Add working implementation of the trucolor module in crystal

lib/trucolor.cr

@@ -0,0 +1,68 @@
+##################################################################################
+#
+#    New Start: A modern Arch workflow built with an emphasis on functionality.
+#    Copyright (C) 2017 Donovan Glover
+#    
+#    Trucolor: A library that makes colorful output trivial.
+#    Copyright (C) 2017 Donovan Glover
+#
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License as published by
+#    the Free Software Foundation, either version 3 of the License, or
+#    (at your option) any later version.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+##################################################################################
+
+module Trucolor
+    # Formats a string *str* with the colors given in the turple *rgb* (0 <= rgb[i] <= 255)
+    def self.format(rgb, str)
+        return "\x1b[38;2;#{rgb[0]};#{rgb[1]};#{rgb[2]}m#{str}\x1b[0m"
+    end
+    
+    # Goes through the colors in such a way that only 256 colors are used (0 <= n <= 255)
+    # @requires self.format()
+    def self.rainbow(n)
+        h = n / 43
+        f = n - 43 * h
+        t = f * 255 / 43
+        q = 255 - t
+        
+        case h
+        when 0
+            return {255, t, 0}
+        when 1
+            return {q, 255, 0}
+        when 2
+            return {0, 255, t}
+        when 3
+            return {0, q, 255}
+        when 4
+            return {t, 0, 255}
+        when 5
+            return {255, 0, q}
+        else
+            return {0, 0, 0}
+        end
+
+    end
+    
+    # Tests the format method by printing a rainbow of colors
+    # @requires self.rainbow()
+    def self.test()
+        n = -1
+        while (n += 1) < 256
+           print self.format(self.rainbow(n), "#{n}".rjust(3, '0')) + " "
+           print "\n" if (n + 1) % 16 == 0
+        end
+    end
+
+end
+