Developing Built-in Native Apps

To create a built-in native app, you must write the source code and prepare the required configuration files.

For easier understanding, the process to create a built-in native app is explained using a sample app in Sample Code Repository. The sample app has the following features:

• Displays a “Hello, Native Qt Application!!” message on screen.
• Calls com.webos.service.applicationmanager/registerApp method.
• Prints logs when it is first launched.
• Prints logs with the updated parameter and status whenever the app is relaunched.

The directory structure of the sample app must be as follows:

native-apps/built-in/
├── build-config/
│   ├── com.example.app.nativeqt.bb
│   └── webos-local.conf
└── com.example.app.nativeqt/
    ├── appinfo.json
    ├── com.example.app.nativeqt.pro
    ├── icon.png
    ├── main.cpp
    ├── MyOpenGLWindow.cpp
    ├── MyOpenGLWindow.h
    ├── README.md
    ├── ServiceRequest.cpp
    └── ServiceRequest.h

Developing a built-in native app requires the following steps:

• Prerequisites
• Step 1: Implementation
• Step 2: Configuration
• Step 3: Build
• Step 4: Verification
• Step 5: Deployment

Before you begin

• Build and flash the webOS OSE image. For detailed information, see Building webOS OSE and Flashing webOS OSE.

• Download the sample repository, and move into samples/native-apps/built-in directory.

  $ git clone https://github.com/webosose/samples
  $ cd samples/native-apps/built-in
  

Step 1: Implement the Native App

Source Code

First, define the functionality of the native app on the source code.

MyOpenGLWindow.cpp

Define MyOpenGLWindow class member functions.

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...
MyOpenGLWindow::MyOpenGLWindow(QRect rect)
    : m_windowRect(rect)
    , m_device(nullptr)
{
    setSurfaceType(QWindow::OpenGLSurface);
    create();

    m_context = new QOpenGLContext(this);
    m_context->create();

    m_context->makeCurrent(this);
    initializeOpenGLFunctions();
}
...

A brief explanation of the above file:

• Line(7) : Set the surface type of MyOpenGLWindow to OpenGLSurface. The type can be OpenGLSurface or RasterGLSurface.

ServiceRequest.h

Define a class that can register to luna-service2 and call registerApp method of System and Application Manager (SAM). This header file has the function declaration.

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...
static PmLogContext getPmLogContext()
{
    static PmLogContext s_context = 0;
    if (0 == s_context)
    {
        PmLogGetContext("NativeQtApp", &s_context);
    }
    return s_context;
}
...

A brief explanation of the above file:

• Line(3~11) : A function that calls PmLogGetContext() in PmLog library to print logs. For more details, see Using PmLogLib in C/C++.

ServiceRequest.cpp

Define ServiceRequest class member functions. In addition, add helper functions related to PbnJson to use the library conveniently.

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#include "ServiceRequest.h"

static pbnjson::JValue convertStringToJson(const char *rawData)
{
    pbnjson::JInput input(rawData);
    pbnjson::JSchema schema = pbnjson::JSchemaFragment("{}");
    pbnjson::JDomParser parser;
    if (!parser.parse(input, schema))
    {
        return pbnjson::JValue();
    }
    return parser.getDom();
}

static std::string convertJsonToString(const pbnjson::JValue json)
{
    return pbnjson::JGenerator::serialize(json, pbnjson::JSchemaFragment("{}"));
}

ServiceRequest::ServiceRequest(std::string appId, QWindow &window)
    : m_mainLoop(g_main_loop_new(nullptr, false))
    , m_serviceHandle(nullptr)
{
    m_appId = appId;
    m_window = &window;
    m_serviceHandle = acquireHandle();
}

ServiceRequest::~ServiceRequest()
{
    clearHandle();
    if (m_mainLoop)
    {
        g_main_loop_quit(m_mainLoop); // optional!
        g_main_loop_unref(m_mainLoop);
        m_mainLoop = nullptr;
    }
}

LSHandle* ServiceRequest::acquireHandle()
{
    LSError lserror;
    LSErrorInit(&lserror);

    LSHandle* handle = nullptr;
    if (!LSRegister(m_appId.c_str(), &handle, &lserror))
    {
        LSErrorPrint(&lserror, stderr);
        return nullptr;
    }

    if (!LSGmainAttach(handle, m_mainLoop, &lserror))
    {
        LSErrorPrint(&lserror, stderr);
        return nullptr;
    }
    return handle;
}

void ServiceRequest::clearHandle()
{
    LSError lserror;
    LSErrorInit(&lserror);
    if (m_serviceHandle)
    {
        LSUnregister(m_serviceHandle, &lserror);
        m_serviceHandle = nullptr;
    }
}

static bool registerAppCallback(LSHandle* sh, LSMessage* msg, void* context)
{
    PmLogInfo(getPmLogContext(), "REGISTER_CALLBACK", 1, PMLOGJSON("payload", LSMessageGetPayload(msg)),  " ");

    pbnjson::JValue response = convertStringToJson(LSMessageGetPayload(msg));
    bool successCallback = response["returnValue"].asBool();
    if (successCallback)
    {
        std::string event = response["event"].asString();
        PmLogInfo(getPmLogContext(), "REGISTER_CALLBACK", 1, PMLOGKS("event", event.c_str()),  " ");

        if (event == "registered")
        {
            //handle "registered" event
        }
        else if (event == "relaunch")
        {
            //relaunch screen
            if (context != nullptr)
            {
                ((ServiceRequest*)context)->m_window->showFullScreen();
            }
            //handle "relaunch" event
            if (response.hasKey("parameters"))
            {
                pbnjson::JValue launchParams = response["parameters"];
                PmLogInfo(getPmLogContext(), "REGISTER_CALLBACK", 1,
                            PMLOGJSON("parameters", convertJsonToString(launchParams).c_str()),  " ");
            }
        }
        else if (event == "close")
        {
            //handle "close" event
        }
    }
    else
    {
        PmLogError(getPmLogContext(), "REGISTER_CALLBACK", 0, "RegisterApp Callback error" );
        // error handling..
    }
    return true;
}

void ServiceRequest::registerApp()
{
    PmLogInfo(getPmLogContext(), "APP_REGISTER", 0, "RegisterApp called");
    LSError lserror;
    LSErrorInit(&lserror);
    LSHandle* handle = getHandle();
    if (!handle)
    {
        PmLogError(getPmLogContext(), "APP_REGISTER", 0, "LSHandle is NULL" );
    }

    if (!LSCall(handle,
                "luna://com.webos.service.applicationmanager/registerApp",
                "{}",
                registerAppCallback,
                this,
                NULL,
                &lserror))
    {
        LSErrorPrint(&lserror, stderr);
    }
}

A brief explanation of the above file:

• Line(3~18) : Create pbnjson utility functions, which convert String to Json and Json to String based on pbnjson library. pbnjson is a JSON engine, implemented as a pair of libraries with APIs for easier C and C++ abstraction.
• Line(20~38) : Define constructor and destructor of ServiceRequest class.
• Line(40~69) : Define functions to register and unregister com.example.app.nativeqt to and from luna-service. For more details about luna-service functions, see the luna-service2 Library API Reference.
• Line(71~112) : Implement the callback function of registerApp.
  • Line(82~85) : When the app first calls the method, the value of event in response is “registered”.
  • Line(86~100) : When the app is already running and SAM’s launch method is called, the value of event comes up as “relaunch”.
    • Line(89~92) : Call the showFullScreen function to change the app’s state from background to foreground.
    • Line(94~99) : If the user gives a parameter of params when calling launch, the app can get the value of params with the property “parameters” in response.
  • Line(101~104) : When the app is closed by SAM’s closeByAppId method, the value of event comes up as “close”.
• Line(114~135) : Call the registerApp method of SAM.

main.cpp

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#include "MyOpenGLWindow.h"
#include "ServiceRequest.h"
#include <QtGui/QGuiApplication>
#include <QtGui/QWindow>
#include <QtGui/QScreen>
#include <qpa/qplatformnativeinterface.h>

int main(int argc, char **argv)
{
    QGuiApplication app(argc, argv);
    PmLogInfo(getPmLogContext(), "MAIN_ARGV1", 1, PMLOGKFV("argv", "%s", argv[1]),  " ");

    QString displayId = (getenv("DISPLAY_ID") ? getenv("DISPLAY_ID") : "0");
    PmLogInfo(getPmLogContext(), "DISPLAY", 1, PMLOGKFV("Id", "%s", displayId.toStdString().c_str()),  " ");

    QScreen *screen = QGuiApplication::primaryScreen();
    QRect screenGeometry = screen->geometry();
    MyOpenGLWindow window(screenGeometry);
    window.resize(screenGeometry.width(), screenGeometry.height());
    window.show();

    ServiceRequest s_request("com.example.app.nativeqt", window);
    s_request.registerApp();

    QGuiApplication::platformNativeInterface()->setWindowProperty(window.handle(), "appId", "com.example.app.nativeqt");
    QGuiApplication::platformNativeInterface()->setWindowProperty(window.handle(), "displayAffinity", displayId);

    return app.exec();
}

A brief explanation of the above file:

• Line(1) : Include MyOpenGLWindow.h header file which has OpenGLSurface type window class.
• Line(2) : Include ServiceRequest.h header file which has member functions that can call services based on luna-service2.
• Line(3~6) : Include Qt header files.
• Line(11) : argv[1] holds the value that SAM gives to the native app when the app is first launched. The value passed as “params” in SAM’s launch method call can be received as “parameters”, and the lifecycle “event” of the native app comes up as “launch”.
• Line(13~14) : Get the DISPLAY_ID property from the environment variable so that the app can be launched on the display corresponding to the displayAffinity value passed as a launch parameter.
• Line(16~20) : Create a MyOpenGLWindow object. Set the window’s size and display the text on the screen.
• Line(22~23) : Create a ServiceRequest object and call the registerApp() function.
• Line(25~26) : Use QWindow::Handle() to get QPlatformWindow from MyOpenGLWindow. Set “appId” and “displayAffinity” to the window.
• Line(28) : Enters the main event loop and waits until exit() is called, then returns the value that was set to exit(): 0 if exit() is called via quit().

For detailed information on Qt, see Qt documentation.

README.md

This file provides general information of the native app.

Summary
-------
native app sample

Description
-----------

native app sample

How to Build on Linux
---------------------

## Dependencies

Below are the tools and libraries (and their minimum versions) required to build sample program:

* qmake

## Building

    $ cd build-webos
    $ source oe-init-build-env
    $ bitbake com.example.app.nativeqt

Copyright and License Information
=================================
Unless otherwise specified, all content, including all source code files and
documentation files in this repository are:

Copyright (c) 2020 LG Electronics, Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

SPDX-License-Identifier: Apache-2.0

Step 2: Configure the Native App

This section describes how to prepare the configuration files required to build and test the native app.

appinfo.json

Apps are required to have metadata before they can be packaged. This metadata is stored in a file called appinfo.json, which is used by the webOS device to identify the app, its icon, and other information that is needed to launch the app.

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{
    "id": "com.example.app.nativeqt",
    "version": "0.1.0",
    "vendor": "My Company",
    "type": "native",
    "main": "nativeqt",
    "title": "Native qt App",
    "icon": "icon.png",
    "requiredPermissions" : ["application.operation"],
    "nativeLifeCycleInterfaceVersion": 2
}

A brief explanation of the above file:

• Line(2) : The ID for the app.
• Line(5) : The type of the native app.
• Line(6) : The executable file name.
• Line(7) : The title to be shown on the Launchpad.
• Line(8) : The icon to be shown on the Launchpad and App Bar. Make sure the icon file is available in the project root directory. You can use your own icon.png (80*80) file or attached icon.png.
• Line(9) : Specify the group to which the external service’s method called by the app belongs. Because SAM’s registerApp method belongs to “application.operation” group, put “application.operation” in this property. To check the group of each method, use ls-monitor command with “-i” option.
• Line(10) : This field is required to use SAM’s registerApp method.

For more details, see appinfo.json.

qmake Project File

This file specifies the application name and the qmake template to be used for generating the project, as well as the source, header, and UI files included in the project.

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TARGET = nativeqt

CONFIG += qt
QT += core gui-private
# if you use QT 6.x , you should include opengl. because opengl is not included by default.
# but if you use QT 5.x under, opengl is included by default so you do not include opengl.
greaterThan(QT_MAJOR_VERSION, 5) {
    QT += opengl
}

CONFIG += link_pkgconfig
PKGCONFIG += luna-service2 glib-2.0 pbnjson_cpp PmLogLib

SOURCES += ServiceRequest.cpp MyOpenGLWindow.cpp main.cpp
HEADERS += ServiceRequest.h MyOpenGLWindow.h

INSTALL_APPDIR = $${WEBOS_INSTALL_WEBOS_APPLICATIONSDIR}/com.example.app.nativeqt

target.path = $${INSTALL_APPDIR}

icon.path = $${INSTALL_APPDIR}
icon.files = icon.png

appinfo.path = $${INSTALL_APPDIR}
appinfo.files = appinfo.json

INSTALLS += target icon appinfo

A brief explanation of the above file:

• Line(1) : Set TARGET name. It must be an executable file name of the app.
• Line(3) : The CONFIG variable is a special variable that ‘qmake’ uses when generating a Makefile. qt is added to the list of existing values contained in CONFIG.
• Line(4) : Link against the QtCore Module. Add ‘gui-private’ to use private GUI include directories.
• Line(11~12) : ‘qmake’ can configure the build process to make use of external libraries that are supported by pkg-config, such as the luna-service2, glib, pbnjson, and PmLog libraries.
• Line(14) : A list of source code files to be used when building the project.
• Line(15) : A list of filenames of header (.h) files used when building the project.
• Line(17) : Set installed directory on the target board. INSTALL_APPDIR would be /usr/palm/applications/com.example.app.nativeqt on the target.
• Line(19~25) : *.files specifies a path in project directory and *.path specifies the path to the file system to be installed on the target.
• Line(27) : Add targets, icons, and appinfo files from the INSTALLS list.

For more details, see qmake Project Files.

Step 3: Build the Native App

After implementing and configuring the native app, you must build the app.

Add the Recipe File

webOS OSE uses OpenEmbedded of Yocto Project to build its components. OpenEmbedded needs a recipe file that configures the build environment. For more details about the recipe, see Yocto Project Reference Manual.

You must move the recipe file into webOS OSE project directory.

• Recipe file: samples/native-apps/built-in/build-config/com.example.app.nativeqt.bb
• Destination Directory: build-webos/meta-webosose/meta-webos/recipes-webos/<native app name>

where <native app name> is the name of the native app. For the sample native app, <native app name> must be replaced by ‘com.example.app.nativeqt’.

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SUMMARY = "Native Qt App"
SECTION = "webos/apps"
LICENSE = "Apache-2.0"
LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/Apache-2.0;md5=89aea4e17d99a7cacdbeed46a0096b10"

WEBOS_VERSION = "1.0.0"
PR = "r0"

DEPENDS = "qtbase luna-service2 glib-2.0 libpbnjson"

inherit webos_submissions
inherit webos_qmake5
inherit webos_app
inherit webos_pkgconfig

OE_QMAKE_PATH_HEADERS = "${OE_QMAKE_PATH_QT_HEADERS}"

FILES:${PN} += "${webos_applicationsdir}"

A brief explanation of the above file:

• Line(1~4) : Basic descriptions of the component.
• Line(6) : Version of the component. For the webOS OSE component, this field is mandatory.
• Line(7) : Revision version of the recipe. Each recipe requires a counter to track its modification history. Make sure that you increment the version when you edit the recipe, unless you only change the value of the WEBOS_VERSION field or comments.
• Line(9) : A list of a recipe’s build-time dependencies.
• Line(11) : Instruct OpenEmbedded to use the WEBOS_VERSION value as the component version number. If you develop your component on a local repository, this entry is required.
• Line(12) : Instruct OpenEmbedded that the component uses QMake for configuration, which is the preferred choice for webOS components.
• Line(13) : Inherit webos_app, because the component is an app.
• Line(14) : For the component that uses pkg-config at build time or installs a pkg-config file (.pc), this entry is required.
• Line(16) : Put OE_QMAKE_PATH_HEADERS = "${OE_QMAKE_PATH_QT_HEADERS}" so that Qt header files can be included at compile time.
• Line(18) : ${webos_applicationsdir} indicates /usr/palm/applications. ${PN} is the package name, which is set to webos.example.app.nativeqt.

Configure the Local Source Directory

To build a component that is located on the local system, you must specify the directory information.

You must move the configuration file into webOS OSE project directory.

• Configuration file: samples/native-apps/built-in/build-config/webos-local.conf
• Destination directory: build-webos

For the sample native app (com.example.app.nativqt), you must provide the local path where the source exists.

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INHERIT += "externalsrc"
EXTERNALSRC:pn-com.example.app.nativeqt = "/home/username/project/com.example.app.nativeqt/"
EXTERNALSRC_BUILD:pn-com.example.app.nativeqt = "/home/username/project/com.example.app.nativeqt/build/"
PR:append:pn-com.example.app.nativeqt =".local0"

A brief explanation of the above file:

• Line(1) : Inherit externalsrc bbclass file.
• Line(2) : The local source directory. The syntax of the property is EXTERNALSRC:pn-<component>. For the value, input "<absolute path of the project directory>"
• Line(3) : The local build directory. The syntax of the property is EXTERNALSRC_BUILD:pn-<component>. For the value, input "<absolute path of the project directory>/build/"
• Line(4) : The appended revision version (PR) for building local source files. The syntax of the property is PR:append:pn-<component>. This property is optional.

Build the App

To build the component on the OpenEmbedded environment, enter the following commands on the shell.

build-webos$ source oe-init-build-env
build-webos$ bitbake com.example.app.nativeqt

Step 4: Run and Verify the Native App

After building the app, you must verify its functionality.

1. Copy the IPK to the target.

   When the build is successful, oe-related directories are created under the project root directory. These directories are linked to the directory where the build output is generated from the actual build-webos sub-directory.

   com.example.app.nativeqt
   ├── appinfo.json
   ├── build
   ├── com.example.app.nativeqt.pro
   ├── icon.png
   ├── main.cpp
   ├── MyOpenGLWindow.cpp
   ├── MyOpenGLWindow.h
   ├── oe-logs -> /home/username/build/build-webos/BUILD/work/raspberrypi4_64-webos-linux-gnueabi/com.example.app.nativeqt/1.0.0-r0.local0/temp
   ├── oe-workdir -> /home/username/build/build-webos/BUILD/work/raspberrypi4_64-webos-linux-gnueabi/com.example.app.nativeqt/1.0.0-r0.local0
   ├── .md
   ├── ServiceRequest.cpp
   └── ServiceRequest.h
   

   If you go to oe-workdir/deploy-ipks/raspberrypi4_64, you can see com.example.app.nativeqt_1.0.0-r0.local0_raspberrypi4_64.ipk file.

   com.example.app.nativeqt/oe-workdir/deploy-ipks/raspberrypi4_64$
   └── com.example.app.nativeqt_1.0.0-r0.local0_raspberrypi4_64.ipk
   

   Copy the IPK file to the target device using the scp command.

   com.example.app.nativeqt/oe-workdir/deploy-ipks/raspberrypi4_64$ scp com.example.app.nativeqt_1.0.0-r0.local0_raspberrypi4_64.ipk root@<target IP address>:/media/internal/downloads/
   

2. Install the app on the target.

   Connect to the target using the ssh command and install com.example.app.nativeqt_1.0.0-r0.local0_raspberrypi4_64.ipk.

   $ ssh root@<target IP address>
       root@raspberrypi4-64:/sysroot/home/root# cd /media/internal/downloads/
       root@raspberrypi4-64:/media/internal/downloads# opkg install com.example.app.nativeqt_1.0.0-r0.local0_raspberrypi4_64.ipk
       Installing com.example.app.nativeqt (1.0.0) on root.
       Configuring com.example.app.nativeqt.
   

3. Discover the LS2 configuration files.

   To make LS2 daemon scan the LS2 configuration files of the app, use the ls-control command as follows.

   root@raspberrypi4-64:/media/internal/downloads# ls-control scan-services
   
       telling hub to reload setting and rescan all directories
   

   Note
   For the native app, LS2 configuration files are generated during the build process. To run the app properly, you must make the system scan the newly generated configuration files.

4. Scan the app.

   To make System and Application Manager (SAM) scan the app, restart SAM using the systemctl command. This step is required so that the app can be added to the app list, which in turn makes the app appear on the Launchpad.

   root@raspberrypi4-64:/# systemctl restart sam
   

   Note
   Rebooting the target after installing the app will have the same effect as running the ls-control and systemctl commands. However, using the commands allows you to continue testing without rebooting.

5. Run the native app.

   Drag the mouse cursor upward from the bottom of the screen (or swipe up from the bottom of the screen if you’re using a touch display).

   Note
   On webOS OSE 1.x, press the Windows key.

   Click the Launchpad icon.

   

   Click the app icon to see the window titled “Native qt app” with the following page:

   

6. Verify the execution of the native app.

   • Using SAM’s running method

     You can check whether the app is running by using SAM. For more SAM methods, see com.webos.service.applicationmanager.

     root@raspberrypi4-64:/# luna-send -i -f luna://com.webos.service.applicationmanager/running '{"subscribe":true}'
     {
         "subscribed": true,
         "running": [
             {
                 "webprocessid": "",
                 "instanceId": "0d67ed57-6585-4de5-b1cb-6f63ea04716d0",
                 "displayId": 0,
                 "defaultWindowType": "card",
                 "appType": "native",
                 "id": "com.example.app.nativeqt",
                 "processid": "1337",
                 "launchPointId": "com.example.app.nativeqt_default"
             }
         ],
         "returnValue": true
     }
     

   • Using the log file

     You can use the journalctl command on the target for debugging the native app.

     Launch the app when the app is in the foreground, and the “relaunch” event is received.

     root@raspberrypi4-64:/# luna-send -n 1 -f luna://com.webos.service.applicationmanager/launch '{"id":"com.example.app.nativeqt", "params":{"test":"key2"}}
     

     See the log file.

     root@raspberrypi4-64:/#journalctl | grep NativeQtApp
     
     Dec 31 16:00:35 raspberrypi4-64 nativeqt[1538]: [] [pmlog] NativeQtApp REGISTER_CALLBACK {"payload":{"event":"relaunch","returnValue":true,"appId":"com.example.app.nativeqt","message":"relaunch","parameters":{"test":"key2","displayAffinity":0},"reason":"com.webos.lunasend-1552"}}
     Dec 31 16:00:35 raspberrypi4-64 nativeqt[1538]: [] [pmlog] NativeQtApp REGISTER_CALLBACK {"event":"relaunch"}
     Dec 31 16:00:35 raspberrypi4-64 nativeqt[1538]: [] [pmlog] NativeQtApp REGISTER_CALLBACK {"parameters":{"test":"key2","displayAffinity":0}}
     

Step 5: Deploy the Native App

You are now ready to build the webOS image including the native app and flash it to the target device.

Perform the following steps:

1. Add the native app to the build recipe file.

   • Filename: packagegroup-webos-extended.bb
   • Directory: build-webos/meta-webosose/meta-webos/recipes-core/packagegroups
   • Updates to be made: Add the native app name to RDEPENDS:${PN} =

   ...
   RDEPENDS:${PN} = " \
       activitymanager \
       audiod \
       ...
       com.example.app.nativeqt \
       ${VIRTUAL-RUNTIME_appinstalld}
       ...
   

   For more details, see Yocto Project Reference Manual.

2. Build the webOS image using the following commands.

   build-webos$ source oe-init-build-env
   build-webos$ bitbake webos-image
   

3. Flash the generated webOS image to the SD card.

   Path to image: build-webos/BUILD/deploy/images/raspberrypi4-64/webos-image-raspberrypi4-64.rootfs.wic

   build-webos/BUILD/deploy/images/raspberrypi4-64$ sudo dd bs=4M if=webos-image-raspberrypi4-64.rootfs.wic of=/dev/sdc
   

   For more details, see the Flashing webOS OSE page.

After rebooting, the native app becomes available on the Launchpad.