如何在Powershell中保存来自WPF RichTextBox的rtf文件？

<Window x:Class="WpfApp.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <RichTextBox x:Name="richTextBox" HorizontalAlignment="Left" Height="396" Margin="10,10,0,0" VerticalAlignment="Top" Width="760"/>
    </Grid>
</Window>

using System.Windows;
using System.Windows.Controls;

namespace WpfApp
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void SaveRtfButton_Click(object sender, RoutedEventArgs e)
        {
            string filePath = "path_to_save_file.rtf";
            using (System.IO.FileStream fileStream = new System.IO.FileStream(filePath, System.IO.FileMode.Create))
            {
                richTextBox.SelectAll();
                richTextBox.Selection.Save(fileStream, DataFormats.Rtf);
            }
        }
    }
}

# 启动WPF应用程序
$app = Start-Process -FilePath "path_to_your_wpf_app.exe" -PassThru

# 等待应用程序启动
Start-Sleep -Seconds 5

# 这里需要使用自动化工具来模拟点击保存按钮的操作
# 例如，如果你使用的是Windows Forms自动化，可以使用以下代码：
# 注意：以下代码仅为示例，实际实现可能需要根据你的应用程序UI结构进行调整
Add-Type -TypeDefinition @"
using System;
using System.Runtime.InteropServices;

public static class Win32 {
    [DllImport("user32.dll", SetLastError=true)]
    public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

    [DllImport("user32.dll")]
    public static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindow);

    [DllImport("user32.dll")]
    public static extern void SendMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);
}
"@

# 假设保存按钮的类名为"Button"，窗口标题为"MainWindow"
$hwnd = [Win32]::FindWindow("MainWindow", "MainWindow")
$btnHwnd = [Win32]::FindWindowEx($hwnd, [IntPtr]::Zero, "Button", "SaveRtfButton")
[Win32]::SendMessage($btnHwnd, 0x00F5, [IntPtr]::Zero, [IntPtr]::Zero) # BM_CLICK消息

# 等待保存操作完成
Start-Sleep -Seconds 2

# 关闭应用程序
Stop-Process -Id $app.Id