This page documents details on JOSM's ​MapCSS implementation. At the moment (Feb-2011) it is under active development and anything may change without warning.

General Structure

A MapCSS style sheet has rules of the form

selector {
    prop: value;
    ...
    prop: value;
}

The algorithm to find the styles for a given object is like this:

 - for each rule:
     if the selector applies, set the properties from the { } block
 - analyze the final list of properties and generate styles from it

Selectors

Examples for selectors are

way[highway=residential] {...}
way|z11-14[amenity=parking][access=public]:closed:new::layer_1 {...}
area[amenity=parking][access=public], area[amenity=parking][!access] {...}
relation[type=route][route=foot] > way::relation_underlay {..}

The different elements (type-, zoom- , condition selector, pseudo classes, layer identifier, grouping and child combinator) are explained below.

Type selector

node, way, relation

applies to the osm objects of the given type

*

accepts any object

area

The "area" type selector is a convenient way to select areas, e.g.

area[natural=beach] {...} 

is the same as

way[natural=beach], relation[type=multipolygon][natural=beach] {...} 

Note that area selects unclosed ways as well, so it may be useful to add the :closed pseudo class. The JOSM Validator will give a warning for unclosed ways that have an area style.

meta

The meta selector starts a special rule that should stand at the beginning of the file. It gives some general information on the style sheet. All software that supports MapCSS should be able to parse this sections without errors, so do not use exotic syntax extensions in this part.

meta {
    title: "Parking lanes";   /* title shown in the menu */
    icon: "images/logo.png";  /* small icon shown in the menu next to the title */
}

canvas

Some style information not specific to nodes, ways or relations.

canvas {
    background-color: #ffffea;
}

Zoom selector

You can restrict the scale at that the a given rule applies.

way|z12 {...}	At zoom level 12
way|z13-15 {...}	From 13 to 15
way|z16- {...}	16 and above
way|z-12 {...}	12 and below
way {...}	any zoom level

The precise definition of scale ranges for each zoom level may change in future. By rule of thumb you can expect to be approximately at zoom level n when imagery displays slippymap tiles of level n.

Condition selector

You can add any number of conditions, which must all be fulfilled, otherwise the block of declarations will not be executed for that object. Possible conditions are:

way[building]	way with building tag set
way[!building]	way with building tag not set
way[oneway?]	way with oneway set to yes, true or 1
way[highway=residential]	way with tag highway=residential
way[highway!=residential]	way that doesn't have the tag highway=residential
node[place=city][population<50000]	city-node with population less than 50000
*[amenity=vending_machine][vending~=stamps]	any object, that is a vending machine and offers stamps (assumes that the value is a list of semicolon delimited entries)
way[highway][name*="straße"]	any highway where the string "straße" is contained somewhere in the value of the name tag. (Quotes are required if characters other than "a"-"z", underscore or dash are used.)
*[name=~/.../]	​Regex

In addition, eval expressions can be used in the brackets, e.g.

way[eval(prop("opacity")<0.2)]	any way where the current value of the opacity property is less then 0.2
node[eval(JOSM_search("role:forward_stop | role:backward_stop"))]	JOSM search expression - in this case any node that is member of a relation as forward_stop or backward_stop

Pseudo Classes

:closed	true for ways where the first node is the same as the last and for any multipolygon relation
:new	all new objects
:connection	true for nodes that are used by more than one way

Layer Identifier

Layers can be used to create more than one style for a single object. Here is an example:

way[highway=secondary] {
    width: 3;
    color: yellow;
}

way[highway=tertiary] {
    width: 2;
    color: orange;
}

way[access][access!=public]::non_public_access_layer {
    width: +2; 
    color:red; 
    dashes: 2; 
    object-z-index:-1.0;
}

way[bridge]::bridge_layer {
    width: +3; 
    color:#000080;
    opacity:0.5;
    object-z-index:1.0; 
}

This draws all secondary and tertiary roads in yellow and orange respectively. Any road with an access tag other than public will get an extra line style below (object-z-index:-1.0;) the main line. If that part of the street happens to be a bridge, it will also get a half transparent blue overlay. The relative width value (width: +2;) refers to the width on the default layer (2 or 3 in this case).

The name for the layer can be any identifier.

default

If you omit the layer in the selector, this is the same as using ::default.

*

In addition, you can use the * layer to override and initialize all layers.
It overrides all existing subparts, so

way::A { a; } 
way::B { b; } 
way::* { c; } 

is equivalent to

way::A { a; } 
way::B { b; } 
way::A { c; } 
way::B { c; }

And it initializes new subparts. In other words:

way::* { a; } 
way::A { b; } 

is equivalent to

way::A {} 
way::* { a; } 
way::A { b; } 

which is in turn the same as

way::A { a; } 
way::A { b; } 

or

way::A { a; b; }

Child combinator

You can select nodes that are part of specific ways and any object that is member of a certain relation:

relation[type=route][route=foot] > way|z12-::relation_underlay {...}

Zoom selector and Layer identifier are only relevant for the part right of the ">" sign.

Grouping

Rules with common declaration block can be grouped into one:

area[landuse=forest] { color: green;   width: 2; }
area[natural=wood] { color: green;   width: 2; }

is the same as

area[landuse=forest], area[natural=wood] { color: green;   width: 2; }

Properties

General properties

Key	Description	Value Format	Default Value
z-index	specify the order the objects are drawn: The objects with higher z-index are drawn on top of objects with lower z-index	Number (can be negative)	0

Icon and symbol styles

Key	Description	Value Format	Default Value
icon-image	The icon at node position	Image	-
icon-opacity	Opacity of the icon image	Opacity	1.0
symbol-shape	Display a symbol at the position of the node	square, circle	-
symbol-size	Size of the symbol	Number, can be relative ("+4")	10
symbol-stroke-width	outline stroke width	Width	1.0 if symbol-stroke-color is set
symbol-stroke-color	line color	Color	#FFC800 if symbol-stroke-width is set
symbol-stroke-opacity	line opacity	Opacity	1.0
symbol-fill-color	fill color for the shape	Color	blue, unless either symbol-stroke-width or symbol-stroke-color is set
symbol-fill-opacity	fill opacity	Opacity	1.0
text-..., font-...	general text & font properties
text-anchor-horizontal	horizontal text label placement	left, center, right	right
text-anchor-vertical	vertical text label placement	above, top, center, bottom, below	bottom

Do not rely on the default values for symbol-... properties (except for opacity). They are intended for "quick & dirty" style sheets and should be set to an explicit value.

Line styles

Key	Description	Value Format	Default Value
width	Line width	Width	-
color	Line color	Color	value of fill-color or (if unset) JOSM's default untagged color (#808080)
opacity	How transparent the line is.	Opacity	1.0
dashes	An array of alternating on/off lengths	list of numbers, e.g. > 15, 5 or written as expression: > list(3, 4, 5, 6)	-
dashes-offset	shift the dash pattern by a certain amount	Number (>= 0)	0
dashes-background-color	The color to use in between the dashes (optional)	Color	-
dashes-background-opacity	Opacity value for the dashes background	Opacity	value of opacity
linecap	Shape at the end of the line (see ​here)	none, round, square	none
linejoin	Shape at the line corners	round, miter, bevel	round
miterlimit	Applies for linejoin: miter. Sets the maximum overshoot when line segments meet at a very small angle	Number (>= 1.0)	10.0
text-position	set to line, if text should be drawn along the line	line, center	-
text-..., font-...	general text & font properties

All these properties (except for text-... and font-...) exist also with the casing- prefix. The casing is a second independent line element, that is drawn below the normal line and can be used to draw a thin frame around the line in another color.

Key	Description	Value Format	Default Value
casing-width	Casing width	Width (revers to width if relative width is specified)	-
casing-color	Casing color	Color	value of fill-color or (if unset) JOSM's default untagged color (#808080)
casing-opacity	How transparent the casing is.	Opacity	1.0
casing-...	...	...	...

Area styles

Key	Description	Value Format	Default Value
fill-color	Color in which to fill the area	Color	-
fill-image	Image pattern	Image	-
fill-opacity	How transparent the fill is; applies to both color and image	Opacity	1.0
text-position	set to center, if text should be drawn in the center of the area	line, center	-
text-..., font-...	general text & font properties

Required properties to create an Area style: fill-color or fill-image

Text & Font properties

Key	Description	Value Format	Default Value
text	how to find the label text; no label is displayed, unless this property is set	> auto derive the text automatically. At time of writing, the following tags are searched and the first one that is found will be used: "name:"+<LANG>, "name", "int_name", "ref", "operator", "brand" and "addr:housenumber" > String use as key to look up the value	-
text-color	the text color	Color	white for lines and nodes, #c0c0c0 for areas (JOSM "text" and "areatext" color preferences)
text-offset-x	shift the text horizontally, (not supported for text along line)	Number	0
text-offset-y (can also be written as text-offset)	shift the text vertically, positive values shift the text in upwards direction	Number	0
font-family	font family	String	"Helvetica" (JOSM preference "mappaint.font")
font-size	font size	Number	8 (JOSM preference "mappaint.fontsize")
font-wheight	bold or not	bold, normal	normal
font-style	italic or not	italic, normal	normal

Width

• 14.0 (any positive number)
• default (use JOSM's default line width, which is 2, but can be configured)
• thinnest (draws the line as thin as possible)
• +3 (with plus sign in front) adds the amount to the width on the default layer. This applies only for styles that are not on the default layer, e.g. highlights. Another way to write this would be prop("width","default")+3. For casing-width, this refers to the width value on the same layer.

Color

• named color as found in ​this list
• html style: #ff0000
• rgb(0.0, 1.0 , 0.2) - rgb value with arguments from 0.0 to 1.0

Opacity

• from 0.0 (transparent) to 1.0 (opaque)

String

• any character sequence, in quotes, e.g. "images/fill.png". If the string is an identifier, quotes are optional. (Quote and backslash sign can be escaped.)

Number

• integer or floating point (in simple form e.g. 0.3). In general can be negative, but most properties do not support negative numbers
• has a special meaning if you put a "+" sign in front (relative width)

Eval expressions

See ​source for details and an up to date list.

+, -, *, /

arithmetic operations

||, &&, !

boolean operations

<, >, <=, >=, ==

comparison operators

asin, atan, atan2, ceil, cos, cosh, exp, floor, log, max, min, random, round, signum, sin, sinh, sqrt, tan, tanh

the usual meaning, ​details

cond(b, fst, snd)

b ? fst : snd

if (b) then fst else snd

list(a, b, ...)

create list of values, e.g. for the dashes property

prop(p_name)

value of the property p_name, e.g. prop("width")

prop(p_name, layer_name)

property from the layer layer_name

is_prop_set(p_name)

true, if property p_name is set

is_prop_set(p_name, layer_name)

true, if property p_name is set

get_tag_value(key_name)

get the value of the key key_name from the object in question

has_tag_key(key_name)

true, if the object has a tag with the given key

rgb(r, g, b)

create color value (arguments from 0.0 to 1.0)

red(clr), blue(clr), blue(clr)

get value of color channels in rgb color model

length(str)

length of a string

JOSM_search("...")

true, if JOSM search applies to the object

Examples

• circle symbol for house number with size depending of the number of digits

  node[addr:housenumber] { 
      symbol-shape: circle; 
      symbol-size: eval((min(length(get_tag_value("addr:housenumber")), 3) * 5) + 3); 
      symbol-fill-color: #B0E0E6; 
  
      text: "addr:housenumber"; 
      text-anchor-horizontal: center; 
      text-anchor-vertical: center; 
      text-offset-x: -1; 
      text-offset-y: -1; }
      
  node[addr:housenumber]::hn_casing { 
      z-index: -100; 
      symbol-shape: circle; 
      symbol-size: +2; 
      symbol-fill-color: blue; 
  }
  

• invert colors

  *::* {
      color: eval(rgb(1 - red(prop(color)), 1 - green(prop(color)), 1 - blue(prop(color))));
      fill-color: eval(rgb(1 - red(prop(fill-color)), 1 - green(prop(fill-color)), 1 - blue(prop(fill-color))));
  }
  

• random stuff

  way {
      width: eval(random() * 20);
      color: eval(rgb(random(), random(), random()));
  }
  

Compatibility notes

MapCSS 0.2

Grammar

• descendant combinator is not supported, use child combinator instead.
• JOSM MapCSS is not liberal with white spaces in the selector, they are only permitted before and after comma and greater sign (Grouping and Child combinator).
• way[oneway=yes] does not have any magic, you can use way[oneway?] instead
• set is not supported, instead of

  way[highway=footway] { set path; color: #FF6644; width: 2; }
  way[highway=path]    { set path; color: brown; width: 2; }
  way.path { text:auto; text-color: green; text-position: line; text-offset: 5; }
  

  you can write

  way[highway=footway] { path-set : true; color: #FF6644; width: 2; }
  way[highway=path]    { path-set : true; color: brown; width: 2; }
  way[eval(prop(path-set))] { text:auto; text-color: green; text-position: line; text-offset: 5; }
  

• no stacking of declaration blocks, you have to provide explicit layer names
• no @import
• JOSM does not require eval(...) to be wrapped around expressions, but for compatibility with other MapCSS implementations you should write it out.

Properties

At the moment, JOSM does not support the following properties:

canvas:

fill-color is called background-color, the rest is not supported

line:

image

point/icon:

icon-width, icon-height

label:

font-variant, text-decoration, text-transform, max-width, text-halo-color, text-halo-radius

shield:

not supported

JOSM uses the MapCSS 0.1 way to specify casing-width, i.e. casing-width: 9; is an absolute value. You can write casing-width: +4; to specify a 2px casing on both sides.

Halcyon (Potlatch 2)

• Text label is placed in the center of the icon. For compatibility with Halcyon put

  node { text-anchor-vertical: center; text-anchor-horizontal: center; }
  

  at the beginning of your style sheet.
• standard z-index seems to be different from 0 (FIXME: what is it?)
• image: circle; corresponds to symbol-shape: circle;

Kothic

• Kothic has support for eval, which probably differs from JOSM's eval.
• Kothic understands units, whereas JOSM always calculates in pixel.
• The extrusion features are not available in JOSM

Ceyx

• seems to have [tunnel=1] instead of [tunnel=yes] (Halcyon) or [tunnel?] (JOSM)