119 lines
4.4 KiB
JavaScript
119 lines
4.4 KiB
JavaScript
/**
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* @module ol/source/mapguide
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*/
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import {decode} from '../Image.js';
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import {getCenter, getHeight, getWidth} from '../extent.js';
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import {appendParams} from '../uri.js';
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import {getRequestExtent} from './Image.js';
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/**
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* @typedef {Object} LoaderOptions
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* @property {string} url The mapagent url.
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* @property {null|string} [crossOrigin] The `crossOrigin` attribute for loaded images. Note that
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* you must provide a `crossOrigin` value if you want to access pixel data with the Canvas renderer.
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* See https://developer.mozilla.org/en-US/docs/Web/HTML/CORS_enabled_image for more detail.
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* @property {number} [displayDpi=96] The display resolution.
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* @property {number} [metersPerUnit=1] The meters-per-unit value.
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* @property {boolean} [hidpi=true] Use the `ol/Map#pixelRatio` value when requesting
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* the image from the remote server.
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* @property {boolean} [useOverlay] If `true`, will use `GETDYNAMICMAPOVERLAYIMAGE`.
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* @property {number} [ratio=1] Ratio. `1` means image requests are the size of the map viewport, `2` means
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* twice the width and height of the map viewport, and so on. Must be `1` or higher.
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* @property {Object} [params] Additional query parameters.
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* @property {function(HTMLImageElement, string): Promise<import('../DataTile.js').ImageLike>} [load] Function
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* to perform loading of the image. Receives the created `HTMLImageElement` and the desired `src` as argument and
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* returns a promise resolving to the loaded or decoded image. Default is {@link module:ol/Image.decode}.
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*/
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/**
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* @param {import("../extent.js").Extent} extent The map extents.
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* @param {import("../size.js").Size} size The viewport size.
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* @param {number} metersPerUnit The meters-per-unit value.
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* @param {number} dpi The display resolution.
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* @return {number} The computed map scale.
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*/
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function getScale(extent, size, metersPerUnit, dpi) {
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const mcsW = getWidth(extent);
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const mcsH = getHeight(extent);
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const devW = size[0];
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const devH = size[1];
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const mpp = 0.0254 / dpi;
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if (devH * mcsW > devW * mcsH) {
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return (mcsW * metersPerUnit) / (devW * mpp); // width limited
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}
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return (mcsH * metersPerUnit) / (devH * mpp); // height limited
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}
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/**
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* @param {string} baseUrl The mapagent url.
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* @param {Object<string, string|number>} params Request parameters.
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* @param {import("../extent.js").Extent} extent Extent.
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* @param {import("../size.js").Size} size Size.
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* @param {boolean} useOverlay If `true`, will use `GETDYNAMICMAPOVERLAYIMAGE`.
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* @param {number} metersPerUnit The meters-per-unit value.
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* @param {number} displayDpi The display resolution.
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* @return {string} The mapagent map image request URL.
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*/
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function getUrl(
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baseUrl,
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params,
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extent,
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size,
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useOverlay,
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metersPerUnit,
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displayDpi,
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) {
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const scale = getScale(extent, size, metersPerUnit, displayDpi);
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const center = getCenter(extent);
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const baseParams = {
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'OPERATION': useOverlay ? 'GETDYNAMICMAPOVERLAYIMAGE' : 'GETMAPIMAGE',
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'VERSION': '2.0.0',
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'LOCALE': 'en',
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'CLIENTAGENT': 'ol/source/ImageMapGuide source',
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'CLIP': '1',
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'SETDISPLAYDPI': displayDpi,
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'SETDISPLAYWIDTH': Math.round(size[0]),
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'SETDISPLAYHEIGHT': Math.round(size[1]),
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'SETVIEWSCALE': scale,
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'SETVIEWCENTERX': center[0],
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'SETVIEWCENTERY': center[1],
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};
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Object.assign(baseParams, params);
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return appendParams(baseUrl, baseParams);
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}
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/**
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* Creates a loader for MapGuide images.
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* @param {LoaderOptions} options Image ArcGIS Rest Options.
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* @return {import('../Image.js').ImageObjectPromiseLoader} ArcGIS Rest image.
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* @api
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*/
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export function createLoader(options) {
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const load = options.load || decode;
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const useOverlay = options.useOverlay ?? false;
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const metersPerUnit = options.metersPerUnit || 1;
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const displayDpi = options.displayDpi || 96;
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const ratio = options.ratio ?? 1;
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const crossOrigin = options.crossOrigin ?? null;
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return function (extent, resolution, pixelRatio) {
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const image = new Image();
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image.crossOrigin = crossOrigin;
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extent = getRequestExtent(extent, resolution, pixelRatio, ratio);
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const width = getWidth(extent) / resolution;
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const height = getHeight(extent) / resolution;
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const size = [width * pixelRatio, height * pixelRatio];
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const src = getUrl(
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options.url,
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options.params,
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extent,
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size,
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useOverlay,
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metersPerUnit,
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displayDpi,
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);
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return load(image, src).then((image) => ({image, extent, pixelRatio}));
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};
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}
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