/*!
* Stylus - plugin - url
* Copyright(c) 2010 LearnBoost <dev@learnboost.com>
* MIT Licensed
*/
/**
* Module dependencies.
*/
var utils = require('../utils')
, nodes = require('../nodes')
, fs = require('fs');
/**
* Initialize a new `Image` with the given `ctx` and `path.
*
* @param {Evaluator} ctx
* @param {String} path
* @api private
*/
var Image = module.exports = function Image(ctx, path) {
this.ctx = ctx;
this.path = utils.lookup(path, ctx.paths);
if (!this.path) throw new Error('failed to locate file ' + path);
};
/**
* Open the image for reading.
*
* @api private
*/
Image.prototype.open = function(){
this.fd = fs.openSync(this.path, 'r');
};
/**
* Close the file.
*
* @api private
*/
Image.prototype.close = function(){
if (this.fd) fs.closeSync(this.fd);
};
/**
* Return the type of image, supports:
*
* - gif
* - png
* - jpeg
*
* @return {String}
* @api private
*/
Image.prototype.type = function(){
var type
, buf = new Buffer(4);
fs.readSync(this.fd, buf, 0, 4, 0);
// GIF
if (0x47 == buf[0] && 0x49 == buf[1] && 0x46 == buf[2]) type = 'gif';
// PNG
else if (0x50 == buf[1] && 0x4E == buf[2] && 0x47 == buf[3]) type = 'png';
// JPEG
else if (0xff == buf[0] && 0xd8 == buf[1]) type = 'jpeg';
return type;
};
/**
* Return image dimensions `[width, height]`.
*
* @return {Array}
* @api private
*/
Image.prototype.size = function(){
var type = this.type()
, width
, height
, buf;
function uint16(b) { return b[1] << 8 | b[0]; }
function uint32(b) { return b[0] << 24 | b[1] << 16 | b[2] << 8 | b[3]; }
// Determine dimensions
switch (type) {
case 'jpeg':
throw new Error('image-size() jpeg support not yet implemented');
break;
case 'png':
buf = new Buffer(8);
// IHDR chunk width / height uint32_t big-endian
fs.readSync(this.fd, buf, 0, 8, 16);
width = uint32(buf);
height = uint32(buf.slice(4, 8));
break;
case 'gif':
buf = new Buffer(4);
// width / height uint16_t little-endian
fs.readSync(this.fd, buf, 0, 4, 6);
width = uint16(buf);
height = uint16(buf.slice(2, 4));
break;
}
if ('number' != typeof width) throw new Error('failed to find width of "' + this.path + '"');
if ('number' != typeof height) throw new Error('failed to find height of "' + this.path + '"');
return [width, height];
};