add texture patching to content events (#173)

1 files changed, 51 insertions, 0 deletions

diff --git a/src/StardewModdingAPI/Framework/ContentEventHelper.cs b/src/StardewModdingAPI/Framework/ContentEventHelper.cs
index a58efe32..ebd04692 100644
--- a/src/StardewModdingAPI/Framework/ContentEventHelper.cs
+++ b/src/StardewModdingAPI/Framework/ContentEventHelper.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Graphics;
 
 namespace StardewModdingAPI.Framework
@@ -85,6 +86,56 @@ namespace StardewModdingAPI.Framework
             data[key] = value(data[key]);
         }
 
+        /// <summary>Overwrite part of the image.</summary>
+        /// <param name="source">The image to patch into the content.</param>
+        /// <param name="sourceArea">The part of the <paramref name="source"/> to copy (or <c>null</c> to take the whole texture). This must be within the bounds of the <paramref name="source"/> texture.</param>
+        /// <param name="targetArea">The part of the content to patch (or <c>null</c> to patch the whole texture). The original content within this area will be erased. This must be within the bounds of the existing spritesheet.</param>
+        /// <param name="patchMode">Indicates how an image should be patched.</param>
+        /// <exception cref="ArgumentNullException">One of the arguments is null.</exception>
+        /// <exception cref="ArgumentOutOfRangeException">The <paramref name="targetArea"/> is outside the bounds of the spritesheet.</exception>
+        /// <exception cref="InvalidOperationException">The content being read isn't an image.</exception>
+        public void PatchImage(Texture2D source, Rectangle? sourceArea = null, Rectangle? targetArea = null, PatchMode patchMode = PatchMode.Replace)
+        {
+            // get texture
+            Texture2D target = this.GetData<Texture2D>();
+
+            // get areas
+            sourceArea = sourceArea ?? new Rectangle(0, 0, source.Width, source.Height);
+            targetArea = targetArea ?? new Rectangle(0, 0, Math.Min(sourceArea.Value.Width, target.Width), Math.Min(sourceArea.Value.Height, target.Height));
+
+            // validate
+            if (source == null)
+                throw new ArgumentNullException(nameof(source), "Can't patch from a null source texture.");
+            if (sourceArea.Value.X < 0 || sourceArea.Value.Y < 0 || sourceArea.Value.Right > source.Width || sourceArea.Value.Bottom > source.Height)
+                throw new ArgumentOutOfRangeException(nameof(sourceArea), "The source area is outside the bounds of the source texture.");
+            if (targetArea.Value.X < 0 || targetArea.Value.Y < 0 || targetArea.Value.Right > target.Width || targetArea.Value.Bottom > target.Height)
+                throw new ArgumentOutOfRangeException(nameof(targetArea), "The target area is outside the bounds of the target texture.");
+            if (sourceArea.Value.Width != targetArea.Value.Width || sourceArea.Value.Height != targetArea.Value.Height)
+                throw new InvalidOperationException("The source and target areas must be the same size.");
+
+            // get source data
+            int pixelCount = sourceArea.Value.Width * sourceArea.Value.Height;
+            Color[] sourceData = new Color[pixelCount];
+            source.GetData(0, sourceArea, sourceData, 0, pixelCount);
+
+            // merge data in overlay mode
+            if (patchMode == PatchMode.Overlay)
+            {
+                Color[] newData = new Color[targetArea.Value.Width * targetArea.Value.Height];
+                target.GetData(0, targetArea, newData, 0, newData.Length);
+                for (int i = 0; i < sourceData.Length; i++)
+                {
+                    Color pixel = sourceData[i];
+                    if (pixel.A != 0) // not transparent
+                        newData[i] = pixel;
+                }
+                sourceData = newData;
+            }
+
+            // patch target texture
+            target.SetData(0, targetArea, sourceData, 0, pixelCount);
+        }
+
         /// <summary>Replace the entire content value with the given value. This is generally not recommended, since it may break compatibility with other mods or different versions of the game.</summary>
         /// <param name="value">The new content value.</param>
         /// <exception cref="ArgumentNullException">The <paramref name="value"/> is null.</exception>