Monogame-Extended/source/MonoGame.Extended/Tilemaps/TilemapTileset.cs

using System.Collections.Generic;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;

namespace MonoGame.Extended.Tilemaps
{
    /// <summary>
    /// Represents a collection of tiles from a single texture atlas.
    /// </summary>
    public class TilemapTileset
    {
        private readonly Dictionary<int, TilemapTileData> _tileData = new();

        /// <summary>
        /// Gets the name of the tileset.
        /// </summary>
        public string Name { get; }

        /// <summary>
        /// Gets the width of each tile in pixels.
        /// </summary>
        public int TileWidth { get; }

        /// <summary>
        /// Gets the height of each tile in pixels.
        /// </summary>
        public int TileHeight { get; }

        /// <summary>
        /// Gets the total number of tiles in the tileset.
        /// </summary>
        public int TileCount { get; }

        /// <summary>
        /// Gets the number of columns in the tileset.
        /// </summary>
        public int Columns { get; }

        /// <summary>
        /// Gets the spacing between tiles in pixels.
        /// </summary>
        public int Spacing { get; }

        /// <summary>
        /// Gets the margin around the tileset in pixels.
        /// </summary>
        public int Margin { get; }

        /// <summary>
        /// Gets the first global tile ID for tiles in this tileset.
        /// </summary>
        /// <remarks>
        /// This value determines the range of global IDs this tileset covers.
        /// Tiles in this tileset have IDs from FirstGlobalId to FirstGlobalId + TileCount - 1.
        /// </remarks>
        public int FirstGlobalId { get; internal set; }

        /// <summary>
        /// Gets the texture atlas.
        /// </summary>
        public Texture2D Texture { get; }

        /// <summary>
        /// Gets or sets the offset applied when rendering tiles from this tileset.
        /// </summary>
        public Vector2 TileOffset { get; set; }

        /// <summary>
        /// Gets the custom properties of the tileset.
        /// </summary>
        public TilemapProperties Properties { get; }

        /// <summary>
        /// Initializes a new instance of the <see cref="TilemapTileset"/> class.
        /// </summary>
        /// <param name="name">The name of the tileset.</param>
        /// <param name="texture">The texture atlas.</param>
        /// <param name="tileWidth">The width of each tile in pixels.</param>
        /// <param name="tileHeight">The height of each tile in pixels.</param>
        /// <param name="tileCount">The total number of tiles.</param>
        /// <param name="columns">The number of columns in the tileset.</param>
        /// <param name="spacing">The spacing between tiles in pixels.</param>
        /// <param name="margin">The margin around the tileset in pixels.</param>
        public TilemapTileset(string name, Texture2D texture, int tileWidth, int tileHeight, int tileCount, int columns, int spacing = 0, int margin = 0)
        {
            Name = name;
            Texture = texture;
            TileWidth = tileWidth;
            TileHeight = tileHeight;
            TileCount = tileCount;
            Columns = columns;
            Spacing = spacing;
            Margin = margin;
            Properties = new TilemapProperties();
        }

        /// <summary>
        /// Adds tile data for a specified local tile ID.
        /// </summary>
        /// <param name="tileData">The tile data to add.</param>
        internal void AddTileData(TilemapTileData tileData)
        {
            _tileData[tileData.LocalId] = tileData;
        }

        /// <summary>
        /// Gets the tile data for a specific local tile ID.
        /// </summary>
        /// <param name="localId">The local tile ID within this tileset.</param>
        /// <returns>The tile data, or <see langword="null"/> if not found.</returns>
        public TilemapTileData GetTileData(int localId)
        {
            if (_tileData.TryGetValue(localId, out var data))
            {
                return data;
            }

            return null;
        }

        /// <summary>
        /// Determines whether this tileset contains the specified global tile ID.
        /// </summary>
        /// <param name="globalTileId">The global tile ID to check.</param>
        /// <returns>
        /// <see langword="true"/> if the ID is within this tileset's range; otherwise, <see langword="false"/>.
        /// </returns>
        public bool ContainsGlobalId(int globalTileId)
        {
            return globalTileId >= FirstGlobalId &&
                   globalTileId < FirstGlobalId + TileCount;
        }

        /// <summary>
        /// Gets the source rectangle for a tile within the texture atlas.
        /// </summary>
        /// <param name="localId">The local tile ID within this tileset.</param>
        /// <returns>The source rectangle for the tile.</returns>
        /// <remarks>
        /// This method accounts for spacing and margin when calculating the tile position.
        /// </remarks>
        public Rectangle GetTileRegion(int localId)
        {
            int column = localId % Columns;
            int row = localId / Columns;

            int x = Margin + column * (TileWidth + Spacing);
            int y = Margin + row * (TileHeight + Spacing);


            return new Rectangle(x, y, TileWidth, TileHeight);
        }
    }
}