Application Launcher

This guide explains how to create a basic application launcher. The application launcher is the main application that normally starts after the system boots. This app is commonly replaced in the platform adjustment process. It is easy to use the .NET APIs in the application launcher implementation.

Every application launcher must be able to do the following tasks:

List installed and runnable applications
Run applications selected by the user

You can also implement advanced functionalities such as the following:

Grouping installed applications into folders
Removing applications
Rearrangement of icons
Viewing notifications
Viewing widgets

Prerequisites

To list the installed applications and launch them, the launcher app must have defined privileges in the project manifest file:


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<?xml version="1.0" encoding="utf-8"?>
  <ui-application appid="NUIApplicationLauncher">
    <!-- Auto generated manifest properties -->
  </ui-application>
  <privileges>
    <privilege>http://tizen.org/privilege/packagemanager.info</privilege>
    <privilege>http://tizen.org/privilege/appmanager.launch</privilege>
  </privileges>

Manage app launcher

The following steps illustrate how to implement the simple application launcher using:

NUI for the view implementation
Package Manager to gather installed applications
TizenFX AppControl to launch an app on touch event

Figure: NUI application launcher

Application launcher

To use mentioned API’s, the following namespaces have to be included:


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using System;
using System.Collections.Generic;

using Tizen.Applications;

using Tizen.NUI;
using Tizen.NUI.BaseComponents;

To group application launcher responsibilities, three classes in the NUIApplicationLauncher namespace are defined which represent the main application structure:


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namespace NUIApplicationLauncher
{
    //Each touch event needs additional data like application ID to launch application
    partial class ApplicationIconClickedEventArgs : EventArgs
    {
        //...
    }

    //Application Icon component with ImageView and Label. Also OnTouch Event is handler here.
    class ApplicationIcon : View
    {
        //...
    }

    //Main Application Code
    class Program : NUIApplication
    {
        //...
    }
}

To add an application ID field, create the event arguments derived class. The application ID is used by AppControl to launch the application:


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partial class ApplicationIconClickedEventArgs : EventArgs
{
    public string AppId = "";

    public ApplicationIconClickedEventArgs(string id)
    {
        AppId = id;
    }
}

The ApplicationIcon class stores the application ID. The Icon component and OriginSize are used to resize Icon when it is in the pressed state. The ApplicationIconClicked is invoked when touch changes its state to finished:


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class ApplicationIcon : View
{
    private string AppId;

    private ImageView Icon;
    private Size2D OriginSize;

    public event EventHandler<ApplicationIconClickedEventArgs> ApplicationIconClicked;
}

The ApplicationIcon constructor is responsible for the following:

Set AppId and OriginSize.
Create view components: Label which is used to show an application name and Icon which load resource from path string and show loaded image.
Create Layout of the ApplicationIcon. In this case, the vertical linear layout is used.
Setup the TouchEvent handler.


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public ApplicationIcon(string name, string path, Size2D size, string id)
{
    this.AppId = id;
    OriginSize = new Size2D(size.Width - 40, size.Height - 40);

    this.Size2D = size;

    TextLabel label = new TextLabel()
    {
        PointSize = 6,
        Text = name,
        MultiLine = true,
        Size2D = new Size2D(size.Width, 40),
        HorizontalAlignment = HorizontalAlignment.Center,
        VerticalAlignment = VerticalAlignment.Center,
    };

    Icon = new ImageView()
    {
        Size2D = new Size2D(size.Height - 40, size.Height - 40),
        ResourceUrl = path,
    };

    this.Layout = new LinearLayout()
    {
        HorizontalAlignment = HorizontalAlignment.Center,
        LinearOrientation = LinearLayout.Orientation.Vertical
    };

    this.Add(Icon);
    this.Add(label);

    this.TouchEvent += OnTouchEvent;
}

Figure: Application icons

Application Icons

OnTouchEvent reads state from the TouchEventArgs. If touch is in PointStateType.Down state, the application icon is resized. Otherwise, it returns to normal size and the predefined event is invoked with the proper AppId:


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public bool OnTouchEvent(object sender, TouchEventArgs args)
{
    var state = args.Touch.GetState(0);

    switch (state)
    {
        case PointStateType.Down:
            Icon.Size2D = new Size2D((int)(OriginSize.Width * 1.1f), (int)(OriginSize.Height * 1.1f));
            break;
        case PointStateType.Finished:
            Icon.Size2D = OriginSize;
            ApplicationIconClicked.Invoke(this, new ApplicationIconClickedEventArgs(this.AppId));
            break;
        default:
            break;
    }

    return false;
}

The Program class derived from NUIApplication handles all necessary system events (Application Lifecycle). The AppLauncher is created in Initialize() method and used in an icon touch handler:


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class Program : NUIApplication
{
    private AppControl AppLauncher;

    //...
}

The OnCreate() method calls Initialize() function before the main application loop starts:


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protected override void OnCreate()
{
    base.OnCreate();
    Initialize();
}

The Initialize() method set up key listener, AppControl object, and the application background:


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void Initialize()
{
    var appWindow = Window.Instance;
    appWindow.KeyEvent += OnKeyEvent;

    AppLauncher = new AppControl();
    ImageView background = new ImageView(DirectoryInfo.Resource + "/images/bg.png");

    //Setting the background parameters so that it occupies the entire application window
    background.Size2D = new Size2D(appWindow.Size.Width, appWindow.Size.Height);
    background.Position2D = new Position2D(0, 0);
    appWindow.GetDefaultLayer().Add(background);
}

In the next step, the grid component for application icons is created. Grid spacing and columns number are defined in the GridLayout object. The appGrid component width and height is set to fill its parent:


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View appGrid = new View()
{
    WidthResizePolicy = ResizePolicyType.FillToParent,
    HeightResizePolicy = ResizePolicyType.FillToParent,
    Layout = new GridLayout()
    {
        Columns = 8,
        GridOrientation = GridLayout.Orientation.Horizontal,
        RowSpacing = 35f,
        ColumnSpacing = 12f,
        Padding = new Extents(30, 30, 30, 30)
    }
};

The PackageManager.GetPackages() is used to obtain all installed packages. Each package may contain several applications. Hence, pkg.GetApplications() is used. ApplicationInfo object is used to filter apps that must be displayed. In this case, NUIApplicationLauncher app with no icon or app with IsNoDisplay parameter will not be inserted into appGrid:


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IEnumerable<Package> packageList = PackageManager.GetPackages();

foreach (var pkg in packageList)
{
    var list = pkg.GetApplications();

    foreach (var app in list)
    {
        if (!app.IsNoDisplay && app.IconPath != null && app.Label != "NUIApplicationLauncher") {
            var icon = new ApplicationIcon(app.Label, app.IconPath, new Size2D((), 139), app.ApplicationId);
            icon.ApplicationIconClicked += OnAppIconClicked;
            appGrid.Add(icon);
        }
    }
}

Once appGrid object is created, it must be inserted in the application window:


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    appWindow.GetDefaultLayer().Add(appGrid);

Clicked event set up AppLauncher and pass it to AppControl SendLaunchRequest() API. Now, the selected applications get started:


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public void OnAppIconClicked(object sender, ApplicationIconClickedEventArgs args)
{
    AppLauncher.ApplicationId = args.AppId;
    AppLauncher.Operation = AppControlOperations.Default;
    AppControl.SendLaunchRequest(AppLauncher);
}

The following code shows how to implement back button clicked event. In this case application exits, but normally the launcher app doesn’t call the Exit() API:


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public void OnKeyEvent(object sender, Window.KeyEventArgs args)
{
    Tizen.Log.Info(LogTag, args.Key.ToString());

    if (args.Key.State == Key.StateType.Down && (args.Key.KeyPressedName == "XF86Back" || args.Key.KeyPressedName == "Escape"))
    {
        Exit();
    }
}

The common main code of the NUI application:


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static void Main(string[] args)
{
    var app = new Program();
    app.Run(args);
}

For full source code of the example, see here.

Dependencies
- Tizen 4.0 and Higher

Application Launcher

Prerequisites

Manage app launcher

Related information