Add DecodeCommands support

Author: lilith

src/Imageflow/Fluent/DecodeCommands.cs

@@ -0,0 +1,54 @@
+using System;
+using System.ComponentModel;
+using System.Drawing;
+using System.Linq;
+
+namespace Imageflow.Fluent
+{
+    [Flags]
+    public enum DecderDownscalingMode
+    {
+        /// <summary>
+        /// Use the Imageflow default (usually highest quality)
+        /// </summary>
+        Unspecified = 0,
+        /// <summary>
+        /// Use the fastest method
+        /// </summary>
+        Fastest = 1,
+        
+        /// <summary>
+        /// A slower (but more accurate) scaling method is employed; the DCT blocks are fully decoded, then a true resampling kernel is applied.
+        /// </summary>
+        SpatialLumaScaling = 2,
+        /// <summary>
+        /// Like SpatialLumaScaling, but gamma correction is applied before the resampling kernel, then removed afterwards.
+        /// Has the effect of linear-light scaling
+        /// </summary>
+        GammaCorrectSpatialLumaScaling = 6,
+        Best = 6,
+    }
+    
+    public class DecodeCommands
+    {
+        public Size? DownscaleHint { get; set; } = Size.Empty;
+
+        public DecderDownscalingMode DownscalingMode { get; set; } = DecderDownscalingMode.Unspecified;
+
+        public bool DiscardColorProfile { get; set; } = false;
+
+        public object[] ToImageflowDynamic()
+        {
+            object downscale = DownscaleHint.HasValue ? new { 
+                jpeg_downscale_hints = new {
+                    width = DownscaleHint.Value.Width,
+                    height  = DownscaleHint.Value.Height,
+                    scale_luma_spatially = (DownscalingMode | DecderDownscalingMode.SpatialLumaScaling) > 0,
+                    gamma_correct_for_srgb_during_spatial_luma_scaling = DownscalingMode == DecderDownscalingMode.GammaCorrectSpatialLumaScaling
+                } 
+             }: null;
+            object ignore = DiscardColorProfile ? new {discard_color_profile = (string) null} : null;
+            return new object[] {downscale, ignore}.Where(obj => obj != null).ToArray();
+        }
+    }
+}

src/Imageflow/Fluent/FluentBuildJob.cs

@@ -29,6 +29,7 @@ internal void AddOutput(int ioId, IOutputDestination destination)
                 throw new ArgumentException("ioId", $"ioId {ioId} has already been assigned");
             _outputs.Add(ioId, destination);
         }
+        [Obsolete("Use Decode(source, ioId, commands) instead")]
         public BuildNode DownscalingDecode(IBytesSource source, int ioId, int widthHint, int heightHint, bool scaleLumaSpatially = false, bool gammaCorrectForSrgbDuringSpatialLumaScaling = false)
         {
             AddInput(ioId, source);
@@ -46,12 +47,34 @@ public BuildNode DownscalingDecode(IBytesSource source, int ioId, int widthHint,
                 }
             });
         }
-        public BuildNode Decode(IBytesSource source, int ioId)
+
+       
+        public BuildNode Decode(IBytesSource source, int ioId, DecodeCommands commands)
         {
             AddInput(ioId, source);
-            return BuildNode.StartNode(this, new {decode = new {io_id = ioId}});
+            if (commands == null)
+            {
+                return BuildNode.StartNode(this,
+                    new
+                    {
+                        decode = new
+                        {
+                            io_id = ioId
+                        }
+                    });
+            }
+            return BuildNode.StartNode(this,
+                new
+                {
+                    decode = new
+                    {
+                        io_id = ioId,
+                        commands = commands.ToImageflowDynamic()
+                    }
+                });
         }
-
+        
+        public BuildNode Decode(IBytesSource source, int ioId) => Decode(source, ioId, null);
         public BuildNode Decode(IBytesSource source) => Decode( source, GenerateIoId());
         public BuildNode Decode(ArraySegment<byte> source) => Decode( new BytesSource(source), GenerateIoId());
         public BuildNode Decode(byte[] source) => Decode( new BytesSource(source), GenerateIoId());

tests/Imageflow.Test/Imageflow.Test.csproj

@@ -11,9 +11,9 @@
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
   <ItemGroup>
-    <PackageReference Include="Imageflow.NativeRuntime.ubuntu_14_04-x86_64" Version="1.0.0-rc3a" />
-    <PackageReference Include="Imageflow.NativeRuntime.win-x86" Version="1.0.0-rc3a" />
-    <PackageReference Include="Imageflow.NativeRuntime.win-x86_64-sandybridge" Version="1.0.0-rc3a" />
+    <PackageReference Include="Imageflow.NativeRuntime.ubuntu_14_04-x86_64" Version="1.0.0-rc5a" />
+    <PackageReference Include="Imageflow.NativeRuntime.win-x86" Version="1.0.0-rc5a" />
+    <PackageReference Include="Imageflow.NativeRuntime.win-x86_64-sandybridge" Version="1.0.0-rc5a" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.3.0-preview-20170628-02" />
     <PackageReference Include="xunit" Version="2.2.0" />
     <PackageReference Include="xunit.extensibility.execution" Version="2.2.0" />

tests/Imageflow.Test/TestApi.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Diagnostics;
+using System.Drawing;
 using Xunit;
 using Imageflow;
 using System.Dynamic;
@@ -44,7 +45,13 @@ public async Task TestCustomDownscaling()
             BuildJobResult r;
             using (var b = new FluentBuildJob())
             {
-                r = await b.DownscalingDecode(new BytesSource(imageBytes), 0, 20,20, false, false)
+                var cmd = new DecodeCommands
+                {
+                    DownscaleHint = new Size(20, 20),
+                    DownscalingMode = DecderDownscalingMode.Fastest,
+                    DiscardColorProfile = true
+                };
+                r = await b.Decode(new BytesSource(imageBytes), 0, cmd)
                     .Distort(30, 20, 50.0f, InterpolationFilter.RobidouxFast, InterpolationFilter.Cubic)
                     .ConstrainWithin(5, 5)
                    .EncodeToBytes(new LibPngEncoder()).FinishAsync();