UIColor de Hex en Monotouch

Question

¿Cómo obtener un UIColor de un valor hexadecimal en Monotouch?

Answer 1

He encontrado algunas soluciones para Objective C y ninguno específicamente para MonoTouch Terminé el desarrollo de un método de extensión basado en la solución más popular para IOS:

public static class UIColorExtensions 
    { 
     public static UIColor FromHex(this UIColor color,int hexValue) 
     { 
      return UIColor.FromRGB(
       (((float)((hexValue & 0xFF0000) >> 16))/255.0f), 
       (((float)((hexValue & 0xFF00) >> 8))/255.0f), 
       (((float)(hexValue & 0xFF))/255.0f) 
      ); 
     } 
    } 

y utilizar de esta manera:

new UIColor().FromHex(0x4F6176); 

Actualización, parece que como fuera de Monotouch 5.4 UIColor no tiene un constructor sin parámetros así que úsala así:

UIColor.Clear.FromHex(0xD12229); 

Answer 2

Aquí uno que le permite utilizar una cadena como en CSS:

UIColor textColorNormal = UIColor.Clear.FromHexString("#f4f28d", 1.0f); 

Y aquí es la clase:

using System; 
using System.Drawing; 

using MonoTouch.Foundation; 
using MonoTouch.UIKit; 
using System.Globalization; 

namespace YourApp 
{ 
    public static class UIColorExtensions 
    { 
     public static UIColor FromHexString (this UIColor color, string hexValue, float alpha = 1.0f) 
     { 
      var colorString = hexValue.Replace ("#", ""); 
      if (alpha > 1.0f) { 
       alpha = 1.0f; 
      } else if (alpha < 0.0f) { 
       alpha = 0.0f; 
      } 

      float red, green, blue; 

      switch (colorString.Length) 
      { 
       case 3 : // #RGB 
       { 
        red = Convert.ToInt32(string.Format("{0}{0}", colorString.Substring(0, 1)), 16)/255f; 
        green = Convert.ToInt32(string.Format("{0}{0}", colorString.Substring(1, 1)), 16)/255f; 
        blue = Convert.ToInt32(string.Format("{0}{0}", colorString.Substring(2, 1)), 16)/255f; 
        return UIColor.FromRGBA(red, green, blue, alpha); 
       } 
       case 6 : // #RRGGBB 
       { 
        red = Convert.ToInt32(colorString.Substring(0, 2), 16)/255f; 
        green = Convert.ToInt32(colorString.Substring(2, 2), 16)/255f; 
        blue = Convert.ToInt32(colorString.Substring(4, 2), 16)/255f; 
        return UIColor.FromRGBA(red, green, blue, alpha); 
       } 

       default : 
         throw new ArgumentOutOfRangeException(string.Format("Invalid color value {0} is invalid. It should be a hex value of the form #RBG, #RRGGBB", hexValue)); 

      } 
     } 
    } 
} 

Answer 3

Tal vez esto le ayuda, si está utilizando Xamarin.Forms:

using Xamarin.Forms; 
using Xamarin.Forms.Platform.iOS; 

... 
Color.FromHex("#00FF00").ToUIColor(); 

Answer 4

Como una opción, por ejemplo

public static UIColor FromHEX(string hex) 
    { 
     int r = 0, g = 0, b = 0, a = 0; 

     if (hex.Contains("#")) 
      hex = hex.Replace("#", ""); 

     switch (hex.Length) 
     { 
      case 2: 
       r = int.Parse(hex, System.Globalization.NumberStyles.AllowHexSpecifier); 
       g = int.Parse(hex, System.Globalization.NumberStyles.AllowHexSpecifier); 
       b = int.Parse(hex, System.Globalization.NumberStyles.AllowHexSpecifier); 
       a = 255; 
       break; 
      case 3: 
       r = int.Parse(hex.Substring(0, 1), System.Globalization.NumberStyles.AllowHexSpecifier); 
       g = int.Parse(hex.Substring(1, 1), System.Globalization.NumberStyles.AllowHexSpecifier); 
       b = int.Parse(hex.Substring(2, 1), System.Globalization.NumberStyles.AllowHexSpecifier); 
       a = 255; 
       break; 
      case 4: 
       r = int.Parse(hex.Substring(0, 1), System.Globalization.NumberStyles.AllowHexSpecifier); 
       g = int.Parse(hex.Substring(1, 1), System.Globalization.NumberStyles.AllowHexSpecifier); 
       b = int.Parse(hex.Substring(2, 1), System.Globalization.NumberStyles.AllowHexSpecifier); 
       a = int.Parse(hex.Substring(3, 1), System.Globalization.NumberStyles.AllowHexSpecifier); 
       break; 
      case 6: 
       r = int.Parse(hex.Substring(0, 2), System.Globalization.NumberStyles.AllowHexSpecifier); 
       g = int.Parse(hex.Substring(2, 2), System.Globalization.NumberStyles.AllowHexSpecifier); 
       b = int.Parse(hex.Substring(4, 2), System.Globalization.NumberStyles.AllowHexSpecifier); 
       a = 255; 
       break; 
      case 8: 
       r = int.Parse(hex.Substring(0, 2), System.Globalization.NumberStyles.AllowHexSpecifier); 
       g = int.Parse(hex.Substring(2, 2), System.Globalization.NumberStyles.AllowHexSpecifier); 
       b = int.Parse(hex.Substring(4, 2), System.Globalization.NumberStyles.AllowHexSpecifier); 
       a = int.Parse(hex.Substring(6, 2), System.Globalization.NumberStyles.AllowHexSpecifier); 
       break; 
     } 

     return UIColor.FromRGBA(r, g, b, a); 
    }