sharper

Automatic image processor built on top of sharp and multer for express.

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How does it work?

When you are working on a website which needs to create multiple size copies of a single image uploaded by user, resize | crop | process and finally upload in a dynamic directory based on current date or time, then this module will save your entire lifetime.

Basically, this module provide an express middleware that do all above things at once. If something goes wrong, you can catch it in error middleware. You need to provide few options that will tell sharper about location of upload, dynamic date format for upload folder to be created, accepted image types, upload size limits, output format, and output sizes with prefixes etc.

This module is based on sharp node-js module for image processing. It's the fastest module there is and based on libvips library.

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Install

npm install --save sharper

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Configure

set options

const sharper = require('sharper');
var Sharper = sharper({
    field : 'file',
    location : '/var/www/uploads/',
    dirFormat : 'yyyy/mmm/d',
    maxFileSize: '20mb',
    fileNameLen : 50,
    accept : ['jpeg', 'jpg', 'png'],
    output : 'jpg',
    sizes : [
        {suffix : 'xlg', width : 1200, height : 1200},
        {suffix : 'lg', width : 800, height : 800},
        {suffix : 'md', width : 500, height : 500},
        {suffix : 'sm', width : 300, height : 300},
        {suffix : 'xs', width : 100, height : 100},
    ]
});

add middleware

app.post('/upload', Sharper, function(err, req, res, next){
    console.log(err);
    res.status(500).send('upload failed...');
}, function(req, res){
    console.log(res.sharper);
    res.send('upload successful...');
});

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Options

var Sharper = sharper(options);

sharper options

option	default	role
field	'file'	input file field in multipart form data. ex. <input type="file" name="file"/>
location	'/var/www/html/'	upload directory.
dirFormat	'yyyy/mmm/d'	date pattern to follow for folder creation for image storage. Explore formats at [node-format module](https://github.com/felixge/node-dateformat#mask-options)
fileNameLen	50	length of the output image filename.
maxFileSize	'10mb'	maximum size of input/upload file to accept.
accept	['png','jpeg','jpg']	array of file types/extensions to accept.
output	'jpg'	type of output file to produce. valid options : jpg, png, gif, webp, tiff, bmp
sizes	[{suffix : 'lg', width : 500, height:500}]	sizes of output images with filename suffix. ex. output-name.lg.jpg

sharp options

Please visit this sharp sharp for detailed overview of specific option.

option	default	role
resize	true	resize images as per their sizes mentioned in options.sizes
crop	false	crop images as per their sizes mentioned in options.sizes
background	{r	200
embed	false	embed on canvas
max	false	set maximum output dimension
min	false	set minimum output dimension
withoutEnlargement	false	do not enlarge small images
ignoreAspectRatio	false	ignore aspect ration while resizing images
extract	false	extract specific part of image
trim	false	Trim boring pixels from all edges
flatten	false	Merge alpha transparency channel, if any, with background.
extend	false	Extends/pads the edges of the image with background.
negate	false	Produces the negative of the image.
rotate	false	Rotate the output image by either an explicit angle
flip	false	Flip the image about the vertical Y axis.
flop	false	Flop the image about the horizontal X axis.
blur	false	Mild blur of the output image
sharpen	false	Mild sharpen of the output image
gamma	false	Apply a gamma correction.
grayscale or greyscale	false	Convert to 8-bit greyscale; 256 shades of grey.
normalize or normalise	false	Enhance output image contrast by stretching its luminance to cover the full dynamic range.
progressive	false	Use progressive (interlace) scan for JPEG and PNG output.
quality	false	The output quality to use for lossy JPEG, WebP and TIFF output formats. The default quality is 80.

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Errors

You can catch errors in error middleware as shown previously. err object includes (but not limited to) following error codes (key code).

code	role
FILE_TYPE_UNSUPPORTED	Input file type is not acceptable to process. check accept option.
LIMIT_FILE_SIZE	Input file size is too large. Check maxFileSize option.

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Success

Upon successful upload, sharper will add sharper object in res response object. It will have following properties.

key	role
dir	dir that was created for storing process image.
destination	absolute path of storage destination.
filename	name of the image files created using sharper.

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Test

• Open terminal and run node test-server.js in demo folder of this module.
• Open your browser and go to http://localhost:8800.
• Upload a photo by clicking on dropzone.
• If upload sucessfully completes, check upload directory /var/www/html.
• If error occurs, check your terminal.