Fixed bugs in Texture2D.FromStream() including unit tests. (MonoGame#…

…5712)

Build/Projects/MonoGame.Tests.definition

@@ -1144,5 +1144,12 @@
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
 
+    <Content Include="Assets\Textures\blue_0.png">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+    <Content Include="Assets\Textures\red_128.png">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+
   </Files>
 </Project>

MonoGame.Framework/Graphics/Texture2D.DirectX.cs

@@ -293,7 +293,7 @@ private void SaveAsImage(Guid encoderId, Stream stream, int width, int height)
 #endif
 #if !WINDOWS_PHONE
 
-        static SharpDX.Direct3D11.Texture2D CreateTex2DFromBitmap(BitmapSource bsource, GraphicsDevice device)
+        static unsafe SharpDX.Direct3D11.Texture2D CreateTex2DFromBitmap(BitmapSource bsource, GraphicsDevice device)
         {
 
             Texture2DDescription desc;
@@ -313,6 +313,18 @@ static SharpDX.Direct3D11.Texture2D CreateTex2DFromBitmap(BitmapSource bsource,
             {
                 bsource.CopyPixels(bsource.Size.Width * 4, s);
 
+                // XNA blacks out any pixels with an alpha of zero.
+                var data = (byte*)s.DataPointer;
+                for (var i = 0; i < s.Length; i+=4)
+                {
+                    if (data[i + 3] == 0)
+                    {
+                        data[i + 0] = 0;
+                        data[i + 1] = 0;
+                        data[i + 2] = 0;
+                    }
+                }
+
                 DataRectangle rect = new DataRectangle(s.DataPointer, bsource.Size.Width * 4);
 
                 return new SharpDX.Direct3D11.Texture2D(device._d3dDevice, desc, rect);
@@ -337,7 +349,7 @@ private static BitmapSource LoadBitmap(Stream stream, out SharpDX.WIC.BitmapDeco
 
             fconv.Initialize(
                 decoder.GetFrame(0),
-                PixelFormat.Format32bppPRGBA,
+                PixelFormat.Format32bppRGBA,
                 BitmapDitherType.None, null,
                 0.0, BitmapPaletteType.Custom);
 

MonoGame.Framework/Graphics/Texture2D.cs

@@ -247,10 +247,14 @@ public void GetData<T> (T[] data) where T : struct
         /// Creates a Texture2D from a stream, supported formats bmp, gif, jpg, png, tif and dds (only for simple textures).
         /// May work with other formats, but will not work with tga files.
         /// </summary>
-        /// <param name="graphicsDevice"></param>
-        /// <param name="stream"></param>
-        /// <returns></returns>
-		public static Texture2D FromStream(GraphicsDevice graphicsDevice, Stream stream)
+        /// <param name="graphicsDevice">The graphics device where the texture will be created.</param>
+        /// <param name="stream">The stream from which to read the image data.</param>
+        /// <returns>The <see cref="SurfaceFormat.Color"/> texture created from the image stream.</returns>
+        /// <remarks>Note that different image decoders may generate slight differences between platforms, but perceptually 
+        /// the images should be identical.  This call does not premultiply the image alpha, but areas of zero alpha will
+        /// result in black color data.
+        /// </remarks>
+        public static Texture2D FromStream(GraphicsDevice graphicsDevice, Stream stream)
 		{
             if (graphicsDevice == null)
                 throw new ArgumentNullException("graphicsDevice");

Test/Framework/Graphics/Texture2DNonVisualTest.cs

@@ -77,6 +77,56 @@ public void FromStreamArgumentNullTest()
 #endif
         }
 
+        [TestCase]
+        public void FromStreamNotPremultiplied()
+        {
+            // XNA will not try to premultiply your image on
+            // load... this test verifies that this doesn't occur.
+
+            using (var stream = File.OpenRead("Assets/Textures/red_128.png"))
+            using (var texture = Texture2D.FromStream(gd, stream))
+            {
+                Assert.AreEqual(8, texture.Width);
+                Assert.AreEqual(8, texture.Height);
+                Assert.AreEqual(1, texture.LevelCount);
+                var pngData = new Color[8 * 8];
+                texture.GetData(pngData);
+
+                for (var i = 0; i < pngData.Length; i++)
+                {
+                    Assert.AreEqual(255,    pngData[i].R);
+                    Assert.AreEqual(0,      pngData[i].G);
+                    Assert.AreEqual(0,      pngData[i].B);
+                    Assert.AreEqual(128,    pngData[i].A);
+                }
+            }
+        }
+
+        [TestCase]
+        public void FromStreamBlackAlpha()
+        {
+            // XNA will make any pixel with an alpha value
+            // of 0 into black throwing out any color data.
+
+            using (var stream = File.OpenRead("Assets/Textures/blue_0.png"))
+            using (var texture = Texture2D.FromStream(gd, stream))
+            {
+                Assert.AreEqual(8, texture.Width);
+                Assert.AreEqual(8, texture.Height);
+                Assert.AreEqual(1, texture.LevelCount);
+                var pngData = new Color[8 * 8];
+                texture.GetData(pngData);
+
+                for (var i = 0; i < pngData.Length; i++)
+                {
+                    Assert.AreEqual(0, pngData[i].R);
+                    Assert.AreEqual(0, pngData[i].G);
+                    Assert.AreEqual(0, pngData[i].B);
+                    Assert.AreEqual(0, pngData[i].A);
+                }
+            }
+        }
+
         [Test]
         public void ZeroSizeShouldFailTest()
         {

Test/MonoGame.Tests.XNA.csproj

@@ -622,6 +622,9 @@
     <Content Include="Assets\tests.xsl">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
+    <Content Include="Assets\Textures\blue_0.png">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
     <Content Include="Assets\Textures\lines-128.xnb">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
@@ -661,6 +664,9 @@
     <Content Include="Assets\Textures\LogoOnly_64px.tif">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
+    <Content Include="Assets\Textures\red_128.png">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
     <Content Include="Assets\Textures\SampleCube64DXT1Mips.dds">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>