'use strict'

var str2arr = require('../common').str2arr

var sliceEq = require('../common').sliceEq

var readInt16LE = require('../common').readInt16LE

var readInt32LE = require('../common').readInt32LE

var readUInt32LE = require('../common').readUInt32LE

var SIG_BM = str2arr('BM')

module.exports = function (data) {

if (data.length < 26) return

if (!sliceEq(data, 0, SIG_BM)) return

var h

var w

var headerSize = readUInt32LE(data, 14)

if (headerSize === 12) {

// BMP v2 header

w = readInt16LE(data, 18)

h = readInt16LE(data, 20)

} else if (headerSize > 12) {

// BMP v3+ header

w = readInt32LE(data, 18)

h = readInt32LE(data, 22)

} else {

// BPM v1 and other garbage (10 bytes usually)

return

}

return {

width: w,

// Height can be negative to indicate a top-down bitmap

height: Math.abs(h),

type: 'bmp',

mime: 'image/bmp',

wUnits: 'px',

hUnits: 'px'

}

}