Minor optimization.

2 files changed, 21 insertions, 15 deletions

diff --git a/NesTiler/ColorExtensions.cs b/NesTiler/ColorExtensions.cs
index 70f8bc0..239497d 100644
--- a/NesTiler/ColorExtensions.cs
+++ b/NesTiler/ColorExtensions.cs
@@ -14,7 +14,8 @@ namespace com.clusterrr.Famicom.NesTiler
 

     static class ColorExtensions

     {

-        static Dictionary<ColorPair, double> cache = new();

+        private static Dictionary<ColorPair, double> cache = new();

+        private static CieDe2000Comparison comparer = new();

 

         public static void ClearCache() => cache.Clear();

 

@@ -38,7 +39,7 @@ namespace com.clusterrr.Famicom.NesTiler
                 return cache[pair];

             var a = new Rgb { R = color1.Red, G = color1.Green, B = color1.Blue };

             var b = new Rgb { R = color2.Red, G = color2.Green, B = color2.Blue };

-            var delta = a.Compare(b, new CieDe2000Comparison());

+            var delta = a.Compare(b, comparer);

             cache[pair] = delta;

             return delta;

         }

diff --git a/NesTiler/FastBitmap.cs b/NesTiler/FastBitmap.cs
index 1015354..5831170 100644
--- a/NesTiler/FastBitmap.cs
+++ b/NesTiler/FastBitmap.cs
@@ -11,27 +11,32 @@ namespace com.clusterrr.Famicom.NesTiler
         public int Width { get; }

         public int Height { get; }

 

-        private readonly SKColor[] colors;

-        private static Dictionary<string, SKBitmap> imagesCache = new Dictionary<string, SKBitmap>();

+        private readonly int verticalOffset;

+        private readonly SKColor[] pixels;

+        private static Dictionary<string, (SKColor[] pixels, int w, int h)> imagesCache = new();

 

-        private FastBitmap(SKBitmap skBitmap, int verticalOffset = 0, int height = -1)

+        private FastBitmap(SKColor[] pixels, int originalWidth, int originalHeight, int verticalOffset = 0, int height = -1)

         {

-            Width = skBitmap.Width;

-            Height = height <= 0 ? skBitmap.Height - verticalOffset : height;

-            if (skBitmap.Height - verticalOffset - Height < 0 || Height <= 0) throw new InvalidOperationException("Invalid image height.");

-            var pixels = skBitmap.Pixels;

-            colors = skBitmap.Pixels.Skip(verticalOffset * Width).Take(Width * Height).ToArray();

+            Width = originalWidth;

+            Height = height <= 0 ? originalHeight - verticalOffset : height;

+            this.verticalOffset = verticalOffset;

+            this.pixels = pixels;

         }

 

         public static FastBitmap? Decode(string filename, int verticalOffset = 0, int height = -1)

         {

+            if (imagesCache.TryGetValue(filename, out (SKColor[] pixels, int w, int h) cachedImage))

+            {

+                return new FastBitmap(cachedImage.pixels, cachedImage.w, cachedImage.h, verticalOffset, height);

+            }

             try

             {

                 using (var image = SKBitmap.Decode(filename))

                 {

                     if (image == null) return null;

-                    imagesCache[filename] = image;

-                    return new FastBitmap(image, verticalOffset, height);

+                    var pixels = image.Pixels;

+                    imagesCache[filename] = (pixels, image.Width, image.Height);

+                    return new FastBitmap(pixels, image.Width, image.Height, verticalOffset, height);

                 }

             }

             finally

@@ -42,12 +47,12 @@ namespace com.clusterrr.Famicom.NesTiler
 

         public SKColor GetPixelColor(int x, int y)

         {

-            return colors[(y * Width) + x];

+            return pixels[((y + verticalOffset) * Width) + x];

         }

 

         public void SetPixelColor(int x, int y, SKColor color)

         {

-            colors[(y * Width) + x] = color;

+            pixels[((y + verticalOffset) * Width) + x] = color;

         }

 

         public byte[] Encode(SKEncodedImageFormat format, int v)

@@ -57,7 +62,7 @@ namespace com.clusterrr.Famicom.NesTiler
             {

                 for (int x = 0; x < Width; x++)

                 {

-                    var color = colors[(y * Width) + x];

+                    var color = GetPixelColor(x, y);

                     skImage.SetPixel(x, y, color);

                 }

             }