[SVGDom] Add viewBox support

The main feature is <svg> viewBox and proper viewport support, but the CL
touches a few other things:

* refactor SkSVGRenderContext to auto-restore canvas state, and split the
  presentation bits into a separate CoW SkSVGPresentationContext

* introduce SkSVGNode::onPrepareToRender(), as a way for nodes to push their
  custom state before the actual onRender() call (instead of relying on
  non-virtual SkSVGNode to know about all possible state bits)

* add a "Type" suffix to SVG types, to disambiguate (e.g. SkSVGRectType vs.
  SkSVGRect)

R=robertphillips@google.com,stephana@google.com
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2222793002

Review-Url: https://codereview.chromium.org/2222793002

1 files changed, 14 insertions, 20 deletions

diff --git a/experimental/svg/model/SkSVGTypes.h b/experimental/svg/model/SkSVGTypes.h
index 6d34d9943a..ab07d7b16c 100644
--- a/experimental/svg/model/SkSVGTypes.h
+++ b/experimental/svg/model/SkSVGTypes.h
@@ -9,25 +9,30 @@
 #define SkSVGTypes_DEFINED
 
 #include "SkColor.h"
+#include "SkRect.h"
 #include "SkScalar.h"
 #include "SkTypes.h"
 
-class SkSVGNumber {
+template <typename T>
+class SkSVGPrimitiveTypeWrapper {
 public:
-    constexpr SkSVGNumber()                    : fValue(0) {}
-    explicit constexpr SkSVGNumber(SkScalar v) : fValue(v) {}
-    SkSVGNumber(const SkSVGNumber&)            = default;
-    SkSVGNumber& operator=(const SkSVGNumber&) = default;
+    SkSVGPrimitiveTypeWrapper() = default;
+    explicit constexpr SkSVGPrimitiveTypeWrapper(T v) : fValue(v) {}
 
+    SkSVGPrimitiveTypeWrapper(const SkSVGPrimitiveTypeWrapper&)            = default;
+    SkSVGPrimitiveTypeWrapper& operator=(const SkSVGPrimitiveTypeWrapper&) = default;
 
-    const SkScalar& value() const { return fValue; }
-
-    operator const SkScalar&() const { return fValue; }
+    const T& value() const { return fValue; }
+    operator const T&() const { return fValue; }
 
 private:
-    SkScalar fValue;
+    T fValue;
 };
 
+using SkSVGColorType   = SkSVGPrimitiveTypeWrapper<SkColor >;
+using SkSVGNumberType  = SkSVGPrimitiveTypeWrapper<SkScalar>;
+using SkSVGViewBoxType = SkSVGPrimitiveTypeWrapper<SkRect  >;
+
 class SkSVGLength {
 public:
     enum class Unit {
@@ -58,15 +63,4 @@ private:
     Unit     fUnit;
 };
 
-class SkSVGColor {
-public:
-    constexpr SkSVGColor()                   : fValue(SK_ColorBLACK) {}
-    explicit constexpr SkSVGColor(SkColor c) : fValue(c) {}
-
-    operator const SkColor&() const { return fValue; }
-
-private:
-    SkColor fValue;
-};
-
 #endif // SkSVGTypes_DEFINED