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- import defined from "../Core/defined.js";
- import DeveloperError from "../Core/DeveloperError.js";
- import Event from "../Core/Event.js";
- import JulianDate from "../Core/JulianDate.js";
- import ReferenceFrame from "../Core/ReferenceFrame.js";
- import PositionProperty from "./PositionProperty.js";
-
- /**
- * A {@link PositionProperty} whose value is lazily evaluated by a callback function.
- *
- * @alias CallbackPositionProperty
- * @constructor
- *
- * @param {CallbackPositionProperty.Callback} callback The function to be called when the position property is evaluated.
- * @param {boolean} isConstant <code>true</code> when the callback function returns the same value every time, <code>false</code> if the value will change.
- * @param {ReferenceFrame} [referenceFrame=ReferenceFrame.FIXED] The reference frame in which the position is defined.
- *
- * @demo {@link https://sandcastle.cesium.com/index.html?id=callback-position-property|Cesium Sandcastle Callback Position Property Demo}
- */
- function CallbackPositionProperty(callback, isConstant, referenceFrame) {
- this._callback = undefined;
- this._isConstant = undefined;
- this._referenceFrame = referenceFrame ?? ReferenceFrame.FIXED;
- this._definitionChanged = new Event();
- this.setCallback(callback, isConstant);
- }
-
- Object.defineProperties(CallbackPositionProperty.prototype, {
- /**
- * Gets a value indicating if this property is constant.
- * @memberof CallbackPositionProperty.prototype
- *
- * @type {boolean}
- * @readonly
- */
- isConstant: {
- get: function () {
- return this._isConstant;
- },
- },
- /**
- * Gets the event that is raised whenever the definition of this property changes.
- * The definition is considered to have changed if a call to getValue would return
- * a different result for the same time.
- * @memberof CallbackPositionProperty.prototype
- *
- * @type {Event}
- * @readonly
- */
- definitionChanged: {
- get: function () {
- return this._definitionChanged;
- },
- },
- /**
- * Gets the reference frame in which the position is defined.
- * @memberof CallbackPositionProperty.prototype
- * @type {ReferenceFrame}
- * @default ReferenceFrame.FIXED;
- */
- referenceFrame: {
- get: function () {
- return this._referenceFrame;
- },
- },
- });
-
- const timeScratch = new JulianDate();
-
- /**
- * Gets the value of the property at the provided time in the fixed frame.
- *
- * @param {JulianDate} [time=JulianDate.now()] The time for which to retrieve the value. If omitted, the current system time is used.
- * @param {Cartesian3} [result] The object to store the value into, if omitted, a new instance is created and returned.
- * @returns {Cartesian3 | undefined} The modified result parameter or a new instance if the result parameter was not supplied.
- */
- CallbackPositionProperty.prototype.getValue = function (time, result) {
- if (!defined(time)) {
- time = JulianDate.now(timeScratch);
- }
- return this.getValueInReferenceFrame(time, ReferenceFrame.FIXED, result);
- };
-
- /**
- * Sets the callback to be used.
- *
- * @param {CallbackPositionProperty.Callback} callback The function to be called when the property is evaluated.
- * @param {boolean} isConstant <code>true</code> when the callback function returns the same value every time, <code>false</code> if the value will change.
- */
- CallbackPositionProperty.prototype.setCallback = function (
- callback,
- isConstant,
- ) {
- //>>includeStart('debug', pragmas.debug);
- if (!defined(callback)) {
- throw new DeveloperError("callback is required.");
- }
- if (!defined(isConstant)) {
- throw new DeveloperError("isConstant is required.");
- }
- //>>includeEnd('debug');
-
- const changed =
- this._callback !== callback || this._isConstant !== isConstant;
-
- this._callback = callback;
- this._isConstant = isConstant;
-
- if (changed) {
- this._definitionChanged.raiseEvent(this);
- }
- };
-
- /**
- * Gets the value of the property at the provided time and in the provided reference frame.
- *
- * @param {JulianDate} time The time for which to retrieve the value.
- * @param {ReferenceFrame} referenceFrame The desired referenceFrame of the result.
- * @param {Cartesian3} [result] The object to store the value into, if omitted, a new instance is created and returned.
- * @returns {Cartesian3 | undefined} The modified result parameter or a new instance if the result parameter was not supplied.
- */
- CallbackPositionProperty.prototype.getValueInReferenceFrame = function (
- time,
- referenceFrame,
- result,
- ) {
- //>>includeStart('debug', pragmas.debug);
- if (!defined(time)) {
- throw new DeveloperError("time is required.");
- }
- if (!defined(referenceFrame)) {
- throw new DeveloperError("referenceFrame is required.");
- }
- //>>includeEnd('debug');
-
- const value = this._callback(time, result);
-
- return PositionProperty.convertToReferenceFrame(
- time,
- value,
- this._referenceFrame,
- referenceFrame,
- result,
- );
- };
-
- /**
- * Compares this property to the provided property and returns
- * <code>true</code> if they are equal, <code>false</code> otherwise.
- *
- * @param {Property} [other] The other property.
- * @returns {boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
- */
- CallbackPositionProperty.prototype.equals = function (other) {
- return (
- this === other ||
- (other instanceof CallbackPositionProperty &&
- this._callback === other._callback &&
- this._isConstant === other._isConstant &&
- this._referenceFrame === other._referenceFrame)
- );
- };
-
- /**
- * A function that returns the value of the position property.
- * @callback CallbackPositionProperty.Callback
- *
- * @param {JulianDate} [time=JulianDate.now()] The time for which to retrieve the value. If omitted, the current system time is used.
- * @param {Cartesian3} [result] The object to store the value into. If omitted, the function must create and return a new instance.
- * @returns {Cartesian3 | undefined} The modified result parameter, or a new instance if the result parameter was not supplied or is unsupported.
- */
- export default CallbackPositionProperty;
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