[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

1 files changed, 194 insertions, 0 deletions

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;
+}