imagecache

#Imagecache

What is it?

Node image generation module based on CamanJS and inspired by Drupal's image styles.

Installation

Linux prerequisites

• aptitude install libcairo-dev libgif-dev libjpeg-dev

Mac OS X prerequisites

It's quite painful, be warned.

• Install X Server (http://xquartz.macosforge.org/trac/wiki/X112.7.6).
• Install X Code (https://itunes.apple.com/gb/app/xcode/id497799835?mt=12) and command line tools.
• Install Homebrew (https://github.com/Homebrew/homebrew/wiki/Installation).
• export PKG_CONFIG_PATH=/opt/X11/lib/pkgconfig.
• Install Cairo from source: brew install --build-from-source cairo.

Usage

var presets = require('./presets.js');
var ImageCache = require('imagecache');

var imagecache = new ImageCache(presets);

imagecache.render('./in.png', 'preset_one', function (err, image) {
  // Save the image
  image.save('out_s_crop_teaser.png');

  // or

  // Get a buffer, stream it etc
  image.canvas.toBuffer();
})

Presets structure

{
  preset_one: {
    presetname: 'preset_one',
    actions: [
      {
        action: 'scale_and_crop',
        config: {
          width: 100,
          height: 300
        }
      },
      {
        action: 'define_canvas',
        config: {
          color: '#333333',
          exact: {
            width: 400,
            height: 400,
            xpos: 'center',
            ypos: 'center'
          }
        }
      }
    ]
  },
  preset_two: {
    presetname: 'preset_two',
    actions: [
      {
        action: 'scale_and_crop',
        config: {
          width: 70,
          height: 70,
        }
      }
    ]
  }
}

Creating plugins

Breeze is used for plugin management. There are two types of plugins available:

• Utility plugins that add functions to be used by other plugins. For example see plugins/_converters.js that adds utility functions for parsing parameters that are used by all other plugins.
• Action plugins that expose one or more functions that implement actions.

For example, a plugin that implements the sharpen action will attach a sharpen function to the plugin registry. The function signature is image, config, callback where image is the CamanJS object, config is the action configuration from the preset and callback is the function that triggers the completion of the action.

var self = module.exports = {
  attach: function (options) {
    this.sharpen = function (image, config, callback) {
      var value = this.convertInt(config.value);

      if (value > 100) {
        value = 100;
      }
      if (value < 0) {
        value = 0;
      }

      image.sharpen(value);
      callback();
    };
  }
};

##Imagecache actions:

• Brightness [✓]
• Crop [✓]
• Define canvas [✓]
• Desaturate [✓]
• Negative image [✓]
• Resize [✓]
• Scale [✓]
• Scale and crop [✓]
• Sharpen [✓]
• Contrast [✓]
• Clip [✓]
• Colorize [✓]
• Exposure [✓]
• Gamma [✓]
• Hue [✓]
• Noise [✓]
• Saturation [✓]
• Sepia [✓]
• Vibrance [✓]
• Curves [✓]
• Overlay (watermark) [✓]
• CamanJS filters (vintage, lomo, clarity, sinCity, sunrise, crossProcess, orangePeel, love, grungy, jarques, pinhole, oldBoot, glowingSun, hazyDays, herMajesty, nostalgia, hemingway, concentrate) [✓]

Legend:

• [✓] - Implemented
• [✗] - Will not be implemented
• [] - Not implemented yet