少有人走的路

MainWindow.axaml

<Window xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        x:Class="_04_TextInput.MainWindow"
        Title="Text Input - 文本输入演示"
        Width="450"
        Height="400">
  <StackPanel Margin="30" Spacing="20">

    <TextBlock Text="TextBox（文本框）" FontSize="16" FontWeight="Bold"/>

    <StackPanel Spacing="5">
      <TextBlock Text="请输入您的名字:"/>
      <TextBox x:Name="NameTextBox"
               Watermark="在这里输入..."
               MaxLength="50"/>
    </StackPanel>

    <StackPanel Spacing="5">
      <TextBlock Text="多行文本框:"/>
      <TextBox x:Name="MultiLineTextBox"
               AcceptsReturn="True"
               AcceptsTab="True"
               TextWrapping="Wrap"
               Height="80"
               Watermark="支持多行输入..."/>
    </StackPanel>

    <Button x:Name="SubmitButton"
            Content="提交"
            HorizontalAlignment="Center"
            Padding="30,10"/>

    <TextBlock x:Name="ResultText"
               Text=""
               FontSize="14"
               Foreground="#2196F3"
               TextWrapping="Wrap"/>

  </StackPanel>
</Window>

MainWindow.axaml.cs

using Avalonia;
using Avalonia.Controls;
using Avalonia.Interactivity;

namespace _04_TextInput;

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
        SubmitButton.Click += OnSubmitClick;
    }

    private void OnSubmitClick(object? sender, RoutedEventArgs e)
    {
        string name = NameTextBox.Text ?? "";
        string description = MultiLineTextBox.Text ?? "";

        if (string.IsNullOrWhiteSpace(name))
        {
            ResultText.Text = "请输入名字！";
            return;
        }

        ResultText.Text = $"您好，{name}！\n您的描述：{(string.IsNullOrWhiteSpace(description) ? "无" : description)}";
    }
}

效果：