Add Binary Data Formatter with Hexadecimal View

src/Microsoft.DotNet.Interactive.Formatting.Tests/BinaryFormatterTests.cs

@@ -0,0 +1,110 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+using System.IO;
+using FluentAssertions;
+using Microsoft.DotNet.Interactive.Formatting.Tests.Utility;
+using Xunit;
+
+namespace Microsoft.DotNet.Interactive.Formatting.Tests;
+
+public class BinaryFormatterTests : FormatterTestBase
+{
+    [Fact]
+    public void Byte_array_formats_as_hex_dump_in_plain_text()
+    {
+        var bytes = new byte[] { 
+            0x48, 0x65, 0x6C, 0x6C, 0x6F, 0x20, 0x57, 0x6F, 0x72, 0x6C, 0x64, 0x21,  // "Hello World!"
+            0x48, 0x65, 0x6C, 0x6C, 0x6F, 0x20, 0x57, 0x6F, 0x72, 0x6C, 0x64, 0x21
+        };
+
+        var formatted = bytes.ToDisplayString(PlainTextFormatter.MimeType);
+
+        formatted.Should().Contain("00000000");
+        formatted.Should().Contain("48 65 6C 6C 6F 20 57 6F");
+        formatted.Should().Contain("|Hello World!");
+    }
+
+    [Fact]
+    public void Byte_array_formats_as_hex_dump_in_html()
+    {
+        var bytes = new byte[] { 0x48, 0x65, 0x6C, 0x6C, 0x6F };
+
+        var formatted = bytes.ToDisplayString(HtmlFormatter.MimeType).RemoveStyleElement();
+
+        formatted.Should().Contain("<pre class=\"dni-binary\">");
+        formatted.Should().Contain("00000000");
+        formatted.Should().Contain("48 65 6C 6C 6F");
+        formatted.Should().Contain("</pre>");
+    }
+
+    [Fact]
+    public void Empty_byte_array_produces_empty_output()
+    {
+        var bytes = Array.Empty<byte>();
+
+        var formatted = bytes.ToDisplayString(PlainTextFormatter.MimeType);
+
+        formatted.Should().BeEmpty();
+    }
+
+    [Fact]
+    public void Null_byte_array_shows_null_string()
+    {
+        byte[] bytes = null;
+
+        var formatted = bytes.ToDisplayString(PlainTextFormatter.MimeType);
+
+        formatted.Should().Contain(Formatter.NullString);
+    }
+
+    [Fact]
+    public void Long_byte_array_spans_multiple_lines()
+    {
+        var bytes = new byte[32]; // Two lines worth
+        for (int i = 0; i < bytes.Length; i++)
+        {
+            bytes[i] = (byte)i;
+        }
+
+        var formatted = bytes.ToDisplayString(PlainTextFormatter.MimeType);
+
+        formatted.Should().Contain("00000000");
+        formatted.Should().Contain("00000010");
+    }
+
+    [Fact]
+    public void Non_printable_characters_show_as_dots()
+    {
+        var bytes = new byte[] { 0x00, 0x01, 0x02, 0xFF };
+
+        var formatted = bytes.ToDisplayString(PlainTextFormatter.MimeType);
+
+        formatted.Should().Contain("|....|");
+    }
+
+    [Fact]
+    public void ReadOnlyMemory_byte_formats_like_byte_array()
+    {
+        var bytes = new byte[] { 0x48, 0x65, 0x6C, 0x6C, 0x6F };
+        var memory = new ReadOnlyMemory<byte>(bytes);
+
+        var formatted = memory.ToDisplayString(PlainTextFormatter.MimeType);
+
+        formatted.Should().Contain("00000000");
+        formatted.Should().Contain("48 65 6C 6C 6F");
+    }
+
+    [Fact]
+    public void Partial_last_line_is_padded_correctly()
+    {
+        var bytes = new byte[] { 0x01, 0x02, 0x03, 0x04 }; // Only 4 bytes
+
+        var formatted = bytes.ToDisplayString(PlainTextFormatter.MimeType);
+
+        // Should have proper spacing even with fewer than 16 bytes
+        formatted.Should().Contain("01 02 03 04");
+        formatted.Should().Contain("|....|");
+    }
+}

src/Microsoft.DotNet.Interactive.Formatting/BinaryFormatter.cs

@@ -0,0 +1,135 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+using System.IO;
+
+namespace Microsoft.DotNet.Interactive.Formatting;
+
+/// <summary>
+/// Provides formatting for binary data (byte arrays) with hexadecimal representation.
+/// </summary>
+public static class BinaryFormatter
+{
+    private const int BytesPerLine = 16;
+
+    public static string FormatBytes(byte[] bytes)
+    {
+        if (bytes is null || bytes.Length == 0)
+        {
+            return string.Empty;
+        }
+
+        using var writer = new StringWriter();
+        FormatBytesTo(bytes, writer);
+        return writer.ToString();
+    }
+
+    public static void FormatBytesTo(byte[] bytes, TextWriter writer)
+    {
+        if (bytes is null || bytes.Length == 0)
+        {
+            return;
+        }
+
+        for (int offset = 0; offset < bytes.Length; offset += BytesPerLine)
+        {
+            // Write address offset
+            writer.Write($"{offset:X8}  ");
+
+            // Write hex values
+            int bytesInLine = Math.Min(BytesPerLine, bytes.Length - offset);
+
+            for (int i = 0; i < BytesPerLine; i++)
+            {
+                if (i < bytesInLine)
+                {
+                    writer.Write($"{bytes[offset + i]:X2} ");
+                }
+                else
+                {
+                    writer.Write("   ");
+                }
+
+                // Add extra space after 8 bytes for readability
+                if (i == 7)
+                {
+                    writer.Write(" ");
+                }
+            }
+
+            // Write ASCII representation
+            writer.Write(" |");
+            for (int i = 0; i < bytesInLine; i++)
+            {
+                byte b = bytes[offset + i];
+                char c = (b >= 32 && b < 127) ? (char)b : '.';
+                writer.Write(c);
+            }
+            writer.Write("|");
+
+            if (offset + BytesPerLine < bytes.Length)
+            {
+                writer.WriteLine();
+            }
+        }
+    }
+
+    internal static ITypeFormatter[] DefaultFormatters { get; } =
+    {
+        // PlainText formatter for byte arrays
+        new PlainTextFormatter<byte[]>((bytes, context) =>
+        {
+            if (bytes is null)
+            {
+                context.Writer.Write(Formatter.NullString);
+                return true;
+            }
+
+            FormatBytesTo(bytes, context.Writer);
+            return true;
+        }),
+
+        // HTML formatter for byte arrays
+        new HtmlFormatter<byte[]>((bytes, context) =>
+        {
+            if (bytes is null)
+            {
+                context.Writer.Write(Formatter.NullString);
+                return true;
+            }
+
+            context.Writer.Write("<pre class=\"dni-binary\">");
+            FormatBytesTo(bytes, context.Writer);
+            context.Writer.Write("</pre>");
+            return true;
+        }),
+
+        // PlainText formatter for ReadOnlyMemory<byte>
+        new AnonymousTypeFormatter<object>(
+            type: typeof(ReadOnlyMemory<byte>),
+            mimeType: PlainTextFormatter.MimeType,
+            format: (value, context) =>
+            {
+                var readOnlyMemory = (ReadOnlyMemory<byte>)value;
+                var bytes = readOnlyMemory.ToArray();
+                FormatBytesTo(bytes, context.Writer);
+                return true;
+            }),
+
+        // HTML formatter for ReadOnlyMemory<byte>
+        new AnonymousTypeFormatter<object>(
+            type: typeof(ReadOnlyMemory<byte>),
+            mimeType: HtmlFormatter.MimeType,
+            format: (value, context) =>
+            {
+                var readOnlyMemory = (ReadOnlyMemory<byte>)value;
+                var bytes = readOnlyMemory.ToArray();
+
+                context.Writer.Write("<pre class=\"dni-binary\">");
+                FormatBytesTo(bytes, context.Writer);
+                context.Writer.Write("</pre>");
+                return true;
+            })
+    };
+}

src/Microsoft.DotNet.Interactive.Formatting/Formatter.cs

@@ -117,6 +117,7 @@ public static void ResetToDefault()
         _defaultTypeFormatters.PushRange(((IEnumerable<ITypeFormatter>)JsonFormatter.DefaultFormatters).Reverse().ToArray());
         _defaultTypeFormatters.PushRange(((IEnumerable<ITypeFormatter>)PlainTextSummaryFormatter.DefaultFormatters).Reverse().ToArray());
         _defaultTypeFormatters.PushRange(((IEnumerable<ITypeFormatter>)PlainTextFormatter.DefaultFormatters).Reverse().ToArray());
+        _defaultTypeFormatters.PushRange(((IEnumerable<ITypeFormatter>)BinaryFormatter.DefaultFormatters).Reverse().ToArray());
 
         _defaultPreferredMimeTypes.Push((typeof(string), PlainTextFormatter.MimeType));