ImageryProvider

Members

defaultAlpha :Number

The default alpha blending value of this provider, usually from 0.0 to 1.0. This can either be a simple number or a function with the signature function(frameState, layer, x, y, level). The function is passed the current FrameState, the layer, and the x, y, and level coordinates of the imagery tile for which the alpha is required, and it is expected to return the alpha value to use for the tile. The function is executed for every frame and for every tile, so it must be fast.

Default Value:

• undefined

defaultBrightness :Number

The default brightness of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 makes the imagery darker while greater than 1.0 makes it brighter. This can either be a simple number or a function with the signature function(frameState, layer, x, y, level). The function is passed the current FrameState, the layer, and the x, y, and level coordinates of the imagery tile for which the brightness is required, and it is expected to return the brightness value to use for the tile. The function is executed for every frame and for every tile, so it must be fast.

Default Value:

• undefined

defaultContrast :Number

The default contrast of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the contrast while greater than 1.0 increases it. This can either be a simple number or a function with the signature function(frameState, layer, x, y, level). The function is passed the current FrameState, the layer, and the x, y, and level coordinates of the imagery tile for which the contrast is required, and it is expected to return the contrast value to use for the tile. The function is executed for every frame and for every tile, so it must be fast.

Default Value:

• undefined

defaultGamma :Number

The default gamma correction to apply to this provider. 1.0 uses the unmodified imagery color. This can either be a simple number or a function with the signature function(frameState, layer, x, y, level). The function is passed the current FrameState, the layer, and the x, y, and level coordinates of the imagery tile for which the gamma is required, and it is expected to return the gamma value to use for the tile. The function is executed for every frame and for every tile, so it must be fast.

Default Value:

• undefined

defaultHue :Number

The default hue of this provider in radians. 0.0 uses the unmodified imagery color. This can either be a simple number or a function with the signature function(frameState, layer, x, y, level). The function is passed the current FrameState, the layer, and the x, y, and level coordinates of the imagery tile for which the hue is required, and it is expected to return the hue value to use for the tile. The function is executed for every frame and for every tile, so it must be fast.

Default Value:

• undefined

defaultSaturation :Number

The default saturation of this provider. 1.0 uses the unmodified imagery color. Less than 1.0 reduces the saturation while greater than 1.0 increases it. This can either be a simple number or a function with the signature function(frameState, layer, x, y, level). The function is passed the current FrameState, the layer, and the x, y, and level coordinates of the imagery tile for which the saturation is required, and it is expected to return the saturation value to use for the tile. The function is executed for every frame and for every tile, so it must be fast.

Default Value:

• undefined

Methods

getErrorEvent

Gets an event that is raised when the imagery provider encounters an asynchronous error. By subscribing to the event, you will be notified of the error and can potentially recover from it. Event listeners are passed an instance of TileProviderError.

Returns:

Event The event.

getLogo

Gets the logo to display when this imagery provider is active. Typically this is used to credit the source of the imagery. This function should not be called before ImageryProvider#isReady returns true.

Throws:

DeveloperError : getLogo must not be called before the imagery provider is ready.

Returns:

Image | Canvas A canvas or image containing the log to display, or undefined if there is no logo.

getProxy

Gets the proxy used by this provider.

Returns:

Proxy The proxy.

See:

• DefaultProxy

getTileDiscardPolicy

Gets the tile discard policy. If not undefined, the discard policy is responsible for filtering out "missing" tiles via its shouldDiscardImage function. If this function returns undefined, no tiles are filtered. This function should not be called before ImageryProvider#isReady returns true.

Throws:

DeveloperError : getTileDiscardPolicy must not be called before the imagery provider is ready.

Returns:

TileDiscardPolicy The discard policy.

See:

• DiscardMissingTileImagePolicy
• NeverTileDiscardPolicy

requestImage

Requests the image for a given tile. This function should not be called before ImageryProvider#isReady returns true.

Parameters:

Name	Type	Description
x	Number	The tile X coordinate.
y	Number	The tile Y coordinate.
level	Number	The tile level.

Throws:

DeveloperError : requestImage must not be called before the imagery provider is ready.

Returns:

Promise A promise for the image that will resolve when the image is available, or undefined if there are too many active requests to the server, and the request should be retried later. The resolved image may be either an Image or a Canvas DOM object.

<static> loadImage

Loads an image from a given URL. If the server referenced by the URL already has too many requests pending, this function will instead return undefined, indicating that the request should be retried later.

Parameters:

Name	Type	Description
url		{String} The URL of the image.

Returns:

Promise A promise for the image that will resolve when the image is available, or undefined if there are too many active requests to the server, and the request should be retried later. The resolved image may be either an Image or a Canvas DOM object.

<static> prototype.getExtent

Gets the extent, in radians, of the imagery provided by this instance. This function should not be called before ImageryProvider#isReady returns true.

Throws:

DeveloperError : getExtent must not be called before the imagery provider is ready.

Returns:

Extent The extent.

<static> prototype.getMaximumLevel

Gets the maximum level-of-detail that can be requested. This function should not be called before ImageryProvider#isReady returns true.

Throws:

DeveloperError : getMaximumLevel must not be called before the imagery provider is ready.

Returns:

Number The maximum level, or undefined if there is no maximum level.

<static> prototype.getMinimumLevel

Gets the minimum level-of-detail that can be requested. This function should not be called before ImageryProvider#isReady returns true. Generally, a minimum level should only be used when the extent of the imagery is small enough that the number of tiles at the minimum level is small. An imagery provider with more than a few tiles at the minimum level will lead to rendering problems.

Throws:

DeveloperError : getMinimumLevel must not be called before the imagery provider is ready.

Returns:

Number The minimum level, or undefined if there is no minimum level.

<static> prototype.getTileHeight

Gets the height of each tile, in pixels. This function should not be called before ImageryProvider#isReady returns true.

Throws:

DeveloperError : getTileHeight must not be called before the imagery provider is ready.

Returns:

Number The height.

<static> prototype.getTileWidth

Gets the width of each tile, in pixels. This function should not be called before ImageryProvider#isReady returns true.

Throws:

DeveloperError : getTileWidth must not be called before the imagery provider is ready.

Returns:

Number The width.

<static> prototype.getTilingScheme

Gets the tiling scheme used by this provider. This function should not be called before ImageryProvider#isReady returns true.

Throws:

DeveloperError : getTilingScheme must not be called before the imagery provider is ready.

Returns:

TilingScheme The tiling scheme.

See:

• WebMercatorTilingScheme
• GeographicTilingScheme

<static> prototype.isReady

Gets a value indicating whether or not the provider is ready for use.

Returns:

Boolean True if the provider is ready to use; otherwise, false.