NativeMethods.cs

using System.Runtime.InteropServices;

namespace Roundify;

internal static class NativeMethods
{
    private const string User32 = "user32.dll";

    public const int GWL_EXSTYLE = -20;
    public const int WM_NCHITTEST = 0x0084;
    public const int HTTRANSPARENT = -1;

    public const long WS_EX_TRANSPARENT = 0x00000020L;
    public const long WS_EX_TOOLWINDOW = 0x00000080L;
    public const long WS_EX_NOACTIVATE = 0x08000000L;

    public static readonly IntPtr HWND_TOP = IntPtr.Zero;
    public static readonly IntPtr HWND_TOPMOST = new(-1);

    public const uint SWP_NOSIZE = 0x0001;
    public const uint SWP_NOMOVE = 0x0002;
    public const uint SWP_NOACTIVATE = 0x0010;
    public const uint SWP_SHOWWINDOW = 0x0040;

    [DllImport(User32, EntryPoint = "GetWindowLongPtrW", SetLastError = true)]
    private static extern IntPtr GetWindowLongPtr64(IntPtr hWnd, int nIndex);

    [DllImport(User32, EntryPoint = "GetWindowLongW", SetLastError = true)]
    private static extern int GetWindowLong32(IntPtr hWnd, int nIndex);

    [DllImport(User32, EntryPoint = "SetWindowLongPtrW", SetLastError = true)]
    private static extern IntPtr SetWindowLongPtr64(IntPtr hWnd, int nIndex, IntPtr dwNewLong);

    [DllImport(User32, EntryPoint = "SetWindowLongW", SetLastError = true)]
    private static extern int SetWindowLong32(IntPtr hWnd, int nIndex, int dwNewLong);

    [DllImport(User32, SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static extern bool SetWindowPos(
        IntPtr hWnd,
        IntPtr hWndInsertAfter,
        int X,
        int Y,
        int cx,
        int cy,
        uint uFlags);

    [DllImport(User32)]
    public static extern uint GetDpiForWindow(IntPtr hWnd);

    public static IntPtr GetWindowLongPtr(IntPtr hWnd, int nIndex)
    {
        return IntPtr.Size == 8
            ? GetWindowLongPtr64(hWnd, nIndex)
            : new IntPtr(GetWindowLong32(hWnd, nIndex));
    }

    public static IntPtr SetWindowLongPtr(IntPtr hWnd, int nIndex, IntPtr value)
    {
        return IntPtr.Size == 8
            ? SetWindowLongPtr64(hWnd, nIndex, value)
            : new IntPtr(SetWindowLong32(hWnd, nIndex, value.ToInt32()));
    }
}