ULD Stuff.

Dalamud/Interface/UiBuilder.cs

@@ -263,6 +263,14 @@ public sealed class UiBuilder : IDisposable
         => this.InterfaceManagerWithScene?.LoadImageRaw(imageData, width, height, numChannels)
            ?? throw new InvalidOperationException("Load failed.");
 
+    /// <summary>
+    /// Loads an ULD file that can load textures containing multiple icons in a single texture.
+    /// </summary>
+    /// <param name="uldPath">The path of the requested ULD file.</param>
+    /// <returns>A wrapper around said ULD file.</returns>
+    public UldWrapper LoadUld(string uldPath)
+        => new(this, uldPath);
+
     /// <summary>
     /// Asynchronously loads an image from the specified file, when it's possible to do so.
     /// </summary>

Dalamud/Interface/UldWrapper.cs

@@ -0,0 +1,174 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+using Dalamud.Data;
+using Dalamud.Utility;
+using ImGuiScene;
+using Lumina.Data.Files;
+using Lumina.Data.Parsing.Uld;
+
+namespace Dalamud.Interface;
+
+/// <summary> Wrapper for multi-icon sprite sheets defined by ULD files. </summary>
+public class UldWrapper : IDisposable
+{
+    private readonly DataManager data;
+    private readonly UiBuilder uiBuilder;
+    private readonly Dictionary<string, (uint Id, int Width, int Height, bool HD, byte[] RgbaData)> textures = new();
+
+    /// <summary> Initializes a new instance of the <see cref="UldWrapper"/> class, wrapping an ULD file. </summary>
+    /// <param name="uiBuilder">The UiBuilder used to load textures.</param>
+    /// <param name="uldPath">The requested ULD file.</param>
+    internal UldWrapper(UiBuilder uiBuilder, string uldPath)
+    {
+        this.uiBuilder = uiBuilder;
+        this.data = Service<DataManager>.Get();
+        this.Uld = this.data.GetFile<UldFile>(uldPath);
+    }
+
+    /// <summary> Gets the loaded ULD file if it exists. </summary>
+    public UldFile? Uld { get; private set; }
+
+    /// <summary> Gets a value indicating whether the requested ULD could be loaded. </summary>
+    public bool Valid
+        => this.Uld != null;
+
+    /// <summary> Load a part of a multi-icon sheet as a texture. </summary>
+    /// <param name="texturePath">The path of the requested texture.</param>
+    /// <param name="part">The index of the desired icon.</param>
+    /// <returns>A TextureWrap containing the requested part if it exists and null otherwise.</returns>
+    public TextureWrap? LoadTexturePart(string texturePath, int part)
+    {
+        if (!this.Valid)
+        {
+            return null;
+        }
+
+        if (!this.textures.TryGetValue(texturePath, out var texture))
+        {
+            var tuple = this.GetTexture(texturePath);
+            if (!tuple.HasValue)
+            {
+                return null;
+            }
+
+            texture = tuple.Value;
+            this.textures[texturePath] = texture;
+        }
+
+        return this.CreateTexture(texture.Id, texture.Width, texture.Height, texture.HD, texture.RgbaData, part);
+    }
+
+    /// <summary> Clear all stored data and remove the loaded ULD. </summary>
+    public void Dispose()
+    {
+        this.textures.Clear();
+        this.Uld = null;
+    }
+
+    private TextureWrap? CreateTexture(uint id, int width, int height, bool hd, byte[] rgbaData, int partIdx)
+    {
+        var idx = 0;
+        UldRoot.PartData? partData = null;
+
+        // Iterate over all available parts that have the corresponding TextureId,
+        // count up to the required one and return it if it exists.
+        foreach (var part in this.Uld!.Parts.SelectMany(p => p.Parts))
+        {
+            if (part.TextureId != id)
+            {
+                continue;
+            }
+
+            if (idx++ == partIdx)
+            {
+                partData = part;
+                break;
+            }
+        }
+
+        if (!partData.HasValue)
+        {
+            return null;
+        }
+
+        // Double all dimensions for HD textures.
+        var d = hd ? partData.Value with
+        {
+            H = (ushort)(partData.Value.H * 2),
+            W = (ushort)(partData.Value.W * 2),
+            U = (ushort)(partData.Value.U * 2),
+            V = (ushort)(partData.Value.V * 2),
+        } : partData.Value;
+
+        return this.CopyRect(width, height, rgbaData, d);
+    }
+
+    private TextureWrap? CopyRect(int width, int height, byte[] rgbaData, UldRoot.PartData part)
+    {
+        if (part.V + part.W > width || part.U + part.H > height)
+        {
+            return null;
+        }
+
+        var imageData = new byte[part.W * part.H * 4];
+
+        // Iterate over all lines and copy the relevant ones,
+        // assuming a 4-byte-per-pixel standard layout.
+        for (var y = 0; y < part.H; ++y)
+        {
+            var inputSlice = rgbaData.AsSpan().Slice((((part.V + y) * width) + part.U) * 4, part.W * 4);
+            var outputSlice = imageData.AsSpan(y * part.W * 4);
+            inputSlice.CopyTo(outputSlice);
+        }
+
+        return this.uiBuilder.LoadImageRaw(imageData, part.W, part.H, 4);
+    }
+
+    private (uint Id, int Width, int Height, bool HD, byte[] RgbaData)? GetTexture(string texturePath)
+    {
+        if (!this.Valid)
+        {
+            return null;
+        }
+
+        // Always replace the HD version with the regular one as ULDs do not contain the HD suffix.
+        texturePath = texturePath.Replace("_hr1", string.Empty);
+
+        // Search the requested texture asset in the ULD and store its ID if it exists.
+        var id = uint.MaxValue;
+        foreach (var part in this.Uld!.AssetData)
+        {
+            var maxLength = Math.Min(part.Path.Length, texturePath.AsSpan().Length);
+            if (part.Path.AsSpan()[..maxLength].SequenceEqual(texturePath.AsSpan()[..maxLength]))
+            {
+                id = part.Id;
+                break;
+            }
+        }
+
+        if (id == uint.MaxValue)
+        {
+            return null;
+        }
+
+        // Try to load HD textures first. 
+        var hrPath = texturePath.Replace(".tex", "_hr1.tex");
+        var hd = true;
+        var file = this.data.GetFile<TexFile>(hrPath);
+        if (file == null)
+        {
+            hd = false;
+            file = this.data.GetFile<TexFile>(texturePath);
+
+            // Neither texture could be loaded.
+            if (file == null)
+            {
+                return null;
+            }
+        }
+
+        return (id, file.Header.Width, file.Header.Height, hd, file.GetRgbaImageData());
+    }
+}