A tag to build a shape from multiple paths

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A tag to build a shape from multiple paths

Dominus Carnufex
Hello people,

I know it is extremely late in your schedule for SVG 2 to make a suggestion, but I only recently came across a severe limitation of SVG, which I would enjoy being addressed in the new standard.

As of yet, paths and polylines are treated not as lines, but as surfaces enclosed by the said line (and possibly an implicit last stroke to close the shape). Which means that a group of paths/polylines, together enclosing a zone, do NOT actually enclose the whole surface when being treated by SVG. See joined file for an example of what I mean.

My suggestion would be to offer an additional tag, maybe something like <shape></shape>, that would contain polylines and paths, each of those being either an outer or inner boundary of the whole shape (using an attribute, or <inner> / <outer> subtags). This whole shape could in turn be treated as any other shape, being filled, serving as clip-path, and so on.

What I am describing is actually extremely similar to multipolygon relations used by OpenStreetMap (http://wiki.openstreetmap.org/wiki/Relation:multipolygon), which could give you a basis for reflection, as the OSM format is also an XML derivative.

Why add such a feature? might you ask. Firstly, because it would offer a much simpler way to create donut-like shapes than dealing with nonzero/evenodd and the direction of the path used.

Secondly, in order to considerably simplify the creation of complex maps in SVG, such as this one: https://commons.wikimedia.org/wiki/File:France_maximale.svg The map represents the “départements” of France.

Each colored surface is a path filled with that color, although the boundaries between departments are common, and the colored regions (not visible here, but present in the SVG) are different paths, although regions are nothing more than groups of departments, and the coastline is again another path, which in turn is not the same path as the the international boundaries.

And there is no simpler way to do it as of yet! Not only would such a feature make SVG maps simpler, but also lighter: the whole code would be around half as long if only we could share boundaries between different shapes.

Thirdly, speaking of OSM, such a multipolygon feature, together with the approved “smooth curves” proposal (https://www.w3.org/Graphics/SVG/WG/wiki/SVG2_Requirements_Input#Smooth_curves_through_points) would make it extremely simple to rasterize OSM maps directly in SVG, offering better graphical quality, more accessible maps for the whole of Internet.

I hope this proposal will be met with enthusiasm, and bid you my farewell.

Yours,

clippaths.svg (1K) Download Attachment