Flutter Engine 编译

一、编译Flutter Engine

1. 创建工作目录 engine

2. 添加 depot_tools 到环境变量，并在engine目录下创建.gclient文件

   solutions = [
     {
       "managed": False,
       "name": "src/flutter",
       "url": "[email protected]:<your_name_here>/engine.git",
       "custom_deps": {},
       "deps_file": "DEPS",
       "safesync_url": "",
     },
   ]

3. 在engine目录执行 gclient sync 命令同步源码和编译工具链

4. 进入 engine/src 目录下，如果是linux平台执行：

   sudo ./build/install-build-deps-android.sh
   sudo ./build/install-build-deps.sh
   
   sudo ./flutter/build/install-build-deps-linux-desktop.sh

   如果是mac平台，安装jdk 1.8 和ant：

   brew install ant

5. 在engine/src 目录下，生成编译配置文件

   ./flutter/tools/gn --android --unoptimized

   生成目录 engine/src/out/android_debug_unopt

6. 在engine/src 目录下，执行编译命令

   ninja -C out/android_debug_unopt

二、如何在mac下编译linux平台的产物？

1. 创建docker镜像，由于需要科学上网，需要自行设置代理

   FROM ubuntu:16.04
   
   ENV DEPOT_TOOLS_PATH /home/admin/depot_tools
   ENV BUILDROOT_PATH /home/admin/buildroot
   ENV PATH $PATH:$DEPOT_TOOLS_PATH
   
   # Notes:
   # - libx11-dev is used by Flutter for desktop linux (see also install-build-deps-linux-desktop.sh)
    # - chrome is used by Flutter for web.
    RUN export http_proxy=http://*.*.*.*:*** && \
        export https_proxy=http://*.*.*.*:*** && \
        export socks_proxy=socks://*.*.*.*:*** && \
        apt-get update && \
        apt-get install -y sudo wget zip unzip git lsb-release openssh-client curl apt-transport-https libx11-dev software-properties-common build-essential libfreetype6-dev lib32stdc++6 libstdc++6 libpulse0 libglu1-mesa python pkg-config && \
        git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git $DEPOT_TOOLS_PATH && \
        git config --global http.proxy http://*.*.*.*:*** && \
        git config --global https.proxy http://*.*.*.*:*** && \ 
        git clone https://github.com/flutter/buildroot.git $BUILDROOT_PATH && \
        cd $BUILDROOT_PATH && \
        ./build/install-build-deps.sh --no-prompt && \
        ./build/install-build-deps-android.sh --no-prompt && \
        apt-get clean
    RUN git config --global --unset http.proxy && \
        git config --global --unset https.proxy && \
        unset http_proxy && \
        unset https_proxy && \
        unset socks_proxy && \
        chmod -R 777 $DEPOT_TOOLS_PATH &&

   创建image

   docker build  --rm -f "Dockerfile" -t flutter-engine-bulder:latest "."

2. 拉去镜像，如果是本地构建的镜像，则已经存在，如果上传到hub上，则拉去

   docker images | grep flutter-engine-bulder &>/dev/null
   if [ $? -ne 0 ]; then
       echo "flutter-engine-bulder does not exist,we will docker pull it"
       docker pull flutter-engine-bulder:latest
   else
       echo "flutter-engine-bulder already exists"
   fi

3. 通过docker 执行gclient sync，将宿主的源码目录engine映射到容器内/home/admin/engine，

   docker run --rm --privileged=true  -v engine:/home/admin/engine -w /home/admin/engine/ flutter-engine-bulder:latest gclient sync

4. 生成配置文件

   docker run --rm --privileged=true  -v engine:/home/admin/engine -w /home/admin/engine/src flutter-engine-bulder:latest ./flutter/tools/gn --android --unoptimized

5. 执行编译

   docker run --rm --privileged=true  -v engine:/home/admin/engine -w /home/admin/engine/src flutter-engine-bulder:latest ninja -C out/android_debug_unopt

docker编译如果很慢，可以自行根据电脑性能设置docker参数：

1. 增大docker可使用的cpu核心数
2. 增加docker可使用的内存
3. 增加docker可使用的交换空间，如果交换空间太小，会出现clang错误

在运行容器时，使用4核cpu编译：

docker run --rm --privileged=true --cpus=4  -v engine:/home/admin/engine -w /home/admin/engine/src flutter-engine-bulder:latest ninja -C out/android_debug_unopt

---

参考

https://github.com/flutter/flutter/wiki/Setting-up-the-Engine-development-environment

https://github.com/flutter/flutter/wiki/Compiling-the-engine

https://github.com/flutter/engine/blob/master/ci/docker/build/Dockerfile

https://github.com/flutter/engine/blob/master/.cirrus.yml