[SVGDom] Initial SVGLength support

Mostly plumb new length types, but also introduce a stateful parser,
rect shape and named color support.

R=reed@google.com,robertphillips@google.com,stephana@google.com
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2202053002

Review-Url: https://codereview.chromium.org/2202053002

20 files changed, 667 insertions, 78 deletions

diff --git a/experimental/svg/model/SkSVGAttribute.cpp b/experimental/svg/model/SkSVGAttribute.cpp
index c4a374e7e1..79c355176f 100644
--- a/experimental/svg/model/SkSVGAttribute.cpp
+++ b/experimental/svg/model/SkSVGAttribute.cpp
@@ -12,12 +12,12 @@ SkSVGPresentationAttributes::SkSVGPresentationAttributes()
     : fFillIsSet(false)
     , fStrokeIsSet(false) { }
 
-void SkSVGPresentationAttributes::setFill(SkColor c) {
+void SkSVGPresentationAttributes::setFill(const SkSVGColor& c) {
     fFill = c;
     fFillIsSet = true;
 }
 
-void SkSVGPresentationAttributes::setStroke(SkColor c) {
+void SkSVGPresentationAttributes::setStroke(const SkSVGColor& c) {
     fStroke = c;
     fStrokeIsSet = true;
 }
diff --git a/experimental/svg/model/SkSVGAttribute.h b/experimental/svg/model/SkSVGAttribute.h
index 83a35527c5..64465b13c9 100644
--- a/experimental/svg/model/SkSVGAttribute.h
+++ b/experimental/svg/model/SkSVGAttribute.h
@@ -8,14 +8,18 @@
 #ifndef SkSVGAttribute_DEFINED
 #define SkSVGAttribute_DEFINED
 
-#include "SkColor.h"
+#include "SkSVGTypes.h"
 #include "SkTLazy.h"
 
 enum class SkSVGAttribute {
     kD,
     kFill,
+    kHeight,
     kStroke,
     kTransform,
+    kWidth,
+    kX,
+    kY,
 
     kUnknown,
 };
@@ -26,15 +30,15 @@ class SkSVGPresentationAttributes {
 public:
     SkSVGPresentationAttributes();
 
-    void setFill(SkColor);
-    void setStroke(SkColor);
+    void setFill(const SkSVGColor&);
+    void setStroke(const SkSVGColor&);
 
     void applyTo(SkTCopyOnFirstWrite<SkSVGRenderContext>&) const;
 
 private:
     // Color only for now.
-    SkColor fFill;
-    SkColor fStroke;
+    SkSVGColor fFill;
+    SkSVGColor fStroke;
 
     unsigned fFillIsSet   : 1;
     unsigned fStrokeIsSet : 1;
diff --git a/experimental/svg/model/SkSVGAttributeParser.cpp b/experimental/svg/model/SkSVGAttributeParser.cpp
new file mode 100644
index 0000000000..75e5d12f38
--- /dev/null
+++ b/experimental/svg/model/SkSVGAttributeParser.cpp
@@ -0,0 +1,194 @@
+/*
+ * 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 "SkParse.h"
+#include "SkSVGAttributeParser.h"
+#include "SkSVGTypes.h"
+
+namespace {
+
+// TODO: these should be shared with SkParse.cpp
+
+inline bool is_between(char c, char min, char max) {
+    SkASSERT(min <= max);
+    return (unsigned)(c - min) <= (unsigned)(max - min);
+}
+
+inline bool is_eos(char c) {
+    return !c;
+}
+
+inline bool is_ws(char c) {
+    return is_between(c, 1, 32);
+}
+
+inline bool is_sep(char c) {
+    return is_ws(c) || c == ',' || c == ';';
+}
+
+} // anonymous ns
+
+SkSVGAttributeParser::SkSVGAttributeParser(const char attributeString[])
+    : fCurPos(attributeString) {}
+
+template <typename F>
+inline bool SkSVGAttributeParser::advanceWhile(F f) {
+    auto initial = fCurPos;
+    while (f(*fCurPos)) {
+        fCurPos++;
+    }
+    return fCurPos != initial;
+}
+
+inline bool SkSVGAttributeParser::parseEOSToken() {
+    return is_eos(*fCurPos);
+}
+
+inline bool SkSVGAttributeParser::parseSepToken() {
+    return this->advanceWhile(is_sep);
+}
+
+inline bool SkSVGAttributeParser::parseWSToken() {
+    return this->advanceWhile(is_ws);
+}
+
+inline bool SkSVGAttributeParser::parseExpectedStringToken(const char* expected) {
+    const char* c = fCurPos;
+
+    while (*c && *expected && *c == *expected) {
+        c++;
+        expected++;
+    }
+
+    if (*expected) {
+        return false;
+    }
+
+    fCurPos = c;
+    return true;
+}
+
+bool SkSVGAttributeParser::parseScalarToken(SkScalar* res) {
+    if (const char* next = SkParse::FindScalar(fCurPos, res)) {
+        fCurPos = next;
+        return true;
+    }
+    return false;
+}
+
+bool SkSVGAttributeParser::parseHexToken(uint32_t* res) {
+     if (const char* next = SkParse::FindHex(fCurPos, res)) {
+         fCurPos = next;
+         return true;
+     }
+     return false;
+}
+
+bool SkSVGAttributeParser::parseLengthUnitToken(SkSVGLength::Unit* unit) {
+    static const struct {
+        const char*       fUnitName;
+        SkSVGLength::Unit fUnit;
+    } gUnitInfo[] = {
+        { "%" , SkSVGLength::Unit::kPercentage },
+        { "em", SkSVGLength::Unit::kEMS        },
+        { "ex", SkSVGLength::Unit::kEXS        },
+        { "px", SkSVGLength::Unit::kPX         },
+        { "cm", SkSVGLength::Unit::kCM         },
+        { "mm", SkSVGLength::Unit::kMM         },
+        { "in", SkSVGLength::Unit::kIN         },
+        { "pt", SkSVGLength::Unit::kPT         },
+        { "pc", SkSVGLength::Unit::kPC         },
+    };
+
+    for (size_t i = 0; i < SK_ARRAY_COUNT(gUnitInfo); ++i) {
+        if (this->parseExpectedStringToken(gUnitInfo[i].fUnitName)) {
+            *unit = gUnitInfo[i].fUnit;
+            return true;
+        }
+    }
+    return false;
+}
+
+bool SkSVGAttributeParser::parseNamedColorToken(SkColor* c) {
+    if (const char* next = SkParse::FindNamedColor(fCurPos, strlen(fCurPos), c)) {
+        fCurPos = next;
+        return true;
+    }
+    return false;
+}
+
+bool SkSVGAttributeParser::parseHexColorToken(SkColor* c) {
+    uint32_t v;
+    const char* initial = fCurPos;
+
+    if (!this->parseExpectedStringToken("#") || !this->parseHexToken(&v)) {
+        return false;
+    }
+
+    switch (fCurPos - initial) {
+    case 7:
+        // matched #xxxxxxx
+        break;
+    case 4:
+        // matched '#xxx;
+        v = ((v << 12) & 0x00f00000) |
+            ((v <<  8) & 0x000ff000) |
+            ((v <<  4) & 0x00000ff0) |
+            ((v <<  0) & 0x0000000f);
+        break;
+    default:
+        return false;
+    }
+
+    *c = v | 0xff000000;
+    return true;
+}
+
+// https://www.w3.org/TR/SVG/types.html#DataTypeColor
+bool SkSVGAttributeParser::parseColor(SkSVGColor* color) {
+    SkColor c;
+
+    // TODO: rgb(...)
+    if (this->parseHexColorToken(&c) || this->parseNamedColorToken(&c)) {
+        *color = SkSVGColor(c);
+        return true;
+    }
+
+    return false;
+}
+
+// https://www.w3.org/TR/SVG/types.html#DataTypeNumber
+bool SkSVGAttributeParser::parseNumber(SkSVGNumber* number) {
+    // consume WS
+    this->parseWSToken();
+
+    SkScalar s;
+    if (this->parseScalarToken(&s)) {
+        *number = SkSVGNumber(s);
+        // consume trailing separators
+        this->parseSepToken();
+        return true;
+    }
+
+    return false;
+}
+
+// https://www.w3.org/TR/SVG/types.html#DataTypeLength
+bool SkSVGAttributeParser::parseLength(SkSVGLength* length) {
+    SkScalar s;
+    SkSVGLength::Unit u = SkSVGLength::Unit::kNumber;
+
+    if (this->parseScalarToken(&s) &&
+        (this->parseLengthUnitToken(&u) || this->parseSepToken() || this->parseEOSToken())) {
+        *length = SkSVGLength(s, u);
+        // consume trailing separators
+        this->parseSepToken();
+        return true;
+    }
+
+    return false;
+}
diff --git a/experimental/svg/model/SkSVGAttributeParser.h b/experimental/svg/model/SkSVGAttributeParser.h
new file mode 100644
index 0000000000..aef0286504
--- /dev/null
+++ b/experimental/svg/model/SkSVGAttributeParser.h
@@ -0,0 +1,45 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkSVGAttributeParser_DEFINED
+#define SkSVGAttributeParser_DEFINED
+
+#include "SkSVGTypes.h"
+
+class SkSVGAttributeParser : public SkNoncopyable {
+public:
+    SkSVGAttributeParser(const char[]);
+
+    bool parseColor(SkSVGColor*);
+    bool parseNumber(SkSVGNumber*);
+    bool parseLength(SkSVGLength*);
+
+private:
+    // Stack-only
+    void* operator new(size_t) = delete;
+    void* operator new(size_t, void*) = delete;
+
+    template <typename F>
+    bool advanceWhile(F func);
+
+    bool parseWSToken();
+    bool parseEOSToken();
+    bool parseSepToken();
+    bool parseExpectedStringToken(const char*);
+    bool parseScalarToken(SkScalar*);
+    bool parseHexToken(uint32_t*);
+    bool parseLengthUnitToken(SkSVGLength::Unit*);
+    bool parseNamedColorToken(SkColor*);
+    bool parseHexColorToken(SkColor*);
+
+    // The current position in the input string.
+    const char* fCurPos;
+
+    typedef SkNoncopyable INHERITED;
+};
+
+#endif // SkSVGAttributeParser_DEFINED
diff --git a/experimental/svg/model/SkSVGDOM.cpp b/experimental/svg/model/SkSVGDOM.cpp
index 4e2f898942..df589230e0 100644
--- a/experimental/svg/model/SkSVGDOM.cpp
+++ b/experimental/svg/model/SkSVGDOM.cpp
@@ -10,45 +10,20 @@
 #include "SkParse.h"
 #include "SkParsePath.h"
 #include "SkString.h"
+#include "SkSVGAttributeParser.h"
 #include "SkSVGDOM.h"
 #include "SkSVGG.h"
 #include "SkSVGNode.h"
 #include "SkSVGPath.h"
+#include "SkSVGRect.h"
+#include "SkSVGRenderContext.h"
 #include "SkSVGSVG.h"
+#include "SkSVGTypes.h"
 #include "SkSVGValue.h"
 #include "SkTSearch.h"
 
 namespace {
 
-SkColor ParseColor(const char* str) {
-    // FIXME: real parser
-    if (*str++ != '#') {
-        return SK_ColorBLACK;
-    }
-
-    uint32_t v;
-    const char* consumed = SkParse::FindHex(str, &v);
-
-    switch(consumed - str) {
-    case 6:
-        // matched '#xxxxxx'
-        break;
-    case 3:
-        // matched '#xxx;
-        v = ((v << 12) & 0x00f00000) |
-            ((v <<  8) & 0x000ff000) |
-            ((v <<  4) & 0x00000ff0) |
-            ((v <<  0) & 0x0000000f);
-        break;
-    default:
-        // failed
-        v = 0;
-        break;
-    }
-
-    return v | 0xff000000;
-}
-
 const char* ParseScalarPair(const char* str, SkScalar v[2]) {
     str = SkParse::FindScalar(str, v);
     if (str) {
@@ -98,7 +73,13 @@ SkMatrix ParseTransform(const char* str) {
 
 bool SetPaintAttribute(const sk_sp<SkSVGNode>& node, SkSVGAttribute attr,
                        const char* stringValue) {
-    node->setAttribute(attr, SkSVGColorValue(ParseColor(stringValue)));
+    SkSVGColor color;
+    SkSVGAttributeParser parser(stringValue);
+    if (!parser.parseColor(&color)) {
+        return false;
+    }
+
+    node->setAttribute(attr, SkSVGColorValue(color));
     return true;
 }
 
@@ -119,6 +100,18 @@ bool SetTransformAttribute(const sk_sp<SkSVGNode>& node, SkSVGAttribute attr,
     return true;
 }
 
+bool SetLengthAttribute(const sk_sp<SkSVGNode>& node, SkSVGAttribute attr,
+                        const char* stringValue) {
+    SkSVGLength length;
+    SkSVGAttributeParser parser(stringValue);
+    if (!parser.parseLength(&length)) {
+        return false;
+    }
+
+    node->setAttribute(attr, SkSVGLengthValue(length));
+    return true;
+}
+
 // Breaks a "foo: bar; baz: ..." string into key:value pairs.
 class StyleIterator {
 public:
@@ -185,16 +178,21 @@ struct AttrParseInfo {
 };
 
 SortedDictionaryEntry<AttrParseInfo> gAttributeParseInfo[] = {
-    { "d",         { SkSVGAttribute::kD,         SetPathDataAttribute  }},
-    { "fill",      { SkSVGAttribute::kFill,      SetPaintAttribute     }},
-    { "stroke",    { SkSVGAttribute::kStroke,    SetPaintAttribute     }},
-    { "style",     { SkSVGAttribute::kUnknown,   SetStyleAttributes    }},
+    { "d"        , { SkSVGAttribute::kD        , SetPathDataAttribute  }},
+    { "fill"     , { SkSVGAttribute::kFill     , SetPaintAttribute     }},
+    { "height"   , { SkSVGAttribute::kHeight   , SetLengthAttribute    }},
+    { "stroke"   , { SkSVGAttribute::kStroke   , SetPaintAttribute     }},
+    { "style"    , { SkSVGAttribute::kUnknown  , SetStyleAttributes    }},
     { "transform", { SkSVGAttribute::kTransform, SetTransformAttribute }},
+    { "width"    , { SkSVGAttribute::kWidth    , SetLengthAttribute    }},
+    { "x"        , { SkSVGAttribute::kX        , SetLengthAttribute    }},
+    { "y"        , { SkSVGAttribute::kY        , SetLengthAttribute    }},
 };
 
 SortedDictionaryEntry<sk_sp<SkSVGNode>(*)()> gTagFactories[] = {
     { "g"   , []() -> sk_sp<SkSVGNode> { return SkSVGG::Make();    }},
     { "path", []() -> sk_sp<SkSVGNode> { return SkSVGPath::Make(); }},
+    { "rect", []() -> sk_sp<SkSVGNode> { return SkSVGRect::Make(); }},
     { "svg" , []() -> sk_sp<SkSVGNode> { return SkSVGSVG::Make();  }},
 };
 
@@ -294,7 +292,8 @@ sk_sp<SkSVGDOM> SkSVGDOM::MakeFromStream(SkStream& svgStream, const SkSize& cont
 
 void SkSVGDOM::render(SkCanvas* canvas) const {
     if (fRoot) {
-        fRoot->render(canvas);
+        SkSVGRenderContext ctx(fContainerSize);
+        fRoot->render(canvas, ctx);
     }
 }
 
diff --git a/experimental/svg/model/SkSVGNode.cpp b/experimental/svg/model/SkSVGNode.cpp
index 58e0ad4989..eb82834f38 100644
--- a/experimental/svg/model/SkSVGNode.cpp
+++ b/experimental/svg/model/SkSVGNode.cpp
@@ -16,10 +16,6 @@ SkSVGNode::SkSVGNode(SkSVGTag t) : fTag(t) { }
 
 SkSVGNode::~SkSVGNode() { }
 
-void SkSVGNode::render(SkCanvas* canvas) const {
-    this->render(canvas, SkSVGRenderContext());
-}
-
 void SkSVGNode::render(SkCanvas* canvas, const SkSVGRenderContext& ctx) const {
     SkTCopyOnFirstWrite<SkSVGRenderContext> localContext(ctx);
     fPresentationAttributes.applyTo(localContext);
@@ -51,6 +47,7 @@ void SkSVGNode::onSetAttribute(SkSVGAttribute attr, const SkSVGValue& v) {
         }
         break;
     default:
+        SkDebugf("attribute ID <%d> ignored for node <%d>\n", attr, fTag);
         break;
     }
 }
diff --git a/experimental/svg/model/SkSVGNode.h b/experimental/svg/model/SkSVGNode.h
index 407e69ac63..168b03c73b 100644
--- a/experimental/svg/model/SkSVGNode.h
+++ b/experimental/svg/model/SkSVGNode.h
@@ -19,6 +19,7 @@ class SkSVGValue;
 enum class SkSVGTag {
     kG,
     kPath,
+    kRect,
     kSvg
 };
 
@@ -30,7 +31,6 @@ public:
 
     virtual void appendChild(sk_sp<SkSVGNode>) = 0;
 
-    void render(SkCanvas*) const;
     void render(SkCanvas*, const SkSVGRenderContext&) const;
 
     void setAttribute(SkSVGAttribute, const SkSVGValue&);
diff --git a/experimental/svg/model/SkSVGPath.cpp b/experimental/svg/model/SkSVGPath.cpp
index 7d905945bc..07e0a3e545 100644
--- a/experimental/svg/model/SkSVGPath.cpp
+++ b/experimental/svg/model/SkSVGPath.cpp
@@ -13,17 +13,6 @@
 
 SkSVGPath::SkSVGPath() : INHERITED(SkSVGTag::kPath) { }
 
-void SkSVGPath::doRender(SkCanvas* canvas, const SkPaint* paint) const {
-    if (paint) {
-        canvas->drawPath(fPath, *paint);
-    }
-}
-
-void SkSVGPath::onRender(SkCanvas* canvas, const SkSVGRenderContext& ctx) const {
-    this->doRender(canvas, ctx.fillPaint());
-    this->doRender(canvas, ctx.strokePaint());
-}
-
 void SkSVGPath::onSetAttribute(SkSVGAttribute attr, const SkSVGValue& v) {
     switch (attr) {
     case SkSVGAttribute::kD:
@@ -35,3 +24,7 @@ void SkSVGPath::onSetAttribute(SkSVGAttribute attr, const SkSVGValue& v) {
         this->INHERITED::onSetAttribute(attr, v);
     }
 }
+
+void SkSVGPath::onDraw(SkCanvas* canvas, const SkSVGLengthContext&, const SkPaint& paint) const {
+    canvas->drawPath(fPath, paint);
+}
diff --git a/experimental/svg/model/SkSVGPath.h b/experimental/svg/model/SkSVGPath.h
index b650f67463..e72f0d137e 100644
--- a/experimental/svg/model/SkSVGPath.h
+++ b/experimental/svg/model/SkSVGPath.h
@@ -9,30 +9,26 @@
 #define SkSVGPath_DEFINED
 
 #include "SkPath.h"
-#include "SkSVGTransformableNode.h"
+#include "SkSVGShape.h"
 
-class SkSVGPath final : public SkSVGTransformableNode {
+class SkSVGPath final : public SkSVGShape {
 public:
     virtual ~SkSVGPath() = default;
     static sk_sp<SkSVGPath> Make() { return sk_sp<SkSVGPath>(new SkSVGPath()); }
 
-    void appendChild(sk_sp<SkSVGNode>) override { }
-
     void setPath(const SkPath& path) { fPath = path; }
 
 protected:
-    void onRender(SkCanvas*, const SkSVGRenderContext&) const override;
-
     void onSetAttribute(SkSVGAttribute, const SkSVGValue&) override;
 
+    void onDraw(SkCanvas*, const SkSVGLengthContext&, const SkPaint&) const override;
+
 private:
     SkSVGPath();
 
-    void doRender(SkCanvas*, const SkPaint*) const;
-
     SkPath fPath;
 
-    typedef SkSVGTransformableNode INHERITED;
+    typedef SkSVGShape INHERITED;
 };
 
 #endif // SkSVGPath_DEFINED
diff --git a/experimental/svg/model/SkSVGRect.cpp b/experimental/svg/model/SkSVGRect.cpp
new file mode 100644
index 0000000000..288fc48258
--- /dev/null
+++ b/experimental/svg/model/SkSVGRect.cpp
@@ -0,0 +1,68 @@
+/*
+ * 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 "SkRect.h"
+#include "SkSVGRect.h"
+#include "SkSVGRenderContext.h"
+#include "SkSVGValue.h"
+
+SkSVGRect::SkSVGRect() : INHERITED(SkSVGTag::kRect) {}
+
+void SkSVGRect::setX(const SkSVGLength& x) {
+    fX = x;
+}
+
+void SkSVGRect::setY(const SkSVGLength& y) {
+    fY = y;
+}
+
+void SkSVGRect::setWidth(const SkSVGLength& w) {
+    fWidth = w;
+}
+
+void SkSVGRect::setHeight(const SkSVGLength& h) {
+    fHeight = h;
+}
+
+void SkSVGRect::onSetAttribute(SkSVGAttribute attr, const SkSVGValue& v) {
+    switch (attr) {
+    case SkSVGAttribute::kX:
+        if (const auto* x = v.as<SkSVGLengthValue>()) {
+            this->setX(*x);
+        }
+        break;
+    case SkSVGAttribute::kY:
+        if (const auto* y = v.as<SkSVGLengthValue>()) {
+            this->setY(*y);
+        }
+        break;
+    case SkSVGAttribute::kWidth:
+        if (const auto* w = v.as<SkSVGLengthValue>()) {
+            this->setWidth(*w);
+        }
+        break;
+    case SkSVGAttribute::kHeight:
+        if (const auto* h = v.as<SkSVGLengthValue>()) {
+            this->setHeight(*h);
+        }
+        break;
+    default:
+        this->INHERITED::onSetAttribute(attr, v);
+    }
+}
+
+void SkSVGRect::onDraw(SkCanvas* canvas, const SkSVGLengthContext& lctx,
+                       const SkPaint& paint) const {
+    const SkRect r = SkRect::MakeXYWH(
+        lctx.resolve(fX, SkSVGLengthContext::LengthType::kHorizontal),
+        lctx.resolve(fY, SkSVGLengthContext::LengthType::kVertical),
+        lctx.resolve(fWidth, SkSVGLengthContext::LengthType::kHorizontal),
+        lctx.resolve(fHeight, SkSVGLengthContext::LengthType::kVertical));
+
+    canvas->drawRect(r, paint);
+}
diff --git a/experimental/svg/model/SkSVGRect.h b/experimental/svg/model/SkSVGRect.h
new file mode 100644
index 0000000000..b4cd363d77
--- /dev/null
+++ b/experimental/svg/model/SkSVGRect.h
@@ -0,0 +1,40 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkSVGRect_DEFINED
+#define SkSVGRect_DEFINED
+
+#include "SkSVGShape.h"
+#include "SkSVGTypes.h"
+
+class SkSVGRect final : public SkSVGShape {
+public:
+    virtual ~SkSVGRect() = default;
+    static sk_sp<SkSVGRect> Make() { return sk_sp<SkSVGRect>(new SkSVGRect()); }
+
+    void setX(const SkSVGLength&);
+    void setY(const SkSVGLength&);
+    void setWidth(const SkSVGLength&);
+    void setHeight(const SkSVGLength&);
+
+protected:
+    void onSetAttribute(SkSVGAttribute, const SkSVGValue&) override;
+
+    void onDraw(SkCanvas*, const SkSVGLengthContext&, const SkPaint&) const override;
+
+private:
+    SkSVGRect();
+
+    SkSVGLength fX      = SkSVGLength(0);
+    SkSVGLength fY      = SkSVGLength(0);
+    SkSVGLength fWidth  = SkSVGLength(0);
+    SkSVGLength fHeight = SkSVGLength(0);
+
+    typedef SkSVGShape INHERITED;
+};
+
+#endif // SkSVGRect_DEFINED
diff --git a/experimental/svg/model/SkSVGRenderContext.cpp b/experimental/svg/model/SkSVGRenderContext.cpp
index 703606c528..38498d36c8 100644
--- a/experimental/svg/model/SkSVGRenderContext.cpp
+++ b/experimental/svg/model/SkSVGRenderContext.cpp
@@ -6,8 +6,44 @@
  */
 
 #include "SkSVGRenderContext.h"
+#include "SkSVGTypes.h"
 
-SkSVGRenderContext::SkSVGRenderContext() { }
+namespace {
+
+SkScalar length_size_for_type(const SkSize& viewport, SkSVGLengthContext::LengthType t) {
+    switch (t) {
+    case SkSVGLengthContext::LengthType::kHorizontal:
+        return viewport.width();
+    case SkSVGLengthContext::LengthType::kVertical:
+        return viewport.height();
+    case SkSVGLengthContext::LengthType::kOther:
+        return SkScalarSqrt(viewport.width() * viewport.height());
+    }
+
+    SkASSERT(false);  // Not reached.
+    return 0;
+}
+
+} // anonymous ns
+
+SkScalar SkSVGLengthContext::resolve(const SkSVGLength& l, LengthType t) const {
+    switch (l.unit()) {
+    case SkSVGLength::Unit::kNumber:
+        return l.value();
+        break;
+    case SkSVGLength::Unit::kPercentage:
+        return l.value() * length_size_for_type(fViewport, t) / 100;
+        break;
+    default:
+        SkDebugf("unsupported unit type: <%d>\n", l.unit());
+        break;
+    }
+
+    return 0;
+}
+
+SkSVGRenderContext::SkSVGRenderContext(const SkSize& initialViewport)
+    : fLengthContext(initialViewport) {}
 
 SkSVGRenderContext& SkSVGRenderContext::operator=(const SkSVGRenderContext& other) {
     if (other.fFill.isValid()) {
diff --git a/experimental/svg/model/SkSVGRenderContext.h b/experimental/svg/model/SkSVGRenderContext.h
index 8ebaf12f0c..50a6d59e5e 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
diff --git a/experimental/svg/model/SkSVGSVG.cpp b/experimental/svg/model/SkSVGSVG.cpp
index aeccc7082b..42bd280a5e 100644
--- a/experimental/svg/model/SkSVGSVG.cpp
+++ b/experimental/svg/model/SkSVGSVG.cpp
@@ -6,5 +6,49 @@
  */
 
 #include "SkSVGSVG.h"
+#include "SkSVGValue.h"
 
 SkSVGSVG::SkSVGSVG() : INHERITED(SkSVGTag::kSvg) { }
+
+void SkSVGSVG::setX(const SkSVGLength& x) {
+    fX = x;
+}
+
+void SkSVGSVG::setY(const SkSVGLength& y) {
+    fY = y;
+}
+
+void SkSVGSVG::setWidth(const SkSVGLength& w) {
+    fWidth = w;
+}
+
+void SkSVGSVG::setHeight(const SkSVGLength& h) {
+    fHeight = h;
+}
+
+void SkSVGSVG::onSetAttribute(SkSVGAttribute attr, const SkSVGValue& v) {
+    switch (attr) {
+    case SkSVGAttribute::kX:
+        if (const auto* x = v.as<SkSVGLengthValue>()) {
+            this->setX(*x);
+        }
+        break;
+    case SkSVGAttribute::kY:
+        if (const auto* y = v.as<SkSVGLengthValue>()) {
+            this->setY(*y);
+        }
+        break;
+    case SkSVGAttribute::kWidth:
+        if (const auto* w = v.as<SkSVGLengthValue>()) {
+            this->setWidth(*w);
+        }
+        break;
+    case SkSVGAttribute::kHeight:
+        if (const auto* h = v.as<SkSVGLengthValue>()) {
+            this->setHeight(*h);
+        }
+        break;
+    default:
+        this->INHERITED::onSetAttribute(attr, v);
+    }
+}
diff --git a/experimental/svg/model/SkSVGSVG.h b/experimental/svg/model/SkSVGSVG.h
index 8e69d144d6..27631f5a31 100644
--- a/experimental/svg/model/SkSVGSVG.h
+++ b/experimental/svg/model/SkSVGSVG.h
@@ -9,6 +9,7 @@
 #define SkSVGSVG_DEFINED
 
 #include "SkSVGContainer.h"
+#include "SkSVGTypes.h"
 
 class SkSVGSVG : public SkSVGContainer {
 public:
@@ -16,9 +17,22 @@ public:
 
     static sk_sp<SkSVGSVG> Make() { return sk_sp<SkSVGSVG>(new SkSVGSVG()); }
 
+    void setX(const SkSVGLength&);
+    void setY(const SkSVGLength&);
+    void setWidth(const SkSVGLength&);
+    void setHeight(const SkSVGLength&);
+
+protected:
+    void onSetAttribute(SkSVGAttribute, const SkSVGValue&) override;
+
 private:
     SkSVGSVG();
 
+    SkSVGLength fX      = SkSVGLength(0);
+    SkSVGLength fY      = SkSVGLength(0);
+    SkSVGLength fWidth  = SkSVGLength(100, SkSVGLength::Unit::kPercentage);
+    SkSVGLength fHeight = SkSVGLength(100, SkSVGLength::Unit::kPercentage);
+
     typedef SkSVGContainer INHERITED;
 };
 
diff --git a/experimental/svg/model/SkSVGShape.cpp b/experimental/svg/model/SkSVGShape.cpp
new file mode 100644
index 0000000000..d26eff482d
--- /dev/null
+++ b/experimental/svg/model/SkSVGShape.cpp
@@ -0,0 +1,25 @@
+/*
+ * 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 "SkSVGRenderContext.h"
+#include "SkSVGShape.h"
+
+SkSVGShape::SkSVGShape(SkSVGTag t) : INHERITED(t) {}
+
+void SkSVGShape::onRender(SkCanvas* canvas, const SkSVGRenderContext& ctx) const {
+    if (const SkPaint* fillPaint = ctx.fillPaint()) {
+        this->onDraw(canvas, ctx.lengthContext(), *fillPaint);
+    }
+
+    if (const SkPaint* strokePaint = ctx.strokePaint()) {
+        this->onDraw(canvas, ctx.lengthContext(), *strokePaint);
+    }
+}
+
+void SkSVGShape::appendChild(sk_sp<SkSVGNode>) {
+    SkDebugf("cannot append child nodes to an SVG shape.\n");
+}
diff --git a/experimental/svg/model/SkSVGShape.h b/experimental/svg/model/SkSVGShape.h
new file mode 100644
index 0000000000..2b3ea96d54
--- /dev/null
+++ b/experimental/svg/model/SkSVGShape.h
@@ -0,0 +1,33 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkSVGShape_DEFINED
+#define SkSVGShape_DEFINED
+
+#include "SkSVGTransformableNode.h"
+
+class SkSVGLengthContext;
+class SkPaint;
+
+class SkSVGShape : public SkSVGTransformableNode {
+public:
+    virtual ~SkSVGShape() = default;
+
+    void appendChild(sk_sp<SkSVGNode>) override;
+
+protected:
+    SkSVGShape(SkSVGTag);
+
+    void onRender(SkCanvas*, const SkSVGRenderContext&) const final;
+
+    virtual void onDraw(SkCanvas*, const SkSVGLengthContext&, const SkPaint&) const = 0;
+
+private:
+    typedef SkSVGTransformableNode INHERITED;
+};
+
+#endif // SkSVGShape_DEFINED
diff --git a/experimental/svg/model/SkSVGTypes.h b/experimental/svg/model/SkSVGTypes.h
new file mode 100644
index 0000000000..6d34d9943a
--- /dev/null
+++ b/experimental/svg/model/SkSVGTypes.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkSVGTypes_DEFINED
+#define SkSVGTypes_DEFINED
+
+#include "SkColor.h"
+#include "SkScalar.h"
+#include "SkTypes.h"
+
+class SkSVGNumber {
+public:
+    constexpr SkSVGNumber()                    : fValue(0) {}
+    explicit constexpr SkSVGNumber(SkScalar v) : fValue(v) {}
+    SkSVGNumber(const SkSVGNumber&)            = default;
+    SkSVGNumber& operator=(const SkSVGNumber&) = default;
+
+
+    const SkScalar& value() const { return fValue; }
+
+    operator const SkScalar&() const { return fValue; }
+
+private:
+    SkScalar fValue;
+};
+
+class SkSVGLength {
+public:
+    enum class Unit {
+        kUnknown,
+        kNumber,
+        kPercentage,
+        kEMS,
+        kEXS,
+        kPX,
+        kCM,
+        kMM,
+        kIN,
+        kPT,
+        kPC,
+    };
+
+    constexpr SkSVGLength()                    : fValue(0), fUnit(Unit::kUnknown) {}
+    explicit constexpr SkSVGLength(SkScalar v, Unit u = Unit::kNumber)
+        : fValue(v), fUnit(u) {}
+    SkSVGLength(const SkSVGLength&)            = default;
+    SkSVGLength& operator=(const SkSVGLength&) = default;
+
+    const SkScalar& value() const { return fValue; }
+    const Unit&     unit()  const { return fUnit;  }
+
+private:
+    SkScalar fValue;
+    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
diff --git a/experimental/svg/model/SkSVGValue.cpp b/experimental/svg/model/SkSVGValue.cpp
index 674a200a34..aec49d239f 100644
--- a/experimental/svg/model/SkSVGValue.cpp
+++ b/experimental/svg/model/SkSVGValue.cpp
@@ -5,4 +5,5 @@
  * found in the LICENSE file.
  */
 
+#include "SkSVGTypes.h"
 #include "SkSVGValue.h"
diff --git a/experimental/svg/model/SkSVGValue.h b/experimental/svg/model/SkSVGValue.h
index 3d3cd6efc1..a83c4fe07f 100644
--- a/experimental/svg/model/SkSVGValue.h
+++ b/experimental/svg/model/SkSVGValue.h
@@ -11,14 +11,16 @@
 #include "SkColor.h"
 #include "SkMatrix.h"
 #include "SkPath.h"
+#include "SkSVGTypes.h"
 #include "SkTypes.h"
 
 class SkSVGValue : public SkNoncopyable {
 public:
     enum class Type {
-        Color,
-        Path,
-        Transform,
+        kColor,
+        kLength,
+        kPath,
+        kTransform,
     };
 
     Type type() const { return fType; }
@@ -33,6 +35,8 @@ protected:
 
 private:
     Type fType;
+
+    typedef SkNoncopyable INHERITED;
 };
 
 template <typename SkiaType, SkSVGValue::Type ValueType>
@@ -49,11 +53,12 @@ public:
 private:
     SkiaType fWrappedValue;
 
-    using INHERITED = SkSVGValue;
+    typedef SkSVGValue INHERITED;
 };
 
-using SkSVGColorValue     = SkSVGWrapperValue<SkColor , SkSVGValue::Type::Color    >;
-using SkSVGPathValue      = SkSVGWrapperValue<SkPath  , SkSVGValue::Type::Path     >;
-using SkSVGTransformValue = SkSVGWrapperValue<SkMatrix, SkSVGValue::Type::Transform>;
+using SkSVGColorValue     = SkSVGWrapperValue<SkSVGColor , SkSVGValue::Type::kColor    >;
+using SkSVGLengthValue    = SkSVGWrapperValue<SkSVGLength, SkSVGValue::Type::kLength   >;
+using SkSVGPathValue      = SkSVGWrapperValue<SkPath     , SkSVGValue::Type::kPath     >;
+using SkSVGTransformValue = SkSVGWrapperValue<SkMatrix   , SkSVGValue::Type::kTransform>;
 
 #endif // SkSVGValue_DEFINED