wpf - 如何创建自动滚动文本框

Question

我有一个 WPF 应用程序，其中包含一个用于显示调试文本输出的多行文本框。

如何设置文本框，以便当文本附加到框中时，它会自动滚动到文本框的底部？

• 我正在使用 MVVM 模式。
• 理想情况下，纯 XAML 方法会很好。
• 文本框本身不一定处于焦点中。

Answer 1

@BojinLi 提供的答案效果很好。然而，在阅读了 @GazTheDestroyer 链接的答案后，我决定为 TextBox 实现我自己的版本，因为它看起来更干净。

总而言之，您可以使用附加属性来扩展 TextBox 控件的行为。 (称为 ScrollOnTextChanged)

使用很简单:

<TextBox src:TextBoxBehaviour.ScrollOnTextChanged="True" VerticalScrollBarVisibility="Auto" />

这是 TextBoxBehaviour 类:

using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Controls;

namespace MyNamespace
{
    public class TextBoxBehaviour
    {
        static readonly Dictionary<TextBox, Capture> _associations = new Dictionary<TextBox, Capture>();

        public static bool GetScrollOnTextChanged(DependencyObject dependencyObject)
        {
            return (bool)dependencyObject.GetValue(ScrollOnTextChangedProperty);
        }

        public static void SetScrollOnTextChanged(DependencyObject dependencyObject, bool value)
        {
            dependencyObject.SetValue(ScrollOnTextChangedProperty, value);
        }

        public static readonly DependencyProperty ScrollOnTextChangedProperty =
            DependencyProperty.RegisterAttached("ScrollOnTextChanged", typeof (bool), typeof (TextBoxBehaviour), new UIPropertyMetadata(false, OnScrollOnTextChanged));

        static void OnScrollOnTextChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e)
        {
            var textBox = dependencyObject as TextBox;
            if (textBox == null)
            {
                return;
            }
            bool oldValue = (bool) e.OldValue, newValue = (bool) e.NewValue;
            if (newValue == oldValue)
            {
                return;
            }
            if (newValue)
            {
                textBox.Loaded += TextBoxLoaded;
                textBox.Unloaded += TextBoxUnloaded;
            }
            else
            {
                textBox.Loaded -= TextBoxLoaded;
                textBox.Unloaded -= TextBoxUnloaded;
                if (_associations.ContainsKey(textBox))
                {
                    _associations[textBox].Dispose();
                }
            }
        }

        static void TextBoxUnloaded(object sender, RoutedEventArgs routedEventArgs)
        {
            var textBox = (TextBox) sender;
            _associations[textBox].Dispose();
            textBox.Unloaded -= TextBoxUnloaded;
        }

        static void TextBoxLoaded(object sender, RoutedEventArgs routedEventArgs)
        {
            var textBox = (TextBox) sender;
            textBox.Loaded -= TextBoxLoaded;
            _associations[textBox] = new Capture(textBox);
        }

        class Capture : IDisposable
        {
            private TextBox TextBox { get; set; }

            public Capture(TextBox textBox)
            {
                TextBox = textBox;
                TextBox.TextChanged += OnTextBoxOnTextChanged;
            }

            private void OnTextBoxOnTextChanged(object sender, TextChangedEventArgs args)
            {
                TextBox.ScrollToEnd();
            }

            public void Dispose()
            {
                TextBox.TextChanged -= OnTextBoxOnTextChanged;
            }
        }

    }
}