Create Binding.md

Binding.md

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+SkiaSharp provides the same features as the native C++ library through a method of wrapping 
+the C++ API with a C API that we P/Invoke into.
+
+Then C# wraps the C API to provide an API similar to the object oriented binding provided by C++.
+
+For example, given this C++ API:
+
+```cpp
+class SK_API SkPaint {
+public:
+  bool isAntiAlias() const;
+  void setAntiAlias(bool aa);
+};
+```
+
+This is then wrapped in a C API:
+
+```cpp
+bool sk_paint_is_antialias(const sk_paint_t* cpaint) {
+  return AsPaint(cpaint)->isAntiAlias();
+}
+void sk_paint_set_antialias(sk_paint_t* cpaint, bool aa) {
+  AsPaint(cpaint)->setAntiAlias(aa);
+}
+```
+
+Which is then pulled into the C# project via P/Invoke:
+
+```csharp
+public extern static bool sk_paint_is_antialias (sk_paint_t t);
+public extern static void sk_paint_set_antialias (sk_paint_t t, bool aa);
+```
+
+Finally, this is wrapped into a neat C# class:
+
+```csharp
+public class SKPaint : SKObject
+{
+  public bool IsAntialias {
+    get { return SkiaApi.sk_paint_is_antialias (Handle); }
+    set { SkiaApi.sk_paint_set_antialias (Handle, value); }
+  }
+}
+```
+
+As a result, the C# API functions and appears the same as the C++ API.
+
+Since the C API is currently a work in progress of the Skia project, we 
+maintain a fork in github.com/mono/skia that has our additions.   We intend
+to upstream those changes to Google.