openlayers/doc/ol3.md

CLASS HIERARCHY

goog.math.Coordinate  // Simple 2D point


goog.math.Coordinate3
|
+- TileCoord

goog.math.Box
|
+- TileBounds  // A range of tiles in two dimensions, integer coordinates, z not stored
|
+- Extent  // The extent of a single object in two dimensions, projection not stored
|
+- Bounds  // A range of objects in two dimensions


Projection


goog.events.EventTarget
|
+- MVCObject
|  |
|  +- Camera
|  |
|  +- Control
|  |  |
|  |  +- ?
|  |
|  +- Layer
|  |  |
|  |  +- TileLayer
|  |  |  |
|  |  |  +- TMSTileLayer
|  |  |  |
|  |  |  +- WMTSTileLayer
|  |  |  |
|  |  |  +- XYZTileLayer / OSMTileLayer
|  |  |
|  |  +- VectorLayer
|  |  |
|  |  +- ImageLayer
|  |
|  +- LayerRenderer
|  |
|  +- LayerView
|  |
|  +- Map
|  |
|  +- MapRenderer
|  |  |
|  |  +- HTMLMapRenderer
|  |  |
|  |  +- WebGLMapRenderer
|  |
|  +- MVCArray
|  |  |
|  |  +- ControlArray
|  |  |
|  |  +- LayerViewArray
|
|  +- TileQueue
|
+- Tile

Layer renderer hierarchy

goog.events.EventTarget
|
+- MVCObject
   |
   +- LayerRenderer
      |
      +- SingleTileLayerRenderer
      |  |
      |  +- HTMLSingleTileLayerRenderer
      |  |
      |  +- WebGLSingleTileLayerRenderer
      |
      +- TileLayerRenderer
      |  |
      |  +- HTMLTileLayerRenderer
      |  |
      |  +- WebGLTileLayerRenderer
      |
      +- VectorLayerRenderer
      |  |
      |  +- HTMLVectorLayerRenderer
      |  |  |
      |  |  +- SVGHTMLVectorLayerRenderer
      |  |  |
      |  |  +- Canvas2DHTMLVectorLayerRenderer
      |  |  |
      |  |  +- VMLHTMLVectorLayerRenderer
      |  |
      |  +- WebGLVectorLayerRenderer

OBJECT PROPERTIES AND METHODS

Notation:

• property type property with type, trailing ? indicates unsure, getters and setters are assumed to exist.
• f(args) -> type function taking args returning type.
• f(args) -> type = something f is a trivial wrapper around something.
• fires 'x' fires events of type 'x'.

Principles:

• All non-trivial objects inherit from MVCObject.
• All non-trivial collections are either MVCArrays or a child class thereof.
• Resolutions are Array.<number>, infinitely scalable resources (e.g. vectore layers) have resolutions == null.

MVCObject
  as Google Maps MVCObject
  freeze()
  unfreeze()

TileCoord
  getHash() -> number

Tile
  tileCoord TileCoord
  url string
  state UNLOADED | LOADING | LOADED
  fires 'loaded' // when loaded
  fires 'aborted'  // when loading is aborted

Camera
   center goog.math.Coordinate
   resolution number
   rotation number

Layer
   projections Array.<Projection>
   extent Extent ?
   getResolutions() -> Array.<number>|null
   fires 'change' // when data changes

LayerArray
   getResolutions() -> Array.<number>|null
   getMaxResolution() = this.getResolutions()[0] | null

LayerView
   layer Layer
   visible boolean
   opacity number
   brightness number
   color number
   hue number
   saturation number

Map
   projection Projection
   renderer Renderer
   layers LayerArray
   addLayer(layer) = layers.push(layer)
   getExtent() -> Extent
   getMaxResolution() = layers.getMaxResolution()

TileGrid
   resolutions Array.<number>
   extent Extent
   corner TOP_LEFT | BOTTOM_LEFT
   origin(s) Coord|Array.<Coord>
   tileSize goog.math.Size
   getTileBounds(z, extent) -> TileBounds
   getTileCoordCenter(tileCoord) -> goog.math.Coordinate
   getTileCoord(coordinate) -> TileCoord
   getTileCoordExtent(tileCoord) -> Extent
   getZForResolution(resolution) -> number
   yieldTileCoordChildren(tileCoord, function(z, TileBounds))
   yieldTileCoordParents(tileCoord, function(z, TileBounds))

TileLayer
   tileGrid TileGrid
   tileUrl function(tileCoord) -> string
   getTileCoordUrl(tileCoord) -> string = this.tileUrl(tileCoord)

TileQueue
   camera Camera  // or maybe MVCArray.<Camera> ?
   getTileCoordPriority(tileCoord) -> number  // private
   enqueueTile(Tile)

VectorLayer
   yieldFeatures(resolution, extent, projection, function(Feature))

Renderer
   target HTMLDivElement
   map Map
   camera Camera
   getCapabilities() -> Array.<string>  // maybe ?

Questions:

• Store tile layer extent in TileLayer or in TileGrid? (not clear)
• Who determines "best" resolution? (static function?)

Todo: if tile layer extent stored in TileLayer rather than TileGrid then extent will occasionally need to be passed to TileGrid functions for cropping.

DESIGN ASSERTIONS

Map

• A map has a renderer (the map renderer).
• A map has a camera.
• Multiple maps can share the same camera.
• A map has a layer list.

Layer

• A layer can have multiple projections (the supported projections).
• A layer advertizes the projections it supports.
• A layer returns no data if asked data for an unsupported projection.

LayerView

• A layer view stores view-related states for a layer.
• View-related states include visibility, opacity, saturation, hue, etc.
• A layer view has a layer.
• Multiple layer views can share the same layer.
• In other words a layer can be viewed in different manners.

Renderer

• The map renderer responds to events.
• The map renderer receives events from the camera.
• The map renderer creates layer renderers.

Control

• A control may listen to map events.
• A control may listen to camera events.
• A map navigation control acts on the camera.

MVC

• Types can be described in MVC terms.
• Models don't know what rendering means.
• Maps are models.
• Layers are models.
• Layer views are models (sorry!).
• Cameras are models.
• Layer lists are collections.
• Renderers are views.
• Controls are views or controllers or both.
• An attribution control is a view.
• A map navigation control is a controller.
• A zoom slider control is both a view and a controller.