evieliu / leaflet.timeline

Display arbitrary GeoJSON on a map with a timeline slider and play button

Leaflet.timeline 0.3.2

Show any changing geospatial data over time, from points to polygons.

If you want smooth motion of markers from point to point, this is not your plugin. Please check out LeafletPlayback, or for real-time data, try Leaflet Realtime, both plugins from which I may or may not have pilfered some ideas.

Usage

Leaflet.timeline is a subclass of L.GeoJSON, so use it as you would that. The data you pass in should be something like this:

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {
        "start": "1970-01-01",
        "end": "2014-12-04"
      },
      "geometry": { ... }
    }
  ]
}

The date can really be anything Date() can process.

It does add some extra options:

Options

see also all GeoJSON's options

start

default: earliest start in GeoJSON

The beginning/minimum value of the timeline.

end

default: latest end in GeoJSON

The end/maximum value of the timeline.

position

default: bottomleft

Position for the timeline controls. Probably doesn't really matter as you'll likely want to expand them anyway.

formatDate

default: (date) -> ""

A function that takes in a Unix timestamp and outputs a string. Ideally for formatting the timestamp, but hey, you can do whatever you want.

enablePlayback

default: true

Show playback controls (i.e. prev/play/pause/next).

steps

default: 1000

How many steps to break the timeline into. Each step will then be (end-start) / steps. Only affects playback.

duration

default: 10000

Minimum time, in ms, for the playback to take. Will almost certainly actually take at least a bit longer -- after each frame, the next one displays in duration/steps ms, so each frame really takes frame processing time PLUS step time.

showTicks

default: true

Show tick marks on slider, representing changes in value(s).

waitToUpdateMap

default: false

Wait until the user is finished changing the date to update the map. By default, both the map and the date update for every change. With complex data, this can slow things down, so set this to true to only update the displayed date.

Events

change

Fired when the selected time changes (either through manually sliding or through playback).

Methods

setTime

Sets the current timeline time. Will parse any dates in just about any format you throw at it.

getDisplayed

Returns the original GeoJSON of the features that are currently being displayed on the map.

Examples

Earthquakes

Example here. USGS provides GeoJSON(P) files with earthquake data, including time and magnitude. For this example, that data is read, parsed to the right format (start and end values in the GeoJSON properties), and added to a Leaflet.timeline.

Country borders after WWII

Example here. I found some historical country border data here, though unfortunately it was not in GeoJSON. Converted it with ogr2ogr:

$ ogr2ogr -f "GeoJSON" \
  -select CNTRY_NAME,COWSYEAR,COWSMONTH,COWSDAY,COWEYEAR,COWEMONTH,COWEDAY \
  borders.json cshapes.shp

Then wrangled the data into the right format (examples/borders-parse.js). After that, just pass the data to Leaflet.timeline and let it handle everything.

Change log

0.3.0

• Fixed Pause button not turning back into Play button on playback completion
• Fixed clicks on control buttons zooming map
• Fixed getDisplayed and event timing
• Major performance improvements
• Add waitToUpdateMap option to allow dragging the slider without updating the map until user is done

0.2.0

• Added previous/next/pause
• Change behavior of play button (will play from wherever it is rather than reset to the beginning)
• Lots of code restructuring
• Add more extensive default styling, using Sass

0.1.0

• It kinda works?