Flutter Engine

Source of the original repository: https://github.com/flutter/engine

Repository Description

This repository is an extension of the Flutter engine repository. It enables Flutter engine to run on OpenHarmony devices.

How to Build

• Build environment:

1. Linux or macOS that support Flutter engine; Windows that supports gen_snapshot.
2. Access to the allowed_hosts field in the DEPS file.

• Build steps:

1. Set up a basic environment. For details, see the official document.

   The following libraries need to be installed:

   sudo apt install python3
   sudo apt install pkg-config
   sudo apt install ninja-build
   

   Configure node. Specifically, download node, unzip it, and configure it into environment variables.

   # nodejs
   export NODE_HOME=/home/<user>/env/node-v14.19.1-linux-x64
   export PATH=$NODE_HOME/bin:$PATH
   

   For Windows: Refer to the section "Compiling for Windows" in the official document.

2. Configure the file. Specifically, create an empty folder engine, create the .gclient file in this folder, and edit the file.

   solutions = [
   {
      "managed": False,
      "name": "src/flutter",
      "url": "git@gitee.com:openharmony-sig/flutter_engine.git",
      "custom_deps": {},
      "deps_file": "DEPS",
      "safesync_url": "",
   },
   ]
   

3. Synchronize the code. In the engine directory, execute gclient sync. The engine source code and packages repository will be synchronized, and the ohos_setup task will be executed.

4. Download the SDK. Download the supporting development kits from HarmonyOS SDK. Suites downloaded from other platforms are not supported.

   # Environment variables to set: HarmonyOS SDK, ohpm, hvigor, and node.
   export TOOL_HOME=/Applications/DevEco-Studio.app/Contents # macOS environment
   export DEVECO_SDK_HOME=$TOOL_HOME/sdk # command-line-tools/sdk
   export PATH=$TOOL_HOME/tools/ohpm/bin:$PATH # command-line-tools/ohpm/bin
   export PATH=$TOOL_HOME/tools/hvigor/bin:$PATH # command-line-tools/ hvigor/bin
   export PATH=$TOOL_HOME/tools/node/bin:$PATH # command-line-tools/tool/node/bin
   

5. Start building. In the engine directory, execute ./ohos to start building the Flutter engine that supports ohos devices.

6. Update the code. In the engine directory, execute ./ohos -b master.

Engine Build Products

See Build Products.

FAQs

1. The message Member notfound:'isOhos' is reported during project running.
   Install all dart patches in the src/third_party/dart directory. (The patches are located in the src/flutter/attachment/repos directory, and you can use git apply to apply the patches). Recompile the engine after installing the patches.

2. The message Permission denied is reported.
   Execute chmod +x < script file > to add the execution permission.

3. To compile the engine in debug, release, or profile mode, execute ./ohos -t debug, ./ohos -t release, or ./ohos -t profile, respectively.

4. To find the help, execute ./ohos -h.

5. Different ways for handling newline characters by Windows, macOS, and Linux will cause different results of dart vm snapshot hash when installing the dart patches. You can obtain the value of snapshot hash through the following method:

   python xxx/src/third_party/dart/tools/make_version.py --format='{{SNAPSHOT_HASH}}'
   

   Here, xxx is the engine path you created.

   If the obtained value is not 8af474944053df1f0a3be6e6165fa7cf, check whether all lines of the xxx/src/third_party/dart/runtime/vm/dart.cc file and the xxx/src/third_party/dart/runtime/vm/image_snapshot.cc file end with LF. For Windows, you can use Notepad++ to check; for other systems, consult specific methods on your own.

Code Building at the Embedding Layer

1. Edit shell/platform/ohos/flutter_embedding/local.properties as follows:

   sdk.dir=<OpenHarmony SDK directory>
   nodejs.dir=<nodejs SDK directory>
   

2. Copy the file to shell/platform/ohos/flutter_embedding/flutter/libs/arm64-v8a/ from the built engine directory.

   1. For the debug or release version, copy libflutter.so.
   2. For the profile version, copy libflutter.so and libvmservice_snapshot.so.

3. In the shell/platform/ohos/flutter_embedding directory, execute the following instruction:

   # buildMode can be set to debug, release, or profile.
   hvigorw --mode module -p module=flutter@default -p product=default -p buildMode=debug assembleHar --no-daemon
   

4. Find the HAR file from the path shell/platform/ohos/flutter_embedding/flutter/build/default/outputs/default/flutter.har.

5. Rename the HAR file in the flutter.har.BUILD_TYPE.API format, where BUILD_TYPE indicates debug, release, or profile, and API indicates the current SDK version (for example, 11 indicates API version 11). For example, to build a debug version of API version 11, rename the file flutter.har.debug.11.

6. Replace the corresponding file in the flutter_flutter/packages/flutter_tools/templates/app_shared/ohos.tmpl/har/har_product.tmpl/ directory and execute the project again for the modification to take effect.

If you are using DevEco Studio of a Beta version and encounter the error message must have required property 'compatibleSdkVersion', location: build-profile.json5:17:11 when building the project, refer to the section "Configuring Plugins" in chapter 6 "Creating a Project and Runing Hello World" of DevEco Studio Environment Setup.docx to modify the shell/platform/ohos/flutter_embedding/hvigor/hvigor-config.json5 file.