Add viewbox fallback logic for dimension parsing

SVG's now have fallback on viewbox. Still debugging the boost Qi parser

src/svg/svg_parser.cpp

@@ -158,19 +158,20 @@ double parse_double_optional_percent(T & error_messages, const char* str, bool &
 }
 
 template <typename T>
-bool parse_integer_list(T & error_messages, const char* str, int* list)
+bool parse_double_list(T & error_messages, const char* str, double* list)
 {
     using namespace boost::spirit::qi;
     using boost::phoenix::ref;
     qi::_1_type _1;
-    qi::int_type int_;
+    qi::double_type double_;
+    qi::char_type char_;
 
-    if (!parse(str, str + std::strlen(str), int_[ref(list[0])=_1] >> ' ' | ','
-                >> int_[ref(list[1])=_1] >> ' ' | ','
-                >> int_[ref(list[2])=_1] >> ' ' | ','
-                >> int_[ref(list[3])=_1]))
+    if (!parse(str, str + std::strlen(str), double_[ref(list[0])=_1] >> char_(' ') | char_(',')
+                >> double_[ref(list[1])=_1] >> char_(' ') | char_(',')
+                >> double_[ref(list[2])=_1] >> char_(' ') | char_(',')
+                >> double_[ref(list[3])=_1]))
     {
-        error_messages.emplace_back("failed to parse list of integers from " + std::string(str));
+        error_messages.emplace_back("failed to parse list of doubles from " + std::string(str));
         return false;
     }
     return true;
@@ -484,16 +485,51 @@ void parse_dimensions(svg_parser & parser, rapidxml::xml_node<char> const* node)
 {
     double width = 0;
     double height = 0;
+    double aspect_ratio = 1;
+    double viewbox[4] = {0,0,0,0};
+    bool has_viewbox = false;
+    bool has_percent_height = true;
+    bool has_percent_width = true;
+
     auto const* width_attr = node->first_attribute("width");
     if (width_attr)
     {
-        width = parse_double(parser.error_messages_, width_attr->value());
+        width = parse_double_optional_percent(parser.error_messages_, width_attr->value(), has_percent_width);
     }
     auto const* height_attr = node->first_attribute("height");
     if (height_attr)
     {
-        height = parse_double(parser.error_messages_, height_attr->value());
+        height = parse_double_optional_percent(parser.error_messages_, height_attr->value(), has_percent_height);
     }
+    auto const* viewbox_attr = node->first_attribute("viewBox");
+    if (viewbox_attr)
+    {
+        has_viewbox = parse_double_list(parser.error_messages_, viewbox_attr->value(), viewbox);
+    }
+
+    std::cout << "Width = " << width << std::endl;
+    std::cout << "Width has percent = " << has_percent_width << std::endl;
+    std::cout << "Height has percent = " << has_percent_height << std::endl;
+    std::cout << "Viewbox = " << viewbox[0] << "," << viewbox[1] << "," << viewbox[2] << "," << viewbox[3] << std::endl;
+    std::cout << "Viewbox exists = " << has_viewbox << std::endl;
+
+
+    if (has_percent_width && !has_percent_height && has_viewbox)
+    {
+        aspect_ratio = viewbox[2] / viewbox[3];
+        width = aspect_ratio * height;
+    }
+    else if (!has_percent_width && has_percent_height && has_viewbox)
+    {
+        aspect_ratio = viewbox[2] / viewbox[3];
+        height = height / aspect_ratio;
+    }
+    else if (has_percent_width && has_percent_height && has_viewbox)
+    {
+        width = viewbox[2];
+        height = viewbox[3];
+    }
+    
     parser.path_.set_dimensions(width, height);
 }
 

test/data

@@ -1 +1 @@
-Subproject commit 07ea03efceb0631d0436dca3184b1211acb32cdd
+Subproject commit 644f8db7b62720e436aaa0489338029fcae771e6

test/unit/svg/svg_parser_test.cpp

@@ -333,6 +333,26 @@ TEST_CASE("SVG parser") {
         REQUIRE(std::equal(expected.begin(),expected.end(), vec.begin(),detail::vertex_equal<3>()));
     }
 
+    SECTION("SVG viewbox fallback")
+    {
+        std::string svg_name("./test/data/svg/viewbox-missing-width-and-height.svg");
+        std::ifstream in(svg_name.c_str());
+        std::string svg_str((std::istreambuf_iterator<char>(in)),
+                        std::istreambuf_iterator<char>());
+
+        using namespace mapnik::svg;
+        mapnik::svg_storage_type path;
+        vertex_stl_adapter<svg_path_storage> stl_storage(path.source());
+        svg_path_adapter svg_path(stl_storage);
+        svg_converter_type svg(svg_path, path.attributes());
+        svg_parser p(svg);
+        p.parse_from_string(svg_str);
+        auto width = svg.width();
+        auto height = svg.height();
+        REQUIRE(width == 100);
+        REQUIRE(height == 100);
+    }
+
     SECTION("SVG rounded <rect>s missing rx or ry")
     {
         std::string svg_name("./test/data/svg/rounded_rect-missing-one-radius.svg");