75 lines
2.2 KiB
JavaScript
75 lines
2.2 KiB
JavaScript
/**
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* @module ol/loadingstrategy
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*/
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import {fromUserExtent, fromUserResolution, toUserExtent} from './proj.js';
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/**
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* Strategy function for loading all features with a single request.
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* @param {import("./extent.js").Extent} extent Extent.
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* @param {number} resolution Resolution.
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* @return {Array<import("./extent.js").Extent>} Extents.
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* @api
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*/
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export function all(extent, resolution) {
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return [[-Infinity, -Infinity, Infinity, Infinity]];
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}
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/**
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* Strategy function for loading features based on the view's extent and
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* resolution.
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* @param {import("./extent.js").Extent} extent Extent.
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* @param {number} resolution Resolution.
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* @return {Array<import("./extent.js").Extent>} Extents.
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* @api
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*/
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export function bbox(extent, resolution) {
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return [extent];
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}
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/**
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* Creates a strategy function for loading features based on a tile grid.
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* @param {import("./tilegrid/TileGrid.js").default} tileGrid Tile grid.
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* @return {function(import("./extent.js").Extent, number, import("./proj.js").Projection): Array<import("./extent.js").Extent>} Loading strategy.
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* @api
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*/
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export function tile(tileGrid) {
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return (
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/**
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* @param {import("./extent.js").Extent} extent Extent.
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* @param {number} resolution Resolution.
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* @param {import("./proj.js").Projection} projection Projection.
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* @return {Array<import("./extent.js").Extent>} Extents.
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*/
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function (extent, resolution, projection) {
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const z = tileGrid.getZForResolution(
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fromUserResolution(resolution, projection)
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);
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const tileRange = tileGrid.getTileRangeForExtentAndZ(
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fromUserExtent(extent, projection),
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z
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);
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/** @type {Array<import("./extent.js").Extent>} */
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const extents = [];
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/** @type {import("./tilecoord.js").TileCoord} */
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const tileCoord = [z, 0, 0];
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for (
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tileCoord[1] = tileRange.minX;
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tileCoord[1] <= tileRange.maxX;
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++tileCoord[1]
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) {
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for (
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tileCoord[2] = tileRange.minY;
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tileCoord[2] <= tileRange.maxY;
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++tileCoord[2]
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) {
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extents.push(
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toUserExtent(tileGrid.getTileCoordExtent(tileCoord), projection)
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);
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}
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}
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return extents;
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}
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);
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}
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