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Allow arbitrary scales to be specified, e.g. @4.2x (particularly useful for static api and printing) #36

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Allow arbitrary scales to be specified, e.g. @4.2x (particularly useful for static api and printing) #36

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e6bfccb
Allow arbitrary scale to be specified, e.g. @4.2x (particularly usefu…
samwillis Jan 4, 2016
80f7bbc
Merge remote-tracking branch 'mojodna/master'
samwillis Jun 9, 2016
128988c
Merge remote-tracking branch 'mojodna/master'
samwillis Aug 29, 2017
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46 changes: 39 additions & 7 deletions lib/app.js
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@ var tessera = require("./index");
debug = debug("tessera");

var FLOAT_PATTERN = "[+-]?(?:\\d+|\\d+\.?\\d+)";
var SCALE_PATTERN = "@[23]x";
var SCALE_PATTERN = "@(?:\\d+|\\d+\.?\\d+)x";

// TODO a more complete implementation of this exists...somewhere
var getExtension = function(format) {
Expand All @@ -33,7 +33,7 @@ var getExtension = function(format) {
};

var getScale = function(scale) {
return (scale || "@1x").slice(1, 2) | 0;
return parseFloat((scale || "@1x").slice(1));
};

var normalizeHeaders = function(headers) {
Expand Down Expand Up @@ -121,18 +121,50 @@ module.exports = function(tilelive, options) {
1: uri
};

[2, 3].forEach(function(scale) {
var retinaURI = clone(uri);
// We cache 100 sourceURIs, randomly evict when over limit
var sourceURIsCacheKeys = [];
var sourceURIsCacheSizeLimit = 100;

var makeScaledSourceURI = function(scale, permanent) {
var retinaURI = clone(uri),
randomIndex;

retinaURI.query.scale = scale;
// explicitly tell tilelive-mapnik to use larger tiles
retinaURI.query.tileSize = scale * 256;

retinaURI.query.tileSize = (scale * 256) | 0;

if (!permanent) {
// Save the URI to the uri cache, but limit its size
while (sourceURIsCacheKeys.length > sourceURIsCacheSizeLimit) {
// Delete random sourceURI
randomIndex = Math.floor(Math.random()*sourceURIsCacheKeys.length);
delete sourceURIs[sourceURIsCacheKeys[randomIndex]];
sourceURIsCacheKeys.splice(randomIndex, 1);
}
sourceURIsCacheKeys.push(scale);
}
sourceURIs[scale] = retinaURI;

return retinaURI;
};

// make scaled source urls for retina @2x and @3x
[2, 3].forEach(function(scale) {
// these are not added to sourceURIsCacheKeys so that they are not ever removed from the cache
makeScaledSourceURI(scale, true);
});

var getSourceURI = function(scale) {
if (scale in sourceURIs) {
return sourceURIs[scale];
} else {
// scaled uri does not exist so we make one
return makeScaledSourceURI(scale);
}
};

var getTile = function(z, x, y, scale, format, callback) {
var sourceURI = sourceURIs[scale],
var sourceURI = getSourceURI(scale),
params = {
tile: {
zoom: z,
Expand Down