add platform-independant interface for loading Image objects from streams. add SDL backend support

SDL2# does not include anything suitable for using Streams with, so we
just use System.Drawing instead for now

Blarg.GameFramework.SDL2/Blarg.GameFramework.SDL2.csproj

@@ -41,6 +41,7 @@
     <Reference Include="SDL2#">
       <HintPath>..\Libs\SDL2#.dll</HintPath>
     </Reference>
+    <Reference Include="System.Drawing" />
   </ItemGroup>
   <ItemGroup>
     <Compile Include="Properties\AssemblyInfo.cs" />
@@ -53,6 +54,7 @@
     <Compile Include="CurrentOS.cs" />
     <Compile Include="Input\SDLKeyMapper.cs" />
     <Compile Include="SDLApplication.cs" />
+    <Compile Include="Graphics\SDLBitmap.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <ItemGroup>
@@ -64,5 +66,6 @@
   <ItemGroup>
     <Folder Include="Input\" />
     <Folder Include="IO\" />
+    <Folder Include="Graphics\" />
   </ItemGroup>
 </Project>

Blarg.GameFramework.SDL2/Graphics/SDLBitmap.cs

@@ -0,0 +1,125 @@
+using System;
+using System.Drawing;
+using System.Drawing.Imaging;
+using System.IO;
+using System.Runtime.InteropServices;
+
+namespace Blarg.GameFramework.Graphics
+{
+	public class SDLBitmap : IPlatformBitmap
+	{
+		byte[] _pixels;
+		int _width;
+		int _height;
+		Graphics.ImageFormat _format;
+
+		public byte[] Pixels
+		{
+			get { return _pixels; }
+		}
+
+		public int Width
+		{
+			get { return _width; }
+		}
+
+		public int Height
+		{
+			get { return _height; }
+		}
+
+		public Graphics.ImageFormat Format
+		{
+			get { return _format; }
+		}
+
+		public SDLBitmap(Stream file)
+		{
+			_pixels = GetBitmap(file, out _width, out _height, out _format);
+		}
+
+		private byte[] GetBitmap(Stream file, out int width, out int height, out Graphics.ImageFormat format)
+		{
+			if (file == null)
+				throw new ArgumentNullException("file");
+
+			using (Bitmap bitmap = (Bitmap)Bitmap.FromStream(file))
+			{
+				int bpp = 0;
+				if (bitmap.PixelFormat == PixelFormat.Format32bppArgb)
+				{
+					bpp = 32;
+					format = Graphics.ImageFormat.RGBA;
+				}
+				else if (bitmap.PixelFormat == PixelFormat.Format24bppRgb)
+				{
+					bpp = 24;
+					format = Graphics.ImageFormat.RGB;
+				}
+				else if (bitmap.PixelFormat == PixelFormat.Alpha)
+				{
+					bpp = 8;
+					format = Graphics.ImageFormat.A;
+				}
+				else
+					throw new InvalidOperationException(String.Format("Unsupported bitmap pixel format: {0}", bitmap.PixelFormat.ToString()));
+
+				width = bitmap.Width;
+				height = bitmap.Height;
+
+				byte[] pixels;
+
+				var lockRegion = new Rectangle(0, 0, bitmap.Width, bitmap.Height);
+				var bitmapData = bitmap.LockBits(lockRegion, ImageLockMode.ReadOnly, bitmap.PixelFormat);
+				try
+				{
+					int bitmapSizeInBytes = bitmap.Width * bitmap.Height * (bpp / 8);
+					int expectedPitch = bitmap.Width * (bpp / 8);
+					int actualPitch = bitmapData.Stride;
+
+					if (expectedPitch != actualPitch)
+						throw new InvalidOperationException("Expected bitmap pitch mismatch. Uncaught unsupported bitmap format?");
+
+					pixels = new byte[bitmapData.Stride * bitmap.Height];
+					Marshal.Copy(bitmapData.Scan0, pixels, 0, bitmapSizeInBytes);
+				}
+				finally
+				{
+					bitmap.UnlockBits(bitmapData);
+				}
+
+				// TODO: are there any cases where this should *not* be run?
+				SwapRgbOrdering(pixels, format);
+
+				return pixels;
+			}
+		}
+
+		private void SwapRgbOrdering(byte[] pixels, Graphics.ImageFormat pixelFormat)
+		{
+			if (pixelFormat == Graphics.ImageFormat.A)
+				return;
+
+			// assumption is that this will only ever be 3 or 4 (RGB, or RGBA)
+			int pixelSizeBytes;
+			if (pixelFormat == Graphics.ImageFormat.RGB)
+				pixelSizeBytes = 3;
+			else
+				pixelSizeBytes = 4;
+
+			if (pixels.Length % pixelSizeBytes != 0)
+				throw new InvalidDataException("Pixel data format mismatch.");
+
+			// swap R and B values for each pixel
+			for (int i = 0; i < pixels.Length; i += pixelSizeBytes)
+			{
+				byte r = pixels[i];
+				byte b = pixels[i + 2];
+				pixels[i] = b;
+				pixels[i + 2] = r;
+			}
+		}
+
+	}
+}
+

Blarg.GameFramework.SDL2/SDLApplication.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Diagnostics;
+using System.IO;
 using SDL2;
 using PortableGL;
 using PortableGL.SDL;
@@ -612,6 +613,15 @@ namespace Blarg.GameFramework
 
 		#endregion
 
+		#region Support Functions
+
+		public override IPlatformBitmap LoadBitmap(Stream file)
+		{
+			return new SDLBitmap(file);
+		}
+
+		#endregion
+
 		#region IDisposable
 
 		protected override void Release()

Blarg.GameFramework/BaseApplication.cs

@@ -1,4 +1,5 @@
 using System;
+using System.IO;
 using PortableGL;
 using Blarg.GameFramework.Graphics;
 using Blarg.GameFramework.Input;
@@ -38,6 +39,8 @@ namespace Blarg.GameFramework
 		public abstract void Run(IGameApp gameApp, IPlatformConfiguration config);
 		public abstract void Quit();
 
+		public abstract IPlatformBitmap LoadBitmap(Stream file);
+
 		protected void OnInit()
 		{
 			Logger.Info(LOG_TAG, "Initializing application objects.");

Blarg.GameFramework/Blarg.GameFramework.csproj

@@ -124,6 +124,8 @@
     <Compile Include="Graphics\BuiltinShaders\Sprite2DShader.cs" />
     <Compile Include="Graphics\BuiltinShaders\Sprite3DShader.cs" />
     <Compile Include="Support\StringExtensions.cs" />
+    <Compile Include="Graphics\ImageFormat.cs" />
+    <Compile Include="Graphics\IPlatformBitmap.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildExtensionsPath32)\Microsoft\Portable\$(TargetFrameworkVersion)\Microsoft.Portable.CSharp.targets" />
   <ItemGroup>

Blarg.GameFramework/Graphics/IPlatformBitmap.cs

@@ -0,0 +1,12 @@
+using System;
+
+namespace Blarg.GameFramework.Graphics
+{
+	public interface IPlatformBitmap
+	{
+		byte[] Pixels { get; }
+		int Width { get; }
+		int Height { get; }
+		ImageFormat Format { get; }
+	}
+}

Blarg.GameFramework/Graphics/Image.cs

@@ -1,14 +1,8 @@
 using System;
+using System.IO;
 
 namespace Blarg.GameFramework.Graphics
 {
-	public enum ImageFormat
-	{
-		RGB,
-		RGBA,
-		A
-	}
-
 	public partial class Image
 	{
 		private byte[] _pixels;
@@ -47,28 +41,15 @@ namespace Blarg.GameFramework.Graphics
 			Create(source, copyX, copyY, copyWidth, copyHeight);
 		}
 
-		private Image(byte[] pixels, int width, int height, ImageFormat format)
+		public Image(Stream file)
 		{
-			if (pixels == null)
-				throw new ArgumentNullException("pixels");
+			if (file == null)
+				throw new ArgumentNullException("file");
 
-			int bpp = 0;
-			if (format == ImageFormat.RGB)
-				bpp = 24;
-			else if (format == ImageFormat.RGBA)
-				bpp = 32;
-			else if (format == ImageFormat.A)
-				bpp = 8;
+			var bitmap = Platform.Application.LoadBitmap(file);
 
-			if (bpp == 0)
-				throw new ArgumentException("pixelFormat");
-
-			_pixels = pixels;
-			Width = width;
-			Height = height;
-			BitsPerPixel = bpp;
-			PixelFormat = format;
-			Pitch = Width * (BitsPerPixel / 8);
+			CreateBaseImage(bitmap.Width, bitmap.Height, bitmap.Format);
+			Buffer.BlockCopy(bitmap.Pixels, 0, _pixels, 0, bitmap.Pixels.Length);
 		}
 
 		private void CreateBaseImage(int width, int height, ImageFormat pixelFormat)

Blarg.GameFramework/Graphics/ImageFormat.cs

@@ -0,0 +1,11 @@
+using System;
+
+namespace Blarg.GameFramework.Graphics
+{
+	public enum ImageFormat
+	{
+		RGB,
+		RGBA,
+		A
+	}
+}

Blarg.GameFramework/IApplication.cs

@@ -1,4 +1,5 @@
 using System;
+using System.IO;
 using PortableGL;
 using Blarg.GameFramework.Graphics;
 using Blarg.GameFramework.Input;
@@ -30,6 +31,8 @@ namespace Blarg.GameFramework
 
 		void Run(IGameApp gameApp, IPlatformConfiguration config);
 		void Quit();
+
+		IPlatformBitmap LoadBitmap(Stream file);
 	}
 }