separated Writer code

1 files changed, 83 insertions, 0 deletions

diff --git a/NImg/NImg/Writer.cs b/NImg/NImg/Writer.cs
index c15cee1..ef1d2d2 100644
--- a/NImg/NImg/Writer.cs
+++ b/NImg/NImg/Writer.cs
@@ -1,5 +1,8 @@
 using System;
+using System.Collections.Generic;
 using System.IO;
+using System.Linq;
+using System.Text.RegularExpressions;
 using Zoltar;
 
 namespace NImg
@@ -27,5 +30,85 @@ namespace NImg
                 }
             }
         }
+
+        public static void WriteImageMetadata(this BinaryWriter writer, int imageWidth, int imageHeight, int colorIndexBytes)
+        {
+            writer.Write(imageWidth);
+            writer.Write(imageHeight);
+            writer.Write(Convert.ToByte(colorIndexBytes));
+        }
+
+        public static void WriteAIByte(this BinaryWriter writer, int inARow)
+        {
+            //NOTE: 11110000 -> inARow = 1, not 0, increase by 1
+            // "Use AI" bytes are in the form 1111 + (number of pixels)
+            writer.Write(Convert.ToByte("1111" + Convert.ToString(inARow - 1, 2).PadLeft(4, '0'), 2));
+        }
+
+        public static void WriteColorIndex(this BinaryWriter writer, int colorIndexBytes, int colorIndex)
+        {
+            switch (colorIndexBytes)
+            {
+                case 1:
+                    writer.Write(Convert.ToByte(colorIndex));
+                    break;
+                case 2:
+                    var byteStr = Convert.ToString(colorIndex, 2).PadLeft(16, '0');
+                    writer.Write(Convert.ToByte(byteStr.Substring(0, 8), 2));
+                    writer.Write(Convert.ToByte(byteStr.Substring(8), 2));
+                    break;
+            }
+        }
+
+        public static void WriteColor(this BinaryWriter writer, int colorIndexBytes, List<int[]> colorList, int[] colorToWrite, BinaryWriter colorsWriter, int colorTolerance)
+        {
+            if (colorIndexBytes > 0)
+            {
+                var existing = colorList.FirstOrDefault(color =>
+                    Math.Abs(colorToWrite[0] - color[0]) < colorTolerance &&
+                    Math.Abs(colorToWrite[1] - color[1]) < colorTolerance &&
+                    Math.Abs(colorToWrite[2] - color[2]) < colorTolerance);
+
+                var maxColorIndex = (colorIndexBytes == 1 ? 239 : 61440);
+
+                if (existing != null)
+                {
+                    var index = colorList.IndexOf(existing);
+
+                    writer.WriteColorIndex(colorIndexBytes, index);
+                }
+                else if (colorList.Count >= maxColorIndex)
+                {
+                    //Over 239/61440 the byte starts with "1111", which is interpreted as a "Use AI" byte.
+                    //At this point, just assume that the AI will give a better approximation of the accurate color
+                    Console.WriteLine("Hit max colors, defaulting to AI");
+                    writer.WriteAIByte(1);
+                }
+                else
+                {
+                    //Add a new color to the dictionary
+                    colorList.Add(colorToWrite);
+                    colorsWriter.Write(Convert.ToByte(colorToWrite[0]));
+                    colorsWriter.Write(Convert.ToByte(colorToWrite[1]));
+                    colorsWriter.Write(Convert.ToByte(colorToWrite[2]));
+
+                    writer.WriteColorIndex(colorIndexBytes, colorList.IndexOf(colorToWrite));
+                }
+            }
+            else
+            {
+                //Write the color to the file
+                for (var i = 0; i < colorToWrite.Length; i++)
+                {
+                    var binaryStr = Convert.ToString(colorToWrite[0], 2);
+
+                    //Any color component starting with 1111 will be interpreted as a "Use AI" bit, this is a hacky way to get around that
+                    //This will drop any component above 239 by 16 units
+                    binaryStr = Regex.Replace(binaryStr, "^1111", "1110");
+
+                    writer.Write(Convert.ToByte(binaryStr, 2));
+                }
+            }
+        }
     }
 }