maui -Minimum width and minimum height in content page

Question

Hi,

i used net 7 + vs 17.4

in main page i used and got null reference on window

protected override void OnAppearing()
    {
        base.OnAppearing();
        this.Window.MinimumHeight = 300;
        this.Window.MinimumWidth = 600;
    }

first i login using app shell as follow:

public App()
        {
            InitializeComponent();

            MainPage =  new AppShell();

<?xml version="1.0" encoding="UTF-8" ?>
<Shell
    x:Class="GssdDesktopClient.Maui.AppShell"
    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    xmlns:local="clr-namespace:GssdDesktopClient.Maui.Pages"
    Shell.FlyoutBehavior="Disabled">
    <ShellContent
        ContentTemplate="{DataTemplate local:LoginPage}"
        Route="LoginPage" />
        
</Shell>

Later on login button click i move to main page and there i put :

await Application.Current.MainPage.Navigation.PushAsync(new MainPage(), true);

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="GssdDesktopClient.Maui.Pages.MainPage"
             xmlns:telerik="http://schemas.telerik.com/2022/xaml/maui"
             xmlns:CustomControls ="clr-namespace:GssdDesktopClient.Maui.CustomControls"
       Shell.NavBarIsVisible="False">
    <Shell.BackButtonBehavior>
        <BackButtonBehavior IsVisible="False" />
    </Shell.BackButtonBehavior> 

but this code on main page n

protected override void OnAppearing()
        {
            base.OnAppearing();
           this.Window.MinimumHeight = 600;
           this.Window.MinimumWidth = 600;
        }

ot working:

Answer 1

Hello,

I can reproduce your issue, you can create a window in the app.xaml.cs, then set window to static, then you can change the MinimumHeight and MinimumWidth in the MainPage's OnAppearing method.

public partial class App : Application
  {
      public App()
      {
          InitializeComponent();
          //remove following code
          //  MainPage = new AppShell();
      }
      public static Window window;
      protected override Window CreateWindow(IActivationState activationState)
      {
         window = new Window(new AppShell());   
          return window;
      }
 }

Then you can set it in the MainPage's OnAppearing method.

protected override void OnAppearing()
  {
      base.OnAppearing();
        App.window.MinimumWidth = 600;
        App.window.MinimumHeight = 600;

 }

Best Regards,

Leon Lu

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