torque/doc/API.md

Torque API

L.TorqueLayer(options)

One of two core classes for the Torque library - it is used to create an animated torque layer with custom settings.

Usage example

  // initialize a torque layer that uses the CartoDB account details and SQL API to pull in data
  var torqueLayer = new L.TorqueLayer({
    user       : 'viz2',
    table      : 'ow',
    cartocss:  CARTOCSS
  });

Options

Provider options

Option	type	Default	Description	Options
provider	string	sql_api	Where is the data coming from	sql_api, url_template, or windshaft

CartoDB data options (SQL API provider)

Option	type	Default	Description
user_name	string	null	CartoDB account name. Found from: http://accountname.cartodb.com
table_name	string	null	CartoDB table name where data is found
query	string	null	SQL query to be performed to fetch the data. You must use this param or table, not at the same time
cartocss	string	null	CartoCSS style for this map
loop	boolean	true	If false, the animation is paused when it reaches the last frame

Time methods

Method	options	returns	Description
setStep(step)	time numeric	this	sets the animation to the step indicated by step, must be between 0 and steps
play()		this	starts the animation
stop()		this	stops the animation and set time to step 0
pause()		this	stops the animation but keep the current time (play enables the animation again)
toggle()		this	toggles (pause/play) the animation
getStep()		current animation step (integer)	gets the current animation step
getTime()		current animation time (Date)	gets the real animation time
isRunning()		true/false	describes whether the Torque layer is playing or is stopped

Layer control methods

Method	options	returns	Description
hide()	none	this	hides the Torque layer
show()	none	this	shows the Torque layer

Style methods

Method	options	returns	Description
setCartoCSS(cartocss)	cartocss string	this	style the map rendering using client-side cartocss (not available with named maps)

The full CartoCSS spec is not supported by Torque but instead only a limited subset with some additions related to torque rendering. To see the full list of supported parameters, read the Torque CartoCSS documentation. value and zoom variables can be used. value is the value of aggregation (see countby constructor option). zoom is the current zoom being rendered

TorqueLayer currently expects marker styling.

CartoCSS Example

This should be string encoded in Javascript.

#layer {
  marker-fill: #662506;
  marker-width: 20;
  [value > 1] { marker-fill: #FEE391; }
  [value > 2] { marker-fill: #FEC44F; }
  [value > 3] { marker-fill: #FE9929; }
  [value > 4] { marker-fill: #EC7014; }
  [value > 5] { marker-fill: #CC4C02; }
  [value > 6] { marker-fill: #993404; }
  [value > 7] { marker-fill: #662506; }
  [frame-offset = 1] {  marker-width: 20; marker-fill-opacity: 0.05;}' // renders the previous frame
  [frame-offset = 2] {  marker-fill: red; marker-width: 30; marker-fill-opacity: 0.02;}' // renders two frames ago from the current being rendered
}

Data methods

Method	options	returns	Description
setSQL(sql statement)	SQL string	this	Change the SQL on the data table (not available with named maps)
error(callback)	callback function with a list of errors as argument	this	specifies a callback function to run if there are query errors

SQL Example

Limit the data used in the Torque map.

torqueLayer.setSQL("SELECT * FROM table LIMIT 100");

Interaction methods (only available for Leaflet)

Method	options	returns	Description
getValueForPos(x, y[, step])		an object like { bbox:[], value: VALUE } if there is value for the pos, null otherwise	allows to get the value for the coordinate (in map reference system) for a concrete step. If step is not specified the animation one is used. This method is expensive in terms of CPU so be careful. It returns the value from the raster data not the rendered data
getValueForBBox(xstart, ystart, xend, yend)		a number	returns an accumulated numerical value from all the torque areas within the specified bounds
getActivePointsBBox(step)		list of bbox	returns the list of bounding boxes active for step
invalidate()			forces a reload of the layer data.

Interaction methods (only available for Leaflet)

Method	options	returns	Description
getActivePointsBBox(step)		list of bbox	returns the list of bounding boxes active for step
invalidate()			forces a reload of the layer data.

Events

Events in Torque follow the format:

torqueLayer.on('event-type', function([callback_obj]) {
    // do something
});

Events	callback object	Description
change:steps	current step	When a map changes steps, this event is triggered
change:time	current time, step number	When a map changes time, this event is triggered
play	none	Triggered when the Torque layer is played
pause	none	Triggered when the Torque layer is paused
stop	none	Triggered when the Torque layer is stopped
load	none	Triggered when the Torque layer is loaded

Event Example

Print the current step to the console log.

torqueLayer.on('change:steps', function(step) {
    // do something with step
    console.log("Current step is " + step);
});

Google Maps Layers

GMapsTorqueLayer(options)

This class does exactly the same as L.TorqueLayer but using Google Maps instead. The main difference is that this class is not a layer but is an overlay, so in order to add it to the a map use, layer.setMap instead of overlayMapTypes. See the Overlay View reference in Google Maps API doc.

Options

options

Option	type	Default	Description
map	google.maps.Map		google.maps.Map instance

see L.TorqueLayer for the rest of the options.