add stroke params to c api

src/c/sk_types_priv.h

Index: src/c/sk_types_priv.h
diff --git a/src/c/sk_types_priv.h b/src/c/sk_types_priv.h
new file mode 100644
index 0000000000000000000000000000000000000000..92089d7266303e9b9bf6f93def7aca010aa2a80e
--- /dev/null
+++ b/src/c/sk_types_priv.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef sk_types_priv_DEFINED
+#define sk_types_priv_DEFINED
+
+#include "sk_types.h"
+
+class SkMaskFilter;
+class SkPaint;
+class SkShader;
+
+static inline const SkPaint& AsPaint(const sk_paint_t& cpaint) {
+    return reinterpret_cast<const SkPaint&>(cpaint);
+}
+
+static inline const SkPaint* AsPaint(const sk_paint_t* cpaint) {
+    return reinterpret_cast<const SkPaint*>(cpaint);
+}
+
+static inline SkPaint* AsPaint(sk_paint_t* cpaint) {
+    return reinterpret_cast<SkPaint*>(cpaint);
+}
+
+static inline SkMaskFilter* AsMaskFilter(sk_maskfilter_t* cfilter) {
+    return reinterpret_cast<SkMaskFilter*>(cfilter);
+}
+
+static inline sk_maskfilter_t* ToMaskFilter(SkMaskFilter* filter) {
+    return reinterpret_cast<sk_maskfilter_t*>(filter);
+}
+
+static inline SkShader* AsShader(sk_shader_t* cshader) {
+    return reinterpret_cast<SkShader*>(cshader);
+}
+
+#endif