add transform parse

src/Avalonia.Visuals/Media/Transform.cs

@@ -28,6 +28,16 @@ namespace Avalonia.Media
         /// </summary>
         public abstract Matrix Value { get; }
 
+        /// <summary>
+        /// Parses a <see cref="Transform"/> string.
+        /// </summary>
+        /// <param name="s">The string.</param>
+        /// <returns>The <see cref="Transform"/>.</returns>
+        public static Transform Parse(string s)
+        {
+            return new MatrixTransform(Matrix.Parse(s));
+        }
+
         /// <summary>
         /// Raises the <see cref="Changed"/> event.
         /// </summary>
@@ -35,5 +45,14 @@ namespace Avalonia.Media
         {
             Changed?.Invoke(this, EventArgs.Empty);
         }
+
+        /// <summary>
+        /// Returns a String representing this transform matrix instance.
+        /// </summary>
+        /// <returns>The string representation.</returns>
+        public override string ToString()
+        {
+            return Value.ToString();
+        }
     }
 }