XY Color Space (CIE 1931) Support for EntityControl

Overview

The EntityControl component now supports XY color space (CIE 1931) alongside the existing RGB and CCT color controls. This implementation provides a HUE slider abstraction that makes it intuitive for users to control lights that use the XY color model.

Features Added

1. XY Color Space Detection

supportsXy property detects if a light entity supports the XY color mode
Updates hasAdvancedControls to include XY support

2. XY Color State Management

currentXyColor property retrieves current XY coordinates from the entity state
currentHue and currentSaturation properties convert XY to HSV for user-friendly controls
Default to D65 white point [0.3127, 0.3290] when no XY data is available

3. XY Color Controls UI

Hue Slider: Intuitive 0-360° hue control with rainbow gradient background
Saturation Slider: 0-100% saturation control with gradient from white to full color
Color Preset Buttons: Quick access to common colors in XY space
Current Color Indicator: Shows the current XY coordinates and color preview

4. Color Conversion Functions

XY to RGB Conversion (`xyToRgb`)

Converts CIE 1931 xy coordinates to RGB values
Uses proper XYZ to sRGB transformation matrix
Applies gamma correction for accurate color representation
Clamps values to valid RGB range [0-255]

XY to HSV Conversion

xyToHue: Converts XY coordinates to HSV hue (0-360°)
xyToSaturation: Converts XY coordinates to HSV saturation (0-1)

HSV to XY Conversion (`hueToXy`)

Converts HSV hue and saturation back to XY coordinates
Handles proper RGB to XYZ transformation
Applies inverse gamma correction
Clamps to valid CIE 1931 color space bounds

Utility Functions

xyToRgbColor: Returns Qt color object for UI display
hueToRgbColor: Returns pure hue color for gradient displays

Usage

In QML

The XY controls automatically appear for lights that support the XY color mode:

EntityControl {
    entityId: "light.philips_hue_bulb"
    displayName: "Living Room Light"
    controlType: "light"
    showExpandedControls: true
}

Home Assistant Integration

The component sends XY color commands to Home Assistant:

// Set specific XY coordinates
controlActivated(entityId, "turn_on", { xy_color: [0.7006, 0.2993] })

// Set color via hue/saturation sliders
var xyColor = hueToXy(180, 0.8) // Cyan at 80% saturation
controlActivated(entityId, "turn_on", { xy_color: [xyColor.x, xyColor.y] })

Color Presets

The implementation includes 6 carefully chosen color presets in XY space:

Red: [0.7006, 0.2993] - Deep red
Green: [0.1724, 0.7468] - Vivid green
Blue: [0.1357, 0.0399] - Pure blue
Yellow: [0.4316, 0.5016] - Bright yellow
White: [0.3127, 0.3290] - D65 white point
Deep Blue: [0.1670, 0.0090] - Deep blue

Entity Information Display

The Entity Information section now shows:

Current XY coordinates in 4-decimal precision
Properly formatted as “(x, y)” pairs
Only displays when XY color data is available

Technical Details

Color Space Accuracy

Uses proper sRGB color space transformations
Implements CIE 1931 XY chromaticity coordinates
Handles edge cases with fallback to D65 white point
Maintains color accuracy across different light hardware

Performance Considerations

Color conversions are cached where possible
Slider updates are debounced to prevent excessive API calls
Gradient generation is optimized for smooth UI rendering

Compatibility

Works alongside existing RGB and CCT controls
Automatically hides when XY mode is not supported
Maintains backward compatibility with existing configurations

Browser Support

The XY color space implementation works with:

Philips Hue lights (native XY support)
LIFX lights (with XY color mode)
Other smart lights supporting CIE 1931 XY color space
Home Assistant lights with xy in supported_color_modes

Future Enhancements

Potential improvements could include:

2D color picker with XY gamut visualization
Color temperature to XY conversion
Gamut limiting for specific light models
Color harmony suggestions based on current XY values