heli-agri/dist/ImageCanvas.js

HeliAgri is a high-performance, feature-packed library for creating interactive maps on the web. It can display map tiles, vector data and markers loaded from any source on any web page. OpenLayers has been developed to further the use of geographic infor

/**
 * @module ol/ImageCanvas
 */
import ImageBase from './ImageBase.js';
import ImageState from './ImageState.js';
/**
 * A function that is called to trigger asynchronous canvas drawing.  It is
 * called with a "done" callback that should be called when drawing is done.
 * If any error occurs during drawing, the "done" callback should be called with
 * that error.
 *
 * @typedef {function(function(Error=): void): void} Loader
 */
class ImageCanvas extends ImageBase {
    /**
     * @param {import("./extent.js").Extent} extent Extent.
     * @param {number} resolution Resolution.
     * @param {number} pixelRatio Pixel ratio.
     * @param {HTMLCanvasElement} canvas Canvas.
     * @param {Loader} [loader] Optional loader function to
     *     support asynchronous canvas drawing.
     */
    constructor(extent, resolution, pixelRatio, canvas, loader) {
        const state = loader !== undefined ? ImageState.IDLE : ImageState.LOADED;
        super(extent, resolution, pixelRatio, state);
        /**
         * Optional canvas loader function.
         * @type {?Loader}
         * @private
         */
        this.loader_ = loader !== undefined ? loader : null;
        /**
         * @private
         * @type {HTMLCanvasElement}
         */
        this.canvas_ = canvas;
        /**
         * @private
         * @type {?Error}
         */
        this.error_ = null;
    }
    /**
     * Get any error associated with asynchronous rendering.
     * @return {?Error} Any error that occurred during rendering.
     */
    getError() {
        return this.error_;
    }
    /**
     * Handle async drawing complete.
     * @param {Error} [err] Any error during drawing.
     * @private
     */
    handleLoad_(err) {
        if (err) {
            this.error_ = err;
            this.state = ImageState.ERROR;
        }
        else {
            this.state = ImageState.LOADED;
        }
        this.changed();
    }
    /**
     * Load not yet loaded URI.
     */
    load() {
        if (this.state == ImageState.IDLE) {
            this.state = ImageState.LOADING;
            this.changed();
            this.loader_(this.handleLoad_.bind(this));
        }
    }
    /**
     * @return {HTMLCanvasElement} Canvas element.
     */
    getImage() {
        return this.canvas_;
    }
}
export default ImageCanvas;