Added Image constructor support

Author: tomvanenckevort

Diff for: src/AngleSharp.Js.Tests/ScriptEvalTests.cs

@@ -75,6 +75,13 @@ public async Task CreateXmlHttpRequestShouldWork()
             Assert.AreEqual("1", result);
         }
 
+        [Test]
+        public async Task CreateImageShouldWork()
+        {
+            var result = await EvaluateComplexScriptAsync("var img = new Image(400, 200); img.src = '/image.jpg';", SetResult("img.width"));
+            Assert.AreEqual("400", result);
+        }
+
         [Test]
         public async Task PerformXmlHttpRequestSynchronousToDataUrlShouldWork()
         {

Diff for: src/AngleSharp.Js/Attributes/DomConstructorFunctionAttribute.cs

@@ -0,0 +1,28 @@
+namespace AngleSharp.Js.Attributes
+{
+    using System;
+
+    /// <summary>
+    /// This attribute is used to mark a method to be uses as a
+    /// constructor function from scripts.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Method, Inherited = false)]
+    public sealed class DomConstructorFunctionAttribute : Attribute
+    {
+        /// <summary>
+        /// Creates a new DomConstructorFunctionAttribute.
+        /// </summary>
+        /// <param name="officialName">
+        /// The official name of the decorated method.
+        /// </param>
+        public DomConstructorFunctionAttribute(String officialName)
+        {
+            OfficialName = officialName;
+        }
+
+        /// <summary>
+        /// Gets the official name of the given class.
+        /// </summary>
+        public String OfficialName { get; }
+    }
+}

Diff for: src/AngleSharp.Js/Cache/CreatorCache.cs

@@ -1,4 +1,6 @@
 using AngleSharp.Attributes;
+using AngleSharp.Js.Attributes;
+using AngleSharp.Js.Proxies;
 using Jint.Native.Object;
 using Jint.Runtime.Descriptors;
 using System;
@@ -40,6 +42,39 @@ public static Action<EngineInstance, ObjectInstance> GetConstructorAction(this T
             return action;
         }
 
+        private static readonly Dictionary<Type, Action<EngineInstance, ObjectInstance>> _constructorFunctionActions = new Dictionary<Type, Action<EngineInstance, ObjectInstance>>();
+
+        public static Action<EngineInstance, ObjectInstance> GetConstructorFunctionAction(this Type type)
+        {
+            if (!_constructorFunctionActions.TryGetValue(type, out var action))
+            {
+                var constructorFunctions = type.GetTypeInfo().GetMethods().Where(m => m.GetCustomAttributes<DomConstructorFunctionAttribute>().Any());
+
+                if (constructorFunctions.Any())
+                {
+                    action = (engine, obj) =>
+                    {
+                        foreach (var constructorFunction in constructorFunctions)
+                        {
+                            var attribute = constructorFunction.GetCustomAttribute<DomConstructorFunctionAttribute>();
+
+                            var constructorFunctionInstance = new DomConstructorFunctionInstance(engine, constructorFunction, attribute.OfficialName);
+
+                            obj.FastSetProperty(attribute.OfficialName, new PropertyDescriptor(constructorFunctionInstance, false, true, false));
+                        }
+                    };
+                }
+                else
+                {
+                    action = (e, o) => { };
+                }
+
+                _constructorFunctionActions.Add(type, action);
+            }
+
+            return action;
+        }
+
         private static readonly Dictionary<Type, Action<EngineInstance, ObjectInstance>> _instanceActions = new Dictionary<Type, Action<EngineInstance, ObjectInstance>>();
 
         public static Action<EngineInstance, ObjectInstance> GetInstanceAction(this Type type)

Diff for: src/AngleSharp.Js/Dom/WindowExtensions.cs

@@ -4,6 +4,8 @@ namespace AngleSharp.Js.Dom
     using AngleSharp.Browser;
     using AngleSharp.Dom;
     using AngleSharp.Dom.Events;
+    using AngleSharp.Html.Dom;
+    using AngleSharp.Js.Attributes;
     using System;
 
     /// <summary>
@@ -42,5 +44,30 @@ public static Console Console(this IWindow window)
         {
             return new Console(window);
         }
+
+        /// <summary>
+        /// Creates a new IHtmlImageElement instance.
+        /// </summary>
+        /// <param name="window"></param>
+        /// <param name="width"></param>
+        /// <param name="height"></param>
+        /// <returns></returns>
+        [DomConstructorFunction("Image")]
+        public static IHtmlImageElement Image(this IWindow window, int? width = null, int? height = null)
+        {
+            var imageElement = window.Document.CreateElement(TagNames.Img) as IHtmlImageElement;
+
+            if (width.HasValue)
+            {
+                imageElement.DisplayWidth = width.Value;
+            }
+
+            if (height.HasValue)
+            {
+                imageElement.DisplayHeight = height.Value;
+            }
+
+            return imageElement;
+        }
     }
 }

Diff for: src/AngleSharp.Js/EngineInstance.cs

@@ -47,6 +47,7 @@ public EngineInstance(IWindow window, IDictionary<String, Object> assignments, I
             foreach (var lib in libs)
             {
                 this.AddConstructors(_window, lib);
+                this.AddConstructorFunctions(_window, lib);
                 this.AddInstances(_window, lib);
             }
 

Diff for: src/AngleSharp.Js/Extensions/EngineExtensions.cs

@@ -178,6 +178,14 @@ public static void AddConstructors(this EngineInstance engine, ObjectInstance ct
             }
         }
 
+        public static void AddConstructorFunctions(this EngineInstance engine, ObjectInstance ctx, Assembly assembly)
+        {
+            foreach (var exportedType in assembly.ExportedTypes)
+            {
+                engine.AddConstructorFunction(ctx, exportedType);
+            }
+        }
+
         public static void AddInstances(this EngineInstance engine, ObjectInstance obj, Assembly assembly)
         {
             foreach (var exportedType in assembly.ExportedTypes)
@@ -192,6 +200,12 @@ public static void AddConstructor(this EngineInstance engine, ObjectInstance obj
             apply.Invoke(engine, obj);
         }
 
+        public static void AddConstructorFunction(this EngineInstance engine, ObjectInstance obj, Type type)
+        {
+            var apply = type.GetConstructorFunctionAction();
+            apply.Invoke(engine, obj);
+        }
+
         public static void AddInstance(this EngineInstance engine, ObjectInstance obj, Type type)
         {
             var apply = type.GetInstanceAction();

Diff for: src/AngleSharp.Js/Extensions/JsValueExtensions.cs

@@ -73,6 +73,17 @@ public static Object As(this JsValue value, Type targetType, EngineInstance engi
                 {
                     return TypeConverter.ToInt32(value);
                 }
+                else if (targetType == typeof(Nullable<Int32>))
+                {
+                    if (value.IsUndefined())
+                    {
+                        return null;
+                    }
+                    else
+                    {
+                        return TypeConverter.ToInt32(value);
+                    }
+                }
                 else if (targetType == typeof(Double))
                 {
                     return TypeConverter.ToNumber(value);

Diff for: src/AngleSharp.Js/Proxies/DomConstructorFunctionInstance.cs

@@ -0,0 +1,31 @@
+namespace AngleSharp.Js.Proxies
+{
+    using Jint.Native;
+    using Jint.Native.Object;
+    using Jint.Runtime;
+    using System.Reflection;
+
+    sealed class DomConstructorFunctionInstance : Constructor
+    {
+        private readonly EngineInstance _instance;
+        private readonly MethodInfo _constructorFunction;
+
+        public DomConstructorFunctionInstance(EngineInstance instance, MethodInfo constructorFunction, string name) : base(instance.Jint, name)
+        {
+            _instance = instance;
+            _constructorFunction = constructorFunction;
+        }
+
+        public override ObjectInstance Construct(JsValue[] arguments, JsValue newTarget)
+        {
+            try
+            {
+                return _instance.Call(_constructorFunction, _instance.Window, arguments) as DomNodeInstance;
+            }
+            catch
+            {
+                throw new JavaScriptException(_instance.Jint.Intrinsics.Error);
+            }
+        }
+    }
+}