Add helper method for RGB24 convert

src/RxTelegram.Bot/Interface/ChatBackground/BackgroundTypeWallpaper.cs

@@ -1,6 +1,31 @@
+using RxTelegram.Bot.Interface.BaseTypes;
+
 namespace RxTelegram.Bot.Interface.ChatBackground;
 
-public class BackgroundTypeWallpaper
+public class BackgroundTypeWallpaper : BackgroundType
 {
-
+    /// <summary>
+    /// Type of the background, always “wallpaper”
+    /// </summary>
+    public override string Type { get; } = "wallpaper";
+
+    /// <summary>
+    /// Document with the wallpaper
+    /// </summary>
+    public Document Document { get; set; }
+
+    /// <summary>
+    /// Dimming of the background in dark themes, as a percentage; 0-100
+    /// </summary>
+    public int DarkThemeDimming { get; set; }
+
+    /// <summary>
+    /// Optional. True, if the wallpaper is downscaled to fit in a 450x450 square and then box-blurred with radius 12
+    /// </summary>
+    public bool IsBlurred { get; set; }
+
+    /// <summary>
+    /// Optional. True, if the background moves slightly when the device is tilted
+    /// </summary>
+    public bool IsMoving { get; set; }
 }

src/RxTelegram.Bot/Utils/HexToRGB24Converter.cs

@@ -0,0 +1,26 @@
+using System;
+using System.Globalization;
+
+namespace RxTelegram.Bot.Utils;
+
+public class HexToRgb24
+{
+    public int Convert(string hexColor) => int.Parse(FormatHexString(hexColor), NumberStyles.HexNumber);
+
+    public bool TryConvert(string hexColor, out int result) => int.TryParse(FormatHexString(hexColor), NumberStyles.HexNumber, null, out result);
+
+    private static string FormatHexString(string hexColor)
+    {
+        hexColor = hexColor.TrimStart('#');
+        if (hexColor.Length == 3)
+        {
+            hexColor = string.Concat(hexColor[0], hexColor[0], hexColor[1], hexColor[1], hexColor[2], hexColor[2]);
+        }
+        else if (hexColor.Length != 6)
+        {
+            throw new ArgumentException("Hex color must be 3 or 6 characters long.");
+        }
+
+        return hexColor;
+    }
+}