Support writing SVG to scale

src/ifcconvert/IfcConvert.cpp

@@ -340,6 +340,7 @@ int main(int argc, char** argv) {
 #endif
     short precision;
 	double section_height;
+	std::string svg_scale;
 
     po::options_description serializer_options("Serialization options");
     serializer_options.add_options()
@@ -351,6 +352,9 @@ int main(int argc, char** argv) {
         ("bounds", po::value<std::string>(&bounds),
             "Specifies the bounding rectangle, for example 512x512, to which the "
             "output will be scaled. Only used when converting to SVG.")
+		("scale", po::value<std::string>(&svg_scale),
+			"Interprets SVG bounds in mm, centers layout and draw elements to scale. "
+			"Only used when converting to SVG. Example 1:100.")
 		("door-arcs", "Draw door openings arcs for IfcDoor elements")
 		("section-height", po::value<double>(&section_height),
 		    "Specifies the cut section height for SVG 2D geometry.")
@@ -891,6 +895,16 @@ int main(int argc, char** argv) {
 		if (vmap.count("door-arcs")) {
 			static_cast<SvgSerializer*>(serializer.get())->setDrawDoorArcs(true);
 		}
+		if (vmap.count("scale")) {
+			int s0, s1;
+			if (sscanf(svg_scale.c_str(), "%u:%u", &s0, &s1) == 2 && s0 > 0 && s1 > 0) {
+				static_cast<SvgSerializer*>(serializer.get())->setScale((double)s0 / s1);
+			} else {
+				cerr_ << "[Error] Invalid use of --scale" << std::endl;
+				print_options(serializer_options);
+				return EXIT_FAILURE;
+			}
+		}
 	}
 
     if (convert_back_units) {

src/serializers/SvgSerializer.cpp

@@ -706,17 +706,21 @@ void SvgSerializer::finalize() {
 		const double dx = xmax - xmin;
 		const double dy = ymax - ymin;
 
-		double sc = 1.;
-
-		if (dx / width > dy / height) {
-			sc = width / dx;
+		double sc, cx, cy;
+		if (scale_) {
+			sc = (*scale_) * 1000;
+			cx = (xmax + xmin) / 2. * sc - width / 2.;
+			cy = (ymax + ymin) / 2. * sc - height / 2.;
 		} else {
-			sc = height / dy;
+			if (dx / width > dy / height) {
+				sc = width / dx;
+			} else {
+				sc = height / dy;
+			}
+			cx = xmin * sc;
+			cy = ymin * sc;
 		}
 
-		const double cx = xmin * sc;
-		const double cy = ymin * sc;
-
 		{std::vector< boost::shared_ptr<util::string_buffer::float_item> >::const_iterator it;
 		for (it = xcoords.begin(); it != xcoords.end(); ++it) {
 			double& v = (*it)->value();
@@ -760,7 +764,15 @@ void SvgSerializer::finalize() {
 }
 
 void SvgSerializer::writeHeader() {
-	svg_file << "<svg xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">\n"
+	svg_file << "<svg xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"";
+	if (scale_) {
+		svg_file << 
+			" width=\"" << width << "mm\""
+			" height=\"" << height << "mm\"" << 
+			" viewBox=\"0 0 " << width << " " << height << "\"";
+	}
+		
+	svg_file << ">\n"
 		"    <defs>\n"
 		"        <marker id=\"arrowend\" markerWidth=\"10\" markerHeight=\"7\" refX=\"10\" refY=\"3.5\" orient=\"auto\">\n"
 		"          <polygon points=\"0 0, 10 3.5, 0 7\" />\n"
@@ -774,7 +786,16 @@ void SvgSerializer::writeHeader() {
 		"        .IfcAnnotation path {\n"
 		"            marker-end: url(#arrowend);\n"
 		"            marker-start: url(#arrowstart);\n"
-		"        }\n"
+		"        }\n";
+	
+	if (scale_) {
+		svg_file <<
+		"        text {\n"           //       (pt)  (px)  (in)  (mm)
+		"        	font-size: 4;\n" // approx 12 / 0.75 / 96 * 25.4
+		"        }\n";
+	}
+
+	svg_file << 
 		"    ]]>\n"
 		"    </style>\n";
 }

src/serializers/SvgSerializer.h

@@ -73,6 +73,7 @@ protected:
 	std::ofstream svg_file;
 	double xmin, ymin, xmax, ymax, width, height;
 	boost::optional<std::vector<std::pair<std::pair<double, double>, IfcUtil::IfcBaseEntity*>>> section_heights;
+	boost::optional<double> scale_;
 	bool rescale, print_space_names_, print_space_areas_, draw_door_arcs_, with_section_heights_from_storey_;
 	std::multimap<IfcUtil::IfcBaseEntity*, path_object, storey_sorter> paths;
 	std::vector< boost::shared_ptr<util::string_buffer::float_item> > xcoords;
@@ -90,6 +91,9 @@ public:
 		, ymax(-std::numeric_limits<double>::infinity())
 		, with_section_heights_from_storey_(false)
 		, rescale(false)
+		, print_space_names_(false)
+		, print_space_areas_(false)
+		, draw_door_arcs_(false)
 		, file(0)
 		, storey_(0)
 	{}
@@ -113,6 +117,7 @@ public:
 	void setPrintSpaceNames(bool b) { print_space_names_ = b; }
 	void setPrintSpaceAreas(bool b) { print_space_areas_ = b; }
 	void setDrawDoorArcs(bool b) { draw_door_arcs_ = b; }
+	void setScale(double s) { scale_ = s; }
     std::string nameElement(const IfcUtil::IfcBaseEntity* storey, const IfcGeom::Element<real_t>* elem);
 	std::string nameElement(const IfcUtil::IfcBaseEntity* elem);
 	std::string idElement(const IfcUtil::IfcBaseEntity* elem);