Class: tileLayer

geo. tileLayer

new geo.tileLayer(arg){geo.tileLayer}

This method defines a tileLayer, an abstract class defining a layer divided into tiles of arbitrary data. Notably, this class provides the core functionality of geo.osmLayer, but hooks exist to render tiles more generically. When multiple zoom levels are present in a given dataset, this class assumes that the space occupied by tile (i, j) at level z is covered by a 2x2 grid of tiles at zoom level z + 1:

  (2i, 2j),     (2i, 2j + 1)
  (2i + 1, 2j), (2i + 1, 2j + 1)

The higher level tile set should represent a 2x increase in resolution.

Name Type Description
arg geo.tileLayer.spec optional

Specification for the layer.

Returns:
Type Description
geo.tileLayer

Extends

Type Definitions

geo.tileLayer.specgeo.layer.spec

Object specification for a tile layer.

Properties:
Name Type Argument Default Description
minLevel number <optional>
0

The minimum zoom level available.

maxLevel number <optional>
18

The maximum zoom level available.

tileOverlap object <optional>

Pixel overlap between tiles.

Properties
Name Type Argument Description
x number <optional>

Horizontal overlap.

y number <optional>

Vertical overlap.

tileWidth number <optional>
256

The tile width without overlap.

tileHeight number <optional>
256

The tile height without overlap.

tilesAtZoom function <optional>
null

A function that is given a zoom level and returns {x: (num), y: (num)} with the number of tiles at that zoom level.

cacheSize number <optional>
400

The maximum number of tiles to cache. The default is 200 if keepLower is false.

queueSize number <optional>
6

The queue size. Most browsers make at most 6 requests to any domain, so this should be no more than 6 times the number of subdomains used.

initialQueueSize number <optional>
0

The initial queue size. 0 to use the queue size. When querying a tile server that needs to load information before serving the first time, having an initial queue size of 1 can reduce the load on the tile server. After the initial queue of tiles are loaded, the queueSize is used for all additional queries unless the initialQueueSize is set again or the tile cache is reset.

keepLower boolean <optional>
true

When truthy, keep lower zoom level tiles when showing high zoom level tiles. This uses more memory but results in smoother transitions.

wrapX boolean <optional>
true

Wrap in the x-direction.

wrapY boolean <optional>
false

Wrap in the y-direction.

url string | function <optional>
null

A function taking the current tile indices (x, y, level, subdomains) and returning a URL or jquery ajax config to be passed to the {geo.tile} constructor. Example:

  (x, y, z, subdomains) => "http://example.com/z/y/x.png"

If this is a string, a template url with {x}, {y}, {z}, and {s} as template variables. {s} picks one of the subdomains parameter and may contain a comma-separated list of subdomains.

subdomain string | list <optional>
"abc"

Subdomains to use in template url strings. If a string, this is converted to a list before being passed to a url function.

baseUrl string <optional>
null

If defined, use the old-style base url instead of the url parameter. This is functionally the same as using a url of baseUrl/{z}/{x}/{y}.(imageFormat || png). If the specified string does not end in a slash, one is added.

imageFormat string <optional>
'png'

This is only used if a baseUrl is specified, in which case it determines the image name extension used in the url.

animationDuration number <optional>
0

The number of milliseconds for the tile loading animation to occur. Only some renderers support this.

attribution string <optional>

An attribution to display with the layer (accepts HTML).

tileRounding function <optional>
Math.round

This function determines which tiles will be loaded when the map is at a non-integer zoom. For example, Math.floor, will use tile level 2 when the map is at zoom 2.9.

tileOffset function <optional>

This function takes a zoom level argument and returns, in units of pixels, the coordinates of the point (0, 0) at the given zoom level relative to the bottom left corner of the domain.

tilesMaxBounds function <optional>
null

This function takes a zoom level argument and returns an object with x and y in pixels which is used to crop the last row and column of tiles. Note that if tiles wrap, only complete tiles in the wrapping direction(s) are supported, and this max bounds will probably not behave properly.

topDown boolean <optional>
false

True if the gcs is top-down, false if bottom-up (the ingcs does not matter, only the gcs coordinate system). When falsy, this inverts the gcs y-coordinate when calculating local coordinates.

id number <optional>

The id of the layer. Defaults to a increasing sequence.

map geo.map <optional>
null

Parent map of the layer.

renderer string | geo.renderer <optional>

Renderer to associate with the layer. If not specified, either annotations or features can be used to determine the renderer. If a geo.renderer instance, the renderer is not recreated; not all renderers can be shared by multiple layers.

autoshareRenderer boolean <optional>
true

If truthy and the renderer supports it, auto-share renderers between layers. Currently, auto-sharing can only occur for webgl renderers, and will only occur between adjacent layers than have the same opacity. Shared renderers has slightly different behavior than non-shared renderers: changing z-index may result in rerendering and be slightly slower; only one DOM canvas is used for all shared renderers. Some features have slight z-stacking differences in shared versus non-shared renderers.

canvas HTMLElement <optional>

If specified, use this canvas rather than a canvas associaied with the renderer directly. Renderers may not support sharing a canvas.

annotations Array.<string> | object <optional>

A list of annotations that will be used on this layer, used to select a renderer. Instead of a list, if this is an object, the keys are the annotation names, and the values are each a list of modes that will be used with that annotation. See featuresForAnnotations more details. This is ignored if renderer is specified.

features Array.<string> <optional>

A list of features that will be used on this layer, used to select a renderer. Features are the basic feature names (e.g., 'quad'), or the feature name followed by a required capability (e.g., 'quad.image'). This is ignored if renderer or annotations is specified.

active boolean <optional>
true

Truthy if the layer has the active css class and may receive native mouse events.

opacity number <optional>
1

The layer opacity on a scale of [0-1].

name string <optional>
''

A name for the layer for user convenience. If specified, this is also the id property of the containing DOM element.

selectionAPI boolean <optional>
true

Truthy if the layer can generate selection and other interaction events.

sticky boolean <optional>
true

Truthy if the layer should navigate with the map.

visible boolean <optional>
true

Truthy if the layer is visible.

zIndex number <optional>

The z-index to assign to the layer (defaults to the index of the layer inside the map).

Static Members

staticgeo.tileLayer.defaults

This object contains the default options used to initialize the tileLayer.

Members

activeTiles

Readonly accessor to the active tile mapping. This is an object containing all currently drawn tiles (hash(tile) => tile).

Properties:
Name Type Description
activeTiles object

The keys are hash(tile) and the values are tiles.

cache

Readonly accessor to the tile cache object.

Properties:
Name Type Description
cache geo.tileCache

The tile cache object.

inherited idle

Getter for the idle state. Read only.

Properties:
Name Type Description
idle boolean

true if the object is idle (onIdle would call a handler immediately).

inherited protectednewLayerId

Gets a new id number for a layer.

options

Readonly accessor to the options object.

Properties:
Name Type Description
options object

A copy of the options object.

queueSize

Get/set the initial queue size.

Properties:
Name Type Description
size number

The initial queue size. 0 to use the queue size.

queueSize

Get/set the queue size.

Properties:
Name Type Description
size number

The queue size.

Methods

inherited active(arg){boolean|this}

Get/Set whether or not the layer is active. An active layer will receive native mouse when the layer is on top. Non-active layers will never receive native mouse events.

Name Type Description
arg boolean optional

If specified, the new active value.

Returns:
Type Description
boolean | this

inherited addChild(child){this}

Add a child (or an array of children) to the object.

Name Type Description
child geo.object | Array.<geo.object>

A child object or array of child objects.

Returns:
Type Description
this

inherited addFeature(feature){this}

Add a feature to the layer if it is not already present.

Name Type Description
feature object

the feature to add.

Returns:
Type Description
this

inherited addPromise(promise){this}

Add the promise here and also propagate up the scene tree.

Name Type Description
promise Promise

A promise object.

Returns:
Type Description
this

inherited attribution(arg){string|this}

Get or set the attribution html content that will displayed with the layer. By default, nothing will be displayed. Note, this content is not html escaped, so care should be taken when renderering user provided content.

Name Type Description
arg string nullable

An html fragment

Returns:
Type Description
string | this Chainable as a setter

inherited autoshareRenderer(){boolean}

Get the setting of autoshareRenderer.

Returns:
Type Description
boolean

inherited canvas(){HTMLCanvasElement}

Get canvas of the layer.

Returns:
Type Description
HTMLCanvasElement The canvas element associated with the layer.

Get an array of the child objects.

Returns:
Type Description
Array.<geo.object> A copy of the array of child objects.

clear(){Array.<geo.tile>}

Remove all active tiles from the canvas.

Returns:
Type Description
Array.<geo.tile> The array of tiles removed.

inherited createFeature(featureName, arg){geo.feature}

Create a feature by name.

Name Type Description
featureName string

The name of the feature to create.

arg object

Properties for the new feature.

Returns:
Type Description
geo.feature The created feature.

Return last time data got changed.

Returns:
Type Description
geo.timestamp The data time.

inherited deleteFeature(feature){this}

Delete feature.

Name Type Description
feature geo.feature

The feature to delete.

Returns:
Type Description
this

displayToLevel(pt, zoom){object}

Convert display pixel coordinates (where (0,0) is the upper left) to layer pixel coordinates (typically (0,0) is the center of the map and the upper-left has the most negative values). By default, this is done at the current base zoom level.

Name Type Description
pt object optional

The point to convert with x and y. If undefined, use the center of the display.

zoom number optional

If specified, the zoom level to use.

Returns:
Type Description
object The point in level coordinates with x and y.

Draw. If the layer is visible, call the parent class's draw function and the renderer's render function.

Returns:
Type Description
this

drawTile(tile)

Draw the given tile on the active canvas .

Name Type Description
tile geo.tile

The tile to draw.

inherited features(val){Array.<geo.feature>|this}

Get/Set drawables.

Name Type Description
val Array.<geo.feature>

A list of features, or unspecified to return the current feature list. If a list is provided, features are added or removed as needed.

Returns:
Type Description
Array.<geo.feature> | this The current features associated with the layer or the current layer.

fromLevel(coord, level){object}

Convert a coordinate from pixel coordinates at the given zoom level to world coordinates.

Name Type Description
coord object
Name Type Description
x number

The offset in pixels (level 0) from the left edge.

y number

The offset in pixels (level 0) from the bottom edge.

level number

The zoom level of the source coordinates.

Returns:
Type Description
object World coordinates with x and y.

fromLocal(pt, zoom){object}

Compute world coordinates from the given local coordinates. The tile layer uses units of pixels relative to the world space coordinate origin.

Name Type Description
pt object

A point in world space coordinates with x and y.

zoom number | undefined

If unspecified, use the map zoom.

Returns:
Type Description
object Local coordinates with x and y.

gcs(arg){string|this}

Get or set the layer gcs. This defaults to the map's gcs.

Name Type Description
arg string optional

If undefined, return the current gcs. Otherwise, a new value for the gcs. If null, use the map's gcs.

Returns:
Type Description
string | this A string used by geo.transform.

inherited gcsFeatures(val){string|this}

Get or set the gcs for all features. For features, the default is usually the map's ingcs.

Name Type Description
val string optional nullable

If undefined, return the current gcs. If null, use the map's interface gcs. Otherwise, set a new value for the gcs. When getting the current gcs, if not all features have the same gcs, undefined will be returned.

Returns:
Type Description
string | this A string used by geo.transform. If the map interface gcs is in use, that value will be returned. If the gcs is set, return the current class instance.

gcsTileBounds(indexOrTile, gcs){object}

Returns a tile's bounds in a gcs.

Name Type Description
indexOrTile object | tile

Either a tile or an object with {x, y, level}` specifying a tile.

gcs string | geo.transform | null optional

undefined to use the interface gcs, null to use the map gcs, or any other transform.

Returns:
Type Description
object The tile bounds in the specified gcs.

inherited geoIsOn(event, handler){boolean}

Report if an event handler is bound to this object.

Name Type Description
event string | Array.<string>

An event or list of events to check.

handler function optional

A function that might be bound. If undefined, this will report true if there is any handler for the specified event.

Returns:
Type Description
boolean true if any of the specified events are bound to the specified handler.

inherited geoOff(event, arg){this}

Remove handlers from one event or an array of events. If no event is provided all handlers will be removed.

Name Type Description
event string | Array.<string> optional

An event or a list of events from geo.event or defined by the user, or undefined to remove all events (in which case arg is ignored).

arg function | Array.<function()> optional nullable

A function or array of functions to remove from the events or a falsy value to remove all handlers from the events.

Returns:
Type Description
this

inherited geoOn(event, handler){this}

Bind an event handler to this object.

Name Type Description
event string

An event from geo.event or a user-defined value.

handler function

A function that is called when event is triggered. The function is passed a geo.event object.

Returns:
Type Description
this

inherited geoTrigger(event, args, childrenOnly){this}

Trigger an event (or events) on this object and call all handlers.

Name Type Description
event string

The event to trigger.

args object

Arbitrary argument to pass to the handler.

childrenOnly boolean optional

If truthy, only propagate down the tree.

Returns:
Type Description
this

inherited height(){number}

Return the height of the layer in pixels.

Returns:
Type Description
number The height of the parent map in pixels.

inherited id(val){string|this}

Get/Set id of the layer.

Name Type Description
val string | null optional

If null, generate a new layer id. Otherwise, if specified, the new id of the layer.

Returns:
Type Description
string | this

inherited initialized(val){boolean|this}

Get/Set if the layer has been initialized.

Name Type Description
val boolean optional

If specified, update the intialized value. Otherwise, return the current instance.

Returns:
Type Description
boolean | this Either the initialized value or this.

isValid(index){boolean}

Returns true if the given tile index is valid:

  • min level <= level <= max level
  • 0 <= x <= 2^level - 1
  • 0 <= y <= 2^level - 1 If the layer wraps, the x and y values may be allowed to extend beyond these values.
Name Type Description
index object

The tile index.

Name Type Description
x number
y number
level number
Returns:
Type Description
boolean

Get the map associated with this layer.

Returns:
Type Description
geo.map The map associated with the layer.

inherited modified(){this}

Update the timestamp to the next global timestamp value.

Returns:
Type Description
this

inherited moveDown(n){this}

Bring the layer below the given number of layers. This will rotate the current z-indices for this and the previous n layers.

Name Type Default Description
n number 1 optional

The number of positions to move.

Returns:
Type Description
this

inherited moveToBottom(){this}

Bring the layer to the bottom of the map layers.

Returns:
Type Description
this

inherited moveToTop(){this}

Bring the layer to the top of the map layers.

Returns:
Type Description
this

inherited moveUp(n){this}

Bring the layer above the given number of layers. This will rotate the current z-indices for this and the next n layers.

Name Type Default Description
n number 1 optional

The number of positions to move.

Returns:
Type Description
this

inherited name(val){string|this}

Get/Set name of the layer.

Name Type Description
val string optional

If specified, the new name of the layer.

Returns:
Type Description
string | this

inherited node(){div}

Get root node of the layer.

Returns:
Type Description
div

inherited onIdle(handler){this}

Bind a handler that will be called one time when all internal promises are resolved. If there are no outstanding promises, this is invoked synchronously.

Name Type Description
handler function

A function taking no arguments.

Returns:
Type Description
this

inherited opacity(opacity){number|this}

Get or set the current layer opacity. The opacity is in the range [0-1]. An opacity of 0 is not the same as setting visible(false), as interactions can still occurr with the layer.

Name Type Description
opacity number optional

If specified, set the opacity. Otherwise, return the opacity.

Returns:
Type Description
number | this The current opacity or the current layer.

Get/set parent of the object.

Name Type Description
arg geo.sceneObject optional

The new parant or undefined to get the current parent.

Returns:
Type Description
this | geo.sceneObject

prefetch(level, bounds){jQuery.Deferred}

Prefetches tiles up to a given zoom level around a given bounding box.

Name Type Description
level number

The zoom level.

bounds geo.geoBounds

The map bounds.

Returns:
Type Description
jQuery.Deferred resolves when all of the tiles are fetched.

remove(tile){geo.tile}

Remove the given tile from the canvas and the active cache.

Name Type Description
tile geo.tile | string

The tile (or hash) to remove.

Returns:
Type Description
geo.tile The tile removed from the active layer.

inherited removeChild(child){this}

Remove a child (or array of children) from the object.

Name Type Description
child geo.object | Array.<geo.object>

A child object or array of child objects.

Returns:
Type Description
this

inherited removeFeature(feature){this}

Remove a feature without destroying it.

Name Type Description
feature geo.feature

The feature to remove.

Returns:
Type Description
this

Get the renderer for the layer.

Returns:
Type Description
geo.renderer The renderer associated with the layer or null if there is no renderer.

inherited rendererName(){string}

Get the name of the renderer.

Returns:
Type Description
string

reset(){this}

Reset the layer to the initial state, clearing the canvas and resetting the tile cache.

Returns:
Type Description
this

inherited selectionAPI(val){boolean|this}

Get/Set selectionAPI of the layer.

Name Type Description
val boolean optional

If specified change the selectionAPI state of the layer, otherwise return the current state.

Returns:
Type Description
boolean | this The selectionAPI state or the current layer.

inherited sticky(){boolean}

Get whether or not the layer is sticky (navigates with the map).

Returns:
Type Description
boolean

subdomains(subdomains){string|list|this}

Get or set the subdomains used for templating.

Name Type Description
subdomains string | list optional

A comma-separated list, a string of single character subdomains, or a list.

Returns:
Type Description
string | list | this

tileAtPoint(point, level){object}

Returns the tile indices at the given point.

Name Type Description
point object

The coordinates in pixels relative to the map origin.

Name Type Description
x number
y number
level number

The target zoom level.

Returns:
Type Description
object The tile indices. This has x and y properties.

tileCropFromBounds(tile){object}

Get the crop values for a tile based on the tilesMaxBounds function. Returns undefined if the tile should not be cropped.

Name Type Description
tile object

The tile to compute crop values for.

Returns:
Type Description
object Either undefined or an object with x and y values which is the size in pixels for the tile.

tilesAtZoom(level){object}

The number of tiles at the given zoom level. The default implementation just returns Math.pow(2, z).

Name Type Description
level number

A zoom level.

Returns:
Type Description
object The number of tiles in each axis in the form {x: nx, y: ny}.

tilesMaxBounds(level){object}

The maximum tile bounds at the given zoom level, or null if no special tile bounds.

Name Type Description
level number

A zoom level.

Returns:
Type Description
object The maximum tile bounds in pixels for the specified level, or null if none specified ({x: width, y: height}).

inherited timestamp(){number}

Get time.

Returns:
Type Description
number The timestamp. This is 0 if the timestamp has never been modified.

toLevel(coord, level){object}

Convert a coordinate from layer coordinates to pixel coordinates at the given zoom level.

Name Type Description
coord object
Name Type Description
x number

The offset in pixels (level 0) from the left edge.

y number

The offset in pixels (level 0) from the bottom edge.

level number

The zoom level of the new coordinates.

Returns:
Type Description
object The pixel coordinates with x and y.

toLocal(pt, zoom){object}

Compute local coordinates from the given world coordinates. The tile layer uses units of pixels relative to the world space coordinate origin.

Name Type Description
pt object

A point in world space coordinates with x and y.

zoom number | undefined

If unspecified, use the map zoom.

Returns:
Type Description
object Local coordinates with x and y.

Return the modified time for the last update that did something.

Returns:
Type Description
geo.timestamp The update time.

url(url){string|function|this}

Get or set the tile url string or function. If changed, load the new tiles.

Name Type Description
url string | function optional

The new tile url.

Returns:
Type Description
string | function | this

visible(val){boolean|this}

Get/Set visibility of the layer.

Name Type Description
val boolean | undefined

If unspecified, return the visibility, otherwise set it.

Returns:
Type Description
boolean | this Either the visibility (if getting) or the layer (if setting).

inherited width(){number}

Return the width of the layer in pixels.

Returns:
Type Description
number The width of the parent map in pixels.

inherited zIndex(zIndex, allowDuplicate){number|this}

Get or set the z-index of the layer. The z-index controls the display order of the layers in much the same way as the CSS z-index property.

Name Type Description
zIndex number optional

The new z-index, or undefined to return the current z-index.

allowDuplicate boolean optional

When setting the z index, if this is truthy, allow other layers to have the same z-index. Otherwise, ensure that other layers have distinct z-indices from this one.

Returns:
Type Description
number | this