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https://github.com/rust-skia/rust-skia

Rust Bindings for the Skia Graphics Library
https://github.com/rust-skia/rust-skia

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Rust Bindings for the Skia Graphics Library

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README

        

# Safe Rust bindings for the [Skia Graphics Library](https://skia.org/).

[![crates.io](https://img.shields.io/crates/v/skia-safe)](https://crates.io/crates/skia-safe) [![license](https://img.shields.io/crates/l/skia-safe)](LICENSE) [![Windows QA](https://github.com/rust-skia/rust-skia/actions/workflows/windows-qa.yaml/badge.svg?branch=master)](https://github.com/rust-skia/rust-skia/actions/workflows/windows-qa.yaml) [![Linux QA](https://github.com/rust-skia/rust-skia/actions/workflows/linux-qa.yaml/badge.svg?branch=master)](https://github.com/rust-skia/rust-skia/actions/workflows/linux-qa.yaml) [![macOS QA](https://github.com/rust-skia/rust-skia/actions/workflows/macos-qa.yaml/badge.svg?branch=master)](https://github.com/rust-skia/rust-skia/actions/workflows/macos-qa.yaml)

Skia Submodule Status: chrome/m124 ([upstream changes][skia-upstream], [our changes][skia-ours]).

[skia-upstream]: https://github.com/rust-skia/skia/compare/m124-0.72.3...google:chrome/m124
[skia-ours]: https://github.com/google/skia/compare/chrome/m124...rust-skia:m124-0.72.3

## About

This project provides _up to date_ safe bindings that bridge idiomatic Rust with Skia's C++ API on desktop and mobile platforms, including GPU rendering backends for [Vulkan](), [Metal](), [OpenGL](https://en.wikipedia.org/wiki/OpenGL), and [Direct3D](https://en.wikipedia.org/wiki/Direct3D).

## Status

### Documentation

Because we [can't build on docs.rs](https://docs.rs/crate/skia-safe/0.34.0/builds), the `cargo doc` output for skia-safe is manually created and uploaded to [rust-skia.github.io](https://rust-skia.github.io/doc/skia_safe).

We (slowly) [add more documentation](https://github.com/rust-skia/rust-skia/issues/446) by converting Skia's Doxygen comments to Rust.

### Crate

A prerelease crate is available from [crates.io](https://crates.io/crates/skia-safe) and invoking

```bash
cargo add skia-safe
```

in your project's folder should get you started. And you might want to take a look at the [gl-window](https://github.com/rust-skia/rust-skia/tree/master/skia-safe/examples/gl-window) example if you plan to render to a window.

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

```bash
sudo apt-get install pkg-config libssl-dev
```

For other platforms, more information is available at the [OpenSSL crate documentation](https://docs.rs/openssl/0.10.24/openssl/#automatic).

### 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` attempts to download prebuilt binaries from [the skia-binaries repository](https://github.com/rust-skia/skia-binaries/releases) using the `curl` command line tool.

| Platform | Binaries |
| --------------------------------- | ---------------------------------------------------------- |
| Windows | `x86_64-pc-windows-msvc` |
| Linux Ubuntu 16+
CentOS 7, 8 | `x86_64-unknown-linux-gnu`
`aarch64-unknown-linux-gnu` |
| macOS | `x86_64-apple-darwin`
`aarch64-apple-darwin` |
| Android | `aarch64-linux-android`
`x86_64-linux-android` |
| iOS | `aarch64-apple-ios`
`x86_64-apple-ios` |
| WebAssembly | `wasm32-unknown-emscripten` |

### Wrappers & Codecs & Supported Features

The supported wrappers, Skia codecs, and additional Skia features are documented in the [skia-safe package's readme](skia-safe/README.md). 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 3** are needed:

**LLVM**

We recommend the version that comes preinstalled with your platform, or, if not available, the [latest official LLVM release](http://releases.llvm.org/download.html). To see which version of LLVM/Clang is installed on your system, use `clang --version`.

**Python 3**

The build script probes for `python --version` and `python3 --version` and uses the first one that looks like a version 3 executable for building Skia.

### On macOS

- Install the Command Line Tools for Xcode with

```bash
xcode-select --install
```

or download and install the [Command Line Tools for Xcode](https://developer.apple.com/download/more/).

- **macOS Mojave only**: install the SDK headers:

```bash
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](https://github.com/rust-lang/rust-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 2022 Build Tools](https://visualstudio.microsoft.com/downloads/) or one of the other IDE editions. If you installed the IDE, make sure that the [Desktop Development with C++ workload](https://docs.microsoft.com/en-us/cpp/build/vscpp-step-0-installation?view=msvc-170) is installed.

- Install the [latest LLVM](http://releases.llvm.org/download.html) 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](https://www.msys2.org/):

- Install Python 3 with `pacman -S python`.

- Windows Shell (`Cmd.exe`):

- Download and install Python 3 from [python.org](https://www.python.org/downloads).

- Install and select the MSVC toolchain:
```bash
rustup default stable-msvc
```

### On Linux

#### Ubuntu 16+

- LLVM/Clang should be available already, if not, [install the latest version](http://releases.llvm.org/download.html).
- If OpenGL libraries are missing, install the drivers for you graphics card, or a mesa package like `libgl1-mesa-dev`.
- For **X11**, build with feature `x11`.
- For **Wayland**, install `libwayland-dev` and build with the `wayland` feature.

#### CentOS 7

- Install the following packages:

```bash
sudo yum install gcc openssl-devel libX11-devel python3 fontconfig-devel mesa-libGL-devel
```

- [Install and enable the LLVM toolset 7](https://www.softwarecollections.org/en/scls/rhscl/llvm-toolset-7.0/)

- [Install and enable the Developer Toolset 8](https://www.softwarecollections.org/en/scls/rhscl/devtoolset-8/)

#### CentOS 8

- Install the following packages:

```bash
sudo yum install gcc openssl-devel libX11-devel python3 clang fontconfig-devel mesa-libGL-devel
```

- Set `/usr/bin/python3` as the default `python` command:

```bash
sudo alternatives --set python /usr/bin/python3
```

### 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):

We recommend to use [cargo apk](https://crates.io/crates/cargo-apk), but if that does not work for you, following are some instructions on how we build Android targets with GitHub Actions:

For example, to compile for `aarch64`:

1. Install the Rust target:
```bash
rustup target install aarch64-linux-android
```
2. Download the [r25b NDK](https://developer.android.com/ndk/downloads) (or newer) for your host architecture and unzip it.
3. Compile your package for the `aarch64-linux-android` target:

On **macOS**:

```bash
export ANDROID_NDK=:path-to-android-ndk-r25b
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 AR_aarch64_linux_android=llvm-ar
export CARGO_TARGET_AARCH64_LINUX_ANDROID_LINKER=aarch64-linux-android26-clang

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

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

On **Linux**:

```bash
export ANDROID_NDK=:path-to-android-ndk-r25b
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 AR_aarch64_linux_android=llvm-ar
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:

```bash
export ANDROID_NDK=:path-to-android-ndk-r25b
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 AR_aarch64_linux_android=llvm-ar
export CARGO_TARGET_AARCH64_LINUX_ANDROID_LINKER=aarch64-linux-android26-clang.cmd

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

_Notes:_

- At the time of this writing, the Rust compiler will [automatically add a `-lgcc` argument](https://github.com/rust-windowing/android-ndk-rs/issues/149) to the linker, which results in a linker error, because newer NDKs do not contain `libgcc.a` anymore. To fix this, we created a workaround and [copy `libunwind.a` over to `libgcc.a`](https://github.com/pragmatrix/rust-skia-containers/blob/master/linux/Dockerfile#L48-L52). Cargo apk does something [similar](https://github.com/rust-windowing/android-ndk-rs/issues/149#issuecomment-963988601).
- The `CARGO_TARGET_${TARGET}_LINKER` environment variable name [needs to be all uppercase](https://github.com/rust-lang/cargo/issues/1109#issuecomment-386850387).
- 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](https://github.com/rust-skia/rust-skia/issues/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`). The ARM64**e** architecture is [not supported yet](https://github.com/rust-lang/rust/issues/73628).

### For WebAssembly

Install `emscripten` version 3.1.1 or superior. In the examples below, we assume
`emsdk` version `3.1.1` was installed with [asdf](http://asdf-vm.com/).

Build with the `wasm32-unknown-emscripten` target (`wasm32-unknown-unknown` is
unsupported because it is [fundamentally incompatible with linking C code](https://github.com/rustwasm/team/issues/291#issuecomment-645482430):

```bash
export EMSDK=~/.asdf/installs/emsdk/3.1.1
export EMCC_CFLAGS="-s ERROR_ON_UNDEFINED_SYMBOLS=0"

cargo build --target wasm32-unknown-emscripten
```

The `EMSDK` environment variable must be set to the root of your `emscripten` SDK.

In `EMCC_CFLAGS`, `-s ERROR_ON_UNDEFINED_SYMBOLS` is a
[workaround](https://github.com/rust-lang/rust/issues/85821#issuecomment-969369677) to build with
`emscripten > 2.0.9`.

If you want to enable WebGL, you will also have to set `MAX_WEBGL_VERSION=2`:

```bash
export EMSDK=~/.asdf/installs/emsdk/3.1.1
export EMCC_CFLAGS="-s ERROR_ON_UNDEFINED_SYMBOLS=0 -s MAX_WEBGL_VERSION=2"

cargo build --target wasm32-unknown-emscripten --features gl
```

On MacOS there is a problem with the OS version of `ar` so you will have to install the GNU version from homebrew:

```bash
brew install binutils
```

Then prepend `binutils` path for the build. The path depends on your CPU
architecture, and can be retrieved with `brew info binutils`. Here is an
example for Apple silicon:

```bash
export EMSDK=~/.asdf/installs/emsdk/3.1.1
export EMCC_CFLAGS="-s ERROR_ON_UNDEFINED_SYMBOLS=0"
export PATH="/opt/homebrew/opt/binutils/bin:$PATH"

cargo build --target wasm32-unknown-emscripten
```

### 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](skia-bindings/README.md).

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

```bash
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](https://skia.org/) and [ported to the Rust API](skia-org/).

```bash
cargo run -- [OUTPUT_DIR]
```

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

```bash
cargo run -- [OUTPUT_DIR] --driver opengl
```

And to show the drivers that are supported

```bash
cargo run -- --help
```

### gl-window

An example that opens an OpenGL Window and draws the rust-skia icon with skia-safe (contributed by [@nornagon](https://github.com/nornagon)).

```bash
cargo run --example gl-window --features gl
```

On Linux the feature `x11` needs to be enabled:

```bash
cargo run --example gl-window --features gl,x11
```

## Example Images

Fill, Radial Gradients, Stroke, Stroke with Gradient, Transparency:
[![Rust-skia icon](artwork/rust-skia-icon_512x512.png)](https://matracas.org/tmp/rust-skia-icon.html)

Fill, Stroke, Text:

![Fill, Stroke, Text](https://rust-skia.github.io/skia-org/cpu/SkPaint-Overview/02-fill-and-stroke.png)

Sweep Gradient:

![Sweep Gradient](https://rust-skia.github.io/skia-org/cpu/SkPaint-Overview/08-sweep-gradient-shader.png)

Dash Path Effect:

![Dash Path Effect](https://rust-skia.github.io/skia-org/cpu/SkPaint-Overview/19-dash-path-effect.png)

For more, you may take a look at the [rust-skia.github.io](https://github.com/rust-skia/rust-skia.github.io/tree/master/skia-org/cpu) repository.

## This project needs contributions!

If you'd like to help with the bindings, take a look at the [Wiki](https://github.com/rust-skia/rust-skia/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](https://github.com/rust-skia/rust-skia/labels/help%20wanted). And if you like to help making the Rust API nicer to use, look out for open issues with the label [api ergonomics](https://github.com/rust-skia/rust-skia/issues?q=is%3Aissue+is%3Aopen+label%3A%22api+ergonomics%22).

More details can be found at [CONTRIBUTING.md](https://github.com/rust-skia/rust-skia/tree/master/CONTRIBUTING.md).

## Notable Contributions

- Denis Kolodin ([@DenisKolodin](https://github.com/DenisKolodin)) contributed build support for Android.
- Alberto González Palomo ([@AlbertoGP](https://github.com/AlbertoGP)) designed the Rust-Skia Logo and the example program that renders it.
- Luper Rouch ([@flupke](https://github.com/flupke), sponsored by [Jitter](https://jitter.video/))
added build support for the `wasm32-unknown-emscripten` target.
- Osei Fortune ([@triniwiz](https://github.com/triniwiz)) contributed rendering SVG files.

## Maintainers

- LongYinan ([@Brooooooklyn](https://github.com/Brooooooklyn))
- Armin ([@pragmatrix](https://github.com/pragmatrix))

## License

MIT