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Allow data tile source loader to return a value or a promise

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This commit is contained in:
Tim Schaub
2021-11-20 13:49:10 -07:00
parent fcb39c84ce
commit f6f34f82e5
10 changed files with 100 additions and 13 deletions
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2
examples/data-tiles.js
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@@ -32,7 +32,7 @@ const map = new Map({
context.strokeRect(0, 0, size, size);
const data = context.getImageData(0, 0, size, size).data;
// converting to Uint8Array for increased browser compatibility
return Promise.resolve(new Uint8Array(data.buffer));
return new Uint8Array(data.buffer);
},
// disable opacity transition to avoid overlapping labels during tile loading
transition: 0,

21
src/ol/functions.js
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@@ -58,3 +58,24 @@ export function memoizeOne(fn) {
return lastResult;
};
}
/**
* @template T
* @param {function(): (T | Promise<T>)} getter A function that returns a value or a promise for a value.
* @return {Promise<T>} A promise for the value.
*/
export function toPromise(getter) {
function promiseGetter() {
let value;
try {
value = getter();
} catch (err) {
return Promise.reject(err);
}
if (value instanceof Promise) {
return value;
}
return Promise.resolve(value);
}
return promiseGetter();
}

20
src/ol/source/DataTile.js
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@@ -10,11 +10,18 @@ import {assign} from '../obj.js';
import {createXYZ, extentFromProjection} from '../tilegrid.js';
import {getKeyZXY} from '../tilecoord.js';
import {getUid} from '../util.js';
import {toPromise} from '../functions.js';
/**
* Data tile loading function. The function is called with z, x, and y tile coordinates and
* returns {@link import("../DataTile.js").Data data} for a tile or a promise for the same.
* @typedef {function(number, number, number) : (import("../DataTile.js").Data|Promise<import("../DataTile.js").Data>)} Loader
*/
/**
* @typedef {Object} Options
* @property {function(number, number, number) : Promise<import("../DataTile.js").Data>} [loader] Data loader. Called with z, x, and y tile coordinates.
* Returns a promise that resolves to a {@link import("../DataTile.js").Data}.
* @property {Loader} [loader] Data loader. Called with z, x, and y tile coordinates.
* Returns {@link import("../DataTile.js").Data data} for a tile or a promise for the same.
* @property {number} [maxZoom=42] Optional max zoom level. Not used if `tileGrid` is provided.
* @property {number} [minZoom=0] Optional min zoom level. Not used if `tileGrid` is provided.
* @property {number|import("../size.js").Size} [tileSize=[256, 256]] The pixel width and height of the tiles.
@@ -31,7 +38,7 @@ import {getUid} from '../util.js';
/**
* @classdesc
* Base class for sources providing tiles divided into a tile grid.
* A source for typed array data tiles.
*
* @fires import("./Tile.js").TileSourceEvent
* @api
@@ -86,7 +93,7 @@ class DataTileSource extends TileSource {
}
/**
* @param {function(number, number, number) : Promise<import("../DataTile.js").Data>} loader The data loader.
* @param {Loader} loader The data loader.
* @protected
*/
setLoader(loader) {
@@ -109,8 +116,11 @@ class DataTileSource extends TileSource {
}
const sourceLoader = this.loader_;
function loader() {
return sourceLoader(z, x, y);
return toPromise(function () {
return sourceLoader(z, x, y);
});
}
const tile = new DataTile(

2
test/browser/spec/ol/renderer/webgl/Layer.test.js
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@@ -252,7 +252,7 @@ describe('ol/renderer/webgl/Layer', function () {
className: className,
source: new DataTileSource({
loader(z, x, y) {
return Promise.resolve(new ImageData(256, 256));
return new ImageData(256, 256);
},
}),
});

2
test/browser/spec/ol/renderer/webgl/TileLayer.test.js
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@@ -25,7 +25,7 @@ describe('ol/renderer/webgl/TileLayer', function () {
context.fillStyle = 'rgba(100, 100, 100, 0.5)';
context.fillRect(0, 0, size, size);
const data = context.getImageData(0, 0, size, size).data;
return Promise.resolve(data);
return data;
},
}),
});

58
test/node/ol/functions.test.js
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@@ -1,7 +1,63 @@
import expect from '../expect.js';
import {memoizeOne} from '../../../src/ol/functions.js';
import {memoizeOne, toPromise} from '../../../src/ol/functions.js';
describe('ol/functions.js', function () {
describe('toPromise()', () => {
it('returns a promise given a getter for a value', (done) => {
const getter = () => 'a value';
const promise = toPromise(getter);
expect(promise).to.be.a(Promise);
promise.then((value) => {
expect(value).to.be('a value');
done();
}, done);
});
it('returns a promise given a getter for a promise that resolves', (done) => {
const getter = () => Promise.resolve('a value');
const promise = toPromise(getter);
expect(promise).to.be.a(Promise);
promise.then((value) => {
expect(value).to.be('a value');
done();
}, done);
});
it('returns a promise that rejects given a getter that throws', (done) => {
const getter = () => {
throw new Error('an error');
};
const promise = toPromise(getter);
expect(promise).to.be.a(Promise);
promise.then(
(value) => {
done(new Error(`expected promise to reject, got ${value}`));
},
(err) => {
expect(err).to.be.an(Error);
expect(err.message).to.be('an error');
done();
}
);
});
it('returns a promise that rejects given a getter for a promse that rejects', (done) => {
const getter = () => Promise.reject(new Error('an error'));
const promise = toPromise(getter);
expect(promise).to.be.a(Promise);
promise.then(
(value) => {
done(new Error(`expected promise to reject, got ${value}`));
},
(err) => {
expect(err).to.be.an(Error);
expect(err.message).to.be('an error');
done();
}
);
});
});
describe('memoizeOne()', function () {
it('returns the result from the first call when called a second time with the same args', function () {
const arg1 = {};

2
test/rendering/cases/webgl-data-tile-3-band/main.js
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@@ -34,7 +34,7 @@ new Map({
const bandCount = 3;
const result = data.filter((_, index) => index % 4 < bandCount);
return Promise.resolve(result);
return result;
},
tileSize: size,
}),

2
test/rendering/cases/webgl-data-tile-loosely-packed/main.js
View File

@@ -53,7 +53,7 @@ new Map({
}
}
return Promise.resolve(output);
return output;
},
}),
}),

2
test/rendering/cases/webgl-mixed-layers/main.js
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@@ -66,7 +66,7 @@ new Map({
labelCanvasSize,
labelCanvasSize
).data;
return Promise.resolve(new Uint8Array(data.buffer));
return new Uint8Array(data.buffer);
},
transition: 0,
}),

2
test/rendering/cases/webgl-multiple-layers/main.js
View File

@@ -64,7 +64,7 @@ new Map({
labelCanvasSize,
labelCanvasSize
).data;
return Promise.resolve(new Uint8Array(data.buffer));
return new Uint8Array(data.buffer);
},
transition: 0,
}),