#Express Resizer

Resizes images on the fly and stores them in a cache directory for later usage. You can define presets that provide source and target directories and image manipulation functions. Express-Resizer is an Express app that can be mounted on an existing app.

##Status

Working but not tested in production. API might change.

##Installation

npm install express-resizer

##Usage

###Resizer and Presets

First you need to define a Resizer app that is the home for your presets.

var Resizer = require("express-resizer");
var myResizer = new Resizer(__dirname + "/public");

Then you attach some Presets to the Resizer:

myResizer.attach("squareThumbs")
    .from("/uploads")
    .resizeAndCrop({
        width: 100,
        height: 100,
    })
    .quality(50)
    .to("/thumbs");

myResizer.attach("preview")
    .from("/uploads")
    .resize({
        width: 600,
        height: 600,
    })
    .quality(75)
    .to("/preview");

Then use it as a middleware in your app:

var app = express();
app.use(myResizer);

###new(publicDir)

Initialize a new Resizer object with a public directory.

###attach(presetName)O

Attaches a new preset to a resizer. A name is required, because this is used to generate view helpers.

###from(sourceDirectory)

Defines the directory where your source files are located relatively to the public directory.

###to(targetDirectory)

Defines the where the resized images should be stored relatively to the public directory.

Attention: this freezes the preset object and should therefore be called as your last action.

###resize(options)

Scales the source image to fit within the specified dimensions. Options can contain width and height. In most cases one side of the image will be smaller than the specified dimensions.

###resizeAndCrop(options)

Scales and crops the source image to fill the specified dimensions. Options can contain width, height and gravity. The dimensions of the image will be exactly the specified dimensions. Images are cropped from the center if you do not specify a gravity.

gravity can be center, northwest, north, ....

##Stale caches

Resizer checks the modified date for a file and if the source is newer than the cached image will be regenerated. Therefore it's essential that the Resizer middleware is used before any static file server.

##Views Helper

In your views you can generate a path to your presets with automatically generated helper functions that follow the scheme: PresetNamePath and PresetNameImage

img.thumb(src="#{squareThumbPath("/uploads/test.jpg")}") // /thumbs/test.jpg
!#{squareThumbImage("/uploads/test.jpg", "Thumb")        // <img src="/thumbs/test.jpg" alt="Thumb">

img.preview(src="#{PreviewPath("/uploads/test.jpg)}")    // /preview/test.jpg
!#{previewImage("/uploads/test.jpg", "Preview")          // <img src="/preview/test.jpg" alt="Preview">

##CleanUp Caches

You have two options to clean file caches:

###Clear all files from a Preset

var Resizer = require("express-resizer");
var myResizer = new Resizer(__dirname + "/public");

//attach a preset
myResizer.attach("squareThumbs")
    .from("/uploads")
    .resizeAndCrop({
        width: 100,
        height: 100,
    })
    .quality(50)
    .to("/thumbs");

//use the middleware
var app = express();
app.use(myResizer);

//clear a preset
app.resizer.clearSquareThumb(function (err) {});

Now all cached images in the thumbs folder or deleted.

###Delete all image caches for a file

var Resizer = require("express-resizer");
var myResizer = new Resizer(__dirname + "/public");

//attach a preset
myResizer.attach("squareThumbs")
    .from("/uploads")
    .resizeAndCrop({
        width: 100,
        height: 100,
    })
    .quality(50)
    .to("/thumbs");

//use the middleware
var app = express();
app.use(myResizer);

//clear all file caches for test.png
app.resizer.clear("/uploads/subfolder/test.png", function (err) {});