rewrite SpriteBatch.Begin calls for compatibility (#166)

1 files changed, 30 insertions, 0 deletions

diff --git a/src/StardewModdingAPI.AssemblyRewriters/Rewriters/SpriteBatchRewriter.cs b/src/StardewModdingAPI.AssemblyRewriters/Rewriters/SpriteBatchRewriter.cs
new file mode 100644
index 00000000..1c0a5cf3
--- /dev/null
+++ b/src/StardewModdingAPI.AssemblyRewriters/Rewriters/SpriteBatchRewriter.cs
@@ -0,0 +1,30 @@
+using Microsoft.Xna.Framework.Graphics;
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+using StardewModdingAPI.AssemblyRewriters.Wrappers;
+
+namespace StardewModdingAPI.AssemblyRewriters.Rewriters
+{
+    /// <summary>Rewrites references to <see cref="SpriteBatch"/> to fix inconsistent method signatures between MonoGame and XNA.</summary>
+    /// <remarks>MonoGame has one <c>SpriteBatch.Begin</c> method with optional arguments, but XNA has multiple method overloads. Incompatible method references are rewritten to use <see cref="CompatibleSpriteBatch"/>, which redirects all method signatures to the proper compiled MonoGame/XNA method.</remarks>
+    public class SpriteBatchRewriter : BaseMethodRewriter
+    {
+        /// <summary>Get whether the given method reference can be rewritten.</summary>
+        /// <param name="methodRef">The method reference.</param>
+        public override bool ShouldRewrite(MethodReference methodRef)
+        {
+            return methodRef.DeclaringType.FullName == typeof(SpriteBatch).FullName && this.HasMatchingSignature(typeof(CompatibleSpriteBatch), methodRef);
+        }
+
+        /// <summary>Rewrite a method for compatibility.</summary>
+        /// <param name="module">The module being rewritten.</param>
+        /// <param name="cil">The CIL rewriter.</param>
+        /// <param name="callOp">The instruction which calls the method.</param>
+        /// <param name="methodRef">The method reference invoked by the <paramref name="callOp"/>.</param>
+        /// <param name="assemblyMap">Metadata for mapping assemblies to the current platform.</param>
+        public override void Rewrite(ModuleDefinition module, ILProcessor cil, Instruction callOp, MethodReference methodRef, PlatformAssemblyMap assemblyMap)
+        {
+            methodRef.DeclaringType = module.Import(typeof(CompatibleSpriteBatch));
+        }
+    }
+}
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