feat(lottie): First implementation of theme properties for lottie fil…

…es (custom colors)

src/AddIns/Uno.UI.Lottie/DynamicReloadedLottieAnimatedVisualSource.cs

@@ -0,0 +1,282 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using Windows.Storage.Streams;
+using Windows.UI.Xaml.Data;
+using Uno.Disposables;
+using Windows.UI;
+using Windows.UI.Xaml.Controls;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+using Uno.UI.Lottie;
+using System.Linq;
+using Uno.Extensions;
+
+namespace Microsoft.Toolkit.Uwp.UI.Lottie
+{
+	[Bindable]
+	public class DynamicReloadedLottieAnimatedVisualSource : LottieVisualSourceBase, IDynamicAnimatedVisualSource
+	{
+		private JObject? _currentDocument;
+
+		private readonly Dictionary<string, ColorBinding> _colorsBindings
+			= new Dictionary<string, ColorBinding>(2);
+
+		private UpdatedAnimation? _updateCallback;
+		private string? _sourceCacheKey;
+
+		public void SetColorProperty(string propertyName, Color? color)
+		{
+			if(_colorsBindings.TryGetValue(propertyName, out var existing))
+			{
+				existing.NextValue = color;
+			}
+			else
+			{
+				_colorsBindings[propertyName] = new ColorBinding {NextValue = color};
+			}
+
+			if (_currentDocument == null)
+			{
+				return; // no document to change yet
+			}
+
+			if (ApplyProperties())
+			{
+				NotifyCallback();
+			}
+		}
+
+		protected override bool IsPayloadNeedsToBeUpdated => true;
+
+#if NETFRAMEWORK
+		public Task LoadForTests(
+			IInputStream sourceJson,
+			string sourceCacheKey,
+			UpdatedAnimation updateCallback)
+		{
+			_updateCallback = updateCallback;
+			return LoadAndUpdate(default, sourceCacheKey, sourceJson);
+		}
+
+		public string? GetJson()
+		{
+			return _currentDocument?.ToString(Formatting.Indented);
+		}
+#endif
+
+		protected override IDisposable? LoadAndObserveAnimationData(
+			IInputStream sourceJson,
+			string sourceCacheKey,
+			UpdatedAnimation updateCallback)
+		{
+			var cts = new CancellationTokenSource();
+
+			_updateCallback = updateCallback;
+
+			var t = LoadAndUpdate(cts.Token, sourceCacheKey, sourceJson);
+
+			return Disposable.Create(() =>
+			{
+				cts.Cancel();
+				cts.Dispose();
+			});
+		}
+
+		private async Task LoadAndUpdate(
+			CancellationToken ct,
+			string sourceCacheKey,
+			IInputStream sourceJson)
+		{
+			_sourceCacheKey = sourceCacheKey;
+
+			// Note: we're using Newtownsoft JSON.NET here
+			// because System.Text.Json does not support changing the
+			// parsed document - it's read only.
+
+			// LOAD JSON
+			JObject document;
+			using (var stream = sourceJson.AsStreamForRead(0))
+			{
+				using var streamReader = new StreamReader(stream);
+				using var reader = new JsonTextReader(streamReader);
+				document = JObject.Load(reader);
+			}
+
+			// PARSE JSON
+			ParseDocument(document);
+
+			// APPLY PROPERTIES
+			ApplyProperties();
+
+			// NOTIFY
+			NotifyCallback();
+		}
+
+		private void ParseDocument(JObject document)
+		{
+			_currentDocument = document;
+
+			foreach (var colorBinding in _colorsBindings)
+			{
+				colorBinding.Value.Elements.Clear();
+			}
+
+			void ParseLayers(JToken layersElement)
+			{
+				if (!(layersElement is JArray layers))
+				{
+					return; // potentially invalid lottie file
+				}
+
+				foreach (var layer in layers)
+				{
+					if (layer is JObject l)
+					{
+						var shapesValue = l.GetValue("shapes");
+
+						if (shapesValue is JArray shapes)
+						{
+							foreach (var shape in shapes)
+							{
+								if (shape is JObject s)
+								{
+									ParseShape(s);
+								}
+							}
+						}
+					}
+				}
+			}
+
+			void ParseShape(JObject shapeElement)
+			{
+				var typeValue = shapeElement.GetValue("ty");
+				if (typeValue.Type != JTokenType.String)
+				{
+					return; // potentially invalid lottie file
+				}
+
+				var shapeType = typeValue.Value<string>();
+
+				if (shapeType != null && shapeType.Equals("gr"))
+				{
+					// That's a group
+
+					var itemsProperty = shapeElement.GetValue("it");
+
+					if (itemsProperty is JArray items)
+					{
+						foreach (var item in items)
+						{
+							if (item is JObject s)
+							{
+								ParseShape(s);
+							}
+						}
+					}
+
+					return;
+				}
+
+				var nameProperty = shapeElement.GetValue("nm");
+
+				if (nameProperty.Type != JTokenType.String)
+				{
+					return; // No name
+				}
+
+				var name = nameProperty.Value<string>();
+
+				if (!string.IsNullOrWhiteSpace(name))
+				{
+					var elementBindings = PropertyBindingsParser.ParseBindings(name);
+					if (elementBindings.Length > 0)
+					{
+						foreach (var binding in elementBindings)
+						{
+							if (binding.propertyName.Equals("Color", StringComparison.Ordinal))
+							{
+								if (_colorsBindings.TryGetValue(binding.bindingName, out var colorBinding))
+								{
+									colorBinding.Elements.Add(shapeElement);
+								}
+								else
+								{
+									colorBinding = new ColorBinding();
+									colorBinding.Elements.Add(shapeElement);
+									_colorsBindings[binding.bindingName] = colorBinding;
+								}
+							}
+						}
+					}
+				}
+			}
+
+			if (document.TryGetValue("layers", out var layers))
+			{
+				ParseLayers(layers);
+			}
+		}
+
+		private bool ApplyProperties()
+		{
+			var changed = false;
+			foreach (var colorBinding in _colorsBindings)
+			{
+				if (!(colorBinding.Value.NextValue is {} color))
+				{
+					continue; // nothing to change
+				}
+
+				var colorComponents = new[] {color.R / 255f, color.G / 255f, color.B / 255f, color.A / 255f};
+
+				foreach (var element in colorBinding.Value.Elements)
+				{
+					var k = (element.GetValue("c") as JObject)?.GetValue("k") as JArray;
+
+					if (k != null)
+					{
+						k.Clear();
+						k.Add(new JValue(colorComponents[0]));
+						k.Add(new JValue(colorComponents[1]));
+						k.Add(new JValue(colorComponents[2]));
+						k.Add(new JValue(colorComponents[3]));
+
+						changed = true;
+					}
+				}
+				colorBinding.Value.CurrentValue = colorBinding.Value.NextValue;
+				colorBinding.Value.NextValue = null;
+			}
+
+			return changed;
+		}
+
+		private void NotifyCallback()
+		{
+			if (_updateCallback is {} callback)
+			{
+				var json = _currentDocument?.ToString(Formatting.None);
+				if (json is { })
+				{
+					var propertiesKey = _colorsBindings
+						.SelectToArray(kvp => $"{kvp.Key}-{kvp.Value.CurrentValue}")
+						.JoinBy("-");
+
+					callback(json, _sourceCacheKey + "-" + propertiesKey);
+				}
+			}
+		}
+
+
+		private class ColorBinding
+		{
+			internal List<JObject> Elements { get; } = new List<JObject>(1);
+			internal Color? CurrentValue { get; set; }
+			internal Color? NextValue { get; set; }
+		}
+	}
+}