OpenLayers v4.0.1 API - Namespace: ol

# Namespace: ol

This documentation is for OpenLayers v4.0.1. The latest is v.

## ol

### Classes

AssertionError
Attribution
Collection
DeviceOrientation
Disposable
Feature
Geolocation
Graticule
Image
ImageBase
ImageTile
Kinetic
Map
MapBrowserEvent
MapEvent
Object
Observable
Overlay
Sphere
Tile
VectorTile
View

### Namespaces

color
colorlike
control
coordinate
easing
events
extent
featureloader
format
geom
has
interaction
layer
loadingstrategy
proj
render
renderer
source
style
tilegrid

### Methods

#### ol.inherits(childCtor, parentCtor)

src/ol/index.js, line 221

  Inherit the prototype methods from one constructor into another.

  Usage:

      function ParentClass(a, b) { }
      ParentClass.prototype.foo = function(a) { }

      function ChildClass(a, b, c) {
        // Call parent constructor
        ParentClass.call(this, a, b);
      }
      ol.inherits(ChildClass, ParentClass);

      var child = new ChildClass('a', 'b', 'see');
      child.foo(); // This works.

  Name | Type | Description
  --- | --- | ---
  `childCtor` | function | Child constructor.
  `parentCtor` | function | Parent constructor.

### Type Definitions

#### ol.AttributionLike{string} {Array.<string>} {ol.Attribution} {Array.<ol.Attribution>}

  A type that can be used to provide attribution information for data sources.

  It represents either

  - a simple string (e.g. `'© Acme Inc.'`),
  - an array of simple strings (e.g. `['© Acme Inc.', '© Bacme Inc.']`),
  - an instance of ``ol.Attribution``,
  - or an array with multiple ``ol.Attribution`` instances.

#### ol.CanvasFunctionType()

src/ol/typedefs.js, line 76

  A function returning the canvas element (`{HTMLCanvasElement}`) used by the source as an image. The arguments passed to the function are: `ol.Extent` the image extent, `{number}` the image resolution, `{number}` the device pixel ratio, `ol.Size` the image size, and `ol.proj.Projection` the image projection. The canvas returned by this function is cached by the source. The this keyword inside the function references the `ol.source.ImageCanvas`.

#### ol.Color{Array.<number>}

  A color represented as a short array [red, green, blue, alpha]. red, green, and blue should be integers in the range 0..255 inclusive. alpha should be a float in the range 0..1 inclusive. If no alpha value is given then `1` will be used.

#### ol.ColorLike{string} {CanvasPattern} {CanvasGradient}

  A type accepted by CanvasRenderingContext2D.fillStyle or CanvasRenderingContext2D.strokeStyle. Represents a color, pattern, or gradient. The origin for patterns and gradients as fill style is the top-left corner of the extent of the geometry being filled.

#### ol.Coordinate{Array.<number>}

  An array of numbers representing an xy coordinate. Example: `[16, 48]`.

#### ol.CoordinateFormatType()

src/ol/typedefs.js, line 146

  A function that takes a `ol.Coordinate` and transforms it into a `{string}`.

#### ol.DragBoxEndConditionType()

src/ol/typedefs.js, line 155

  A function that takes a `ol.MapBrowserEvent` and two `ol.Pixel`s and returns a `{boolean}`. If the condition is met, true should be returned.

#### ol.DrawGeometryFunctionType()

src/ol/typedefs.js, line 167

  Function that takes coordinates and an optional existing geometry as arguments, and returns a geometry. The optional existing geometry is the geometry that is returned when the function is called without a second argument.

#### ol.EventsConditionType()

src/ol/typedefs.js, line 176

  A function that takes an `ol.MapBrowserEvent` and returns a `{boolean}`. If the condition is met, true should be returned.

#### ol.EventsKey{Object}

  Key to use with `ol.Observable#unByKey`.

#### ol.Extent{Array.<number>}

  An array of numbers representing an extent: `[minx, miny, maxx, maxy]`.

#### ol.FeatureLoader()

src/ol/typedefs.js, line 229

  `ol.source.Vector` sources use a function of this type to load features.

  This function takes an `ol.Extent` representing the area to be loaded, a `{number}` representing the resolution (map units per pixel) and an `ol.proj.Projection` for the projection as arguments. `this` within the function is bound to the `ol.source.Vector` it's called from.

  The function is responsible for loading the features and adding them to the source.

#### ol.FeatureStyleFunction()

src/ol/typedefs.js, line 240

  A function that returns an array of `styles` given a resolution. The `this` keyword inside the function references the `ol.Feature` to be styled.

#### ol.FeatureUrlFunction()

src/ol/typedefs.js, line 253

  `ol.source.Vector` sources use a function of this type to get the url to load features from.

  This function takes an `ol.Extent` representing the area to be loaded, a `{number}` representing the resolution (map units per pixel) and an `ol.proj.Projection` for the projection as arguments and returns a `{string}` representing the URL.

#### ol.ImageLoadFunctionType()

src/ol/typedefs.js, line 283

  A function that takes an `ol.Image` for the image and a `{string}` for the src as arguments. It is supposed to make it so the underlying image `ol.Image#getImage` is assigned the content specified by the src. If not specified, the default is

      function(image, src) {
        image.getImage().src = src;
      }

  Providing a custom `imageLoadFunction` can be useful to load images with post requests or - in general - through XHR requests, where the src of the image element would be set to a data URI when the content is loaded.

#### ol.LoadingStrategy()

src/ol/typedefs.js, line 335

  A function that takes an `ol.Extent` and a resolution as arguments, and returns an array of `ol.Extent` with the extents to load. Usually this is one of the standard `ol.loadingstrategy` strategies.

#### ol.OverlayPositioning{string}

  Overlay position: `'bottom-left'`, `'bottom-center'`, `'bottom-right'`, `'center-left'`, `'center-center'`, `'center-right'`, `'top-left'`, `'top-center'`, `'top-right'`

#### ol.Pixel{Array.<number>}

  An array with two elements, representing a pixel. The first element is the x-coordinate, the second the y-coordinate of the pixel.

#### ol.ProjectionLike{ol.proj.Projection} {string} {undefined}

  A projection as `ol.proj.Projection`, SRS identifier string or undefined.

#### ol.RasterOperation()

src/ol/typedefs.js, line 428

  A function that takes an array of input data, performs some operation, and returns an array of ouput data. For `pixel` type operations, the function will be called with an array of pixels, where each pixel is an array of four numbers (`[r, g, b, a]`) in the range of 0 - 255. It should return a single pixel array. For `'image'` type operations, functions will be called with an array of `https://developer.mozilla.org/en-US/docs/Web/API/ImageData` and should return a single `https://developer.mozilla.org/en-US/docs/Web/API/ImageData`. The operations are called with a second "data" argument, which can be used for storage. The data object is accessible from raster events, where it can be initialized in "beforeoperations" and accessed again in "afteroperations".

#### ol.SelectFilterFunction()

src/ol/typedefs.js, line 485

  A function that takes an `ol.Feature` or `ol.render.Feature` and an `ol.layer.Layer` and returns `true` if the feature may be selected or `false` otherwise.

#### ol.Size{Array.<number>}

  An array of numbers representing a size: `[width, height]`.

#### ol.StyleFunction()

src/ol/typedefs.js, line 585

  A function that takes an `ol.Feature` and a `{number}` representing the view's resolution. The function should return a `ol.style.Style` or an array of them. This way e.g. a vector layer can be styled.

#### ol.StyleGeometryFunction()

src/ol/typedefs.js, line 595

  A function that takes an `ol.Feature` as argument and returns an `ol.geom.Geometry` that will be rendered and styled for the feature.

#### ol.TileCoord{Array.<number>}

  An array of three numbers representing the location of a tile in a tile grid. The order is `z`, `x`, and `y`. `z` is the zoom level.

#### ol.TileLoadFunctionType()

src/ol/typedefs.js, line 622

  A function that takes an `ol.Tile` for the tile and a `{string}` for the url as arguments.

#### ol.TileUrlFunctionType()

src/ol/typedefs.js, line 655

  `ol.source.Tile` sources use a function of this type to get the url that provides a tile for a given tile coordinate.

  This function takes an `ol.TileCoord` for the tile coordinate, a `{number}` representing the pixel ratio and an `ol.proj.Projection` for the projection as arguments and returns a `{string}` representing the tile URL, or undefined if no tile should be requested for the passed tile coordinate.

#### ol.TransformFunction()

src/ol/typedefs.js, line 666

  A transform function accepts an array of input coordinate values, an optional output array, and an optional dimension (default should be 2). The function transforms the input coordinate values, populates the output array, and returns the output array.

#### ol.WFSFeatureCollectionMetadata{Object}

  Number of features; bounds/extent.

#### ol.WFSTransactionResponse{Object}

  Total deleted; total inserted; total updated; array of insert ids.