[SVGDom] Add <line> support

experimental/svg/model/SkSVGLine.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 "SkSVGLine.h"
+#include "SkSVGRenderContext.h"
+#include "SkSVGValue.h"
+
+SkSVGLine::SkSVGLine() : INHERITED(SkSVGTag::kLine) {}
+
+void SkSVGLine::setX1(const SkSVGLength& x1) {
+    fX1 = x1;
+}
+
+void SkSVGLine::setY1(const SkSVGLength& y1) {
+    fY1 = y1;
+}
+
+void SkSVGLine::setX2(const SkSVGLength& x2) {
+    fX2 = x2;
+}
+
+void SkSVGLine::setY2(const SkSVGLength& y2) {
+    fY2 = y2;
+}
+
+void SkSVGLine::onSetAttribute(SkSVGAttribute attr, const SkSVGValue& v) {
+    switch (attr) {
+    case SkSVGAttribute::kX1:
+        if (const auto* x1 = v.as<SkSVGLengthValue>()) {
+            this->setX1(*x1);
+        }
+        break;
+    case SkSVGAttribute::kY1:
+        if (const auto* y1 = v.as<SkSVGLengthValue>()) {
+            this->setY1(*y1);
+        }
+        break;
+    case SkSVGAttribute::kX2:
+        if (const auto* x2 = v.as<SkSVGLengthValue>()) {
+            this->setX2(*x2);
+        }
+        break;
+    case SkSVGAttribute::kY2:
+        if (const auto* y2 = v.as<SkSVGLengthValue>()) {
+            this->setY2(*y2);
+        }
+        break;
+    default:
+        this->INHERITED::onSetAttribute(attr, v);
+    }
+}
+
+void SkSVGLine::onDraw(SkCanvas* canvas, const SkSVGLengthContext& lctx,
+                       const SkPaint& paint) const {
+    const auto x1 = lctx.resolve(fX1, SkSVGLengthContext::LengthType::kHorizontal);
+    const auto y1 = lctx.resolve(fY1, SkSVGLengthContext::LengthType::kVertical);
+    const auto x2 = lctx.resolve(fX2, SkSVGLengthContext::LengthType::kHorizontal);
+    const auto y2 = lctx.resolve(fY2, SkSVGLengthContext::LengthType::kVertical);
+
+    canvas->drawLine(x1, y1, x2, y2, paint);
+}