Please check the build logs for more information.
See Builds for ideas on how to fix a failed build, or Metadata for how to configure docs.rs builds.
If you believe this is docs.rs' fault, open an issue.
This package contains three components.
- First, full configuration and build support for Skia in
- Additional C bindings to help out bindgen with stuff it has problems with or to work around linker errors. These are
- And a number of functions that are used to download prebuilt binaries.
Skia Build Support
Building Skia is quite exceptional, a number of prerequisites need to be available and configured properly for the target platform.
To configure and build Skia,
build_support/skia.rs does all the hard work: it pulls
skia/ from Google's repositories and a number of additional dependencies by executing
skia/tools/git-sync-deps with Python. After that, it configures Skia with Google's GN tool, and finally builds it by giving control to the
ninja executable from the
src/shaper.cpp contain the C++ code that Rust needs to interact with Skia's codebase. These files are processed by the Rust's binding generator that uses libclang for the layout computation and also compiled by clang.
If both steps went well, the resulting Rust binding code is written to
src/bindings.rs, and the
skia-bindings library is found in the output directory alongside where Skia was built previously.
By default, and for performance reasons, Skia is built in release mode even when cargo creates debug output. Skia debug builds can be enabled only by explicitly setting the environment variable
Because building Skia and creating the bindings is slow and depend on a number of components that lie outside the Rust ecosystem, we decided to experiment with prebuilt binaries.
Whenever a new version of
rust-skia is built from the
release branch on our CI server, the resulting Skia library,
skia-bindings library, and
bindings.rs are uploaded to the releases tab of the skia-binaries repository.
And whenever the build script detects that
skia-bindings is built from inside a crate and a prebuilt archive is available that matches the repository's hash, platform, and features, it downloads the package, unpacks it, and skips the full build step of Skia and the bindings.
Changing the executable used as
On some systems, the bundled
gn executables may not work (as is on NixOS.) To remedy
this, the executables used can be set using the following environment variables:
Changing the Skia source directory
In some cases, one may wish to provide an alternate Skia source directory. This can be achieved by
SKIA_SOURCE_DIR, which must be an absolute path to a Skia source directory with all
Using system libraries
By default, numerous libraries Skia depends upon are built in addition to Skia itself. In the event that this is not wanted (say, if the crate is being built as part of a package's build routine,) this behavior can be disabled by setting the
SKIA_USE_SYSTEM_LIBRARIES environment variable.
Also note that there is one exception here. FreeType is only embedded on Android platforms by default. If your platform does not support a more recent FreeType version, skia-bindings must be built with the feature
Besides of the features
textlayout that can be directly specified when the package is added as a cargo dependency, the Skia build can be customized further in
build.rs by adjusting one of two structs that are defined in
This struct represents the top level build configuration for
skia-bindings and contains a number of individual feature flags.
FinalBuildConfiguration is created from the
BuildConfiguration and contains name value pairs used by GN to parameterize the Skia build and preprocessor defines used to create the
src/bindings.rs file and the
Cross Compiling for Linux
It's possible to cross compile Skia and the Rust bindings for different architectures on Linux. Set the following environment variables and then invoke cargo with the desired --target triple:
CLANGCC: Command line to invoke clang to cross-compile C code for the desired target architecure. This command line may include a
CLANGCXX: Command line to invoke clang to cross-compile C++ code for the desired target architecure. This command line may include a
SDKTARGETSYSROOT: Path to the target sysroot.
CXXproviding command lines to cross-compile (clang is not required) and
HOST_CCproviding a command line for build for the host.
CXX_<target>providing command lines to cross-compile (clang is not required).
When using a Yocto SDK for cross-compiling, all of the above environment variables will be set when entering the Yocto SDK environment by sourcing the
CXX are set to cross-compile. That means it is also necessary to set
HOST_CC, which usually works when set to just
For linking your Rust application, you may also need to instruct cargo to use the correct linker and look for native library dependencies (such as Skia's FreeType dependency) in the sysroot. This can for be done via a
.cargo/config file or via environment variables. For example if your Rust target platform is
aarch64-unknown-linux-gnu and you're Yocto SDK's target is