sbox-public/engine/Sandbox.Engine/Resources/Textures/Loader/HttpImageLoader.cs

using System.IO;
using System.Net.Http;

namespace Sandbox.TextureLoader;

internal static class ImageUrl
{
	/// <summary>
	/// For textures loaded from the web we want to keep them around a bit longer
	/// </summary>
	static CaseInsensitiveDictionary<Texture> Loaded = new();

	internal static bool IsAppropriate( string url )
	{
		return url.StartsWith( "https://" ) || url.StartsWith( "http://" );
	}

	internal static Texture Load( string filename, bool warnOnMissing )
	{
		if ( Loaded.TryGetValue( filename, out var cachedTexture ) )
		{
			return cachedTexture;
		}

		try
		{
			//
			// Create a 1x1 placeholder texture
			//
			var placeholder = Texture.Create( 1, 1 ).WithName( "httpimg-placeholder" ).WithData( new byte[4] { 0, 0, 0, 0 } ).Finish();
			_ = placeholder.ReplacementAsync( LoadFromUrl( filename ) );

			Loaded[filename] = placeholder;

			return placeholder;
		}
		catch ( System.Exception e )
		{
			Log.Warning( $"Couldn't Load from Url {filename} ({e.Message})" );
			return null;
		}
	}

	static HttpClient HttpClient;

	internal static async Task<Texture> LoadFromUrl( string url )
	{
		HttpClient ??= new HttpClient();
		var filename = url;

		try
		{
			// I'd love to retry this multiple times, if it's a weird error that seems recoverable

			var bytes = await HttpClient.GetByteArrayAsync( url );
			Texture texture = null;
			// decode in a thread
			await Task.Run( () =>
			{
				using var ms = new MemoryStream( bytes );
				texture = Image.Load( ms, url );
			} );

			return texture;
		}
		catch ( System.Security.Authentication.AuthenticationException )
		{
			Log.Warning( $"AuthenticationException when downloading {url}" );
		}
		catch ( HttpRequestException e )
		{
			Log.Warning( e, $"HttpRequestException when downloading {url}" );
		}

		return default;
	}
}