144 lines
3.4 KiB
C#
144 lines
3.4 KiB
C#
using Microsoft.AspNetCore.Http;
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using Microsoft.Extensions.Logging;
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using Microsoft.Extensions.Options;
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using Microsoft.Extensions.Primitives;
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using SixLabors.ImageSharp.Web.Commands;
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namespace zero.Media.ImageSharp;
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/// <summary>
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/// Parses commands from the request querystring.
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/// </summary>
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public sealed class PresetRequestParser : IRequestParser
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{
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MediaOptions _options;
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ILogger<PresetRequestParser> _logger;
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const char COLON = ':';
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const string PREFIX = "/:";
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const char SLASH = '/';
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const string MIME_AVIF = "image/avif";
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const string MIME_WEBP = "image/webp";
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public PresetRequestParser(ILogger<PresetRequestParser> logger, IOptionsMonitor<MediaOptions> monitor)
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{
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_logger = logger;
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_options = monitor.CurrentValue;
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monitor.OnChange(opts => _options = opts);
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}
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/// <inheritdoc/>
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public CommandCollection ParseRequestCommands(string preset, HttpContext context = null)
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{
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string focalPoint = null;
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int focalIndex = preset.IndexOf(COLON);
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if (focalIndex > -1)
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{
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focalPoint = preset.Substring(focalIndex + 1, preset.Length - focalIndex - 1);
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preset = preset.Substring(0, focalIndex);
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}
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if (preset == "{rx}")
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{
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return new();
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}
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if (!_options.ImageSharp.Presets.TryGetValue(preset, out string[] transformed))
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{
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_logger.LogWarning("Could not load imaging preset {preset}", preset);
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return new();
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}
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Dictionary<string, string> filters = transformed.Select(x => x.Split("=", 2)).ToDictionary(x => x[0], x => x[1]);
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if (focalPoint != null)
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{
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filters["rxy"] = focalPoint;
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}
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else
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{
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filters["ranchor"] = "center";
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}
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FallbackFormat fallbackFormat = FindFallbackFormatInContext(context);
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// fall back to webp, as avif is not supported yet by ImageSharp
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if (!filters.ContainsKey("format") && fallbackFormat != FallbackFormat.None)
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{
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filters["format"] = "webp";
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}
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if (!filters.ContainsKey("quality"))
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{
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filters["quality"] = _options.ImageSharp.DefaultQuality.ToString();
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}
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CommandCollection collection = new();
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foreach (KeyValuePair<string, string> filter in filters)
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{
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collection.Add(filter);
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}
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return collection;
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}
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/// <inheritdoc/>
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public FallbackFormat FindFallbackFormatInContext(HttpContext context)
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{
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string acceptKey = Microsoft.Net.Http.Headers.HeaderNames.Accept;
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if (context == null || context.Request == null || !context.Request.Headers.ContainsKey(acceptKey))
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{
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return FallbackFormat.None;
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}
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string acceptHeader = context.Request.Headers[acceptKey].ToString();
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if (acceptHeader.IsNullOrEmpty())
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{
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return FallbackFormat.None;
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}
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if (acceptHeader.Contains(MIME_AVIF))
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{
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return FallbackFormat.Avif;
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}
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if (acceptHeader.Contains(MIME_WEBP))
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{
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return FallbackFormat.Webp;
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}
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return FallbackFormat.None;
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}
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/// <inheritdoc/>
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public CommandCollection ParseRequestCommands(HttpContext context)
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{
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string path = context.Request.Path.Value;
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int startSlash = path.IndexOf(PREFIX);
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int lastSlash = path.LastIndexOf(SLASH);
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if (startSlash < 0)
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{
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return new();
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}
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string preset = path.Substring(startSlash + PREFIX.Length, lastSlash - startSlash - PREFIX.Length);
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return ParseRequestCommands(preset, context);
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}
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public enum FallbackFormat
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{
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None = 0,
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Webp = 1,
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Avif = 2
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}
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}
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