Flutter on Tizen from scratch

flutter-engine.md

Building the Flutter engine for Tizen devices

Prerequisites

• Linux host machine
• Tizen (armv7l) device
• Build dependencies (Ubuntu 20.04)
  • sudo apt install texinfo bison flex python libncurses5
• Visual Studio Code (optional)
  • This is a recommended IDE for browsing the source code.

Download the engine source code

• The engine has dependencies on various third party modules. Building the engine requires all their source code to be synced.

• Follow the instructions in Setting up the Engine development environment.

• The directory structure after running gclient sync should look like this.

  src (flutter/buildroot)
  ├── build
  ├── flutter (<user>/engine)
  ├── third_party
  │   ├── dart (https://dart.googlesource.com/sdk.git)
  │   ├── skia (https://skia.googlesource.com/skia.git)
  │   ├── icu (https://chromium.googlesource.com/chromium/deps/icu.git)
  │   └── ...
  └── ...
  

Set up the build environment

• We'll use a clang cross compiler to build the engine binary. The GBS build is not supported at the moment.

• Build clang from source.

  $ git clone https://github.com/llvm/llvm-project.git --depth 1
  $ cd llvm-project
  $ mkdir build && cd build
  $ cmake ../llvm -DLLVM_ENABLE_PROJECTS=clang -G "Unix Makefiles" \
    -DCMAKE_BUILD_TYPE=Release \
    -DCMAKE_INSTALL_PREFIX=<target path>/toolchain \
    -DLLVM_DEFAULT_TARGET_TRIPLE=armv7l-tizen-linux-gnueabi \
    -DLLVM_TARGETS_TO_BUILD=ARM
  $ make -j4
  $ make install

• Build binutils from source.

  $ git clone git://sourceware.org/git/binutils-gdb.git --depth 1
  $ cd binutils-gdb
  $ ./configure --prefix=<target path>/toolchain \
    --enable-gold \
    --enable-ld \
    --target=armv7l-tizen-linux-gnueabi
  $ make -j4
  $ make install

  Clean the entire repo and try again if anything goes wrong.

• Build the sysroot.

  • https://github.com/swift-kim/sysroot

Build libflutter_engine.so

• (Temporary patch) Add Tizen-specific fonts to Linux default font families.

  ./flutter/third_party/txt/src/txt/platform_linux.cc

   std::vector<std::string> GetDefaultFontFamilies() {
  -  return {"Ubuntu", "Cantarell", "DejaVu Sans", "Liberation Sans", "Arial"};
  +  return {"SamsungOneUI", "BreezeSans", "Ubuntu", "Cantarell", "DejaVu Sans", "Liberation Sans", "Arial"};
   }

• Set up the build with gn. (Use --runtime-mode debug for debug build.)

  ./flutter/tools/gn \
  --target-os linux \
  --linux-cpu arm \
  --target-toolchain <toolchain path> \
  --target-sysroot <sysroot path> \
  --target-triple armv7l-tizen-linux-gnueabi \
  --runtime-mode release \
  --embedder-for-target \
  --disable-desktop-embeddings

• Run the ninja build.

  ninja -C out/linux_release_arm