[SVGDom] Radial gradient support

Implement support for
https://www.w3.org/TR/SVG/pservers.html#RadialGradients.

BUG=skia:7074

Change-Id: I19645a4a3bbddfd1ee0d08a2775381a0017acbfc
Reviewed-on: https://skia-review.googlesource.com/57340
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Robert Phillips <robertphillips@google.com>

1 files changed, 85 insertions, 0 deletions

diff --git a/experimental/svg/model/SkSVGRadialGradient.cpp b/experimental/svg/model/SkSVGRadialGradient.cpp
new file mode 100644
index 0000000000..c719693a06
--- /dev/null
+++ b/experimental/svg/model/SkSVGRadialGradient.cpp
@@ -0,0 +1,85 @@
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkGradientShader.h"
+#include "SkSVGRadialGradient.h"
+#include "SkSVGRenderContext.h"
+#include "SkSVGValue.h"
+
+SkSVGRadialGradient::SkSVGRadialGradient() : INHERITED(SkSVGTag::kRadialGradient) {}
+
+void SkSVGRadialGradient::setCx(const SkSVGLength& cx) {
+    fCx = cx;
+}
+
+void SkSVGRadialGradient::setCy(const SkSVGLength& cy) {
+    fCy = cy;
+}
+
+void SkSVGRadialGradient::setR(const SkSVGLength& r) {
+    fR = r;
+}
+
+void SkSVGRadialGradient::setFx(const SkSVGLength& fx) {
+    fFx.set(fx);
+}
+
+void SkSVGRadialGradient::setFy(const SkSVGLength& fy) {
+    fFy.set(fy);
+}
+
+void SkSVGRadialGradient::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;
+    case SkSVGAttribute::kFx:
+        if (const auto* fx = v.as<SkSVGLengthValue>()) {
+            this->setFx(*fx);
+        }
+        break;
+    case SkSVGAttribute::kFy:
+        if (const auto* fy = v.as<SkSVGLengthValue>()) {
+            this->setFy(*fy);
+        }
+        break;
+    default:
+        this->INHERITED::onSetAttribute(attr, v);
+    }
+}
+
+sk_sp<SkShader> SkSVGRadialGradient::onMakeShader(const SkSVGRenderContext& ctx,
+                                                  const SkColor* colors, const SkScalar* pos,
+                                                  int count, SkShader::TileMode tm,
+                                                  const SkMatrix& m) const {
+    const auto&  lctx = ctx.lengthContext();
+    const auto      r = lctx.resolve(fR , SkSVGLengthContext::LengthType::kOther);
+    const auto center = SkPoint::Make(
+            lctx.resolve(fCx, SkSVGLengthContext::LengthType::kHorizontal),
+            lctx.resolve(fCy, SkSVGLengthContext::LengthType::kVertical));
+    const auto  focal = SkPoint::Make(
+        fFx.isValid() ? lctx.resolve(*fFx.get(), SkSVGLengthContext::LengthType::kHorizontal)
+                      : center.x(),
+        fFy.isValid() ? lctx.resolve(*fFy.get(), SkSVGLengthContext::LengthType::kVertical)
+                      : center.y());
+
+    return center == focal
+        ? SkGradientShader::MakeRadial(center, r, colors, pos, count, tm, 0, &m)
+        : SkGradientShader::MakeTwoPointConical(focal, 0, center, r, colors, pos, count, tm, 0, &m);
+}