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title ImageCache
titleTemplate title - API / NativeScript
description Represents a class that stores handles image download requests and caches the already downloaded images.
contributors false

Defined in: ui/image-cache/index.d.ts:29

Represents a class that stores handles image download requests and caches the already downloaded images.

Extends

Constructors

Constructor

new ImageCache(): Cache;

Returns

Cache

Inherited from

Observable.constructor

Properties

maxRequests

maxRequests: number;

Defined in: ui/image-cache/index.d.ts:45

The maximum number of simultaneous download requests. Defaults to 5.

placeholder

placeholder: ImageSource;

Defined in: ui/image-cache/index.d.ts:41

The image to be used to notify for a pending download request - e.g. loading indicator.

downloadedEvent

static downloadedEvent: string;

Defined in: ui/image-cache/index.d.ts:33

String value used when hooking to downloaded event.

downloadErrorEvent

static downloadErrorEvent: string;

Defined in: ui/image-cache/index.d.ts:37

String value used when hooking to download error event.

propertyChangeEvent

static propertyChangeEvent: string;

Defined in: data/observable/index.ts

String value used when hooking to propertyChange event.

Ns Event

propertyChange

Inherited from

Observable.propertyChangeEvent

Methods

_createPropertyChangeData()

_createPropertyChangeData(
   propertyName: string, 
   value: any, 
   oldValue?: any): PropertyChangeData;

Defined in: data/observable/index.ts

This method is intended to be overriden by inheritors to provide additional implementation.

Parameters

Parameter Type
propertyName string
value any
oldValue? any

Returns

PropertyChangeData

Inherited from

Observable._createPropertyChangeData

_emit()

_emit(eventName: string): void;

Defined in: data/observable/index.ts

Parameters

Parameter Type
eventName string

Returns

void

Inherited from

Observable._emit

addEventListener()

addEventListener(
   eventName: string, 
   callback: (data: EventData) => void, 
   thisArg?: any, 
   once?: boolean): void;

Defined in: data/observable/index.ts

Adds a listener for the specified event name.

Parameters

Parameter Type Description
eventName string Name of the event to attach to.
callback (data: EventData) => void A function to be called when some of the specified event(s) is raised.
thisArg? any An optional parameter which when set will be used as "this" in callback method call.
once? boolean An optional parameter which when set will cause the event listener to fire once.

Returns

void

Inherited from

Observable.addEventListener

clear()

clear(): void;

Defined in: ui/image-cache/index.d.ts:80

Removes all the previously cached images.

Returns

void

disableDownload()

disableDownload(): void;

Defined in: ui/image-cache/index.d.ts:54

Temporary disables download requests.

Returns

void

enableDownload()

enableDownload(): void;

Defined in: ui/image-cache/index.d.ts:50

Enables previously suspended download requests.

Returns

void

enqueue()

enqueue(request: DownloadRequest): any;

Defined in: ui/image-cache/index.d.ts:63

Adds a new download request at the end of the download queue. This will be the last download to start.

Parameters

Parameter Type
request DownloadRequest

Returns

any

get()

get(key: string): any;

Defined in: ui/image-cache/index.d.ts:68

Gets the image for the specified key. May be undefined if the key is not present in the cache.

Parameters

Parameter Type
key string

Returns

any

Overrides

Observable.get

hasListeners()

hasListeners(eventName: string): boolean;

Defined in: data/observable/index.ts

Checks whether a listener is registered for the specified event name.

Parameters

Parameter Type Description
eventName string The name of the event to check for.

Returns

boolean

Inherited from

Observable.hasListeners

notify()

notify<T>(data: T): void;

Defined in: data/observable/index.ts

Notify this Observable instance with some data. This causes all event handlers on the Observable instance to be called, as well as any 'global' event handlers set on the instance's class.

Type Parameters

Type Parameter
T extends Optional<EventData, "object">

Parameters

Parameter Type Description
data T an object that satisfies the EventData interface, though with an optional 'object' property. If left undefined, the 'object' property will implicitly be set as this Observable instance.

Returns

void

Inherited from

Observable.notify

notifyPropertyChange()

notifyPropertyChange(
   name: string, 
   value: any, 
   oldValue?: any): void;

Defined in: data/observable/index.ts

Notifies all the registered listeners for the property change event.

Parameters

Parameter Type
name string
value any
oldValue? any

Returns

void

Inherited from

Observable.notifyPropertyChange

off()

off(
   eventName: string, 
   callback?: (data: EventData) => void, 
   thisArg?: any): void;

Defined in: data/observable/index.ts

Removes the listener(s) for the specified event name.

Parameters

Parameter Type Description
eventName string The name of the event.
callback? (data: EventData) => void An optional specific event listener to remove (if omitted, all event listeners by this name will be removed).
thisArg? any An optional parameter which, when set, will be used to refine search of the correct event listener to be removed.

Returns

void

Inherited from

Observable.off

on()

Call Signature

on(
   eventName: string, 
   callback: (args: EventData) => void, 
   thisArg?: any): void;

Defined in: ui/image-cache/index.d.ts:92

Adds a listener for the specified event name.

Parameters
Parameter Type Description
eventName string The name of the event.
callback (args: EventData) => void The event listener to add. Will be called when an event of the given name is raised.
thisArg? any An optional parameter which, when set, will be bound as the this context when the callback is called. Falsy values will be not be bound.
Returns

void

Overrides

Observable.on

Call Signature

on(
   event: "downloaded", 
   callback: (args: DownloadedData) => void, 
   thisArg?: any): void;

Defined in: ui/image-cache/index.d.ts:97

Raised when the image has been downloaded.

Parameters
Parameter Type
event "downloaded"
callback (args: DownloadedData) => void
thisArg? any
Returns

void

Overrides
Observable.on

Call Signature

on(
   event: "downloadError", 
   callback: (args: DownloadError) => void, 
   thisArg?: any): void;

Defined in: ui/image-cache/index.d.ts:102

Raised if the image download errors.

Parameters
Parameter Type
event "downloadError"
callback (args: DownloadError) => void
thisArg? any
Returns

void

Overrides
Observable.on

once()

once(
   eventName: string, 
   callback: (data: EventData) => void, 
   thisArg?: any): void;

Defined in: data/observable/index.ts

Adds a listener for the specified event name, which, once fired, will remove itself.

Parameters

Parameter Type Description
eventName string The name of the event.
callback (data: EventData) => void The event listener to add. Will be called when an event of the given name is raised.
thisArg? any An optional parameter which, when set, will be bound as the this context when the callback is called. Falsy values will be not be bound.

Returns

void

Inherited from

Observable.once

push()

push(request: DownloadRequest): any;

Defined in: ui/image-cache/index.d.ts:59

Adds a new download request at the top of the download queue. This will be the next immediate download to start.

Parameters

Parameter Type
request DownloadRequest

Returns

any

remove()

remove(key: string): void;

Defined in: ui/image-cache/index.d.ts:76

Removes the cache for the specified key.

Parameters

Parameter Type
key string

Returns

void

removeEventListener()

removeEventListener(
   eventName: string, 
   callback?: (data: EventData) => void, 
   thisArg?: any): void;

Defined in: data/observable/index.ts

Removes listener(s) for the specified event name.

Parameters

Parameter Type Description
eventName string Name of the event to attach to.
callback? (data: EventData) => void An optional parameter pointing to a specific listener. If not defined, all listeners for the event names will be removed.
thisArg? any An optional parameter which when set will be used to refine search of the correct callback which will be removed as event listener.

Returns

void

Inherited from

Observable.removeEventListener

set()

set(key: string, image: any): void;

Defined in: ui/image-cache/index.d.ts:72

Sets the image for the specified key.

Parameters

Parameter Type
key string
image any

Returns

void

Overrides

Observable.set

setProperty()

setProperty(name: string, value: any): void;

Defined in: data/observable/index.ts

Updates the specified property with the provided value and raises a property change event and a specific change event based on the property name.

Parameters

Parameter Type
name string
value any

Returns

void

Inherited from

Observable.setProperty

addEventListener()

static addEventListener(
   eventName: string, 
   callback: (data: EventData) => void, 
   thisArg?: any, 
   once?: boolean): void;

Defined in: data/observable/index.ts

Please avoid using the static event-handling APIs as they will be removed in future.

Parameters

Parameter Type
eventName string
callback (data: EventData) => void
thisArg? any
once? boolean

Returns

void

Deprecated

Inherited from

Observable.addEventListener

off()

static off(
   eventName: string, 
   callback?: (data: EventData) => void, 
   thisArg?: any): void;

Defined in: data/observable/index.ts

Please avoid using the static event-handling APIs as they will be removed in future.

Parameters

Parameter Type
eventName string
callback? (data: EventData) => void
thisArg? any

Returns

void

Deprecated

Inherited from

Observable.off

on()

static on(
   eventName: string, 
   callback: (data: EventData) => void, 
   thisArg?: any, 
   once?: boolean): void;

Defined in: data/observable/index.ts

Please avoid using the static event-handling APIs as they will be removed in future.

Parameters

Parameter Type
eventName string
callback (data: EventData) => void
thisArg? any
once? boolean

Returns

void

Deprecated

Inherited from

Observable.on

once()

static once(
   eventName: string, 
   callback: (data: EventData) => void, 
   thisArg?: any): void;

Defined in: data/observable/index.ts

Please avoid using the static event-handling APIs as they will be removed in future.

Parameters

Parameter Type
eventName string
callback (data: EventData) => void
thisArg? any

Returns

void

Deprecated

Inherited from

Observable.once

removeEventListener()

static removeEventListener(
   eventName: string, 
   callback?: (data: EventData) => void, 
   thisArg?: any): void;

Defined in: data/observable/index.ts

Please avoid using the static event-handling APIs as they will be removed in future.

Parameters

Parameter Type
eventName string
callback? (data: EventData) => void
thisArg? any

Returns

void

Deprecated

Inherited from

Observable.removeEventListener