robloo
5 years ago
6 changed files with 174 additions and 60 deletions
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using System; |
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using System.Globalization; |
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using System.Collections.Generic; |
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using Avalonia.Media; |
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using System.Text; |
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namespace Avalonia.Controls.Primitives |
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{ |
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/// <summary>
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/// Contains helpers useful when working with color names.
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/// </summary>
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public static class ColorNameHelpers |
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{ |
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private static readonly Dictionary<Color, string> cachedDisplayNames = new Dictionary<Color, string>(); |
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private static readonly object cacheMutex = new object(); |
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/// <summary>
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/// Determines if color display names are supported based on the current thread culture.
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/// </summary>
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/// <remarks>
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/// Only English names are currently supported following known color names.
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/// In the future known color names could be localized.
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/// </remarks>
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public static bool ToDisplayNameExists |
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{ |
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get => CultureInfo.CurrentUICulture.Name.StartsWith("EN", StringComparison.OrdinalIgnoreCase); |
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} |
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/// <summary>
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/// Determines an approximate display name for the given color.
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/// </summary>
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/// <param name="color">The color to get the display name for.</param>
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/// <returns>The approximate color display name.</returns>
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public static string ToDisplayName(Color color) |
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{ |
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// Without rounding, there are 16,777,216 possible RGB colors (without alpha).
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// This is too many to cache and search through for performance reasons.
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// It is also needlessly large as there are only ~140 known/named colors.
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// Therefore, rounding of the input color's component values is done to
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// reduce the color space into something more useful.
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double rounding = 5; |
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var roundedColor = new Color( |
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0xFF, |
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Convert.ToByte(Math.Round(color.R / rounding) * rounding), |
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Convert.ToByte(Math.Round(color.G / rounding) * rounding), |
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Convert.ToByte(Math.Round(color.B / rounding) * rounding)); |
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// Attempt to use a previously cached display name
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lock (cacheMutex) |
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{ |
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if (cachedDisplayNames.TryGetValue(roundedColor, out var displayName)) |
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{ |
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return displayName; |
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} |
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} |
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// Find the closest known color by measuring 3D Euclidean distance (ignore alpha)
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var closestKnownColor = KnownColor.None; |
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var closestKnownColorDistance = double.PositiveInfinity; |
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var knownColors = (KnownColor[])Enum.GetValues(typeof(KnownColor)); |
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for (int i = 1; i < knownColors.Length; i++) // Skip 'None'
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{ |
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// Transparent is skipped since alpha is ignored making it equivalent to White
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if (knownColors[i] != KnownColor.Transparent) |
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{ |
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Color knownColor = KnownColors.ToColor(knownColors[i]); |
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double distance = Math.Sqrt( |
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Math.Pow((double)(roundedColor.R - knownColor.R), 2.0) + |
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Math.Pow((double)(roundedColor.G - knownColor.G), 2.0) + |
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Math.Pow((double)(roundedColor.B - knownColor.B), 2.0)); |
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if (distance < closestKnownColorDistance) |
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{ |
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closestKnownColor = knownColors[i]; |
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closestKnownColorDistance = distance; |
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} |
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} |
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} |
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// Return the closest known color as the display name
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// Cache results for next time as well
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if (closestKnownColor != KnownColor.None) |
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{ |
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StringBuilder sb = new StringBuilder(); |
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string name = closestKnownColor.ToString(); |
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// Add spaces converting PascalCase to human-readable names
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for (int i = 0; i < name.Length; i++) |
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{ |
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if (i != 0 && |
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char.IsUpper(name[i])) |
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{ |
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sb.Append(' '); |
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} |
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sb.Append(name[i]); |
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} |
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string displayName = sb.ToString(); |
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lock (cacheMutex) |
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{ |
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cachedDisplayNames.Add(roundedColor, displayName); |
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} |
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return displayName; |
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} |
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else |
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{ |
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return string.Empty; |
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} |
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} |
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} |
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} |
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