Files
node-mbtiles/lib/utils.js
2011-06-28 16:47:23 +02:00

78 lines
2.1 KiB
JavaScript

var util = require('util'),
EventEmitter = require('events').EventEmitter,
utils = {};
utils.table = function(fields) {
if (!fields[0]) return;
var lengths = fields[0].map(function(val, i) {
return Math.max.apply(Math, fields.map(function(field) {
if (field[i] === undefined) field[i] = '';
return field[i].toString().length;
}));
});
fields.forEach(function(field) {
console.warn(
field.map(function(val, i) {
if (i >= lengths.length - 1) return val;
return val + Array(lengths[i] - val.toString().length + 1).join(' ');
}).join(' ')
);
});
};
utils.getMimeType = function(data) {
if (data[0] === 0x89 && data[1] === 0x50 && data[2] === 0x4E &&
data[3] === 0x47 && data[4] === 0x0D && data[5] === 0x0A &&
data[6] === 0x1A && data[7] === 0x0A) {
return 'image/png';
} else if (data[0] === 0xFF && data[1] === 0xD8 &&
data[data.length - 2] === 0xFF && data[data.length - 1] === 0xD9) {
return 'image/jpeg';
} else if (data[0] === 0x47 && data[1] === 0x49 && data[2] === 0x46 &&
data[3] === 0x38 && (data[4] === 0x39 || data[4] === 0x37) &&
data[5] === 0x61) {
return 'image/gif';
}
};
function Queue(callback, concurrency) {
this.callback = callback;
this.concurrency = concurrency || 10;
this.next = this.next.bind(this);
this.invoke = this.invoke.bind(this);
this.queue = [];
this.running = 0;
}
util.inherits(Queue, EventEmitter);
Queue.prototype.add = function(item) {
this.queue.push(item);
if (this.running < this.concurrency) {
this.running++;
this.next();
}
};
Queue.prototype.invoke = function() {
if (this.queue.length) {
this.callback(this.queue.shift(), this.next);
} else {
this.next();
}
};
Queue.prototype.next = function(err) {
if (this.queue.length) {
process.nextTick(this.invoke);
} else {
this.running--;
if (!this.running) {
this.emit('empty');
}
}
};
utils.Queue = Queue;
module.exports = utils;