From 8da3a807574934352579949650ba2759cf1ceff0 Mon Sep 17 00:00:00 2001
From: Jerome Laban <jerome.laban@nventive.com>
Date: Thu, 17 Sep 2020 22:50:47 -0400
Subject: [PATCH] feat(skia): Add support for WriteableBitmap

---
 .../Media/Imaging/WriteableBitmap.skia.cs     | 30 +++++++++++++++++++
 src/Uno.UI/Uno.UI.Skia.csproj                 |  1 +
 .../SkiaCompositionSurface.skia.cs            | 11 +++++++
 src/Uno.UWP/Uno.Skia.csproj                   |  1 +
 4 files changed, 43 insertions(+)
 create mode 100644 src/Uno.UI/UI/Xaml/Media/Imaging/WriteableBitmap.skia.cs

diff --git a/src/Uno.UI/UI/Xaml/Media/Imaging/WriteableBitmap.skia.cs b/src/Uno.UI/UI/Xaml/Media/Imaging/WriteableBitmap.skia.cs
new file mode 100644
index 000000000000..8f6d9c68f9be
--- /dev/null
+++ b/src/Uno.UI/UI/Xaml/Media/Imaging/WriteableBitmap.skia.cs
@@ -0,0 +1,30 @@
+using System;
+using System.IO;
+using System.Runtime.InteropServices;
+using Windows.Foundation;
+using Windows.Storage.Streams;
+using Uno.Foundation;
+using Windows.UI.Composition;
+
+namespace Windows.UI.Xaml.Media.Imaging
+{
+	partial class WriteableBitmap
+	{
+		private SkiaCompositionSurface _surface;
+
+		private protected override bool TryOpenSourceSync(int? targetWidth, int? targetHeight, out ImageData image)
+		{
+			var handle = GCHandle.Alloc(_buffer.Data, GCHandleType.Pinned);
+
+			_surface ??= new SkiaCompositionSurface();
+
+			_surface.SetPixels(PixelWidth, PixelHeight, _buffer.Data);
+
+			image = new ImageData {
+				Value = _surface
+			};
+
+			return true;
+		}
+	}
+}
diff --git a/src/Uno.UI/Uno.UI.Skia.csproj b/src/Uno.UI/Uno.UI.Skia.csproj
index 25b7f0d57715..0bfb3e9cf73e 100644
--- a/src/Uno.UI/Uno.UI.Skia.csproj
+++ b/src/Uno.UI/Uno.UI.Skia.csproj
@@ -7,6 +7,7 @@
 		<UnoSourceGeneratorUseGenerationHost>false</UnoSourceGeneratorUseGenerationHost>
 		<NoWarn>$(NoWarn);NU1701</NoWarn>
 		<DefineConstants>$(DefineConstants);IS_UNO</DefineConstants>
+		<AllowUnsafeBlocks>true</AllowUnsafeBlocks>
 
 		<ProduceReferenceAssembly>false</ProduceReferenceAssembly>
 		<Deterministic>true</Deterministic>
diff --git a/src/Uno.UWP/UI/Composition/SkiaCompositionSurface.skia.cs b/src/Uno.UWP/UI/Composition/SkiaCompositionSurface.skia.cs
index e705d4696ced..b735a19d6825 100644
--- a/src/Uno.UWP/UI/Composition/SkiaCompositionSurface.skia.cs
+++ b/src/Uno.UWP/UI/Composition/SkiaCompositionSurface.skia.cs
@@ -5,6 +5,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Runtime.CompilerServices;
 using System.Text;
 using Uno.Extensions;
 using Uno.Logging;
@@ -56,5 +57,15 @@ internal void LoadFromBytes(byte[] image)
 				}
 			}
 		}
+
+		internal unsafe void SetPixels(int pixelWidth, int pixelHeight, byte[] data)
+		{
+			var info = new SKImageInfo(pixelWidth, pixelHeight, SKColorType.Rgba8888, SKAlphaType.Premul);
+
+			fixed (byte* pData = data)
+			{
+				_image = SKImage.FromPixels(info, (IntPtr)pData, pixelWidth * 4);
+			}
+		}
 	}
 }
diff --git a/src/Uno.UWP/Uno.Skia.csproj b/src/Uno.UWP/Uno.Skia.csproj
index 91bff1c7aefb..bee6bb41c914 100644
--- a/src/Uno.UWP/Uno.Skia.csproj
+++ b/src/Uno.UWP/Uno.Skia.csproj
@@ -2,6 +2,7 @@
   
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
+		<AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
 
 	<PropertyGroup Condition="'$(UnoTargetFrameworkOverride)'!=''">