

@@ -0,0 +1,97 @@
+"""External UI theme loader for the warehouse desktop application.
+
+The module reads ``ui_theme.json`` from the workspace root and exposes a few
+helpers to resolve fonts, colors, paddings and section-specific configuration
+without hardcoding presentation details inside each window module.
+"""
+
+from __future__ import annotations
+
+import json
+from functools import lru_cache
+from pathlib import Path
+from typing import Any
+
+THEME_PATH = Path(__file__).with_name("ui_theme.json")
+
+
+@lru_cache(maxsize=1)
+def load_theme() -> dict[str, Any]:
+    """Load the external JSON theme, returning an empty dict on failure."""
+
+    try:
+        return json.loads(THEME_PATH.read_text(encoding="utf-8"))
+    except Exception:
+        return {}
+
+
+def reload_theme() -> dict[str, Any]:
+    """Clear cache and reload the theme from disk."""
+
+    load_theme.cache_clear()
+    return load_theme()
+
+
+def theme_section(name: str, default: dict[str, Any] | None = None) -> dict[str, Any]:
+    """Return one top-level theme section as a dictionary."""
+
+    theme = load_theme()
+    value = theme.get(name)
+    if isinstance(value, dict):
+        return value
+    return dict(default or {})
+
+
+def theme_value(section: dict[str, Any], key: str, default: Any = None) -> Any:
+    """Return a scalar theme value from a section."""
+
+    return section.get(key, default)
+
+
+def theme_color(section: dict[str, Any], key: str, default: Any = None) -> Any:
+    """Return a CTk-compatible color value (string or light/dark tuple)."""
+
+    value = section.get(key, default)
+    if isinstance(value, list) and len(value) == 2:
+        return tuple(value)
+    return value
+
+
+def theme_padding(section: dict[str, Any], key: str, default: tuple[int, ...]) -> tuple[int, ...]:
+    """Return tuple-like padding values from a JSON list."""
+
+    value = section.get(key)
+    if isinstance(value, list):
+        try:
+            return tuple(int(v) for v in value)
+        except Exception:
+            return default
+    return default
+
+
+def theme_font(section: dict[str, Any], key: str, default: tuple[Any, ...]) -> tuple[Any, ...]:
+    """Resolve a Tk font tuple from JSON."""
+
+    spec = section.get(key)
+    if not isinstance(spec, dict):
+        return default
+
+    family = spec.get("family", default[0] if default else "Segoe UI")
+    size = int(spec.get("size", default[1] if len(default) > 1 else 10))
+
+    parts: list[Any] = [family, size]
+
+    weight = str(spec.get("weight", "")).strip().lower()
+    if weight in {"bold", "normal"} and weight != "normal":
+        parts.append(weight)
+
+    slant = str(spec.get("slant", "")).strip().lower()
+    if slant == "italic":
+        parts.append(slant)
+
+    if bool(spec.get("underline", False)):
+        parts.append("underline")
+    if bool(spec.get("overstrike", False)):
+        parts.append("overstrike")
+
+    return tuple(parts)