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Viewer Loading Manager

The ViewerLoadingManager class in the @promaton/scan-viewer package is a utility designed to manage loading requests efficiently. It achieves this by caching responses and de-duplicating parallel requests. While primarily intended for internal use or through ViewerObjectUtils, it can also be leveraged for custom loaders and advanced use cases.

Constructor​

new ViewerLoadingManager()​

Creates a new instance of the ViewerLoadingManager.

Returns:
ViewerLoadingManager

Properties​

cachedLoaders​

A private static property that stores cached loaders. It is a Map where the keys are loader functions, and the values are the corresponding ViewerLoader instances.

Methods​

clearCache(key?)​

Clears all or specific cached loading outputs.

Parameters:

  • key? _(unknown[])_: Optional. Specifies the cache key to clear.

Returns:
void

disposeLoaders()​

Disposes and clears all cached loaders. While loaders are reused for multiple files, they may keep resources like workers alive if not disposed.

Returns:
void

getCacheKey<T>(Proto, input)​

Generates a cache key for a specified loader and input.

Type Parameters:

  • T: The type of the loader.

Parameters:

  • Proto _(() => ViewerLoader<T>)_: The loader function.
  • input _(string | string[])_: The input for the loader.

Returns:
(string | () => ViewerLoader<T>)[]

load&lt;T&gt;(Proto, input, onProgress?, options?)​

A private static method that loads data using the specified loader, with support for caching and progress tracking.

Type Parameters:

  • T: The type of the loaded data.

Parameters:

  • Proto _(() => ViewerLoader<T>)_: The loader function.
  • input _(string | string[])_: The input for the loader.
  • onProgress? _((e, url?) => void)_: Optional. A callback for progress updates.
  • options? _(LoadOptions)_: Optional. Additional loading options.

Returns:
Promise<T>

loadViewerObject&lt;T&gt;(Proto, input, onProgress?, options?)​

Loads an object using the specified loader, either from cache or by pre-loading it.

Type Parameters:

  • T: The type of the loaded object.

Parameters:

  • Proto (() => ViewerLoader<T>): The loader function.

  • input (string | string[]): The input for the loader.

  • onProgress? ((e, url?) => void): Optional. A callback for progress updates.

  • options? (LoadOptions): Optional. Additional loading options.

Returns:
Promise&lt;T&gt;

useViewerLoader&lt;T&gt;(Proto, input, onProgress?, options?)​

A hook to load objects using the specified loader, with caching and de-duplication.

Type Parameters:

  • T: The type of the loaded object.

Parameters:

  • Proto (() => ViewerLoader<T>): The loader function.

  • input (string | string[]): The input for the loader.

  • onProgress? ((e, url?) => void): Optional. A callback for progress updates.

  • options? (LoadOptions): Optional. Additional loading options.

Returns:
T

Summary​

The ViewerLoadingManager is a powerful utility for managing loading requests in the @promaton/scan-viewer package. By leveraging its caching and de-duplication capabilities, developers can optimize resource usage and improve performance in their applications. Whether used internally or for advanced custom loaders, this class provides a robust solution for handling complex loading scenarios.