Safe Rust bindings to the Skia Graphics Library.

Skia Submodule Status: chrome/m81 (pending changes, our changes).

Goals

This project attempts to provide up to date safe bindings that bridge idiomatic Rust with Skia's C++ API on all major desktop and mobile platforms, including GPU rendering support for Vulkan, Metal, and OpenGL.

Status

Crate

A prerelease crate is available from crates.io and adding

[dependencies]
skia-safe = "0"

to your Cargo.toml should get you started.

On Linux you may run into trouble when OpenSSL libraries are missing. On Debian and Ubuntu they can be installed with:

sudo apt-get install pkg-config libssl-dev

For other platforms, more information is available at the OpenSSL crate documentation.

Platform Support, Build Targets, and Prebuilt Binaries

Because building Skia takes a lot of time and needs tools that may be missing, the skia-bindings crate's build.rs tries to download prebuilt binaries from the skia-binaries repository.

Platform	Binaries
Windows	x86_64-pc-windows-msvc
Linux Ubuntu 16, 18 CentOS 7, 8	x86_64-unknown-linux-gnu
macOS	x86_64-apple-darwin
Android	aarch64-linux-android x86_64-linux-android
iOS	aarch64-apple-ios x86_64-apple-ios

There no support for WebAssembly yet. If you'd like to help out, take a look at issue #39.

Bindings & Supported Features

The supported bindings and Skia features are described in the skia-safe package's readme and prebuilt binaries are available for most feature combinations.

Building

If the target platform or feature configuration is not available as a prebuilt binary, skia-bindings' build.rs will try to build Skia and generate the Rust bindings.

To prepare for that, LLVM and Python 2 are needed:

LLVM

We recommend the version that comes preinstalled with your platform, or, if not available, the latest official LLVM release. To see which version of LLVM/Clang is installed on your system, use clang --version.

Python 2

Python version 2.7 must be available.

The build script probes for python --version and python2 --version and uses the first one that looks like a version 2 executable for building Skia.

On macOS

• Install the Command Line Tools for Xcode with

  xcode-select --install

  or download and install the Command Line Tools for Xcode.

• macOS Mojave only: install the SDK headers:

  sudo open /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg

  If not installed, the Skia build may fail to build SkJpegUtility.cpp and the binding generation will fail with 'TargetConditionals.h' file not found . Also note that the Command Line Tools and SDK headers should be reinstalled after an update of XCode.

• As an alternative to Apple's XCode LLVM, install LLVM via brew install llvm or brew install llvm and then set PATH, CPPFLAGS, and LDFLAGS like instructed.

  If the environment variables are not set, bindgen will most likely use the wrong libclang.dylib and cause confusing compilation errors (see #228).

On Windows

• Have the latest versions of git and Rust ready.

• Install Visual Studio 2019 Build Tools or one of the IDE releases. If you installed the IDE, make sure that the Desktop Development with C++ workload is installed.

• Install the latest LLVM distribution.

  If the environment variable LLVM_HOME is not defined, the build script will look for LLVM installations located at C:\Program Files\LLVM\, C:\LLVM\, and %USERPROFILE%\scoop\apps\llvm\current\.

• MSYS2:

  • Install Python2 with pacman -S python2.

• Windows Shell (Cmd.exe):

  • Download and install Python version 2 from python.org.

• Install and select the MSVC toolchain:

  rustup default stable-msvc

On Linux

Ubuntu 16+

• LLVM/Clang should be available already, if not, install the latest version.

• If OpenGL libraries are missing, install the drivers for you graphics card, or a mesa package like libgl1-mesa-dev.

CentOS 7

• Install the following packages:

  sudo yum install gcc openssl-devel libX11-devel python2 fontconfig-devel mesa-libGL-devel

• Install and enable the LLVM toolset 7

• Install and enable the Developer Toolset 8

CentOS 8

• Install the following packages:

  sudo yum install gcc openssl-devel libX11-devel python2 clang fontconfig-devel mesa-libGL-devel

• Set /usr/bin/python2 as the default python command:

  sudo alternatives --set python /usr/bin/python2

For Android

Cross compilation to Android is supported for targeting 64 bit ARM and Intel x86 architectures (aarch64 and x86_64) for API Level 26 (Oreo, Android 8):

For example, to compile for aarch64:

1. Install the rust target:

   rustup target install aarch64-linux-android

2. Download the r21b NDK for your host architecture and unzip it.
3. Compile your package for the aarch64-linux-android target:

On macOS:

export ANDROID_NDK=:path-to-android-ndk-r21b
export PATH=$PATH:$ANDROID_NDK/toolchains/llvm/prebuilt/darwin-x86_64/bin
export CC_aarch64_linux_android=aarch64-linux-android26-clang
export CXX_aarch64_linux_android=aarch64-linux-android26-clang++
export CARGO_TARGET_AARCH64_LINUX_ANDROID_LINKER=aarch64-linux-android26-clang

cargo build -vv --target aarch64-linux-android

Note: we don't support Apple's Clang 11 to build for Android on macOS, so you need to install LLVM and set the PATH like instructed.

On Linux:

export ANDROID_NDK=:path-to-android-ndk-r21b
export PATH=$PATH:$ANDROID_NDK/toolchains/llvm/prebuilt/linux-x86_64/bin
export CC_aarch64_linux_android=aarch64-linux-android26-clang
export CXX_aarch64_linux_android=aarch64-linux-android26-clang++
export CARGO_TARGET_AARCH64_LINUX_ANDROID_LINKER=aarch64-linux-android26-clang

cargo build -vv --target aarch64-linux-android

On Windows the Android NDK clang executable must be invoked through .cmd scripts:

export ANDROID_NDK=:path-to-android-ndk-r21b
export PATH=$PATH:$ANDROID_NDK/toolchains/llvm/prebuilt/windows-x86_64/bin
export CC_aarch64_linux_android=aarch64-linux-android26-clang.cmd
export CXX_aarch64_linux_android=aarch64-linux-android26-clang++.cmd
export CARGO_TARGET_AARCH64_LINUX_ANDROID_LINKER=aarch64-linux-android26-clang.cmd

cargo build -vv --target aarch64-linux-android

Notes:

• The CARGO_TARGET_${TARGET}_LINKER environment variable name needs to be all uppercase.
• In some older shells (for example macOS High Sierra), environment variable replacement can not be used when the variable was defined on the same line. Therefore the ANDROID_NDK variable must be defined before it's used in the PATH variable.
• Rebuilding skia-bindings with a different target may cause linker errors, in that case touch skia-bindings/build.rs will force a rebuild (#10).

For iOS

Compilation to iOS is supported on macOS targeting the iOS simulator (--target x86_64-apple-ios) and 64 bit ARM devices (--target aarch64-apple-ios).

Skia

For situations in which Skia does not build or needs to be configured differently, we support some customization support in skia-bindings/build.rs. For more details take a look at the README of the skia-bindings package.

Please share your build experience so that we can try to automate the build and get to the point where cargo build is sufficient to build the bindings including Skia, and if that is not possible, clearly prompts to what's missing.

Example Applications

icon

The icon example generates the rust-skia icon in the current directory. It computes the position of all the gear teeth etc. based on parameters such as the number of teeth and wheel radius.

If you were able to build the project, run

cargo run --example icon 512

It has a single optional parameter which is the size in pixels for the PNG file. Without parameters, it’ll produce PNG frames for the animated version.

skia-org

The other examples are taken from Skia's website and ported to the Rust API.

cargo run -- [OUTPUT_DIR]

to generate some Skia drawn PNG images in the directory OUTPUT_DIR. To render with OpenGL, use

cargo run -- [OUTPUT_DIR] --driver opengl

And to show the drivers that are supported

cargo run -- --help

gl-window

An example that opens an OpenGL Window and draws a line with skia-safe (contributed by @nornagon).

(cd skia-safe && cargo run --example gl-window --features "gl")

Example Images

Fill, Radial Gradients, Stroke, Stroke with Gradient, Transparency:

Fill, Stroke, Text:

Sweep Gradient:

Dash Path Effect:

For more, you may take a look at the rust-skia.github.io repository.

This project needs contributions!

If you'd like to help with the bindings, take a look at the Wiki to get started and create an issue to prevent duplicate work. For smaller tasks, grep for "TODO"s in the source code. And for heroic work, check out the label help wanted. And if you like to help making the Rust API nicer to use, look out for open issues with the label api ergonomics.

More details can be found at CONTRIBUTING.md.

Notable Contributions

• Denis Kolodin (@DenisKolodin) added build support for Android.
• Alberto González Palomo (@AlbertoGP) designed the Rust-Skia Logo and the example program that renders it.

Maintainers

• LongYinan (@Brooooooklyn)
• Armin (@pragmatrix)

License

MIT