Min Window Size in UWP

Question

In my UWP app I'd like to set a minimum window size so that the window cannot be made smaller than that size.

Everywhere that I searched, it seems that using ApplicationView.PreferredLaunchViewSize is the way to go but for some reason this is not working in my app.

I created a blank UWP app and updated the OnLaunched method as below:

protected override void OnLaunched(LaunchActivatedEventArgs e)
{
    ApplicationView.PreferredLaunchViewSize = new Size(1200, 900);
    ApplicationView.PreferredLaunchWindowingMode = ApplicationViewWindowingMode.PreferredLaunchViewSize;
    ApplicationView.GetForCurrentView().SetPreferredMinSize(new Size(800, 600));

    ...
}

My App launches at the correct size of 1200 x 900 but I can shrink the window smaller than the limit of 800 x 600 which I've set for the app.

What is the right way to limit the window size so that it can't get smaller than a certain size ?

Answer 1

SetPreferredMinSize is the correct API, but there are two important caveats:

• First, remember that the APIs for CoreWindow operate in DIPS (Device Independent Pixel Space), not 'true pixels'. If you want to set a minimum of say 320 x 200 pixels, then you need to make sure to scale the values by the current DPI value.

• Second, in UWP you really don't have hard control over presentation window size but can only express a preference. The reason you can't get 800 x 600 to work is that the 'maximum minimum' size is effectively 500 x 500 pixels. See MSDN.

In my Direct3D VS Game templates I use 320 x 200 as the minimum size:

C++/CX

auto minSize = Size(ConvertPixelsToDips(320), ConvertPixelsToDips(200));
view->SetPreferredMinSize(minSize);

C++/WinRT

auto minSize = Size(ConvertPixelsToDips(320), ConvertPixelsToDips(200));
view.SetPreferredMinSize(minSize);

Answer 2

Add to App.xaml code:

private readonly double minW = 800, minH = 600;

protected override void OnWindowCreated(WindowCreatedEventArgs args) {
    SetWindowMinSize(new Size(args.Window.Bounds.Width, args.Window.Bounds.Height));
    args.Window.CoreWindow.SizeChanged += CoreWindow_SizeChanged;
    base.OnWindowCreated(args);
}

private void CoreWindow_SizeChanged(Windows.UI.Core.CoreWindow sender, Windows.UI.Core.WindowSizeChangedEventArgs args) {
    if (SetWindowMinSize(args.Size)) sender.ReleasePointerCapture();
}

private bool SetWindowMinSize(Size size) {
    if (size.Width < minW || size.Height < minH) {
        if (size.Width < minW) size.Width = minW;
        if (size.Height < minH) size.Height = minH;
        return ApplicationView.GetForCurrentView().TryResizeView(size);
    }
    return false;
}