如何从 MainWindow 上 NavigationView 控件的框架中的页面检索当前 WinUI 3 MainWindow 的 window 句柄

Question

我正在创建我的第一个 WinUI 3 桌面应用程序。我的 MainWindow 上有一个 NavigationView。我有 9 个不同的页面，我通过 NavigationView 中的框架导航到这些页面。其中一页用于打印报告。我需要让 FileSavePicker 从 'reportPage' 开始工作。我已经实施了以下内容，直接遵循 docs.microsoft.com 中的示例。（我还在下面的一个小型虚拟 winui-3 沙盒测试应用程序中添加了相同的 FileSavePicker 代码段，但我将代码放在 MainWindow 的代码隐藏中并且运行良好。）我需要让 FileSavePicker 从页面而不是 MainWindow。感谢大家迄今为止的帮助。

我收到这个调试错误：

我知道问题与获取 MainWindow 的 HWND 有关。

// Retrieve the window handle (HWND) of the current WinUI 3 window.
   var window = (MainWindow)Application.Current.MainWindow; (I tried this, but it did not work)

我从上面一行得到这个错误：

（我试过了，没用）

   var hWnd = WinRT.Interop.WindowNative.GetWindowHandle(window);

我从上面的行中得到这个错误：

我不知道正确的语法。

using Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Controls;
using System;
using System.Collections.Generic;
using Windows.Storage;
using Windows.Storage.Pickers;
using Windows.Storage.Provider;
    
namespace MetricReporting.Pages
{
    /// <summary>
    /// An empty page that can be used on its own or navigated to within a Frame.
    /// </summary>
    public sealed partial class pageReports : Page
    {
        public pageReports()
        {
            this.InitializeComponent();
        }

        private void ButtonBoltReport_Click(object sender, RoutedEventArgs e)
        {
            DisplayBOLTSaveDialog();
        }

        private async void DisplayBOLTSaveDialog()
        {

            FileSavePicker savePicker = new FileSavePicker();

            // Retrieve the window handle (HWND) of the current WinUI 3 window.
            var window = (MainWindow)Application.Current.MainWindow;
            var hWnd = WinRT.Interop.WindowNative.GetWindowHandle(this);

            // Initialize the folder picker with the window handle (HWND).
            WinRT.Interop.InitializeWithWindow.Initialize(savePicker, hWnd);

            savePicker.SuggestedStartLocation = PickerLocationId.DocumentsLibrary;
            // Dropdown of file types the user can save the file as
            savePicker.FileTypeChoices.Add("Plain Text", new List<string>() { ".txt" });
            // Default file name if the user does not type one in or select a file to replace
            savePicker.SuggestedFileName = "New Document";

            StorageFile file = await savePicker.PickSaveFileAsync();
            if (file != null)
            {
                // Prevent updates to the remote version of the file until we finish making changes and call CompleteUpdatesAsync.
                CachedFileManager.DeferUpdates(file);
                // write to file
                await FileIO.WriteTextAsync(file, file.Name);
                // Let Windows know that we're finished changing the file so the other app can update the remote version of the file.
                // Completing updates may require Windows to ask for user input.
                FileUpdateStatus status = await CachedFileManager.CompleteUpdatesAsync(file);
                if (status == FileUpdateStatus.Complete)
                {
                    ReportStatus.Text = "File " + file.Name + " was saved.";
                }
                else
                {
                    ReportStatus.Text = "File " + file.Name + " couldn't be saved.";
                }
            }
            else
            {
                ReportStatus.Text = "Operation cancelled.";
            }
            
        }
    }
}

Answer 1

更改 App.xaml.cs 中 m_window 字段的修饰符：

internal Window m_window;

...或者更好的是通过属性:

公开它

public Window Window => m_window;

然后您可以像这样从页面访问window：

var window = (Application.Current as App)?.m_window as MainWindow;

或

var window = (Application.Current as App)?.Window as MainWindow;

如何从 MainWindow 上 NavigationView 控件的框架中的页面检索当前 WinUI 3 MainWindow 的 window 句柄

How to retrieve the window handle of the current WinUI 3 MainWindow from a page in a frame in a NavigationView control on the MainWindow

c#

hwnd

mainwindow

navigationview

winui-3