TweetDuck/windows/TweetDuck.Video/NativeMethods.cs

#nullable enable
using System;
using System.Diagnostics.CodeAnalysis;
using System.Drawing;
using System.Runtime.InteropServices;

namespace TweetDuck.Video {
	[SuppressMessage("ReSharper", "InconsistentNaming")]
	static class NativeMethods {
		private const int GA_ROOT = 2;
		private const int GWL_HWNDPARENT = -8;

		[DllImport("user32.dll")]
		[return: MarshalAs(UnmanagedType.Bool)]
		public static extern bool GetWindowRect(IntPtr hWnd, out RECT lpRect);

		[DllImport("user32.dll")]
		[return: MarshalAs(UnmanagedType.Bool)]
		public static extern bool GetClientRect(IntPtr hWnd, out RECT lpRect);

		[DllImport("user32.dll")]
		private static extern int SetWindowLong(IntPtr hWnd, int nIndex, IntPtr dwNewLong);

		[DllImport("user32.dll")]
		public static extern bool SetForegroundWindow(IntPtr hWnd);

		[DllImport("user32.dll")]
		public static extern IntPtr GetForegroundWindow();
		
		[DllImport("user32.dll")]
		private static extern IntPtr WindowFromPoint(Point point);
		
		[DllImport("user32.dll")]
		private static extern IntPtr GetAncestor(IntPtr hwnd, int flags);

		[DllImport("user32.dll")]
		public static extern bool SetProcessDPIAware();

		[StructLayout(LayoutKind.Sequential)]
		[SuppressMessage("ReSharper", "InconsistentNaming")]
		[SuppressMessage("ReSharper", "FieldCanBeMadeReadOnly.Global")]
		public struct RECT {
			public int Left;
			public int Top;
			public int Right;
			public int Bottom;
		}

		public static void SetWindowOwner(IntPtr child, IntPtr owner) {
			SetWindowLong(child, GWL_HWNDPARENT, owner);
			/*
			 * "You must not call SetWindowLong with the GWL_HWNDPARENT index to change the parent of a child window"
			 *
			 * ...which I'm not sure they're saying because this is completely unsupported and causes demons to come out of sewers
			 * ...or because GWL_HWNDPARENT actually changes the OWNER and is therefore NOT changing the parent of a child window
			 *
			 * ...so technically, this is following the documentation to the word.
			 */
		}

		public static IntPtr GetFormHandleAt(Point point) {
			IntPtr window = WindowFromPoint(point);
			return window == IntPtr.Zero ? IntPtr.Zero : GetAncestor(window, GA_ROOT);
		}
	}
}