1using System.Drawing;
 2
 3namespace WindowCapture.Helpers
 4{
 5    /// <summary>
 6    /// Shared color utilities: brightness, tint conversion, adaptive text color.
 7    /// </summary>
 8    public static class ColorHelper
 9    {
10        /// <summary>
11        /// Perceived brightness of a color (0.0 = black, 1.0 = white).
12        /// Uses ITU-R BT.601 luma weights: 0.299R + 0.587G + 0.114B.
13        /// </summary>
14        public static float GetBrightness(Color c)
15        {
16            return (c.R * 0.299f + c.G * 0.587f + c.B * 0.114f) / 255f;
17        }
18
19        /// <summary>
20        /// Convert ARGB color + alpha to AABBGGRR int for DWM SetWindowCompositionAttribute.
21        /// </summary>
22        public static int ToABGR(int alpha, Color c)
23        {
24            return (alpha << 24) | (c.B << 16) | (c.G << 8) | c.R;
25        }
26
27        /// <summary>
28        /// Return a light or dark text color depending on the tint brightness.
29        /// </summary>
30        public static Color GetAdaptiveTextColor(Color tint, int textAlpha = 220, float threshold = 0.45f)
31        {
32            float br = GetBrightness(tint);
33            return br < threshold
34                ? Color.FromArgb(textAlpha, 255, 255, 255)
35                : Color.FromArgb(textAlpha, 0, 0, 0);
36        }
37
38        /// <summary>
39        /// Return a copy of the color with a different alpha value (0-255).
40        /// </summary>
41        public static Color WithAlpha(Color c, int alpha)
42        {
43            return Color.FromArgb(alpha, c.R, c.G, c.B);
44        }
45
46        public static string ColorToHex(Color c)
47        {
48            return string.Format("{0:X2}{1:X2}{2:X2}{3:X2}", c.A, c.R, c.G, c.B);
49        }
50
51        public static string ColorToHexWeb(Color c)
52        {
53            if (c.A == 255)
54                return string.Format("#{0:X2}{1:X2}{2:X2}", c.R, c.G, c.B);
55            else
56                return string.Format("#{0:X2}{1:X2}{2:X2}{3:X2}", c.A, c.R, c.G, c.B);
57        }
58    }
59}