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This file documents effors toward establishing a public API for iD, one that can support plugin development.

URL parameters

iD supports several URL parameters. When constructing a URL to a standalone instance of iD (e.g., the following parameters are available in the hash portion of the URL:

  • map - A slash separated zoom level, longitude, and latitude. Example: map=20.00/-77.02271/38.90085.
  • id - The character 'n', 'w', or 'r', followed by the OSM ID of a node, way or relation, respectively. Selects the specified entity, and, unless a map parameter is also provided, centers the map on it.
  • background - The value from a sourcetag property in iD's imagery list, or a custom tile URL. A custom URL is specified in the format custom:<url>, where the URL can contain the standard tile URL placeholders {x}, {y} and {z}, {ty} for flipped TMS-style Y coordinates, and {switch:a,b,c} for DNS multiplexing. Example: background=custom:http://{switch:a,b,c}{z}/{x}/{y}.png

When constructing a URL to an instance of iD embedded in the OpenStreetMap Rails Port (e.g., the following parameters are available as regular URL query parameters:

  • lat, lon, zoom - Self-explanatory.
  • node, way, relation - Select the specified entity.

In addition, the background parameter is available as a hash parameter as above.

CSS selectors

iD has a documented and stable set of classes that can be used to apply style or attach behavior to the visual representation of map data via CSS selectors. These classes relate to the vocabulary of the OSM data model, a related geometric vocabulary established by iD, and to the tags present on OSM entities.

OSM Data Model classes

An SVG element on the map to which an iD.Entity has been bound as a datum shall have a class with that datum's type, i.e. either .node or .way. (If and when we add visual representations for relations, .relation may also be valid.)

The visual representation of a single entity may be composed of several elements, e.g. ways are composed of casing and stroke. Such elements will have a distinct class identifying the particular aspect of representation, e.g. .casing and .stroke.

The particular type of SVG element (path, circle, image etc.) that is used to implement that visual representation is explicitly NOT part of the public API. Avoid naming specific tags in CSS selectors; as iD evolves, we may need to change what SVG elements we use in order to implement a particular visual style.

Geometric classes

In addition to the OSM element vocabulary of nodes, ways, and relations, iD has established a related geometric vocabulary consisting of points, vertices, lines, and areas.

A point is a node that is not a member of any way. Elements representing points have a .point class. Since a point is always a node, they also have a .node class.

A vertex is a node that is a member of one or more ways. Elements representing points have .vertex and .node classes.

A line is a way that is not an area. Elements representing lines have a .line class. Since a line is also a way, they also have a .way class.

An area is a way that is circular, has certain tags, or lacks certain other tags (see iD.Way#isArea for the exact definition). Elements representing areas have .area and .way classes.

Tag classes

Elements also receive classes according to certain of the key-value tags that are assigned to them.

TODO: elaborate.

Special classes

A node that is a member of two or more ways shall have the .shared class.

Two or more nodes at identical coordinates shall each have an .overlapped class. (TODO)

Elements comprising the entity currently under the cursor shall have the .hover class. (The :hover psuedo-class is insufficient when an entity's visual representation consists of several elements, only one of which can be :hovered.)

Elements that are currently active (being clicked or dragged) shall have the .active class. (TODO)

Elements that are currently selected shall have the .selected class.

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