Color.java

package com.bitwig.extension.api;

public class Color
{
   private Color(final double red, final double green, final double blue, final double alpha)
   {
      mRed = red;
      mGreen = green;
      mBlue = blue;
      mAlpha = alpha;
   }

   public static Color fromRGB(double red, double green, double blue)
   {
      return new Color(red, green, blue, 1);
   }

   public static Color fromRGBA(double red, double green, double blue, double alpha)
   {
      return new Color(red, green, blue, alpha);
   }

   public static Color fromRGB255(final int red, final int green, final int blue)
   {
      return new Color(red / 255.0, green / 255.0, blue / 255.0, 1);
   }

   public static Color fromRGBA255(final int red, final int green, final int blue, final int alpha)
   {
      return new Color(red / 255.0, green / 255.0, blue / 255.0, alpha / 255.0);
   }

   public static Color fromHex(String hex)
   {
      if (hex.isEmpty())
         return nullColor();

      // Skip the initialial '#'
      if (hex.charAt(0) == '#')
         hex = hex.substring(1);

      // Check that the color is an hex value
      for (int i = 0; i < hex.length(); ++i)
      {
         char c = hex.charAt(i);
         if (('0' <= c && c <= '9') ||
            ('a' <= c && c <= 'f') ||
            ('A' <= c && c <= 'F'))
            continue;

         return nullColor();
      }

      switch (hex.length())
      {
         case 3: // RGB
         {
            int r = Integer.parseInt(hex.substring(0, 1), 16);
            int g = Integer.parseInt(hex.substring(1, 2), 16);
            int b = Integer.parseInt(hex.substring(2, 3), 16);
            return fromRGB(r / 15.0, g / 15.0, b / 15.0);
         }

         case 4: // RGBA
         {
            int r = Integer.parseInt(hex.substring(0, 1), 16);
            int g = Integer.parseInt(hex.substring(1, 2), 16);
            int b = Integer.parseInt(hex.substring(2, 3), 16);
            int a = Integer.parseInt(hex.substring(2, 3), 16);
            return fromRGBA(r / 15.0, g / 15.0, b / 15.0, a / 15.0);
         }

         case 6: // RRGGBB
         {
            int r = Integer.parseInt(hex.substring(0, 2), 16);
            int g = Integer.parseInt(hex.substring(2, 4), 16);
            int b = Integer.parseInt(hex.substring(4, 6), 16);
            return fromRGB255(r, g, b);
         }

         case 8: // RRGGBBAA
         {
            int r = Integer.parseInt(hex.substring(0, 2), 16);
            int g = Integer.parseInt(hex.substring(2, 4), 16);
            int b = Integer.parseInt(hex.substring(4, 6), 16);
            int a = Integer.parseInt(hex.substring(6, 8), 16);
            return fromRGBA255(r, g, b, a);
         }
      }

      return nullColor();
   }

   public static Color mix(final Color c1, final Color c2, double blend)
   {
      final double b1 = blend;
      final double b2 = 1 - blend;

      return new Color(
         c1.getRed() * b1 + c2.getRed() * b2,
         c1.getGreen() * b1 + c2.getGreen() * b2,
         c1.getBlue() * b1 + c2.getBlue() * b2,
         c1.getAlpha() * b1 + c2.getAlpha() * b2);
   }


   public String toHex()
   {
      int red = getRed255();
      int green = getGreen255();
      int blue = getBlue255();
      int alpha = getAlpha255();


      StringBuilder sb = new StringBuilder(9);
      sb.append("#");
      addHex2Number(sb, red);
      addHex2Number(sb, green);
      addHex2Number(sb, blue);

      if (alpha != 255)
         addHex2Number(sb, alpha);

      return sb.toString();
   }

   private void addHex2Number(StringBuilder sb, int x)
   {
      String hex = Integer.toHexString(x & 0xff);
      if (hex.length() == 1) sb.append(0);
      sb.append(hex);
   }

   public static Color nullColor()
   {
      return fromRGBA(0, 0, 0, 0);
   }
   public static Color blackColor()
   {
      return fromRGBA(0, 0, 0, 1);
   }
   public static Color whiteColor()
   {
      return fromRGBA(1, 1, 1, 1);
   }

   public double getRed() { return mRed; }
   public double getGreen() { return mGreen; }
   public double getBlue() { return mBlue; }
   public double getAlpha() { return mAlpha; }

   public int getRed255() { return (int) (mRed * 255); }
   public int getGreen255() { return (int) (mGreen * 255); }
   public int getBlue255() { return (int) (mBlue * 255); }
   public int getAlpha255() { return (int) (mAlpha * 255); }

   private final double mRed;
   private final double mGreen;
   private final double mBlue;
   private final double mAlpha;
}