[SVGDom] Add <circle>, <ellipse> support

experimental/svg/model/SkSVGCircle.cpp

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkCanvas.h"
+#include "SkSVGCircle.h"
+#include "SkSVGRenderContext.h"
+#include "SkSVGValue.h"
+
+SkSVGCircle::SkSVGCircle() : INHERITED(SkSVGTag::kCircle) {}
+
+void SkSVGCircle::setCx(const SkSVGLength& cx) {
+    fCx = cx;
+}
+
+void SkSVGCircle::setCy(const SkSVGLength& cy) {
+    fCy = cy;
+}
+
+void SkSVGCircle::setR(const SkSVGLength& r) {
+    fR = r;
+}
+
+void SkSVGCircle::onSetAttribute(SkSVGAttribute attr, const SkSVGValue& v) {
+    switch (attr) {
+    case SkSVGAttribute::kCx:
+        if (const auto* cx = v.as<SkSVGLengthValue>()) {
+            this->setCx(*cx);
+        }
+        break;
+    case SkSVGAttribute::kCy:
+        if (const auto* cy = v.as<SkSVGLengthValue>()) {
+            this->setCy(*cy);
+        }
+        break;
+    case SkSVGAttribute::kR:
+        if (const auto* r = v.as<SkSVGLengthValue>()) {
+            this->setR(*r);
+        }
+        break;
+    default:
+        this->INHERITED::onSetAttribute(attr, v);
+    }
+}
+
+void SkSVGCircle::onDraw(SkCanvas* canvas, const SkSVGLengthContext& lctx,
+                         const SkPaint& paint) const {
+    const auto cx = lctx.resolve(fCx, SkSVGLengthContext::LengthType::kHorizontal);
+    const auto cy = lctx.resolve(fCy, SkSVGLengthContext::LengthType::kVertical);
+    const auto  r = lctx.resolve(fR , SkSVGLengthContext::LengthType::kOther);
+
+    if (r > 0) {
+        canvas->drawCircle(cx, cy, r, paint);
+    }
+}