leaflet

@allmaps/leaflet

Allmaps plugin for Leaflet. This plugin allows displaying georeferenced IIIF images on a Leaflet map. The plugin works by loading Georeference Annotations and uses WebGL to transform images from a IIIF image server to overlay them on their correct geographical position. See allmaps.org for more information.

The development of the Allmaps plugin for Leaflet was funded by CLARIAH-VL.

Examples:

• Observable notebook
• HTML example using ESM and Skypack
• HTML example using UMD and jsDelivr

How it works

This plugin exports the class WarpedMapLayer that extends L.Layer. You can add one or multiple Georeference Annotations (or AnnotationPages that contain multiple Georeference Annotations) to a WarpedMapLayer, and add the WarpedMapLayer to your Leaflet map. This will render all georeferenced maps defined by the Georeference Annotations.

To understand what happens under the hood for each georeferenced map, see the @allmaps/render package.

Installation

This package works in browsers and in Node.js as an ESM or an UMD module.

Install with pnpm:

npm install @allmaps/leaflet

You can optionally build this package locally by running:

pnpm run build

As an alternative to loading using import, ESM and UMD bundled versions of the code are also provided under /dist/bundled (once the code is built). These are also published online, so can load them directly in a HTML script tag using a CDN. They require Leaflet to be loaded as L, so place them after loading Leaflet.

<script src="https://cdn.jsdelivr.net/npm/@allmaps/leaflet/dist/bundled/allmaps-leaflet-1.9.umd.js"></script>

When loading the bundled package, its classes are available under the Allmaps global variable:

const warpedMapLayer = new Allmaps.WarpedMapLayer(annotationUrl)

Usage

Built for Leaflet 1.9, but should work with earlier versions as well.

Loading a Georeference Annotation

Creating a WarpedMapLayer and adding it to a map looks like this:

import { WarpedMapLayer } from '@allmaps/leaflet'

const map = L.map('map', {
  center: [51.0518, 3.7278],
  zoom: 14,
  // Zoom animations for more than one zoom level are
  // currently not supported by the Allmaps plugin for Leafet
  zoomAnimationThreshold: 1
})
L.tileLayer('https://tile.openstreetmap.org/{z}/{x}/{y}.png', {
  attribution:
    '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors'
}).addTo(map)

const annotationUrl =
  'https://annotations.allmaps.org/manifests/8f9faeba73d67031'
const warpedMapLayer = new WarpedMapLayer(annotationUrl).addTo(map)

When adding this WarpedMapLayer to the Leaflet map, the georeferenced map specified in the Georeference Annotation will be rendered on the Leaflet map.

Specifying a the URL Georeference Annotation when creating a WarpedMapLayer (as is done above) is optional. A Georeference Annotation can also be added at a later stage using the addGeoreferenceAnnotation and addGeoreferenceAnnotationByUrl functions:

fetch(annotationUrl)
  .then((response) => response.json())
  .then((annotation) => warpedMapLayer.addGeoreferenceAnnotation(annotation))

Or:

await warpedMapLayer.addGeoreferenceAnnotationByUrl(annotationUrl)

Events

The following events are emitted to inform you of the state of the WarpedMapLayer.

Description	Type	Data
A warped map has been added to the warped map list	warpedmapadded	mapId: string
A warped map has been removed from the warped map list	warpedmapremoved	mapId: string
A warped map enters the viewport	warpedmapenter	mapId: string
A warped map leaves the viewport	warpedmapleave	mapId: string
The visibility of some warped maps has changed	visibilitychanged	mapIds: string[]
The cache loaded a first tile of a map	firstmaptileloaded	{mapId: string, tileUrl: string}
All tiles requested for the current viewport have been loaded	allrequestedtilesloaded

You can listen to them in the typical Leaflet way. Here's an example:

map.on('warpedmapadded', (event) => {
  console.log(event.mapId, WarpedMapLayer.getBounds())
})

Some of the functions specified in the API only make sense once a warped map is loaded into the WarpedMapLayer. You can use such listeners to make sure function are run e.g. only after a warped map has been added.

What is a map?

A Leaflet map is an instance of the Leaflet Map class, the central class of the Leaflet API, used to create a map on a page and manipulate it.

In Allmaps there are multiple classes describing maps, one for each phase a map takes through the Allmaps rendering pipeline:

• When a Georeference Annotation is parsed, an instance of the GeoreferencedMap class is created from it.
• When this map is loaded into an application for rendering, an instance of the WarpedMap class is created from it.
• Inside the WebGL2 rendering package, the WebGL2WarpedMap class is used to render the map.

All these map phases originate from the same Georeference Annotation have the same unique mapId property. This string value is used thoughout Allmaps (and in the API below) to identify a map. It is returned after adding a georeference annotation to a WarpedMapLayer, so you can use it later to call functions on a specific map.

API

LeafletWarpedMapLayerOptions

Type

WarpedMapListOptions & WarpedMapOptions & { imageInformations: ImageInformations; fetchFn: FetchFn; } & { opacity: number; ... 4 more ...; imageInformations?: ImageInformations; }

new WarpedMapEvent(type, data)

Parameters

• type (WarpedMapEventType)
• data? (unknown)

Returns

WarpedMapEvent.

Extends

• Event

WarpedMapEvent#data?

Type

unknown

new WarpedMapLayer(annotationOrAnnotationUrl, options)

Creates a WarpedMapLayer

Parameters

• annotationOrAnnotationUrl (unknown)
  • Georeference Annotation or URL of a Georeference Annotation
• options? (Partial<LeafletWarpedMapLayerOptions> | undefined)
  • Options for the layer

Returns

WarpedMapLayer.

Extends

• Layer

WarpedMapLayer#_addEventListeners()

Parameters

There are no parameters.

Returns

void.

WarpedMapLayer#_animateZoom(e)

Parameters

• e (ZoomAnimEvent)

Returns

void.

WarpedMapLayer#_annotationOrAnnotationUrl

Type

unknown

WarpedMapLayer#_contextLost(event)

Parameters

• event (Event)

Returns

void.

WarpedMapLayer#_contextRestored(event)

Parameters

• event (Event)

Returns

void.

WarpedMapLayer#_initGl()

Parameters

There are no parameters.

Returns

void.

WarpedMapLayer#_passWarpedMapEvent(event)

Parameters

• event (Event)

Returns

void.

WarpedMapLayer#_removeEventListeners()

Parameters

There are no parameters.

Returns

void.

WarpedMapLayer#_resized(entries)

Parameters

• entries (Array<ResizeObserverEntry>)

Returns

void.

WarpedMapLayer#_unload()

Parameters

There are no parameters.

Returns

void.

WarpedMapLayer#_update()

Parameters

There are no parameters.

Returns

HTMLDivElement | undefined.

WarpedMapLayer#_updateZIndex()

Parameters

There are no parameters.

Returns

void.

WarpedMapLayer#addGeoreferenceAnnotation(annotation)

Adds a Georeference Annotation.

Parameters

• annotation (unknown)
  • Georeference Annotation

Returns

Promise<Array<string | Error>>.

• the map IDs of the maps that were added, or an error per map

WarpedMapLayer#addGeoreferenceAnnotationByUrl(annotationUrl)

Adds a Georeference Annotation by URL.

Parameters

• annotationUrl (string)
  • Georeference Annotation

Returns

The map IDs of the maps that were added, or an error per map (Promise<Array<string | Error>>).

WarpedMapLayer#addGeoreferencedMap(georeferencedMap)

Adds a Georeferenced map.

Parameters

• georeferencedMap (unknown)
  • Georeferenced map

Returns

The map ID of the map that was added, or an error (Promise<string | Error>).

WarpedMapLayer#bringMapsForward(mapIds)

Bring maps forward

Parameters

• mapIds (Iterable<string>)
  • IDs of the maps

Returns

void.

WarpedMapLayer#bringMapsToFront(mapIds)

Bring maps to front

Parameters

• mapIds (Iterable<string>)
  • IDs of the maps

Returns

void.

WarpedMapLayer#bringToBack()

Brings the layer to the back of other overlays (in the same map pane).

Parameters

There are no parameters.

Returns

this.

WarpedMapLayer#bringToFront()

Brings the layer in front of other overlays (in the same map pane).

Parameters

There are no parameters.

Returns

this.

WarpedMapLayer#canvas

Type

HTMLCanvasElement | undefined

WarpedMapLayer#clear()

Removes all warped maps from the layer

Parameters

There are no parameters.

Returns

this.

WarpedMapLayer#container

Type

HTMLDivElement | undefined

WarpedMapLayer#getBounds()

Returns the bounds of all visible maps (inside or outside of the Viewport), in latitude/longitude coordinates.

Parameters

There are no parameters.

Returns

Array<Array<number>> | undefined.

• L.LatLngBounds in array form of all visible maps

WarpedMapLayer#getCanvas()

Gets the HTML canvas element of the layer

Parameters

There are no parameters.

Returns

HTML Canvas Element (HTMLCanvasElement | undefined).

WarpedMapLayer#getContainer()

Gets the HTML container element of the layer

Parameters

There are no parameters.

Returns

HTML Div Element (HTMLDivElement | undefined).

WarpedMapLayer#getMapOpacity(mapId)

Gets the opacity of a single map

Parameters

• mapId (string)
  • ID of the map

Returns

opacity of the map (number | undefined).

WarpedMapLayer#getMapZIndex(mapId)

Returns the z-index of a single map

Parameters

• mapId (string)
  • ID of the map

Returns

number | undefined.

• z-index of the map

WarpedMapLayer#getOpacity()

Gets the opacity of the layer

Parameters

There are no parameters.

Returns

Layer opacity (number).

WarpedMapLayer#getPaneName()

Gets the pane name the layer is attached to. Defaults to 'tilePane'

Parameters

There are no parameters.

Returns

Pane name (string).

WarpedMapLayer#getWarpedMap(mapId)

Returns a single map's warped map

Parameters

• mapId (string)
  • ID of the map

Returns

the warped map (WebGL2WarpedMap | undefined).

WarpedMapLayer#getWarpedMapList()

Returns the WarpedMapList object that contains a list of the warped maps of all loaded maps

Parameters

There are no parameters.

Returns

WarpedMapList<WebGL2WarpedMap>.

WarpedMapLayer#getZIndex()

Gets the z-index of the layer.

Parameters

There are no parameters.

Returns

number | undefined.

WarpedMapLayer#gl

Type

WebGL2RenderingContext | null | undefined

WarpedMapLayer#hideMap(mapId)

Make a single map invisible

Parameters

• mapId (string)
  • ID of the map

Returns

void.

WarpedMapLayer#hideMaps(mapIds)

Make multiple maps invisible

Parameters

• mapIds (Iterable<string>)
  • IDs of the maps

Returns

void.

WarpedMapLayer#initialize(annotationOrAnnotationUrl, options)

Parameters

• annotationOrAnnotationUrl (unknown)
• options? (Partial<LeafletWarpedMapLayerOptions> | undefined)

Returns

void.

WarpedMapLayer#isMapVisible(mapId)

Returns the visibility of a single map

Parameters

• mapId (string)

Returns

boolean | undefined.

• whether the map is visible

WarpedMapLayer#onAdd(map)

Contains all code code that creates DOM elements for the layer and adds them to map panes where they belong.

Parameters

• map (Map)

Returns

this.

WarpedMapLayer#onRemove(map)

Contains all cleanup code that removes the layer's elements from the DOM.

Parameters

• map (Map)

Returns

this.

WarpedMapLayer#options

Fields

• className (string)
• interactive (false)
• opacity (number)
• pane (string)
• zIndex (number)

WarpedMapLayer#removeGeoreferenceAnnotation(annotation)

Removes a Georeference Annotation.

Parameters

• annotation (unknown)
  • Georeference Annotation

Returns

Promise<Array<string | Error>>.

• the map IDs of the maps that were removed, or an error per map

WarpedMapLayer#removeGeoreferenceAnnotationByUrl(annotationUrl)

Removes a Georeference Annotation by URL.

Parameters

• annotationUrl (string)
  • Georeference Annotation

Returns

The map IDs of the maps that were removed, or an error per map (Promise<Array<string | Error>>).

WarpedMapLayer#removeGeoreferencedMap(georeferencedMap)

Removes a Georeferenced map.

Parameters

• georeferencedMap (unknown)
  • Georeferenced map

Returns

The map ID of the map that was removed, or an error (Promise<string | Error>).

WarpedMapLayer#renderer

Type

WebGL2Renderer | undefined

WarpedMapLayer#resetColorize()

Resets the colorization for all maps

Parameters

There are no parameters.

Returns

this.

WarpedMapLayer#resetMapColorize(mapId)

Resets the colorization of a single map

Parameters

• mapId (string)
  • ID of the map

Returns

this.

WarpedMapLayer#resetMapOpacity(mapId)

Resets the opacity of a single map to 1

Parameters

• mapId (string)
  • ID of the map

Returns

this.

WarpedMapLayer#resetMapRemoveColor(mapId)

Resets the color removal for a single map

Parameters

• mapId (string)
  • ID of the map

Returns

this.

WarpedMapLayer#resetMapSaturation(mapId)

Resets the saturation of a single map to the original colors

Parameters

• mapId (string)
  • ID of the map

Returns

this.

WarpedMapLayer#resetOpacity()

Resets the opacity of the layer to fully opaque

Parameters

There are no parameters.

Returns

this.

WarpedMapLayer#resetRemoveColor()

Resets the color removal for all maps

Parameters

There are no parameters.

Returns

this.

WarpedMapLayer#resetSaturation()

Resets the saturation of a single map to the original colors

Parameters

There are no parameters.

Returns

this.

WarpedMapLayer#resizeObserver

Type

ResizeObserver | undefined

WarpedMapLayer#sendMapsBackward(mapIds)

Send maps backward

Parameters

• mapIds (Iterable<string>)
  • IDs of the maps

Returns

void.

WarpedMapLayer#sendMapsToBack(mapIds)

Send maps to back

Parameters

• mapIds (Array<string>)
  • IDs of the maps

Returns

void.

WarpedMapLayer#setColorize(hexColor)

Sets the colorization for all maps

Parameters

• hexColor (string)
  • desired hex color

Returns

this.

WarpedMapLayer#setImageInformations(imageInformations)

Sets the object that caches image information

Parameters

• imageInformations (globalThis.Map<string, unknown>)
  • Object that caches image information

Returns

void.

WarpedMapLayer#setMapColorize(mapId, hexColor)

Sets the colorization for a single map

Parameters

• mapId (string)
  • ID of the map
• hexColor (string)
  • desired hex color

Returns

this.

WarpedMapLayer#setMapOpacity(mapId, opacity)

Sets the opacity of a single map

Parameters

• mapId (string)
  • ID of the map
• opacity (number)
  • opacity between 0 and 1, where 0 is fully transparent and 1 is fully opaque

Returns

this.

WarpedMapLayer#setMapRemoveColor(mapId, options)

Removes a color from a single map

Parameters

• mapId (string)
  • ID of the map
• options ({ hexColor?: string | undefined threshold?: number | undefined hardness?: number | undefined })
  • remove color options

Returns

this.

WarpedMapLayer#setMapResourceMask(mapId, resourceMask)

Sets the resource mask of a single map

Parameters

• mapId (string)
  • ID of the map
• resourceMask (Array<Point>)
  • new resource mask

Returns

void.

WarpedMapLayer#setMapSaturation(mapId, saturation)

Sets the saturation of a single map

Parameters

• mapId (string)
  • ID of the map
• saturation (number)
  • saturation between 0 and 1, where 0 is grayscale and 1 are the original colors

Returns

this.

WarpedMapLayer#setMapsDistortionMeasure(mapIds, distortionMeasure)

Sets the distortion measure of multiple maps

Parameters

• mapIds (Iterable<string>)
  • IDs of the maps
• distortionMeasure? (DistortionMeasure | undefined)
  • new transformation type

Returns

void.

WarpedMapLayer#setMapsTransformationType(mapIds, transformation)

Sets the transformation type of multiple maps

Parameters

• mapIds (Iterable<string>)
  • IDs of the maps
• transformation ( | 'straight' | 'helmert' | 'polynomial' | 'polynomial1' | 'polynomial2' | 'polynomial3' | 'projective' | 'thinPlateSpline')
  • new transformation type

Returns

void.

WarpedMapLayer#setOpacity(opacity)

Sets the opacity of the layer

Parameters

• opacity (number)
  • Layer opacity

Returns

this.

WarpedMapLayer#setRemoveColor(options)

Removes a color from all maps

Parameters

• options ({ hexColor?: string | undefined threshold?: number | undefined hardness?: number | undefined })
  • remove color options

Returns

this.

WarpedMapLayer#setSaturation(saturation)

Sets the saturation of a single map

Parameters

• saturation (number)
  • saturation between 0 and 1, where 0 is grayscale and 1 are the original colors

Returns

this.

WarpedMapLayer#setZIndex(value)

Changes the z-index of the layer.

Parameters

• value (number)
  • z-index

Returns

this.

WarpedMapLayer#showMap(mapId)

Make a single map visible

Parameters

• mapId (string)
  • ID of the map

Returns

void.

WarpedMapLayer#showMaps(mapIds)

Make multiple maps visible

Parameters

• mapIds (Iterable<string>)
  • IDs of the maps

Returns

void.