Add notification tray icon on windows (boss key)

[adryzz]

This PR adds support for creating/removing notification tray icons, needed for boss key support.

This implementation is windows-only, i have a linux one half working but it'll be its own separate patch.

On windows, notification tray icons are closely intertwined with windowing logic, so i had to add 2 methods to IWindow to handle that.

osu!-side PR: ppy/osu#28972

out1.mp4

In my testing there's a problem with hiding the game window, and it looks like there's 2 windows, one that gets hidden and the other that remains, but i don't know if that's a framework issue or an osu! side issue.

out.mp4

EDIT: this only happens in fullscreen, borderless and windowed work just fine.

[Susko3]

SDL recently added tray icon support for windows, unix and macos. Documentation here: https://wiki.libsdl.org/SDL3/CategoryTray.

Using this API gets us the other two platforms for free.

[adryzz]

that's awesome, i'll start using it then

[adryzz]

fixed conflicts, will now switch to the SDL3 API

[Susko3]

I think the API should be declarative, and make use of the SDL tray menu nesting.

public interface IDesktopWindow : IWindow
{
    // dispose to remove the tray icon
    IDisposable CreateTrayIcon(TrayIcon icon);
}


static void Main()
{
    IWindow window;
    if (window is IDesktopWindow desktopWindow)
    {
        var icon = new TrayIcon
        {
            Label = "osu!",
            Icon = imageSharpImage,
            Menu = new TrayMenuEntry[]
            {
                new TrayButton
                {
                    Label = "Open osu!",
                    Default = true, // label should be in bold and double-clicking the icon will invoke this action
                    Action = () => openOsuAndDisposeTray(),
                },
                new TraySubmenu
                {
                    Label = "Example submenu",
                    Entries = new TrayMenuEntry[]
                    {
                        new TrayCheckbox
                        {
                            Checked = true,
                            Action = b => Logger.Log(b ? "checked" : "unchecked"),
                        }
                    }
                },
                new TraySeparator(),
                new TrayButton
                {
                    Label = "Exit",
                    Action = () => closeTheGameAndDisposeTray(),
                }
            }
        }

        var activeTrayIcon = desktopWindow.CreateTrayIcon(icon)
    }
}

We just walk the tree and call the appropriate SDL functions in order. The created tray icon and menu are readonly, a game can delete the old menu and create a new one if updates are needed.

I might take a stab at it next year.

[adryzz]

yes, actually it's exactly the design i first had in mind when i started working on this many months ago.

when i get home tomorrow i'll get it all working and up to snuff

[adryzz]

alright got it to mostly work in a local branch, but the new version of ppy.SDL3-CS isn't released yet so it only works with a local nuget package