Add DalamudSubstitutionProvider

Penumbra/Api/DalamudSubstitutionProvider.cs

@@ -0,0 +1,46 @@
+using System;
+using Dalamud.Plugin.Services;
+using Penumbra.Collections.Manager;
+using Penumbra.String.Classes;
+
+namespace Penumbra.Api;
+
+public class DalamudSubstitutionProvider : IDisposable
+{
+    private readonly ITextureSubstitutionProvider _substitution;
+    private readonly ActiveCollectionData         _activeCollectionData;
+
+    public DalamudSubstitutionProvider(ITextureSubstitutionProvider substitution, ActiveCollectionData activeCollectionData)
+    {
+        _substitution                      =  substitution;
+        _activeCollectionData              =  activeCollectionData;
+        _substitution.InterceptTexDataLoad += Substitute;
+    }
+
+    public void Dispose()
+        => _substitution.InterceptTexDataLoad -= Substitute;
+
+    private void Substitute(string path, ref string? replacementPath)
+    {
+        // Let other plugins prioritize replacement paths.
+        if (replacementPath != null)
+            return;
+
+        // Only replace interface textures.
+        if (!path.StartsWith("ui/") && !path.StartsWith("common/font/"))
+            return;
+
+        try
+        {
+            if (!Utf8GamePath.FromString(path, out var utf8Path, true))
+                return;
+
+            var resolved = _activeCollectionData.Interface.ResolvePath(utf8Path);
+            replacementPath = resolved?.FullName;
+        }
+        catch
+        {
+            // ignored
+        }
+    }
+}