20240422

Core/mapbox-sdk-cs/Utils/Compression.cs

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+//-----------------------------------------------------------------------
+// <copyright file="Compression.cs" company="Mapbox">
+//     Copyright (c) 2016 Mapbox. All rights reserved.
+// </copyright>
+//-----------------------------------------------------------------------
+
+namespace Mapbox.Utils
+{
+
+	using System.IO;
+	using Mapbox.IO.Compression;
+
+
+	/// <summary> Collection of constants used across the project. </summary>
+	public static class Compression
+	{
+		/// <summary>
+		///     Decompress the specified buffer previously compressed using GZip.
+		/// </summary>
+		/// <param name="buffer">
+		///     The GZip'ed buffer.
+		/// </param>
+		/// <returns>
+		///     Returns the uncompressed buffer or the buffer in case decompression
+		///     is not possible.
+		/// </returns>
+		public static byte[] Decompress(byte[] buffer)
+		{
+			// Test for magic bits.
+			if (buffer.Length < 2 || buffer[0] != 0x1f || buffer[1] != 0x8b)
+			{
+				return buffer;
+			}
+
+			using (GZipStream stream = new GZipStream(new MemoryStream(buffer), CompressionMode.Decompress))
+			{
+				const int Size = 4096; // Pagesize.
+				byte[] buf = new byte[Size];
+
+				using (MemoryStream memory = new MemoryStream())
+				{
+					int count = 0;
+
+					do
+					{
+						try
+						{
+							count = stream.Read(buf, 0, Size);
+						}
+						catch
+						{
+							// For now we return the uncompressed buffer
+							// on error. Assumes the magic check passed
+							// by luck.
+							return buffer;
+						}
+
+						if (count > 0)
+						{
+							memory.Write(buf, 0, count);
+						}
+					}
+					while (count > 0);
+
+					buffer = memory.ToArray();
+				}
+			}
+
+			return buffer;
+		}
+
+
+		public static byte[] Compress(byte[] raw, CompressionLevel compressionLevel)
+		{
+			using (MemoryStream memory = new MemoryStream())
+			{
+				using (GZipStream gzip = new GZipStream(memory, compressionLevel))
+				{
+					gzip.Write(raw, 0, raw.Length);
+				}
+				return memory.ToArray();
+			}
+		}
+
+		public static byte[] CompressModeCompress(byte[] raw)
+		{
+			using (MemoryStream memory = new MemoryStream())
+			{
+				using (GZipStream gzip = new GZipStream(memory, CompressionMode.Compress, true))
+				{
+					gzip.Write(raw, 0, raw.Length);
+				}
+				return memory.ToArray();
+			}
+		}
+
+
+
+
+
+	}
+}