OpenLayers v6.1.1 API - Class: ImageCanvasSource

Class: ImageCanvasSource

ol/source/ImageCanvas~ImageCanvasSource

import ImageCanvasSource from 'ol/source/ImageCanvas';

Base class for image sources where a canvas element is the image.

new ImageCanvasSource(opt_options)

source/ImageCanvas.js, line 54

Name Type Description

options

ImageCanvas options.

Name	Type	Description
`attributions`	module:ol/source/Source~AttributionLike	Attributions.
`canvasFunction`	module:ol/source/ImageCanvas~FunctionType	Canvas function. The function returning the canvas element used by the source as an image. The arguments passed to the function are: `{module:ol/extent~Extent}` the image extent, `{number}` the image resolution, `{number}` the device pixel ratio, `{module:ol/size~Size}` the image size, and `{module:ol/proj/Projection~Projection}` the image projection. The canvas returned by this function is cached by the source. If the value returned by the function is later changed then `changed` should be called on the source for the source to invalidate the current cached image. See: `module:ol/Observable~Observable#changed`
`projection`	module:ol/proj~ProjectionLike	Projection.
`ratio`	number (defaults to 1.5)	Ratio. 1 means canvases are the size of the map viewport, 2 means twice the width and height of the map viewport, and so on. Must be `1` or higher.
`resolutions`	Array.<number>	Resolutions. If specified, new canvases will be created for these resolutions
`state`	module:ol/source/State	Source state.

Fires:

change (module:ol/events/Event~BaseEvent) - Generic change event. Triggered when the revision counter is increased.
error (module:ol/events/Event~BaseEvent) - Generic error event. Triggered when an error occurs.
imageloadend (module:ol/source/Image.ImageSourceEvent) - Triggered when an image finishes loading.
imageloaderror (module:ol/source/Image.ImageSourceEvent) - Triggered if image loading results in an error.
imageloadstart (module:ol/source/Image.ImageSourceEvent) - Triggered when an image starts loading.
propertychange (module:ol/Object.ObjectEvent) - Triggered when a property is changed.

Extends

module:ol/source/Image~ImageSource

Methods

changed() inherited Observable.js, line 36

Increases the revision counter and dispatches a 'change' event.

dispatchEvent(event){boolean|undefined} inherited events/Target.js, line 96

Dispatches an event and calls all listeners listening for events of this type. The event parameter can either be a string or an Object with a type property.

Name	Type	Description
`event`	Object \| module:ol/events/Event~BaseEvent \| string	Event object.

Returns:

false if anyone called preventDefault on the event object or if any of the listeners returned false.

get(key){*} inherited Object.js, line 119

Gets a value.

Name	Type	Description
`key`	string	Key name.

Returns:

Value.

getKeys(){Array.<string>} inherited Object.js, line 132

Get a list of object property names.

Returns:

List of property names.

getProjection(){module:ol/proj/Projection~Projection} inherited source/Source.js, line 119

Get the projection of the source.

Returns:

Projection.

getProperties(){Object.<string, *>} inherited Object.js, line 141

Get an object of all property names and values.

Returns:

Object.

getRevision(){number} inherited Observable.js, line 47

Get the version number for this object. Each time the object is modified, its version number will be incremented.

Returns:

Revision.

getState(){module:ol/source/State} inherited source/Source.js, line 136

Get the state of the source, see module:ol/source/State~State for possible states.

Returns:

State.

on(type, listener){module:ol/events~EventsKey|Array.<module:ol/events~EventsKey>} inherited Observable.js, line 60

Listen for a certain type of event.

Name	Type	Description
`type`	string \| Array.<string>	The event type or array of event types.
`listener`	function	The listener function.

Returns:

Unique key for the listener. If called with an array of event types as the first argument, the return will be an array of keys.

once(type, listener){module:ol/events~EventsKey|Array.<module:ol/events~EventsKey>} inherited Observable.js, line 82

Listen once for a certain type of event.

Name	Type	Description
`type`	string \| Array.<string>	The event type or array of event types.
`listener`	function	The listener function.

Returns:

Unique key for the listener. If called with an array of event types as the first argument, the return will be an array of keys.

refresh() inherited source/Source.js, line 151

Refreshes the source. The source will be cleared, and data from the server will be reloaded.

set(key, value, opt_silent) inherited Object.js, line 164

Sets a value.

Name	Type	Description
`key`	string	Key name.
`value`	*	Value.
`silent`	boolean	Update without triggering an event.

setAttributions(attributions) inherited source/Source.js, line 162

Set the attributions of the source.

Name	Type	Description
`attributions`	module:ol/source/Source~AttributionLike \| undefined	Attributions. Can be passed as `string`, `Array<string>`, `module:ol/source/Source~Attribution`, or `undefined`.

setProperties(values, opt_silent) inherited Object.js, line 183

Sets a collection of key-value pairs. Note that this changes any existing properties and adds new ones (it does not remove any existing properties).

Name	Type	Description
`values`	Object.<string, *>	Values.
`silent`	boolean	Update without triggering an event.

un(type, listener) inherited Observable.js, line 101

Unlisten for a certain type of event.

Name	Type	Description
`type`	string \| Array.<string>	The event type or array of event types.
`listener`	function	The listener function.

unset(key, opt_silent) inherited Object.js, line 195

Unsets a property.

Name	Type	Description
`key`	string	Key name.
`silent`	boolean	Unset without triggering an event.