127 lines
3.3 KiB
JavaScript
127 lines
3.3 KiB
JavaScript
import Frozen from "../Core/Frozen.js";
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import defined from "../Core/defined.js";
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import DeveloperError from "../Core/DeveloperError.js";
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import MetadataSchema from "./MetadataSchema.js";
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import ResourceLoader from "./ResourceLoader.js";
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import ResourceLoaderState from "./ResourceLoaderState.js";
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/**
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* A {@link MetadataSchema} loader.
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* <p>
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* Implements the {@link ResourceLoader} interface.
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* </p>
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*
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* @private
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* @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
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*/
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class MetadataSchemaLoader extends ResourceLoader {
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/**
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* @param {object} options Object with the following properties:
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* @param {object} [options.schema] An object that explicitly defines a schema JSON. Mutually exclusive with options.resource.
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* @param {Resource} [options.resource] The {@link Resource} pointing to the schema JSON. Mutually exclusive with options.schema.
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* @param {string} [options.cacheKey] The cache key of the resource.
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*
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* @exception {DeveloperError} One of options.schema and options.resource must be defined.
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*/
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constructor(options) {
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super();
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options = options ?? Frozen.EMPTY_OBJECT;
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const schema = options.schema;
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const resource = options.resource;
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const cacheKey = options.cacheKey;
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//>>includeStart('debug', pragmas.debug);
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if (defined(schema) === defined(resource)) {
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throw new DeveloperError(
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"One of options.schema and options.resource must be defined.",
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);
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}
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//>>includeEnd('debug');
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this._schema = defined(schema)
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? MetadataSchema.fromJson(schema)
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: undefined;
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this._resource = resource;
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this._cacheKey = cacheKey;
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this._state = ResourceLoaderState.UNLOADED;
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this._promise = undefined;
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}
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/**
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* The cache key of the resource.
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*
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*
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* @type {string}
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* @readonly
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* @private
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*/
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get cacheKey() {
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return this._cacheKey;
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}
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/**
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* The metadata schema object.
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*
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*
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* @type {MetadataSchema}
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* @readonly
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* @private
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*/
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get schema() {
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return this._schema;
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}
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/**
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* Loads the resource.
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* @returns {Promise<MetadataSchemaLoader>} A promise which resolves to the loader when the resource loading is completed.
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* @private
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*/
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async load() {
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if (defined(this._promise)) {
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return this._promise;
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}
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if (defined(this._schema)) {
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this._promise = Promise.resolve(this);
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return this._promise;
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}
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this._promise = loadExternalSchema(this);
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return this._promise;
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}
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/**
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* Unloads the resource.
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* @private
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*/
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unload() {
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this._schema = undefined;
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}
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}
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async function loadExternalSchema(schemaLoader) {
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const resource = schemaLoader._resource;
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schemaLoader._state = ResourceLoaderState.LOADING;
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try {
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const json = await resource.fetchJson();
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if (schemaLoader.isDestroyed()) {
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return;
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}
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schemaLoader._schema = MetadataSchema.fromJson(json);
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schemaLoader._state = ResourceLoaderState.READY;
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return schemaLoader;
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} catch (error) {
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if (schemaLoader.isDestroyed()) {
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return;
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}
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schemaLoader._state = ResourceLoaderState.FAILED;
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const errorMessage = `Failed to load schema: ${resource.url}`;
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throw schemaLoader.getError(errorMessage, error);
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}
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}
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export default MetadataSchemaLoader;
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