Add add_legend method

[giswqs]

[github-actions]

🚀 Deployed on https://69214ccbc9f444aad6a0e7ac--opengeos.netlify.app

[Copilot]

Pull request overview

This PR adds a new add_legend method to the MapLibreMap class, enabling users to add customizable legends to their maps with support for built-in legend presets (NLCD and NWI) and various customization options including colors, shapes, and positioning.

• Adds add_legend method with support for custom and built-in legend configurations
• Implements three shape types (rectangle, circle, line) for legend items
• Includes two built-in legend presets for common land cover classifications

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[Copilot]

Error handling uses print statements instead of raising exceptions, which is inconsistent with the codebase patterns. Other methods in this file (e.g., add_popup at line 1303, add_widget_control at line 1370) raise ValueError for validation errors. This method should raise exceptions instead of printing and returning early.

Consider changing:

• Line 5249-5252: raise ValueError instead of print + return
• Line 5261-5262: raise ValueError instead of print + return
• Line 5264-5267: raise ValueError instead of print + return

[Copilot]

The position parameter documentation lists valid values but there's no validation to ensure only these values are accepted. Invalid position values will be passed directly to add_widget_control which may have its own validation. Consider adding validation at this level for better error messages and early failure detection:

if position not in ["top-left", "top-right", "bottom-left", "bottom-right"]:
    raise ValueError("position must be one of 'top-left', 'top-right', 'bottom-left', or 'bottom-right'")

[Copilot]

Potential XSS vulnerability: The bg_color parameter is inserted directly into the CSS without validation or sanitization. Similar to the color values in legend items, a malicious value could inject arbitrary CSS. Consider validating bg_color against expected patterns or escaping it appropriately.

[Copilot]

Color normalization logic could fail if colors contain values that don't start with '#' but also aren't valid color codes (e.g., colors with "rgba()" or "rgb()" format). The current logic assumes all colors are either hex codes with or without '#'. Consider validating or handling other color formats, or document that only hex colors are supported.

[Copilot]

The built-in legend dictionaries are defined as a local constant within the method. This makes them harder to discover, test, and reuse. Consider moving BUILTIN_LEGENDS to module or class level as a constant, similar to how other configuration constants are typically organized. This would also allow for easier extension and documentation of available built-in legends.