UWP - How to set app launch window size

UWP - Set app launch window size
The following Universal Windows Platform application development tutorial demonstrates how we can set the app launch window size programmatically.

In this UWP tutorial, we will set the ApplicationView class PreferredLaunchViewSize property value to set the app window preferred launch view size. We will also set the ApplicationView class PreferredLaunchWindowingMode property value to set the app window preferred launch windowing mode.

The ApplicationView class represents the active application view and associated states and behaviors.

The ApplicationView class PreferredLaunchViewSize property gets or sets the size that the app launches with when the ApplicationView class PreferredLaunchWindowingMode property is set to PreferredLaunchViewSize, except in cases where the system manages the window size directly. The PreferredLaunchViewSize property value is a Size.

The ApplicationView class PreferredLaunchWindowingMode property gets or sets a value that indicates the windowing mode the app launches with. This property value is an ApplicationViewWindowingMode enumeration value that indicates the windowing mode of the app. By default, PreferredLaunchWindowingMode is set to Auto.

The ApplicationViewWindowingMode enumeration defines constants that specify whether the app window is auto-sized, full-screen, or set to a specific size on launch. The PreferredLaunchViewSize value specifies the window is sized as specified by the ApplicationView class PreferredLaunchViewSize property.
MainPage.xaml

<Page
    x:Class="UniversalAppTutorials.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:UniversalAppTutorials"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    >
    <StackPanel Padding="50">
    </StackPanel>
</Page>
MainPage.xaml.cs

using Windows.UI.Xaml.Controls;
using Windows.UI.ViewManagement;
using Windows.Foundation;


namespace UniversalAppTutorials
{
    public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();

            /*
                ApplicationView
                    Represents the active application view and
                    associated states and behaviors.

                PreferredLaunchViewSize
                    Gets or sets the size that the app launches with when the
                    ApplicationView.PreferredLaunchWindowingMode property is set
                    to PreferredLaunchViewSize, except in cases
                    where the system manages the window size directly.

                ApplicationViewWindowingMode
                    PreferredLaunchViewSize: When launched, the window is sized
                    as specified by the ApplicationView.PreferredLaunchViewSize property.
            */

            // Set the app window preferred launch view size
            ApplicationView.PreferredLaunchViewSize = new Size(Height = 300, Width = 450);

            // Set app window preferred launch windowing mode
            ApplicationView.PreferredLaunchWindowingMode = ApplicationViewWindowingMode.PreferredLaunchViewSize;
        }
    }
}
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