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Add support for getAsync(opts)
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Allows arbitrary parameters for the tilelive's getTile/Grid/Info interface
As discussed in mapbox/tilelive#189
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Yuri Astrakhan committed Apr 3, 2017
1 parent 8589c71 commit fe89f09
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Showing 2 changed files with 93 additions and 38 deletions.
127 changes: 89 additions & 38 deletions backend.js
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ var crypto = require('crypto');
var mapnik = require('mapnik');
var util = require('util');
var sm = new (require('sphericalmercator'))();
var uptile = require('tilelive-promise');

module.exports = Backend;

Expand Down Expand Up @@ -35,64 +36,114 @@ function Backend(opts, callback) {
backend._fillzoom = 'fillzoom' in info && !isNaN(parseInt(info.fillzoom, 10)) ?
parseInt(info.fillzoom, 10) :
undefined;
backend._source = source;
backend._source = uptile(source);
if (callback) callback(null, backend);
}
};

Backend.prototype.getAsync = function(opts) {
let self = this;
return new Promise((accept, reject) => {
try {
if (!self._source) {
throw new Error('Tilesource not loaded');
}
let result;
switch (opts.type) {
case undefined:
case 'tile':
result = _getTile.call(self, opts);
break;
default:
result = self._source.getAsync(opts);
break;
}
accept(result);
} catch (err) {
reject(err);
}
});
};

Backend.prototype.getInfo = function(callback) {
if (!this._source) return callback(new Error('Tilesource not loaded'));
this._source.getInfo(callback);
this.getAsync({type: 'info'}).then(res => {
callback(undefined, res.info);
}, err => {
callback(err);
});
};

// Wrapper around backend.getTile that implements a "locking" cache.
// handle additional parameters attached to callback
Backend.prototype.getTile = function(z, x, y, callback) {
if (!this._source) return callback(new Error('Tilesource not loaded'));
this.getAsync({
z: z,
x: x,
y: y,
legacy: callback.legacy,
scale: callback.scale,
upgrade: callback.upgrade,
setSrcData: callback.setSrcData
}).then(res => {
callback(undefined, res.tile, res.headers);
}, err => {
callback(err);
});
};

// Wrapper around backend.getTile that implements a "locking" cache.
function _getTile(opts) {
var backend = this;

return new Promise((accept, reject) => {
var z = opts.z, x = opts.x, y = opts.y;
if (z < 0 || x < 0 || y < 0 || x >= Math.pow(2,z) || y >= Math.pow(2,z)) {
return callback(new Error('Tile does not exist'));
return reject(new Error('Tile does not exist'));
}
var backend = this;
var source = backend._source;
var now = +new Date;
var legacy = callback.legacy || false;
var scale = callback.scale || backend._scale;
var upgrade = callback.upgrade || false;
var legacy = opts.legacy || false;
var scale = opts.scale || backend._scale;
var upgrade = opts.upgrade || false;

// If scale > 1 adjusts source data zoom level inversely.
// scale 2x => z-1, scale 4x => z-2, scale 8x => z-3, etc.
if (legacy && z >= backend._minzoom) {
var d = Math.round(Math.log(scale)/Math.log(2));
var bz = (z - d) > backend._minzoom ? z - d : backend._minzoom;
var bx = Math.floor(x / Math.pow(2, z - bz));
var by = Math.floor(y / Math.pow(2, z - bz));
opts.z = (z - d) > backend._minzoom ? z - d : backend._minzoom;
opts.x = Math.floor(x / Math.pow(2, z - opts.z));
opts.y = Math.floor(y / Math.pow(2, z - opts.z));
} else {
var bz = z | 0;
var bx = x | 0;
var by = y | 0;
opts.z = z | 0;
opts.x = x | 0;
opts.y = y | 0;
}

var size = 0;
var headers = {};

// Overzooming support.
if (bz > backend._maxzoom) {
bz = backend._maxzoom;
bx = Math.floor(x / Math.pow(2, z - bz));
by = Math.floor(y / Math.pow(2, z - bz));
if (opts.z > backend._maxzoom) {
opts.z = backend._maxzoom;
opts.x = Math.floor(x / Math.pow(2, z - opts.z));
opts.y = Math.floor(y / Math.pow(2, z - opts.z));
headers['x-vector-backend-object'] = 'overzoom';
}

source.getTile(bz, bx, by, function sourceGet(err, body, head) {
source.getAsync(opts).catch(function onGetTileError(err) {
if (typeof backend._fillzoom === 'number' &&
err && err.message === 'Tile does not exist' &&
bz > backend._fillzoom) {
bz = backend._fillzoom;
bx = Math.floor(x / Math.pow(2, z - bz));
by = Math.floor(y / Math.pow(2, z - bz));
opts.z > backend._fillzoom) {
opts.z = backend._fillzoom;
opts.x = Math.floor(x / Math.pow(2, z - opts.z));
opts.y = Math.floor(y / Math.pow(2, z - opts.z));
headers['x-vector-backend-object'] = 'fillzoom';
return source.getTile(bz, bx, by, sourceGet);
return source.getAsync(opts).catch(onGetTileError);
}
if (err && err.message !== 'Tile does not exist') return callback(err);
if (err.message !== 'Tile does not exist') throw err;
return {};
}).then(result => {
var body = result.tile;
var head = result.headers;

if (body instanceof mapnik.VectorTile) {
size = body._srcbytes;
Expand All @@ -115,7 +166,7 @@ Backend.prototype.getTile = function(z, x, y, callback) {
headers = head || {};
return makevtile(body, 'pbf');
// Image sources do not allow overzooming (yet).
} else if (bz < z && headers['x-vector-backend-object'] !== 'fillzoom') {
} else if (opts.z < z && headers['x-vector-backend-object'] !== 'fillzoom') {
headers['x-vector-backend-object'] = 'empty';
return makevtile();
} else {
Expand All @@ -141,34 +192,34 @@ Backend.prototype.getTile = function(z, x, y, callback) {
headers['x-vector-backend-object'] = headers['x-vector-backend-object'] || 'default';

// Pass-thru of an upstream mapnik vector tile (not pbf) source.
if (data instanceof mapnik.VectorTile) return callback(null, data, headers);
if (data instanceof mapnik.VectorTile) return accept({tile: data, headers: headers});

var vtile = new mapnik.VectorTile(bz, bx, by);
var vtile = new mapnik.VectorTile(opts.z, opts.x, opts.y);
vtile._srcbytes = size;
if (callback.setSrcData) vtile._srcdata = data;
if (opts.setSrcData) vtile._srcdata = data;

// null/zero length data is a solid tile be painted.
if (!data || !data.length) return callback(null, vtile, headers);
if (!data || !data.length) return accept({tile: vtile, headers: headers});

try {
if (type === 'pbf') {
// We use addData here over setData because we know it was just created
// and is empty so skips a clear call internally in mapnik.
vtile.addData(data,{upgrade:upgrade},function(err) {
if (err) return callback(err);
return callback(null, vtile, headers);
if (err) return reject(err);
return accept({tile: vtile, headers: headers});
});
} else {
vtile.addImageBuffer(data, backend._layer, function(err) {
if (err) return callback(err);
return callback(null, vtile, headers);
if (err) return reject(err);
return accept({tile: vtile, headers: headers});
});
}
} catch (err) {
return callback(err);
return reject(err);
}
};
};
})};

// Proxies mapnik vtile.query method with the added convienice of
// letting the tilelive-vector backend do the hard work of finding
Expand Down
4 changes: 4 additions & 0 deletions package.json
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,9 @@
"type": "BSD"
}
],
"contributors": [
"Yuri Astrakhan <YuriAstrakhan@gmail.com>"
],
"dependencies": {
"aws-sdk": "^2.2.30",
"s3urls": "^1.3.0",
Expand All @@ -23,6 +26,7 @@
"numeral": "~1.5.3",
"sphericalmercator": "~1.0.5",
"spherical": "~0.1.0",
"tilelive-promise": "^1.0.5",
"underscore": "~1.8.0"
},
"devDependencies": {
Expand Down

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