Skia for Aseprite and laf

Pre-built binaries of Skia in the releases page.

Skia is a 2D graphic library developed by Google Inc., you can find the official website in skia.org.

This fork is used to compile Skia automatically for laf and Aseprite using GitHub Actions.

Building Skia

In the following sections you will find straightforward steps to compile Skia. You can always check the official Skia instructions and select the OS you are building for. Aseprite and laf use the aseprite-m124 branch. So remember to checkout that specific branch.

These are the platform-specific steps to compile Skia:

• Skia on Windows
• Skia on macOS
• Skia on Linux

After this you should have all Skia libraries compiled. After that, when you compile laf or Aseprite remember to add -DSKIA_DIR=$HOME/deps/skia parameter to your cmake call and all other parameters.

Skia on Windows

Download Google depot tools and uncompress it in some place like C:\deps\depot_tools.

It's recommended to compile Skia with Clang to get better performance. So you will need to download Clang, and install it on a folder like C:\deps\llvm (a folder without whitespaces).

Open a command prompt window (cmd.exe) and call:

call "C:\Program Files\Microsoft Visual Studio\2022\Community\Common7\Tools\VsDevCmd.bat" -arch=x64

The command above is required while attempting to compile the 64-bit version of skia. When compiling the 32-bit version, it is possible to open a developer command prompt instead.

Then:

set PATH=C:\deps\depot_tools;%PATH%
cd C:\deps\depot_tools
gclient sync

(The gclient command might print an error like Error: client not configured; see 'gclient config'. Just ignore it.)

cd C:\deps
git clone -b aseprite-m124 https://github.com/aseprite/skia.git
cd skia
set GIT_EXECUTABLE=git.bat
python3 tools/git-sync-deps
python3 bin/fetch-ninja

(The tools/git-sync-deps will take some minutes because it downloads a lot of packages, please wait and re-run the same command in case it fails.)

Finally, if you've downloaded Clang, use this command:

set PATH=C:\deps\llvm\bin;%PATH%
gn gen out/Release-x64 --args="is_debug=false is_official_build=true is_trivial_abi=false skia_use_system_expat=false skia_use_system_icu=false skia_use_system_libjpeg_turbo=false skia_use_system_libpng=false skia_use_system_libwebp=false skia_use_system_zlib=false skia_use_freetype=true skia_use_harfbuzz=true skia_pdf_subset_harfbuzz=true skia_use_system_freetype2=false skia_use_system_harfbuzz=false target_cpu=""x64"" cc=""clang"" cxx=""clang++"" clang_win=""c:\deps\llvm"" clang_win_version=""17.0.6"" win_vc=""C:\Program Files\Microsoft Visual Studio\2022\Community\VC"" extra_cflags=[""-MT""]"
ninja -C out/Release-x64 skia modules

If you haven't installed Clang, and want to compile Skia with MSVC (anyway it's not recommended because the performance penalty is too big), you can use the following commands instead:

gn gen out/Release-x64 --args="is_debug=false is_official_build=true is_trivial_abi=false skia_use_system_expat=false skia_use_system_icu=false skia_use_system_libjpeg_turbo=false skia_use_system_libpng=false skia_use_system_libwebp=false skia_use_system_zlib=false skia_use_freetype=true skia_use_harfbuzz=true skia_pdf_subset_harfbuzz=true skia_use_system_freetype2=false skia_use_system_harfbuzz=false target_cpu=""x64"" win_vc=""C:\Program Files\Microsoft Visual Studio\2022\Community\VC"" extra_cflags=[""-MT""]"
ninja -C out/Release-x64 skia modules

For debugging

For debugging purposes you can compile the debug version of the library, e.g. for LLVM:

set PATH=C:\deps\llvm\bin;%PATH%
gn gen out/Debug-x64 --args="is_debug=true is_official_build=false is_trivial_abi=false skia_use_system_expat=false skia_use_system_icu=false skia_use_system_libjpeg_turbo=false skia_use_system_libpng=false skia_use_system_libwebp=false skia_use_system_zlib=false skia_use_freetype=true skia_use_harfbuzz=true skia_pdf_subset_harfbuzz=true skia_use_system_freetype2=false skia_use_system_harfbuzz=false target_cpu=""x64"" cc=""clang"" cxx=""clang++"" clang_win=""c:\deps\llvm"" clang_win_version=""17.0.6"" win_vc=""C:\Program Files\Microsoft Visual Studio\2022\Community\VC"" extra_cflags=[""-MTd""]"
ninja -C out/Debug-x64 skia modules

Skia on macOS

These steps will create a deps folder in your home directory with a couple of subdirectories needed to build Skia (you can change the $HOME/deps with other directory). Some of these commands will take several minutes to finish:

mkdir $HOME/deps
cd $HOME/deps
git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
git clone -b aseprite-m124 https://github.com/aseprite/skia.git
export PATH="${PWD}/depot_tools:${PATH}"
cd skia
python3 tools/git-sync-deps
python3 bin/fetch-ninja
gn gen out/Release-x64 --args="is_debug=false is_official_build=true skia_use_system_expat=false skia_use_system_icu=false skia_use_system_libjpeg_turbo=false skia_use_system_libpng=false skia_use_system_libwebp=false skia_use_system_zlib=false skia_use_freetype=true skia_use_harfbuzz=true skia_pdf_subset_harfbuzz=true skia_use_system_freetype2=false skia_use_system_harfbuzz=false target_cpu=\"x64\" extra_cflags=[\"-stdlib=libc++\", \"-mmacosx-version-min=10.9\"] extra_cflags_cc=[\"-frtti\"]"
ninja -C out/Release-x64 skia modules

Skia on macOS for Apple Silicon

If you want to compile Skia for Apple Silicon (e.g. M1), you have to specify the arm64 CPU architecture:

gn gen out/Release-arm64 --args="is_debug=false is_official_build=true skia_use_system_expat=false skia_use_system_icu=false skia_use_system_libjpeg_turbo=false skia_use_system_libpng=false skia_use_system_libwebp=false skia_use_system_zlib=false skia_use_freetype=true skia_use_harfbuzz=true skia_pdf_subset_harfbuzz=true skia_use_system_freetype2=false skia_use_system_harfbuzz=false target_cpu=\"arm64\" extra_cflags=[\"-stdlib=libc++\", \"-mmacosx-version-min=11.0\"] extra_cflags_cc=[\"-frtti\"]"
ninja -C out/Release-arm64 skia modules

Skia on Linux

These steps will create a deps folder in your home directory with a couple of subdirectories needed to build Skia (you can change the $HOME/deps with other directory). Some of these commands will take several minutes to finish:

mkdir $HOME/deps
cd $HOME/deps
git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
git clone -b aseprite-m124 https://github.com/aseprite/skia.git
export PATH="${PWD}/depot_tools:${PATH}"
cd skia
python3 tools/git-sync-deps
python3 bin/fetch-ninja
gn gen out/Release-x64 --args="is_debug=false is_official_build=true skia_use_system_expat=false skia_use_system_icu=false skia_use_system_libjpeg_turbo=false skia_use_system_libpng=false skia_use_system_libwebp=false skia_use_system_zlib=false skia_use_freetype=true skia_use_harfbuzz=true skia_pdf_subset_harfbuzz=true skia_use_system_freetype2=false skia_use_system_harfbuzz=false"
ninja -C out/Release-x64 skia modules

Internal Details

• is_trivial_abi: As we are mixing MSVC/Clang, the Windows compilation needs the is_trivial_abi=false option as indicated here, in other case we can get an infinite loop SkOnce::operator()

• -MT: We are creating a static-linked version of Skia library, that's why we have the extra_cflags=["-MTd"] option, so we don't need to distribute the MSVC C++ runtime DLLs.

• -frtti: On macOS we've detected a strange bug where linking object files compiled with -frtti and -fno-rtti (the default Skia option) breaks the normal function of std::exception hierarchy. That's why we're compiling with run-time type information extra_cflags_cc=["-frtti"].