Make colorizer optional

README.md

@@ -36,7 +36,7 @@
    var sizer = new LogSizer(wordCloud);
    using var engine = new SkGraphicEngine(sizer, wordCloud);
    var layout = new SpiralLayout(wordCloud);
-   var colorizer = new RandomColorizer();    
+   var colorizer = new RandomColorizer(); // optional
    var wcg = new WordCloudGenerator<SKBitmap>(wordCloud, engine, layout, colorizer);
    ```
 

examples/WordFrequency.ConsoleApp/Program.cs

@@ -57,7 +57,7 @@ static int Main(string[] args)
                 var sizer = new LogSizer(wordCloud);
                 using var engine = new SkGraphicEngine(sizer, wordCloud);
                 var layout = new SpiralLayout(wordCloud);
-                var colorizer = new RandomColorizer();   //new DefaultColorizer(); uses default color set in WordCloudInput
+                var colorizer = new RandomColorizer(); // optional
                 var wcg = new WordCloudGenerator<SKBitmap>(wordCloud, engine, layout, colorizer);
 
                 // Draw the bitmap on white background.

src/KnowledgePicker.WordCloud/Coloring/IColorizer.cs

@@ -2,6 +2,10 @@ namespace KnowledgePicker.WordCloud.Coloring
 {
     public interface IColorizer
     {
+        /// <summary>
+        /// Gets the hex string color for text.
+        /// </summary>
+        /// <returns>Hex string color in format #RRGGBB.</returns>
         string GetColorAsHex();
     }
 }

src/KnowledgePicker.WordCloud/Coloring/RandomColorizer.cs

@@ -1,43 +1,43 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Drawing;
 
 namespace KnowledgePicker.WordCloud.Coloring
 {
     /// <summary>
-    /// Allows random colors for the word cloud text
+    /// Allows random colors for the word cloud text.
     /// </summary>
     public class RandomColorizer : IColorizer
     {
-        /// <summary>
-        /// Used to select random colors.
-        /// </summary>
-        private Random Random { get; set; } = new Random(Environment.TickCount);
+        private readonly Random random;
+
+        public RandomColorizer() : this(Environment.TickCount) { }
+
+        public RandomColorizer(int seed)
+        {
+            random = new Random(seed);
+        }
 
         /// <summary>
         /// Gets a random color.
         /// </summary>
-        /// <returns>Color</returns>
+        [SuppressMessage("Security", "CA5394:Do not use insecure randomness")]
         private Color GetRandomColor()
         {
-#pragma warning disable CA5394 // Do not use insecure randomness
-            return Color.FromArgb(Random.Next(0, 255), Random.Next(0, 255), Random.Next(0, 255));
-#pragma warning restore CA5394 // Do not use insecure randomness
+            return Color.FromArgb(random.Next(0, 255), random.Next(0, 255), random.Next(0, 255));
         }
 
         /// <summary>
-        /// Converts Color to Hext string
+        /// Converts Color to hex string.
         /// </summary>
-        /// <returns>Color</returns>
         private static string ConvertToHexString(Color c)
         {
             return $"#{c.R:X2}{c.G:X2}{c.B:X2}";
         }
 
         /// <summary>
-        /// Gets the randon RGB color and
-        /// returns a hex string
+        /// Gets the randon RGB color as a hex string.
         /// </summary>
-        /// <returns>Hexstring</returns>
         public string GetColorAsHex()
         {
             Color c = GetRandomColor();

src/KnowledgePicker.WordCloud/Drawing/IGraphicEngine.cs

@@ -26,14 +26,10 @@ public interface IGraphicEngine : IDisposable
         /// Draws <paramref name="text"/> with weight proportional to
         /// <paramref name="count"/>.
         /// </summary>
-        /// <param name="location"></param>
         /// <param name="measured">
         /// Result of <see cref="Measure(string, int)"/>.
         /// </param>
-        /// <param name="text"></param>
-        /// <param name="count"></param>
-        /// <param name="randomColorHex"></param>
-        void Draw(PointD location, RectangleD measured, string text, int count, string randomColorHex);
+        void Draw(PointD location, RectangleD measured, string text, int count, string? colorHex = null);
     }
 
     public interface IGraphicEngine<TBitmap> : IGraphicEngine

src/KnowledgePicker.WordCloud/Drawing/SkGraphicEngine.cs

@@ -40,12 +40,13 @@ public RectangleD Measure(string text, int count)
             return new RectangleD(rect.Left + m, rect.Top + m, rect.Width + 2 * m, rect.Height + 2 * m);
         }
 
-        public void Draw(PointD location, RectangleD measured, string text, int count, string? randomColorHex)
+        public void Draw(PointD location, RectangleD measured, string text, int count, string? colorHex = null)
         {
             // For computation explanation, see
             // https://docs.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/graphics/skiasharp/basics/text.
             textPaint.TextSize = (float)Sizer.GetFontSize(count);
-            textPaint.Color = SKColor.Parse(randomColorHex);
+            if (colorHex != null)
+                textPaint.Color = SKColor.Parse(colorHex);
             canvas.DrawText(text, (float)(location.X - measured.Left),
                 (float)(location.Y - measured.Top), textPaint);
         }

src/KnowledgePicker.WordCloud/WordCloudGenerator.cs

@@ -27,7 +27,8 @@ public class WordCloudGenerator<TBitmap>
         private readonly IColorizer colorizer;
 
         public WordCloudGenerator(WordCloudInput wordCloud,
-            IGraphicEngine<TBitmap> engine, ILayout layout, IColorizer colorizer)
+            IGraphicEngine<TBitmap> engine, ILayout layout,
+            IColorizer? colorizer = null)
         {
             this.wordCloud = wordCloud;
             this.engine = engine;
@@ -67,7 +68,7 @@ public TBitmap Draw()
             {
                 // Draw words.
                 foreach (var item in items)
-                    engine.Draw(item.Location, item.Measured, item.Entry.Word, item.Entry.Count, colorizer.GetColorAsHex());
+                    engine.Draw(item.Location, item.Measured, item.Entry.Word, item.Entry.Count, colorizer?.GetColorAsHex());
                 return engine.Bitmap;
             });
         }