Invalid Color Input Causes Crash

[aaricantto]

🐛 Bug Report: complementary() crashes with ValueError on invalid hex color input

Summary

WebODM throws an unhandled exception when theme color input is not a valid 6-digit hex string. The error occurs in the complementary() function located in webodm/app/templatetags/settings.py.

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🔥 Stack Trace

ValueError: invalid literal for int() with base 16: 'bl'

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📍 Location of Error

The issue originates from the following line:

comp = ['%02X' % (255 - int(a, 16)) for a in rgb]

It assumes the input is a valid hex string (e.g., #AABBCC), but if the input is "blue", "blabla", "bl", or anything invalid, it causes a crash.

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💥 Problematic Code

Here is the current version of the function:

@register.simple_tag
def complementary(hexcolor):
    """Returns complementary RGB color
    Example: complementaryColor('#FFFFFF') --> '#000000'
    """
    if hexcolor[0] == '#':
        hexcolor = hexcolor[1:]
    rgb = (hexcolor[0:2], hexcolor[2:4], hexcolor[4:6])
    comp = ['%02X' % (255 - int(a, 16)) for a in rgb]
    return '#' + ''.join(comp)

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✅ Recommended Fix

Here’s a more robust version that validates the input and prevents crashes:

@register.simple_tag
def complementary(hexcolor):
    """Returns complementary RGB color"""
    try:
        if hexcolor.startswith('#'):
            hexcolor = hexcolor[1:]
        if len(hexcolor) != 6:
            raise ValueError("Invalid hex color length")
        rgb = (hexcolor[0:2], hexcolor[2:4], hexcolor[4:6])
        comp = ['%02X' % (255 - int(a, 16)) for a in rgb]
        return '#' + ''.join(comp)
    except Exception as e:
        logger.warning(f"complementary() failed with input '{hexcolor}': {e}")
        return '#FFFFFF'  # fallback to white

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🧪 Steps to Reproduce

1. Set a theme color in the environment, database, or UI to blue, blabla, or other invalid value.
2. Load a page that uses {% complementary theme_color %}.
3. Observe a ValueError traceback in the logs and a 500 error in the browser.

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💻 Environment

• WebODM Version: webodm_webapp:latest (Docker)
• Deployment: Docker Swarm
• Python: 3.8+
• Customization: Using THEME_COLOR_PRIMARY=blue in .env

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💡 Suggested Action

• Add the validation fix shown above to complementary().
• Optionally sanitize theme color values wherever they are configured or stored.
• Consider applying a default/fallback color (e.g., #FFFFFF) when inputs are invalid.

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❤️ Thanks!

Thank you for the awesome project! WebODM is an incredibly valuable open-source tool for drone data processing. I'd be happy to submit a PR with this fix if you'd prefer it that way