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Creating Bindings
Matthew Leibowitz edited this page May 8, 2018
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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:
class SK_API SkPaint {
public:
bool isAntiAlias() const;
void setAntiAlias(bool aa);
};
This is then wrapped in a C API:
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:
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:
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 https://github.com/mono/skia that has our additions. We intend to upstream those changes to Google.