openlayers/src/ol/layer/BaseTile.js

/**
 * @module ol/layer/BaseTile
 */
import Layer from './Layer.js';
import TileProperty from './TileProperty.js';
import {assign} from '../obj.js';

/***
 * @template Return
 * @typedef {import("../Observable").OnSignature<import("../Observable").EventTypes, import("../events/Event.js").default, Return> &
 *   import("../Observable").OnSignature<import("./Base").BaseLayerObjectEventTypes|
 *     'change:source'|'change:preload'|'change:useInterimTilesOnError', import("../Object").ObjectEvent, Return> &
 *   import("../Observable").OnSignature<import("../render/EventType").LayerRenderEventTypes, import("../render/Event").default, Return> &
 *   import("../Observable").CombinedOnSignature<import("../Observable").EventTypes|import("./Base").BaseLayerObjectEventTypes|
 *   'change:source'|'change:preload'|'change:useInterimTilesOnError'|import("../render/EventType").LayerRenderEventTypes, Return>} BaseTileLayerOnSignature
 */

/**
 * @template {import("../source/Tile.js").default} TileSourceType
 * @typedef {Object} Options
 * @property {string} [className='ol-layer'] A CSS class name to set to the layer element.
 * @property {number} [opacity=1] Opacity (0, 1).
 * @property {boolean} [visible=true] Visibility.
 * @property {import("../extent.js").Extent} [extent] The bounding extent for layer rendering.  The layer will not be
 * rendered outside of this extent.
 * @property {number} [zIndex] The z-index for layer rendering.  At rendering time, the layers
 * will be ordered, first by Z-index and then by position. When `undefined`, a `zIndex` of 0 is assumed
 * for layers that are added to the map's `layers` collection, or `Infinity` when the layer's `setMap()`
 * method was used.
 * @property {number} [minResolution] The minimum resolution (inclusive) at which this layer will be
 * visible.
 * @property {number} [maxResolution] The maximum resolution (exclusive) below which this layer will
 * be visible.
 * @property {number} [minZoom] The minimum view zoom level (exclusive) above which this layer will be
 * visible.
 * @property {number} [maxZoom] The maximum view zoom level (inclusive) at which this layer will
 * be visible.
 * @property {number} [preload=0] Preload. Load low-resolution tiles up to `preload` levels. `0`
 * means no preloading.
 * @property {TileSourceType} [source] Source for this layer.
 * @property {import("../PluggableMap.js").default} [map] Sets the layer as overlay on a map. The map will not manage
 * this layer in its layers collection, and the layer will be rendered on top. This is useful for
 * temporary layers. The standard way to add a layer to a map and have it managed by the map is to
 * use {@link import("../PluggableMap.js").default#addLayer map.addLayer()}.
 * @property {boolean} [useInterimTilesOnError=true] Use interim tiles on error.
 * @property {Object<string, *>} [properties] Arbitrary observable properties. Can be accessed with `#get()` and `#set()`.
 */

/**
 * @classdesc
 * For layer sources that provide pre-rendered, tiled images in grids that are
 * organized by zoom levels for specific resolutions.
 * Note that any property set in the options is set as a {@link module:ol/Object~BaseObject}
 * property on the layer object; for example, setting `title: 'My Title'` in the
 * options means that `title` is observable, and has get/set accessors.
 *
 * @template {import("../source/Tile.js").default} TileSourceType
 * @template {import("../renderer/Layer.js").default} RendererType
 * @extends {Layer<TileSourceType, RendererType>}
 * @api
 */
class BaseTileLayer extends Layer {
  /**
   * @param {Options<TileSourceType>} [opt_options] Tile layer options.
   */
  constructor(opt_options) {
    const options = opt_options ? opt_options : {};

    const baseOptions = assign({}, options);

    delete baseOptions.preload;
    delete baseOptions.useInterimTilesOnError;
    super(baseOptions);

    /***
     * @type {BaseTileLayerOnSignature<import("../events").EventsKey>}
     */
    this.on;

    /***
     * @type {BaseTileLayerOnSignature<import("../events").EventsKey>}
     */
    this.once;

    /***
     * @type {BaseTileLayerOnSignature<void>}
     */
    this.un;

    this.setPreload(options.preload !== undefined ? options.preload : 0);
    this.setUseInterimTilesOnError(
      options.useInterimTilesOnError !== undefined
        ? options.useInterimTilesOnError
        : true
    );
  }

  /**
   * Return the level as number to which we will preload tiles up to.
   * @return {number} The level to preload tiles up to.
   * @observable
   * @api
   */
  getPreload() {
    return /** @type {number} */ (this.get(TileProperty.PRELOAD));
  }

  /**
   * Set the level as number to which we will preload tiles up to.
   * @param {number} preload The level to preload tiles up to.
   * @observable
   * @api
   */
  setPreload(preload) {
    this.set(TileProperty.PRELOAD, preload);
  }

  /**
   * Whether we use interim tiles on error.
   * @return {boolean} Use interim tiles on error.
   * @observable
   * @api
   */
  getUseInterimTilesOnError() {
    return /** @type {boolean} */ (
      this.get(TileProperty.USE_INTERIM_TILES_ON_ERROR)
    );
  }

  /**
   * Set whether we use interim tiles on error.
   * @param {boolean} useInterimTilesOnError Use interim tiles on error.
   * @observable
   * @api
   */
  setUseInterimTilesOnError(useInterimTilesOnError) {
    this.set(TileProperty.USE_INTERIM_TILES_ON_ERROR, useInterimTilesOnError);
  }

  /**
   * Get data for a pixel location.  The return type depends on the source data.  For image tiles,
   * a four element RGBA array will be returned.  For data tiles, the array length will match the
   * number of bands in the dataset.  For requests outside the layer extent, `null` will be returned.
   * Data for a image tiles can only be retrieved if the source's `crossOrigin` property is set.
   *
   * ```js
   * // display layer data on every pointer move
   * map.on('pointermove', (event) => {
   *   console.log(layer.getData(event.pixel));
   * });
   * ```
   * @param {import("../pixel").Pixel} pixel Pixel.
   * @return {Uint8ClampedArray|Uint8Array|Float32Array|DataView|null} Pixel data.
   * @api
   */
  getData(pixel) {
    return super.getData(pixel);
  }
}

export default BaseTileLayer;