Create a window with an NSPanel

[Linlccc]

I see that there is handling of NSPanel in the source code, but it is not open, so how should I obtain it?

Here, AvnPanel has been added based on NSPanel.

Avalonia/native/Avalonia.Native/src/OSX/WindowInterfaces.h

Lines 17 to 19 in acd4653

	@interface AvnPanel : NSPanel <AvnWindowProtocol, NSWindowDelegate, AvnAccessibility>
	-(AvnPanel* _Nonnull) initWithParent: (WindowBaseImpl* _Nonnull) parent contentRect: (NSRect)contentRect styleMask: (NSWindowStyleMask)styleMask;
	@end

Here, the creation of what is determined based on usePanel.

Avalonia/native/Avalonia.Native/src/OSX/WindowBaseImpl.mm

Lines 479 to 486 in acd4653

	void WindowBaseImpl::CreateNSWindow(bool usePanel) {
	if (usePanel) {
	Window = [[AvnPanel alloc] initWithParent:this contentRect:NSRect{0, 0, lastSize} styleMask:NSWindowStyleMaskBorderless];
	[Window setHidesOnDeactivate:false];
	} else {
	Window = [[AvnWindow alloc] initWithParent:this contentRect:NSRect{0, 0, lastSize} styleMask:NSWindowStyleMaskBorderless];
	}
	}

But here the default value is false, not open

Avalonia/native/Avalonia.Native/src/OSX/WindowImpl.mm

Line 13 in acd4653

WindowImpl::WindowImpl(IAvnWindowEvents *events) : TopLevelImpl(events), WindowBaseImpl(events, false) {

I don't know if the creation process is as I imagined.

I hope to get help, what should I do? 🙏

[maxkatz6]

First question would be why do you need NSPanel backed window.
Depending on an answer, if you need a custom defined NSPanel with Avalonia content, see https://github.com/AvaloniaUI/Xamarin.Mac.Interop sample on how to do that

[Linlccc]

I need to implement
https://stackoverflow.com/questions/46023769/how-to-show-a-window-without-stealing-focus-on-macos

[Linlccc]

Based on the sample suggested by @maxkatz6, I simply wrote a NSPanel creation in Avalonia that works with the local API.

[SupportedOSPlatform("macos")]
public class AvNsPanel : EmbeddableControlRoot, IDisposable
{
    /// <summary>
    /// NSPanel's handle
    /// </summary>
    private readonly IntPtr _nsPanelHandle;

    /// <summary>
    /// Avalonia's root control handle
    /// </summary>
    private IMacOSTopLevelPlatformHandle AvaloniaRootHandle
    {
        get
        {
            if (TryGetPlatformHandle() is not IMacOSTopLevelPlatformHandle platformHandle) throw new InvalidOperationException("Platform handle is not available.");
            return platformHandle;
        }
    }

    /// <summary>
    /// NSView handle
    /// </summary>
#pragma warning disable CS0618
    private IntPtr NSViewHandle => AvaloniaRootHandle.NSView;
#pragma warning restore CS0618

    public AvNsPanel()
    {
        Width = 350;
        Height = 240;

        // Create an NSPanel instance
        IntPtr nsPanelClass = LibObjc.ObjcGetClass("NSPanel");
        IntPtr allocSel = LibObjc.SelRegisterName("alloc");
        _nsPanelHandle = LibObjc.ObjcMsgSend(nsPanelClass, allocSel);
        // Initialize
        IntPtr initSel = LibObjc.SelRegisterName("initWithContentRect:styleMask:backing:defer:");
        LibObjc.ObjcMsgSend(_nsPanelHandle, initSel, new CGRect(0, 0, Width, Height), 15, 2, 0);

        // Set view area
        IntPtr setFrameSel = LibObjc.SelRegisterName("setFrame:");
        LibObjc.ObjcMsgSend(NSViewHandle, setFrameSel, new CGRect(0, 0, Width, Height));

        // Additional View
        IntPtr contentViewSel = LibObjc.SelRegisterName("contentView");
        IntPtr contentView = LibObjc.ObjcMsgSend(_nsPanelHandle, contentViewSel);
        IntPtr addSubviewSel = LibObjc.SelRegisterName("addSubview:");
        LibObjc.ObjcMsgSend(contentView, addSubviewSel, NSViewHandle);

        // Rendering
        StartRendering();
        Prepare();
    }

    public void Show()
    {
        IntPtr showSelector = LibObjc.SelRegisterName("orderFrontRegardless");
        LibObjc.ObjcMsgSend(_nsPanelHandle, showSelector);

        IntPtr showSelector2 = LibObjc.SelRegisterName("makeKeyWindow");
        LibObjc.ObjcMsgSend(_nsPanelHandle, showSelector2);

        // IntPtr showSelector1 = NativeMethods.GetSelector("makeKeyAndOrderFront:");
        // NativeMethods.void_objc_msgSend_IntPtr(_nsPanelHandle, showSelector1, IntPtr.Zero);
    }

    public new void Dispose()
    {
        GC.SuppressFinalize(this);
        base.Dispose();
        if (_nsPanelHandle == IntPtr.Zero) return;
        // ps. NSPanel will not automatically release when closed see:https://developer.apple.com/documentation/appkit/nswindow/close()?language=objc
        IntPtr closeSel = LibObjc.SelRegisterName("close");
        LibObjc.ObjcMsgSend(_nsPanelHandle, closeSel);
    }

    public static void TestShow()
    {
        AvNsPanel panel = new();
        Border? border2 = null;
        Border border1 = new()
        {
            Height = 100,
            Width = 80,
            Background = Brushes.Blue,
            Child = new Button()
            {
                Content = "Test_Blue",
                HorizontalAlignment = HorizontalAlignment.Center,
                Command = ReactiveCommand.Create(() => panel.Content = border2)
            }
        };

        border2 = new()
        {
            Width = 300,
            Height = 200,
            Background = Brushes.Red,
            Child = new Button()
            {
                Content = "Test_Red",
                HorizontalAlignment = HorizontalAlignment.Center,
                Command = ReactiveCommand.Create(() => panel.Content = border1)
            }
        };
        panel.Content = border1;
        panel.AttachDevTools();
        panel.Show();
    }
}

public static partial class LibObjc
{
    private const string LibObjC = "/usr/lib/libobjc.dylib";

    [LibraryImport(LibObjC, EntryPoint = "objc_getClass", StringMarshalling = StringMarshalling.Utf8)]
    public static partial IntPtr ObjcGetClass(string name);

    [LibraryImport(LibObjC, EntryPoint = "objc_msgSend")]
    public static partial IntPtr ObjcMsgSend(IntPtr receiver, IntPtr selector);

    [LibraryImport(LibObjC, EntryPoint = "objc_msgSend")]
    public static partial IntPtr ObjcMsgSend(IntPtr receiver, IntPtr selector, IntPtr arg1);

    [LibraryImport(LibObjC, EntryPoint = "objc_msgSend")]
    public static partial IntPtr ObjcMsgSend(IntPtr receiver, IntPtr selector, IntPtr arg1, IntPtr arg2);

    [LibraryImport(LibObjC, EntryPoint = "sel_registerName", StringMarshalling = StringMarshalling.Utf8)]
    public static partial IntPtr SelRegisterName(string name);


    [LibraryImport("/usr/lib/libobjc.dylib", EntryPoint = "objc_msgSend")]
    public static partial IntPtr ObjcMsgSend(IntPtr receiver, IntPtr selector, CGRect rect, IntPtr arg1, IntPtr arg2, IntPtr arg3);
    [LibraryImport("/usr/lib/libobjc.dylib", EntryPoint = "objc_msgSend")]
    public static partial IntPtr ObjcMsgSend(IntPtr receiver, IntPtr selector, CGRect rect);
}

[StructLayout(LayoutKind.Sequential)]
public struct CGRect(double x, double y, double width, double height)
{
    public CGPoint origin = new(x, y);
    public CGSize size = new(width, height);
}

[StructLayout(LayoutKind.Sequential)]
public struct CGPoint(double x, double y)
{
    public double x = x;
    public double y = y;
}

[StructLayout(LayoutKind.Sequential)]
public struct CGSize(double width, double height)
{
    public double width = width;
    public double height = height;
}