Launching a web app on a secondary display

June 11, 2020

Author: NERGI

Since version 2.0.0, webOS OSE has been supporting a dual display feature. Thanks to that feature, a user can select an output display of a webOS OSE app.

For those who want to try out the feature on webOS OSE, this guide introduces a sample app which can select the output display.

How to Install the App

To install the app, first you have to clone the repository.

$ git clone https://github.com/Heeam-Shin/web-app-controller-sample.git
$ cd web-app-controller-sample

The installation procedure is the same as that of a web app. Type the following commands:

$ ares-package .
$ ares-install ./com.dual.webapp.sample_1.0.0_all.ipk -d [your-target-device]

Note
For more details on the above procedure, refer to Developing Downloadable Web Apps.

If the installation succeed, the app card of the installed sample appears in Home Launcher.

Then click the app card to launch the sample app. You can launch/close the built-in YouTube app by clicking the Launch / Close buttons, respectively.

Source Codes

This section explains the codes which are directly related to usage of LS2 API rather than explaining the whole codes.

appinfo.json

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{
  "id": "com.dual.webapp.sample",
  "version": "1.0.0",
  "vendor": "LG Electronics",
  "type": "web",
  "main": "index.html",
  "title": "Secondary display sample",
  "icon": "./images/NERGI.png",
  "requiredPermissions": ["configurator.callbacks","applications","all","applications.launch","applications.internal"]
}

A brief explanation of the above file:

Line(9) : Set ACG (Access Control Groups) information. Every method of LS2 APIs needs ACG information to get security permissions. For more details on how to get the ACG information, see Identify the ACG Group of the Methods.

index.html

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<body>
    <div class="middle-center-align">
        <h1 class="burning-shadow">Launch/Close YouTube App!</h1>
        <h2>(on your secondary display)</h2>
        <div class="center-align">
            <button class="button" onclick="openApp();">Launch</button>
            <button class="button" onclick="closeApp();">Close</button>
        </div>
    </div>
</body>

It’s a pretty basic HTML code. A brief explanation of the above file:

Line(6~7) : Call JavaScript functions using the onclick event.

webapp-test.js

In this file, openApp() function calls the launch method and closeApp() calls the close method using the WebOSServiceBridge API. Both openApp() and closeApp() use the WebOSServiceBridge API in a similar way. So I’ll only explain how openApp() makes use of the API only.

Note
For more details on launch and close, see the com.webos.service.applicationmanager API.

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function openApp(){
    var bridge = new WebOSServiceBridge();

    var url = 'luna://com.webos.service.applicationmanager/launch';
    var params = '{"id":"com.webos.app.test.youtube", "params": {"displayAffinity": 1}}';

    bridge.call(url, params);
}

A brief explanation of the above file:

Line(2) : Create a WebOSServiceBridge object.
Line(4~5) : Define parameters for the call method.
Line(7) : Call a LS2 API with predefined parameters (url, params). You can use various LS2 APIs by changing parameters of the call method.

Note
For more information about other LS2 APIs, see LS2 API Index.