A PHP command line tool for converting SVG images to a set of CSS icons (SVG & PNG, single icons and / or CSS sprites) with support for image optimization and Sass output

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Language: CSS

v1.0.2 2014-02-28 11:01 UTC



is an – at present: proof-of-concept – command line tool that helps you prepare your vector based SVG icons for use with the widest possible range of devices. It takes a folder of SVG files and processes them to a bunch of files including

To leverage iconizr to the greatest extent possible, some additional tools have to be installed on the system independently (see below).

iconizr is written in (namespaced) PHP and meant to be used on the (Linux) command line (i.e. with the PHP CLI SAPI). To be honest, there was only one reason making me go for PHP: It is what I know best. Im sure there are quite some other fancy modern languages and techniques one could use for achieving the same, but I guess I'm just not smart enough for those. Having said this, I'd welcome anyone contributing a port of iconizr.

Getting started

As iconizr is written in PHP, there's nothing much of an installation process. Just put the iconizr.phps script (along with it's accompanying files and directories) to a location of your liking and make sure that it may be executed by setting the proper file permissions. If you'd like to simplify the invocation of iconizr you might create a symlink into your local executables directory, e.g.:

ln -s /path/to/iconizr.phps /usr/local/bin/iconizr

Run iconizr by calling the script with the apropriate command line options (see below). Please consider that – for security reasons – the output directory has to be a sub(sub)directory of the current working directory, so change your working directory first if necessary:

cd /path/to/website/docroot
/path/to/iconizr.phps --css --out css source/svg

or using the symlink mentioned above:

iconizr --css --out css source/svg

This will take all the SVG files found in /path/to/website/docroot/source/svg and render the resulting CSS files and sprites to the directory /path/to/website/docroot/css (and below). For the sake of simplicity, Sass files have been omitted in this example.



iconizr [options] input/dir1 [input/dir2 ...]
Short Long Value Description
-o --out Directory path Provide the path of the output directory here. For security reasons, the output directory has to be a sub(sub)directory of the current working directory. If it doesn't exist, iconizr will try to create it. Along with the input directory this is a mandatory argument.
--sassout Directory path If you want the Sass files to be created in a separate directory, then specify it using this argument. The same restrictions apply as for the standard output directory. If you don't specify this argument, the Sass files will be created in the standard output directory.
-c --css String (optional) If this argument is given, several CSS files will be generated. By default, the filenames will all start with "iconizr" (e.g. "iconizr-svg-data.css"). If you provide a string value for this argument (e.g. "myproject"), this value will be used as the prefix for all generated CSS files (e.g. "myproject-svg-data.css").
-s --sass String (optional) Identical to the -c argument, but applying to the generation of Sass files.
-p --prefix String This is the prefix used for all CSS class names generated. It defaults to "icon", so that a SVG file named example.svg results in a CSS class named "icon-example".
-l --level Integer This is the optimization level for PNG files. It has to lie between 0 and 11 (inclusive) and defaults to 4, with 0 meaning "no optimization", 1 meaning "fast & rough" and 11 meaning "slow & high quality". Setting this to a high value may result in a very long processing time.
-q --quantize If given, iconizr will quantize PNG images (i.e. convert them to 8-bit color depth; please see the requirements for this). The quantized images are only used if they are smaller in file size than their the originals (and this is not necessarily the case for all PNG files). Quantization may also impact the visual image quality, so please make sure to compare the result to the original images.
-e --embed If given, iconizr will use this value as a prefix to the CSS directory path used to embed the stylesheets into your HTML documents (inside the JavaScript loader fragment). By default, the --out directory will be used as a root-relative path (i.e. giving path/to/css as --out directory will result in e.g. /path/to/css/weather-svg-sprite.css as CSS embed path). You may specify a period . here to make the embed path relative to your HTML document (i.e. ./path/to/css/weather-svg-sprite.css), or use any other arbitrary relative path (e.g. ../resources for the embed path ../resources/path/to/css/weather-svg-sprite.css).
--svg Integer This is the maximum length a SVG data URI may have. If only one icon exceeds this threshold, all data URIs of this icon set will be changed to external SVG sprite references. Defaults to 1048576 (1MB), minimum is 1024 (1kB).
--png Integer This is the maximum length a PNG data URI may have. If only one icon exceeds this threshold, all data URIs of this icon set will be changed to external PNG sprite references. Defaults to 32768 (32KB = Internet Explorer 8 limit), minimum is 1024 (1kB).
-d --dims If given, a second CSS rule for each icon will be created, setting the dimensions of the icon (via the width and height properties).
--width Integer Default width for icons (in pixels) in case the SVG file is missing a value. Must be between 1 and the maximum width (including).
--height Integer Default height for icons (in pixels) in case the SVG file is missing a value. Must be between 1 and the maximum height (including).
--maxwidth Integer Maximum width for icons (in pixels). Defaults to 1000.
--maxheight Integer Maximum height for icons (in pixels). Defaults to 1000.
--padding Integer Transparent padding to be added around each icon (in pixels). Defaults to 0.
--pseudo String You may bind an icon to a particular CSS pseudo class (like e.g. :hover, :active, :target). To do so, just append the desired pseudo class to the icon name, separated by a tilde ~. For instance, an icon named foo-bar~hover.svg will result in a CSS class icon-foo-bar:hover. If you need to use another delimiter than a tilde ~, just use this parameter to provide your custom string.
-k --keep During the compilation of the SVG and PNG sprites, iconizr also creates intermediate SVG and PNG versions of each single icon. Usually, these intermediate files are deleted at the end of the compilation process. If you want to keep these files for some reason, just add this argument.
In this case, also an additional set of stylesheets will be created (both CSS and/or Sass), which uses these single image icons (carrying the suffix -single.html). However, it is not recommended to use these stylesheets for production systems, and you should always prefer the CSS sprite or data URI variants for performance reasons. The single image icon stylesheets will also be ignored by the stylesheet loader JavaScript, but at least you will be able to select them explicitly using the icon kit preview documents.
-v --verbose Integer (optional) By default, iconizr operates quietly without any output. If you specify this argument (optionally using the value "1"), some simple status messages will be printed. Use "2" as value to even print the console output of the external tools being used (like e.g. pngcrush or pngquant).
--scour String iconizr can use either SVGO or Scour for cleaning the original SVG files. As far as I can tell, Scour yields slightly better results (i.e. smaller SVG files) than SVGO. As Scour is rather a Python script than an executable, you need to provide the full script path via this option if you want to use it (also, of course, Python has to be available on the system; see requirements).
--python String When using Scour for cleaning the original SVG files, you need to have Python 2 handy, as Scour is based on this version and hasn't been updated for quite a while. If your default Python binary is not version 2, you need to specify the absolute path to an alternative version 2 binary with this parameter.

CSS pseudo classes

As of Beta 5 iconizr supports CSS pseudo classes (like e.g. hover or active states) for individual icons. To bind an icon to a specific pseudo class, just append it as a suffix to the icon file name, separated by the string specified with the --pseudo parameter (defaults to a tilde ~). For example, two icon files named


would result in the CSS rules

    icon-foo-bar { ... }
    icon-foo-bar:hover { ... }

This way you can easily achieve a normal and a hover state for an icon. In general, any conceivable pseudo class can be generated like this, as long as the involved characters are allowed in file names on your system. In fact, iconizr isn't aware of what is a real CSS pseudo class and what isn't, it's just dumb delimiter-to-colon substitution ... These could be some reasonable examples:


The storm icon included in this package is an example for an icon with hover state:

Normal storm icon Thunderstorm icon

In the HTML preview documents both icons will be shown, but also if you hover over the regular one, you will see it's hover state as well.

For every pseudo class iconizr also adds an additional CSS selector which you can use to explicitly apply the stateful icon styles to an element (independently from the element's real state). Starting with version v0.1.2 iconizr even adds such a selector for the regular icon state (which doesn't have a pseudo class by design), so you can also use this icon variant without letting the other pseudo classes become effective:

    icon-foo-bar, icon-foo-bar\:regular { ... }
    icon-foo-bar:hover, icon-foo-bar\:hover { ... }

To apply these icon styles to HTML elements just use them like this:

    <span class="icon-foo-bar:regular">Regular icon state</span>
    <span class="icon-foo-bar:hover">Hover icon state</span>

It may seem weird to use colons als parts of CSS class names, but in fact it's perfectly legal – you just have to escape the colons in your CSS files using a backslash \.

Comparison to grunticon

While doing pretty much the same as the Filament Group's / Scott Jehl's grunticon, iconizr especially focuses on reducing the size of files and number of HTTP requests, addressing mobile devices in particular:

  1. SVG files are cleaned and freed from a lot of cruft typically introduced by SVG editing application before they get converted to data URIs or embedded into the SVG sprite.
  2. PNG files are losslessly optimized (and optionally quantized to 8-bit files) before being used in data URIs or the PNG sprite.
  3. As soon as even one of the icons needs to be loaded externally (due to exceeding a potential data URI size limitation), all icons will get loaded via the corresponding sprite.

Evtl. kein Limit für data-URIs bei SVG? Welcher Browser mit SVG-Support hat das kleinste data-URI-Limit?

Rendering mode grunticon iconizr
PNG images / sprite Requests 11 2
Size (KB) 33.3 / 31.2 20.0 / 21.1
PNG data URI Requests 1 1
Size (KB) 30.1 / 41.1 20.3 / 29.7
SVG sprite Requests - 2
Size (KB) - 42.8 / 496.0
SVG data URI Requests 1 1
Size (KB) 126.0 / 1,913.0 49.4 / 720.0


For iconizr to run, you will need some programs installed on your machine. These are:

  • PHP (kinda obvious)
  • PhantomJS (for rendering PNG images of your SVG drawings)

For SVG optimization you will need either of the following (or both):

For PNG optimization you should have as many of the following as possible:

Other versions

I'm currently working on a native Node.js / Grunt / Gulp.js implementation of iconizr. As a first step, I published svg-sprite (respectively grunt-svg-sprite) which will be the SVG sprite generator component. As opposed to the PHP based iconizr, svg-sprite comes with several improvements like Mustache template based output, so you can produce customized CSS output (formats). I plan to backport these improvements to the PHP based version as well.

Also, I'm very happy to announce that Haithem Bel Haj published an iconizr Grunt plugin that's based on the PHP based version of iconizr, so you can start using iconizr with Grunt right away! Cool, huh?


There are some useful resources on data URIs in general:

As soon as I'll find some time I will do some tests in our Open Device Lab to see if there are any device specific data URI limitations.

Resources on SVG support:


Copyright © 2014 Joschi Kuphal joschi@kuphal.net / @jkphl

As of version 0.1.1, iconizr is licensed under the terms of the MIT license. Before that, a Creative Commons Attribution 3.0 Unported License applied.

The contained example SVG icons are part of the Tango Icon Library and belong to the Public Domain.