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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title xmlns:d="http://docbook.org/ns/docbook">3.3. Icon Cache</title><link rel="stylesheet" type="text/css" href="Common_Content/css/default.css" /><link rel="stylesheet" media="print" href="Common_Content/css/print.css" type="text/css" /><meta xmlns:d="http://docbook.org/ns/docbook" name="generator" content="publican v4.3.2" /><meta xmlns:d="http://docbook.org/ns/docbook" name="package" content="AppStream-AppStream-0.11-en-US-0.0-0" /><link rel="home" href="index.html" title="AppStream" /><link rel="up" href="chap-CollectionData.html" title="Chapter 3. Collection Metadata" /><link rel="prev" href="sect-AppStream-YAML.html" title="3.2. AppStream collection YAML" /><link rel="next" href="chap-Quickstart.html" title="Chapter 4. Metadata Quickstart" /></head><body><p id="title"><a class="left" href="http://www.freedesktop.org/wiki/Distributions/AppStream/"><img alt="Product Site" src="Common_Content/images//image_left.png" /></a><a class="right" href="http://www.freedesktop.org/software/appstream/docs/"><img alt="Documentation Site" src="Common_Content/images//image_right.png" /></a></p><ul class="docnav top"><li class="previous"><a accesskey="p" href="sect-AppStream-YAML.html"><strong>Prev</strong></a></li><li class="home">AppStream</li><li class="next"><a accesskey="n" href="chap-Quickstart.html"><strong>Next</strong></a></li></ul><div xml:lang="en-US" class="section" lang="en-US"><div class="titlepage"><div><div><h2 class="title"><a id="sect-AppStream-IconCache">
</a>3.3. Icon Cache</h2></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="spec-iconcache-introduction">
</a>3.3.1. Introduction</h3></div></div></div><div class="para">
In order to display icons in software-centers, distributors should offer a repository of cached icons for applications defined in their AppStream XML files. The icons should be PNG files or vectorgraphics (PNG is preferred) and match the name referenced in the applications .desktop file. Their size should be 64x64px, it is okay to just provide one size.
</div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="spec-iconcache-location">
</a>3.3.2. Filesystem locations</h3></div></div></div><div class="para">
All icons of type <code class="literal">cached</code> must be placed in <code class="filename">/usr/share/app-info/icons/%{origin}/%{size}/</code> or <code class="filename">/var/cache/app-info/icons/%{origin}/%{size}/</code>, where <code class="literal">origin</code> is the AppStream data origin defined in the AppStream data file (see <a class="xref" href="chap-CollectionData.html#spec-asxml-general">Section 3.1.3, “General XML structure”</a>), and <code class="literal">size</code> is <code class="code">64x64</code> or <code class="code">128x128</code> depending on the size of the icon. And icon might be present with different sizes in both directories.
</div><div class="para">
For example the cache icon <code class="code">krita.png</code> of a component in a data file with the origin <code class="code">jessie</code> should be stored in <code class="filename">/usr/share/app-info/icons/jessie/64x64/krita.png</code> (or in the <code class="filename">/var/cache</code> location).
</div><div class="para">
Icon sclaing factors commonly used for HiDPI display support are part of the size-directory filename and are separated from the regular size via an <code class="code">@</code> sign. If the scaling factor is 1, it must be omitted from the directory name. For example, if the icon scaling factor is <code class="literal">2</code> for icons of size <code class="literal">64x64</code> from origin <code class="literal">jessie</code>, the icon must be placed in <code class="filename">/usr/share/app-info/icons/jessie/64x64@2/</code>.
</div><div xmlns:d="http://docbook.org/ns/docbook" class="note"><div class="admonition_header"><p><strong>Legacy Support</strong></p></div><div class="admonition"><div class="para">
In order to support the old icon cache layout, client applications may also look for icons in the folder below the size-directories, assuming that the icons placed there are of size <code class="code">64x64</code> pixels.
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