Added the ability to cancel the compression operation

SevenZip.Tests/SevenZip.Tests.csproj

@@ -9,6 +9,7 @@
     <SignAssembly>true</SignAssembly>
     <AssemblyOriginatorKeyFile>SevenZipTests.snk</AssemblyOriginatorKeyFile>
     <Configurations>Debug;Release;LiteDebug;LiteRelease</Configurations>
+    <PlatformTarget>AnyCPU</PlatformTarget>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <DefineConstants>SFX</DefineConstants>

SevenZip.Tests/SevenZipCompressorAsynchronousTests.cs

@@ -1,6 +1,8 @@
 namespace SevenZip.Tests
 {
+    using System;
     using System.Collections.Generic;
+    using System.Diagnostics;
     using System.IO;
     using System.Threading;
     using System.Threading.Tasks;
@@ -56,7 +58,7 @@ public void AsynchronousCompressFilesTest()
         {
             var compressionFinishedInvoked = false;
 
-            var compressor = new SevenZipCompressor {DirectoryStructure = false};
+            var compressor = new SevenZipCompressor { DirectoryStructure = false };
             compressor.CompressionFinished += (o, e) => compressionFinishedInvoked = true;
 
             compressor.BeginCompressFiles(TemporaryFile, @"TestData\zip.zip", @"TestData\tar.tar");
@@ -129,7 +131,7 @@ public void AsynchronousModifyArchiveTest()
             var compressionFinishedInvoked = false;
             compressor.CompressionFinished += (o, e) => compressionFinishedInvoked = true;
 
-            compressor.BeginModifyArchive(TemporaryFile, new Dictionary<int, string>{{0, @"tartar"}});
+            compressor.BeginModifyArchive(TemporaryFile, new Dictionary<int, string> { { 0, @"tartar" } });
 
             var timeToWait = 1000;
             while (!compressionFinishedInvoked)
@@ -202,6 +204,24 @@ public async Task CompressFilesAsync()
             }
         }
 
+        [Test]
+        public void CompressFilesAsyncWithCancellationTest()
+        {
+            var compressor = new SevenZipCompressor { DirectoryStructure = false };
+            compressor.Compressing += Compressor_Compressing;
+            var task = compressor.CompressFilesAsync(TemporaryFile, @"TestData\zip.zip", @"TestData\tar.tar");
+
+            Assert.ThrowsAsync<SevenZipCompressionCanceledException>(async () => { await task; });            
+        }
+
+        private void Compressor_Compressing(object sender, ProgressEventArgs e)
+        {
+            if (e.PercentDone > 50)
+            {
+                e.Cancel = true;
+            }
+        }
+
         [Test]
         public async Task CompressDirectoryAsync()
         {

SevenZip/ArchiveUpdateCallback.cs

@@ -325,6 +325,7 @@ private void OnCompressing(ProgressEventArgs e)
             if (Compressing != null)
             {
                 Compressing(this, e);
+                Canceled = e.Cancel;
             }
         }
 
@@ -342,7 +343,12 @@ private void OnFileCompressionFinished(EventArgs e)
 
         public void SetTotal(ulong total) {}
 
-        public void SetCompleted(ref ulong completeValue) {}
+        public void SetCompleted(ref ulong completeValue) {
+            if (Canceled)
+            {
+                throw new SevenZipCompressionCanceledException();
+            }
+        }
 
         public int GetUpdateItemInfo(uint index, ref int newData, ref int newProperties, ref uint indexInArchive)
         {

SevenZip/EventArguments/ProgressEventArgs.cs

@@ -22,5 +22,9 @@ public ProgressEventArgs(byte percentDone, byte percentDelta)
         /// Gets the change in done work percentage.
         /// </summary>
         public byte PercentDelta => _delta;
+        /// <summary>
+        /// Allows you to cancel the compression operation.
+        /// </summary>
+        public bool Cancel { get; set; } = false;
     }
 }

SevenZip/Exceptions/SevenZipCompressionCanceledException.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace SevenZip
+{
+    /// <summary>
+    /// Exception thrown when compression is canceled.
+    /// </summary>
+    public class SevenZipCompressionCanceledException: Exception
+    {
+        /// <summary>
+        /// Message of exception.
+        /// </summary>
+        public override string Message => "Canceled";
+    }
+}

SevenZip/SevenZipBase.cs

@@ -164,7 +164,14 @@ internal void ThrowUserException()
         {
             if (HasExceptions)
             {
-                throw new SevenZipException(SevenZipException.USER_EXCEPTION_MESSAGE);
+                if ((_exceptions.Count == 1) && (_exceptions[0] is SevenZipCompressionCanceledException))
+                {
+                    throw new SevenZipCompressionCanceledException();
+                }
+                else
+                {
+                    throw new SevenZipException(SevenZipException.USER_EXCEPTION_MESSAGE);
+                }
             }
         }
 
@@ -178,6 +185,11 @@ internal void CheckedExecute(int hresult, string message, CallbackBase handler)
         {
             if (hresult != (int)OperationResult.Ok || handler.HasExceptions)
             {
+                if ((handler is ArchiveUpdateCallback) && (handler.Canceled) && (!handler.HasExceptions))
+                {
+                    AddException(new SevenZipCompressionCanceledException());
+                    return;
+                }
                 if (!handler.HasExceptions)
                 {
                     if (hresult < -2000000000)