PowerToys/src/modules/peek/Peek.UI/Extensions/WindowExtensions.cs

// Copyright (c) Microsoft Corporation
// The Microsoft Corporation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System.Runtime.InteropServices;
using Microsoft.UI.Xaml;
using Windows.Win32;
using Windows.Win32.Foundation;
using Windows.Win32.Graphics.Gdi;
using Windows.Win32.UI.WindowsAndMessaging;
using WinUIEx;

namespace Peek.UI.Extensions
{
    public static class WindowExtensions
    {
        public static double GetMonitorScale(this Window window)
        {
            var hwnd = new HWND(window.GetWindowHandle());
            var dpi = PInvoke.GetDpiForWindow(new HWND(hwnd));
            double scalingFactor = dpi / 96d;

            return scalingFactor;
        }

        public static void BringToForeground(this Window window)
        {
            var foregroundWindowHandle = PInvoke.GetForegroundWindow();

            uint targetProcessId = 0;
            uint windowThreadProcessId = 0;
            unsafe
            {
                windowThreadProcessId = PInvoke.GetWindowThreadProcessId(foregroundWindowHandle, &targetProcessId);
            }

            var windowHandle = window.GetWindowHandle();
            var currentThreadId = PInvoke.GetCurrentThreadId();
            PInvoke.AttachThreadInput(windowThreadProcessId, currentThreadId, true);
            PInvoke.BringWindowToTop(new HWND(windowHandle));
            PInvoke.ShowWindow(new HWND(windowHandle), Windows.Win32.UI.WindowsAndMessaging.SHOW_WINDOW_CMD.SW_SHOW);
            PInvoke.AttachThreadInput(windowThreadProcessId, currentThreadId, false);
        }

        internal static void CenterOnMonitor(this Window window, HWND hwndDesktop, double? width = null, double? height = null)
        {
            var hwndToCenter = new HWND(window.GetWindowHandle());
            var monitor = PInvoke.MonitorFromWindow(hwndDesktop, MONITOR_FROM_FLAGS.MONITOR_DEFAULTTONEAREST);
            MONITORINFO info = default(MONITORINFO);
            info.cbSize = 40;
            PInvoke.GetMonitorInfo(monitor, ref info);
            var dpi = PInvoke.GetDpiForWindow(new HWND(hwndDesktop));
            PInvoke.GetWindowRect(new HWND(hwndToCenter), out RECT windowRect);
            var scalingFactor = dpi / 96d;
            var w = width.HasValue ? (int)(width * scalingFactor) : windowRect.right - windowRect.left;
            var h = height.HasValue ? (int)(height * scalingFactor) : windowRect.bottom - windowRect.top;
            var cx = (info.rcMonitor.left + info.rcMonitor.right) / 2;
            var cy = (info.rcMonitor.bottom + info.rcMonitor.top) / 2;
            var left = cx - (w / 2);
            var top = cy - (h / 2);
            SetWindowPosOrThrow(new HWND(hwndToCenter), default(HWND), left, top, w, h, SET_WINDOW_POS_FLAGS.SWP_SHOWWINDOW);
        }

        private static void SetWindowPosOrThrow(HWND hWnd, HWND hWndInsertAfter, int x, int y, int cx, int cy, SET_WINDOW_POS_FLAGS uFlags)
        {
            bool result = PInvoke.SetWindowPos(hWnd, hWndInsertAfter, x, y, cx, cy, uFlags);
            if (!result)
            {
                Marshal.ThrowExceptionForHR(Marshal.GetLastWin32Error());
            }
        }
    }
}