Introduction

前回はパッケージではなくexe単独での動作を確認した。
今回は、 Win32 API を呼び出すことができるかを確認する。
ソースは下記になります

GitHub
Demo/WinUI/01_Win32API at master · takuya-takeuchi/Demo
https://github.com/takuya-takeuchi/Demo/tree/master/WinUI/01_Win32API
Sample source code for Demonstration, Experiment and Test - takuya-takeuchi/Demo

Where is Window handle?

何がなくともハンドルがないと何もできないので、まずはその取得手段を探す。

と思ったら、やはり先人が調べていてくださった。

GitHub
Question: How to get the HWND of a WinUI 3 Desktop app? · Issue #2828 · microsoft/microsoft-ui-xaml
https://github.com/microsoft/microsoft-ui-xaml/issues/2828
I created a WinUI desktop app, but it doesn't expose the underlying Window used. Instead I have a Window class that only exposes Title and S…

が…ちょっとこのissueが古い。
結果としては下記だけでOK.

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using System;
using System.Runtime.InteropServices;

// https://github.com/microsoft/microsoft-ui-xaml/issues/2828#issuecomment-653825561
namespace _01_Win32API
{

    [ComImport]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    [Guid("EECDBF0E-BAE9-4CB6-A68E-9598E1CB57BB")]
    public interface IWindowNative
    {

        IntPtr WindowHandle
        {
            get;
        }

    }

    /// <summary>
    /// An empty window that can be used on its own or navigated to within a Frame.
    /// </summary>
    public sealed partial class MainWindow : Window
    {

        #region P/Invokes

        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        private static extern int GetWindowTextLength(IntPtr hwnd);

        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        private static extern int GetWindowText(IntPtr hWnd, string lpString, int nMaxCount);

        #endregion

        #region Construtors

        public MainWindow()
        {
            this.InitializeComponent();
        }

        #endregion

        #region Event Handlers

        private async void myButton_Click(object sender, RoutedEventArgs e)
        {
            // Require using WinRT; 
            var windowNative = this.As<IWindowNative>();
            var hwnd = windowNative.WindowHandle;

            var length = GetWindowTextLength(hwnd);

            string lpString = new string('0', length + 1);
            var ret = GetWindowText(hwnd, lpString, length + 1);

            var cd = new ContentDialog
            {
                Title = "Hello Win32 API",
                Content = $"GetWindowText returns '{lpString}' [{ret}]",
                CloseButtonText = "OK"
            };

            cd.XamlRoot = this.Content.XamlRoot;
            await cd.ShowAsync();
        }

        #endregion

    }

}

COMを経由してるのか…とげんなりしつつも目的を達成。

app

Source Code

https://github.com/takuya-takeuchi/Demo/tree/master/WinUI/01_Win32API