Add BrotliImpl transformers to reset some header parameters

BrotliBuilder/FormMain.Menu.BrotliImpl.cs

@@ -32,8 +32,16 @@ namespace BrotliBuilder{
         }
 
         private void InitializeMenuTransformers(MainMenuBase.Item menu){
-            menu.Add("Rebuild",                   () => TransformCurrentFile(new TransformRebuild()));
-            menu.Add("Convert to Uncompressed",   () => TransformCurrentFile(new TransformCompressedIntoUncompressed()));
+            menu.Add("Rebuild", () => TransformCurrentFile(new TransformRebuild()));
+
+            menu.AddSeparator();
+
+            menu.Add("Convert to Uncompressed",             () => TransformCurrentFile(new TransformCompressedIntoUncompressed()));
+            menu.Add("Reset Distance Parameters",           () => TransformCurrentFile(new TransformResetDistanceParameters()));
+            menu.Add("Reset Block Splits & Context Models", () => TransformCurrentFile(new TransformResetBlockSplitsContextModels()));
+
+            menu.AddSeparator();
+
             menu.Add("Test Distance Parameters",  () => TransformCurrentFile(new TransformTestDistanceParameters()));
             menu.Add("Split Insert Copy Lengths", () => TransformCurrentFile(new TransformSplitInsertCopyLengths()));
         }

BrotliImpl/Transformers/TransformResetBlockSplitsContextModels.cs

@@ -0,0 +1,24 @@
+using BrotliLib.Brotli;
+using BrotliLib.Brotli.Components;
+using BrotliLib.Brotli.Components.Header;
+using BrotliLib.Brotli.Encode;
+using BrotliLib.Brotli.Encode.Build;
+using BrotliLib.Brotli.Parameters;
+using BrotliLib.Brotli.Utils;
+
+namespace BrotliImpl.Transformers{
+    public class TransformResetBlockSplitsContextModels : BrotliTransformerCompressed{
+        protected override (MetaBlock, BrotliGlobalState) Transform(MetaBlock.Compressed original, BrotliGlobalState state, BrotliCompressionParameters parameters){
+            var builder = new CompressedMetaBlockBuilder(original, state){
+                LiteralCtxMap = ContextMapBuilder.Literals.Simple,
+                DistanceCtxMap = ContextMapBuilder.Distances.Simple
+            };
+
+            foreach(var category in Categories.LID){
+                builder.BlockTypes[category].Reset();
+            }
+
+            return builder.UseSameLiteralContextMode(LiteralContextMode.LSB6).Build(parameters);
+        }
+    }
+}

BrotliImpl/Transformers/TransformResetDistanceParameters.cs

@@ -0,0 +1,16 @@
+using BrotliLib.Brotli;
+using BrotliLib.Brotli.Components;
+using BrotliLib.Brotli.Components.Header;
+using BrotliLib.Brotli.Encode;
+using BrotliLib.Brotli.Encode.Build;
+using BrotliLib.Brotli.Parameters;
+
+namespace BrotliImpl.Transformers{
+    public class TransformResetDistanceParameters : BrotliTransformerCompressed{
+        protected override (MetaBlock, BrotliGlobalState) Transform(MetaBlock.Compressed original, BrotliGlobalState state, BrotliCompressionParameters parameters){
+            return new CompressedMetaBlockBuilder(original, state){
+                DistanceParameters = DistanceParameters.Zero
+            }.Build(parameters);
+        }
+    }
+}