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Detect Zoomify server-side retina tiles

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This commit is contained in:
Andreas Hocevar
2020-03-09 13:19:30 +01:00
parent df1d0ac4a0
commit ad476f6086
2 changed files with 33 additions and 7 deletions
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24
src/ol/source/Zoomify.js
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@@ -11,6 +11,7 @@ import {createCanvasContext2D} from '../dom.js';
import {toSize} from '../size.js';
import TileImage from './TileImage.js';
import TileGrid from '../tilegrid/TileGrid.js';
import {getCenter} from '../extent.js';
/**
@@ -88,7 +89,7 @@ export class CustomTile extends ImageTile {
* @property {number} [tilePixelRatio] The pixel ratio used by the tile service. For example, if the tile service advertizes 256px by 256px tiles but actually sends 512px by 512px images (for retina/hidpi devices) then `tilePixelRatio` should be set to `2`
* @property {number} [reprojectionErrorThreshold=0.5] Maximum allowed reprojection error (in pixels).
* Higher values can increase reprojection performance, but decrease precision.
* @property {string} [url] URL template or base URL of the Zoomify service.
* @property {string} url URL template or base URL of the Zoomify service.
* A base URL is the fixed part
* of the URL, excluding the tile group, z, x, and y folder structure, e.g.
* `http://my.zoomify.info/IMAGE.TIF/`. A URL template must include
@@ -100,7 +101,7 @@ export class CustomTile extends ImageTile {
* A `{?-?}` template pattern, for example `subdomain{a-f}.domain.com`, may be
* used instead of defining each one separately in the `urls` option.
* @property {string} [tierSizeCalculation] Tier size calculation method: `default` or `truncated`.
* @property {import("../size.js").Size} [size] Size of the image.
* @property {import("../size.js").Size} size
* @property {import("../extent.js").Extent} [extent] Extent for the TileGrid that is created.
* Default sets the TileGrid in the
* fourth quadrant, meaning extent is `[0, -height, width, 0]`. To change the
@@ -125,11 +126,11 @@ export class CustomTile extends ImageTile {
class Zoomify extends TileImage {
/**
* @param {Options=} opt_options Options.
* @param {Options} opt_options Options.
*/
constructor(opt_options) {
const options = opt_options || {};
const options = opt_options;
const size = options.size;
const tierSizeCalculation = options.tierSizeCalculation !== undefined ?
@@ -196,7 +197,7 @@ class Zoomify extends TileImage {
}
const urls = expandUrl(url);
const tileWidth = tileSize * tilePixelRatio;
let tileWidth = tileSize * tilePixelRatio;
/**
* @param {string} template Template.
@@ -259,6 +260,19 @@ class Zoomify extends TileImage {
*/
this.zDirection = options.zDirection;
// Server retina tile detection (non-standard):
// Try loading the center tile for the highest resolution. If it is not
// available, we are dealing with retina tiles, and need to adjust the
// tile url calculation.
const tileUrl = tileGrid.getTileCoordForCoordAndResolution(getCenter(tileGrid.getExtent()), resolutions[resolutions.length - 1]);
const testTileUrl = tileUrlFunction(tileUrl, 1, null);
const image = new Image();
image.addEventListener('error', function() {
tileWidth = tileSize;
this.changed();
}.bind(this));
image.src = testTileUrl;
}
}