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Image processing
Some of the built-in plugins depend on external libraries for efficient image processing, most notably the social plugin to generate social cards, and the optimize plugin for applying image optimization. This guide explains how to install those libraries in different environments.
Dependencies
The libraries for image processing are entirely optional, and only need to be
installed if you want to use the social plugin or the optimize plugin. The
libraries are listed under the imaging extra:
pip install "mkdocs-material[imaging]"
This will install compatible versions of the following packages:
Cairo Graphics
Cairo Graphics is a graphics library and dependency of Pillow, which Material for MkDocs makes use of for generating social cards and performing image optimization. See the following section which explains how to install Cairo Graphics and its dependencies on your system:
=== ":material-apple: macOS"
Make sure [Homebrew] is installed, which is a modern package manager for
macOS. Next, use the following command to install all necessary
dependencies:
```
brew install cairo freetype libffi libjpeg libpng zlib
```
=== ":fontawesome-brands-windows: Windows"
As stated in the [installation guide], the easiest way to get up and running
with the [Cairo Graphics] library on Windows is by installing [GTK+]. You
can also download a precompiled [GTK runtime].
=== ":material-linux: Linux"
There are several package managers for Linux with varying availability per
distribution. The [installation guide] explains how to install the [Cairo
Graphics] library for your distribution:
=== ":material-ubuntu: Ubuntu"
```
apt-get install libcairo2-dev libfreetype6-dev libffi-dev libjpeg-dev libpng-dev libz-dev
```
=== ":material-fedora: Fedora"
```
yum install cairo-devel freetype-devel libffi-devel libjpeg-devel libpng-devel zlib-devel
```
=== ":fontawesome-brands-suse: openSUSE"
```
zypper install cairo-devel freetype-devel libffi-devel libjpeg-devel libpng-devel zlib-devel
```
The following environments come with a preinstalled version of Cairo Graphics:
-
No installation needed in Docker image
-
No installation needed in GitHub Actions (Ubuntu)
pngquant
pngquant is an excellent library for lossy PNG compression, and a direct dependency of the built-in optimize plugin. See the following section which explains how to install pngquant system:
=== ":material-apple: macOS"
Make sure [Homebrew] is installed, which is a modern package manager for
macOS. Next, use the following command to install all necessary
dependencies:
```
brew install pngquant
```
=== ":fontawesome-brands-windows: Windows"
Installing [pngquant] on Windows is a little more involved. The
[pngquant-winbuild] repository contains a guide on how to set up an
environment for building [pngquant] on Windows.
=== ":material-linux: Linux"
All popular Linux distributions, regardless of package manager, should
allow to install [pngquant] with the bundled package manager. For example,
on Ubuntu, [pngquant] can be installed with:
```
apt-get install pngquant
```
The same is true for `yum` and `zypper`.
The following environments come with a preinstalled version of pngquant:
-
No installation needed in Docker image
Troubleshooting
Cairo library was not found
After following the installation guide above it may happen that you still get the following error:
no library called "cairo-2" was found
no library called "cairo" was found
no library called "libcairo-2" was found
cannot load library 'libcairo.so.2': error 0x7e. Additionally, ctypes.util.find_library() did not manage to locate a library called 'libcairo.so.2'
cannot load library 'libcairo.2.dylib': error 0x7e. Additionally, ctypes.util.find_library() did not manage to locate a library called 'libcairo.2.dylib'
cannot load library 'libcairo-2.dll': error 0x7e. Additionally, ctypes.util.find_library() did not manage to locate a library called 'libcairo-2.dll'
This means that the cairosvg package was installed, but the
underlying cairocffi dependency couldn't find
the installed library. Depending on the operating system the library lookup
process is different:
!!! tip Before proceeding remember to fully restart any open Terminal windows, and their parent hosts like IDEs to reload any environmental variables, which were altered during the installation process. This might be the quick fix.
=== ":material-apple: macOS"
On macOS the library lookup checks inside paths defined in [dyld][osx-dyld].
Additionally each library `name` is checked in [three variants][find-library-macOS]
with the `libname.dylib`, `name.dylib` and `name.framework/name` format.
[Homebrew] should set every needed variable to point at the installed
library directory, but if that didn't happen, you can use the debug script
below to see what paths are looked up.
A [known workaround][cffi-issue] is to add the Homebrew lib path directly
before running MkDocs:
```bash
export DYLD_FALLBACK_LIBRARY_PATH=/opt/homebrew/lib
```
View source code of [cairo-lookup-macos.py]
```bash title="Python Debug macOS Script"
curl "https://raw.githubusercontent.com/squidfunk/mkdocs-material/master/includes/debug/cairo-lookup-macos.py" | python -
```
=== ":fontawesome-brands-windows: Windows"
On Windows the library lookup checks inside the paths defined in the
environmental `PATH` variable. Additionally each library `name` is checked
in [two variants][find-library-Windows] with the `name` and `name.dll` format.
The default installation path of [GTK runtime] is:
```powershell
C:\Program Files\GTK3-Runtime Win64
```
and the libraries are in the `<INSTALL-DIR>\lib` directory. Use the debug
script below to check if the path is included. If it isn't then:
1. Press ++windows+r++.
2. Run the `SystemPropertiesAdvanced` applet.
3. Select "Environmental Variables" at the bottom.
4. Add the whole path to the `lib` directory to your `Path` variable.
5. Click OK on all open windows to apply changes.
6. Fully restart any open Terminal windows and their parent hosts like IDEs.
```powershell title="You can also list paths using PowerShell"
$env:Path -split ';'
```
View source code of [cairo-lookup-windows.py]
```powershell title="PowerShell - Python Debug Windows Script"
(Invoke-WebRequest "https://raw.githubusercontent.com/squidfunk/mkdocs-material/master/includes/debug/cairo-lookup-windows.py").Content | python -
```
=== ":material-linux: Linux"
On Linux the library lookup can [differ greatly][find-library-Linux] and is
dependent from the installed distribution. For tested Ubuntu and Manjaro
systems Python runs shell commands to check which libraries are available in
[`ldconfig`][ubuntu-ldconfig], in the [`gcc`][ubuntu-gcc]/`cc` compiler, and
in [`ld`][ubuntu-ld].
You can extend the `LD_LIBRARY_PATH` environmental variable with an absolute
path to a library directory containing `libcairo.so` etc. Run this directly
before MkDocs:
```bash
export LD_LIBRARY_PATH=/absolute/path/to/lib:$LD_LIBRARY_PATH
```
You can also modify the `/etc/ld.so.conf` file.
The Python script below shows, which function is being run to find installed
libraries. You can check the source to find out what specific commands are
executed on your system during library lookup.
View source code of [cairo-lookup-linux.py]
```bash title="Python Debug Linux Script"
curl "https://raw.githubusercontent.com/squidfunk/mkdocs-material/master/includes/debug/cairo-lookup-linux.py" | python -
```