[SVGDom/experimental] Initial SVGLength support

experimental/svg/model/SkSVGRenderContext.h

Index: experimental/svg/model/SkSVGRenderContext.h
diff --git a/experimental/svg/model/SkSVGRenderContext.h b/experimental/svg/model/SkSVGRenderContext.h
index 8ebaf12f0c019ce63adfe7acdb99a8b3e94250d0..50a6d59e5e84ee109cbadc1e42d7fe294582f86f 100644
--- a/experimental/svg/model/SkSVGRenderContext.h
+++ b/experimental/svg/model/SkSVGRenderContext.h
@@ -8,17 +8,39 @@
 #ifndef SkSVGRenderContext_DEFINED
 #define SkSVGRenderContext_DEFINED
 
+#include "SkSize.h"
 #include "SkPaint.h"
 #include "SkTLazy.h"
 
 class SkPaint;
+class SkSVGLength;
+
+class SkSVGLengthContext {
+public:
+    SkSVGLengthContext(const SkSize& viewport) : fViewport(viewport) {}
+
+    enum class LengthType {
+        kHorizontal,
+        kVertical,
+        kOther,
+    };
+
+    void setViewPort(const SkSize& viewport) { fViewport = viewport; }
+
+    SkScalar resolve(const SkSVGLength&, LengthType) const;
+
+private:
+    SkSize fViewport;
+};
 
 class SkSVGRenderContext {
 public:
-    SkSVGRenderContext();
+    explicit SkSVGRenderContext(const SkSize& initialViewport);
     SkSVGRenderContext(const SkSVGRenderContext&) = default;
     SkSVGRenderContext& operator=(const SkSVGRenderContext&);
 
+    const SkSVGLengthContext& lengthContext() const { return fLengthContext; }
+
     const SkPaint* fillPaint() const { return fFill.getMaybeNull(); }
     const SkPaint* strokePaint() const { return fStroke.getMaybeNull(); }
 
@@ -29,8 +51,9 @@ private:
     SkPaint& ensureFill();
     SkPaint& ensureStroke();
 
-    SkTLazy<SkPaint> fFill;
-    SkTLazy<SkPaint> fStroke;
+    SkSVGLengthContext fLengthContext;
+    SkTLazy<SkPaint>   fFill;
+    SkTLazy<SkPaint>   fStroke;
 };
 
 #endif // SkSVGRenderContext_DEFINED