Adding SVG icons

SVG icons should be added to a common iconset, or an iconset for your WebUI. These can be custom SVG icons or copies of Polymer's [iron-icons](https://github.com/PolymerElements/iron-icons).

Creating an iconset

To create the iconset your WebUI will use, copy the format of an existing icons file (e.g., cr_elements/icons.html). Change the name of the iron-iconset-svg for your WebUI, and add the SVGs you need (see below). Example:

<iron-iconset-svg name="downloads" size="24">
  <svg>
    <defs>
      <g id="foo">...</g>
      ...
    </defs>
  </svg>
</iron-iconset-svg>

Adding icon definitions

For Polymer icons from iron-icons:

• Find the SVG <g> icon definitions you need in PolymerElements/iron-icons.
• Copy the SVG definitions.
• Insert each line (alphabetically) into the appropriate icons.html file for your WebUI. (For commonly used icons, use cr_elements/icons.html.)

For custom icons:

You can include custom icons or Google Material icons in the same iconset, but mention their source in a comment. Icons exported from GUI tools often are messy; please minify custom icons by flattening transforms, removing meta tags like <title>, and rounding weird numbers like 30.0002118. The SVGOMG optimizer does most of this for you; use it.

If the icon is not the same size as the iconset, either scale it to size, or ensure the <g id="foo"> tag includes the viewBox attribute with the original dimensions. Some code (settings) has multiple iconsets (e.g. "cr" vs. "cr20") depending on the export size. You can skip the viewBox if you put the icon in the right set.

Unless color is important (e.g. a Chromium logo), remove hard-coded colors (e.g. fill="#000") so our WebUI can specify colors in CSS.

Using icons

Import the relevant icons.html from your UI instead of importing Polymer's iron-icons.html (which would load almost a thousand SVGs).

Use the icon in your UI with your custom iconset name prefix wherever you need an icon name (iron-icon, paper-icon-button, etc.):

<link rel="import" href="chrome://downloads/icons.html">
<iron-icon icon="downloads:warning"></iron-icon>

Common icons

A few icons are used in many pages. These can be found in [cr_elements/icons.html](https://code.google.com/p/chromium/codesearch#chromium/src/ui/webui/resources/cr_elements/icons.html&q=file:cr_elements/icons%5C.html&sq=package:chromium&type=cs&l=1) under the iconset name "cr". Having frequently-used icons here prevents excessive duplication of SVG definitions while keeping imports small across all pages.

To use these icons, simply import cr_elements/icons.html and use the cr prefix:

<link rel="import" href="chrome://resources/cr_elements/icons.html">
<iron-icon icon="cr:cancel"></iron-icon>