60 lines
1.8 KiB
JavaScript
60 lines
1.8 KiB
JavaScript
/**
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* @module ol/loadingstrategy
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*/
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/**
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* Strategy function for loading all features with a single request.
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* @param {module:ol/extent~Extent} extent Extent.
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* @param {number} resolution Resolution.
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* @return {Array.<module:ol/extent~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 {module:ol/extent~Extent} extent Extent.
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* @param {number} resolution Resolution.
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* @return {Array.<module:ol/extent~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 {module:ol/tilegrid/TileGrid} tileGrid Tile grid.
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* @return {function(module:ol/extent~Extent, number): Array.<module:ol/extent~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 {module:ol/extent~Extent} extent Extent.
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* @param {number} resolution Resolution.
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* @return {Array.<module:ol/extent~Extent>} Extents.
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*/
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function(extent, resolution) {
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const z = tileGrid.getZForResolution(resolution);
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const tileRange = tileGrid.getTileRangeForExtentAndZ(extent, z);
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/** @type {Array.<module:ol/extent~Extent>} */
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const extents = [];
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/** @type {module:ol/tilecoord~TileCoord} */
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const tileCoord = [z, 0, 0];
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for (tileCoord[1] = tileRange.minX; tileCoord[1] <= tileRange.maxX; ++tileCoord[1]) {
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for (tileCoord[2] = tileRange.minY; tileCoord[2] <= tileRange.maxY; ++tileCoord[2]) {
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extents.push(tileGrid.getTileCoordExtent(tileCoord));
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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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