在嘗試獲取 window 處理程序時，如何在 WinUI3 中解決此 System.InvalidCastException？

Question

我正在 WinUI 3 中開發一個應用程序，我需要打開一個文件夾選擇器對話框。 為此，我訪問了文檔和 GitHub 頁，這就是我寫的內容 (PrincipalPage.xaml.cs)：

(...)
private async void Select_Click(object sender, Microsoft.UI.Xaml.RoutedEventArgs e)
{
    var task = SelectFile();
    await task;
}

public async Task SelectFile()
{
    var folderPicker = new FolderPicker();
    var hwnd = WinRT.Interop.WindowNative.GetWindowHandle(this);
    WinRT.Interop.InitializeWithWindow.Initialize(folderPicker, hwnd);
    folderPicker.FileTypeFilter.Add("*");
    var file = await folderPicker.PickSingleFolderAsync();
    storePath = file.Path;
    DestinationURLTextBox.Text = file.Path;
}
(...)

我試圖找到我做錯了什么，甚至試圖將代碼直接放在按鈕點擊方法下但沒有任何改變。

這是外部配置還是...只是我做錯了什么？

Answer 1

由於此代碼位於Page (PrincipalPage.xaml.cs) 中，因此您將Page傳遞給GetWindowHandle 。 您需要傳遞一個Window 。

你可以這樣做。

應用程序.xaml.cs

public partial class App : Application
{
    public Window? MainWindow { get; private set; }

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

    protected override void OnLaunched(Microsoft.UI.Xaml.LaunchActivatedEventArgs args)
    {
        MainWindow = new MainWindow();
        MainWindow.Activate();
    }
}

PrincipalPage.xaml.cs

public sealed partial class PrincipalPage: Page
{
    public BlankPage1()
    {
        this.InitializeComponent();
    }

    private async void Select_Click(object sender, RoutedEventArgs e)
    {
        var task = SelectFile();
        await task;
    }

    public async Task SelectFile()
    {
        var folderPicker = new FolderPicker();

        var mainWindow = (App.Current as App)?.MainWindow;
        var hwnd = WinRT.Interop.WindowNative.GetWindowHandle(mainWindow);

        WinRT.Interop.InitializeWithWindow.Initialize(folderPicker, hwnd);
        folderPicker.FileTypeFilter.Add("*");
        var file = await folderPicker.PickSingleFolderAsync();
        storePath = file.Path;
        DestinationURLTextBox.Text = file.Path;
    }
}