openlayers/src/ol/layer/Base.js

/**
 * @module ol/layer/Base
 */
import BaseObject from '../Object.js';
import LayerProperty from '../layer/Property.js';
import {clamp} from '../math.js';
import {assign} from '../obj.js';


/**
 * @typedef {Object} Options
 * @property {number} [opacity=1] Opacity (0, 1).
 * @property {boolean} [visible=true] Visibility.
 * @property {module:ol/extent~Extent} [extent] The bounding extent for layer rendering.  The layer will not be
 * rendered outside of this extent.
 * @property {number} [zIndex=0] The z-index for layer rendering.  At rendering time, the layers
 * will be ordered, first by Z-index and then by position.
 * @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.
 */


/**
 * @classdesc
 * Abstract base class; normally only used for creating subclasses and not
 * instantiated in apps.
 * Note that with {@link module:ol/layer/Base} and all its subclasses, any property set in
 * the options is set as a {@link module:ol/Object} property on the layer object, so
 * is observable, and has get/set accessors.
 *
 * @api
 */
class BaseLayer extends BaseObject {
  /**
   * @param {module:ol/layer/Base~Options} options Layer options.
   */
  constructor(options) {

    super();

    /**
    * @type {Object<string, *>}
    */
    const properties = assign({}, options);
    properties[LayerProperty.OPACITY] =
       options.opacity !== undefined ? options.opacity : 1;
    properties[LayerProperty.VISIBLE] =
       options.visible !== undefined ? options.visible : true;
    properties[LayerProperty.Z_INDEX] =
       options.zIndex !== undefined ? options.zIndex : 0;
    properties[LayerProperty.MAX_RESOLUTION] =
       options.maxResolution !== undefined ? options.maxResolution : Infinity;
    properties[LayerProperty.MIN_RESOLUTION] =
       options.minResolution !== undefined ? options.minResolution : 0;

    this.setProperties(properties);

    /**
    * @type {module:ol/layer/Layer~State}
    * @private
    */
    this.state_ = /** @type {module:ol/layer/Layer~State} */ ({
      layer: /** @type {module:ol/layer/Layer} */ (this),
      managed: true
    });

    /**
    * The layer type.
    * @type {module:ol/LayerType}
    * @protected;
    */
    this.type;

  }

  /**
  * Get the layer type (used when creating a layer renderer).
  * @return {module:ol/LayerType} The layer type.
  */
  getType() {
    return this.type;
  }

  /**
  * @return {module:ol/layer/Layer~State} Layer state.
  */
  getLayerState() {
    this.state_.opacity = clamp(this.getOpacity(), 0, 1);
    this.state_.sourceState = this.getSourceState();
    this.state_.visible = this.getVisible();
    this.state_.extent = this.getExtent();
    this.state_.zIndex = this.getZIndex();
    this.state_.maxResolution = this.getMaxResolution();
    this.state_.minResolution = Math.max(this.getMinResolution(), 0);

    return this.state_;
  }

  /**
  * @abstract
  * @param {Array<module:ol/layer/Layer>=} opt_array Array of layers (to be
  *     modified in place).
  * @return {Array<module:ol/layer/Layer>} Array of layers.
  */
  getLayersArray(opt_array) {}

  /**
  * @abstract
  * @param {Array<module:ol/layer/Layer~State>=} opt_states Optional list of layer
  *     states (to be modified in place).
  * @return {Array<module:ol/layer/Layer~State>} List of layer states.
  */
  getLayerStatesArray(opt_states) {}

  /**
  * Return the {@link module:ol/extent~Extent extent} of the layer or `undefined` if it
  * will be visible regardless of extent.
  * @return {module:ol/extent~Extent|undefined} The layer extent.
  * @observable
  * @api
  */
  getExtent() {
    return (
    /** @type {module:ol/extent~Extent|undefined} */ (this.get(LayerProperty.EXTENT))
    );
  }

  /**
  * Return the maximum resolution of the layer.
  * @return {number} The maximum resolution of the layer.
  * @observable
  * @api
  */
  getMaxResolution() {
    return /** @type {number} */ (this.get(LayerProperty.MAX_RESOLUTION));
  }

  /**
  * Return the minimum resolution of the layer.
  * @return {number} The minimum resolution of the layer.
  * @observable
  * @api
  */
  getMinResolution() {
    return /** @type {number} */ (this.get(LayerProperty.MIN_RESOLUTION));
  }

  /**
  * Return the opacity of the layer (between 0 and 1).
  * @return {number} The opacity of the layer.
  * @observable
  * @api
  */
  getOpacity() {
    return /** @type {number} */ (this.get(LayerProperty.OPACITY));
  }

  /**
  * @abstract
  * @return {module:ol/source/State} Source state.
  */
  getSourceState() {}

  /**
  * Return the visibility of the layer (`true` or `false`).
  * @return {boolean} The visibility of the layer.
  * @observable
  * @api
  */
  getVisible() {
    return /** @type {boolean} */ (this.get(LayerProperty.VISIBLE));
  }

  /**
  * Return the Z-index of the layer, which is used to order layers before
  * rendering. The default Z-index is 0.
  * @return {number} The Z-index of the layer.
  * @observable
  * @api
  */
  getZIndex() {
    return /** @type {number} */ (this.get(LayerProperty.Z_INDEX));
  }

  /**
  * Set the extent at which the layer is visible.  If `undefined`, the layer
  * will be visible at all extents.
  * @param {module:ol/extent~Extent|undefined} extent The extent of the layer.
  * @observable
  * @api
  */
  setExtent(extent) {
    this.set(LayerProperty.EXTENT, extent);
  }

  /**
  * Set the maximum resolution at which the layer is visible.
  * @param {number} maxResolution The maximum resolution of the layer.
  * @observable
  * @api
  */
  setMaxResolution(maxResolution) {
    this.set(LayerProperty.MAX_RESOLUTION, maxResolution);
  }

  /**
  * Set the minimum resolution at which the layer is visible.
  * @param {number} minResolution The minimum resolution of the layer.
  * @observable
  * @api
  */
  setMinResolution(minResolution) {
    this.set(LayerProperty.MIN_RESOLUTION, minResolution);
  }

  /**
  * Set the opacity of the layer, allowed values range from 0 to 1.
  * @param {number} opacity The opacity of the layer.
  * @observable
  * @api
  */
  setOpacity(opacity) {
    this.set(LayerProperty.OPACITY, opacity);
  }

  /**
  * Set the visibility of the layer (`true` or `false`).
  * @param {boolean} visible The visibility of the layer.
  * @observable
  * @api
  */
  setVisible(visible) {
    this.set(LayerProperty.VISIBLE, visible);
  }

  /**
  * Set Z-index of the layer, which is used to order layers before rendering.
  * The default Z-index is 0.
  * @param {number} zindex The z-index of the layer.
  * @observable
  * @api
  */
  setZIndex(zindex) {
    this.set(LayerProperty.Z_INDEX, zindex);
  }
}


export default BaseLayer;