Avalonia/src/Web/Avalonia.Web.Blazor/Cursor.cs

using Avalonia.Input;
using Avalonia.Platform;

namespace Avalonia.Web.Blazor
{
    public class CssCursor : ICursorImpl
    {
        public const string Default = "default";
        public string? Value { get; set; }
        
        public CssCursor(StandardCursorType type)
        {
            Value = ToKeyword(type);
        }

        /// <summary>
        /// Create a cursor from base64 image
        /// </summary>
        public CssCursor(string base64, string format, PixelPoint hotspot, StandardCursorType fallback)
        {
            Value = $"url(\"data:image/{format};base64,{base64}\") {hotspot.X} {hotspot.Y}, {ToKeyword(fallback)}";
        }
        
        /// <summary>
        /// Create a cursor from url to *.cur file.
        /// </summary>
        public CssCursor(string url, StandardCursorType fallback)
        {
            Value = $"url('{url}'), {ToKeyword(fallback)}";
        }
        
        /// <summary>
        /// Create a cursor from png/svg and hotspot position
        /// </summary>
        public CssCursor(string url, PixelPoint hotSpot, StandardCursorType fallback)
        {
            Value = $"url('{url}') {hotSpot.X} {hotSpot.Y}, {ToKeyword(fallback)}";
        }
        
        private static string ToKeyword(StandardCursorType type) => type switch
        {
            StandardCursorType.Hand => "pointer",
            StandardCursorType.Cross => "crosshair",
            StandardCursorType.Help => "help",
            StandardCursorType.Ibeam => "text",
            StandardCursorType.No => "not-allowed",
            StandardCursorType.None => "none",
            StandardCursorType.Wait => "progress",
            StandardCursorType.AppStarting => "wait",
            
            StandardCursorType.DragMove => "move",
            StandardCursorType.DragCopy => "copy",
            StandardCursorType.DragLink => "alias",
            
            StandardCursorType.UpArrow => "default",/*not found matching one*/
            StandardCursorType.SizeWestEast => "ew-resize",
            StandardCursorType.SizeNorthSouth => "ns-resize",
            StandardCursorType.SizeAll => "move",
            
            StandardCursorType.TopSide => "n-resize",
            StandardCursorType.BottomSide => "s-resize",
            StandardCursorType.LeftSide => "w-resize",
            StandardCursorType.RightSide => "e-resize",
            StandardCursorType.TopLeftCorner => "nw-resize",
            StandardCursorType.TopRightCorner => "ne-resize",
            StandardCursorType.BottomLeftCorner => "sw-resize",
            StandardCursorType.BottomRightCorner => "se-resize",
            
            _ => Default,
        };
        
        public void Dispose() {}
    }

    internal class CssCursorFactory : ICursorFactory
    {
        public ICursorImpl CreateCursor(IBitmapImpl cursor, PixelPoint hotSpot)
        {
            using var imageStream = new MemoryStream();
            cursor.Save(imageStream);
            
            //not memory optimized because CryptoStream with ToBase64Transform is not supported in the browser.
            var base64String = Convert.ToBase64String(imageStream.ToArray());
            return new CssCursor(base64String, "png", hotSpot, StandardCursorType.Arrow);
        }

        ICursorImpl ICursorFactory.GetCursor(StandardCursorType cursorType)
        {
            return new CssCursor(cursorType);
        }
    }
}