WPF TextBox/TextBlock 文本超出显示时,文本靠右显示,TextBlock IsTextTrimmed 判断文本是否超出

C#

浏览数:673

2019-6-14

文本框显示

文本框正常显示:

文本框超出区域显示:

 

 实现方案

判断文本框是否超出区域

请见《TextBlock IsTextTrimmed 判断文本是否超出

设置文本布局显示

1. FlowDirection

当文本超出显示区域时,设置FlowDirection靠右显示

下面是封装的附加属性ScrollEndWhenTextTrimmed

 1         /// <summary>
 2         /// 当文本超出显示时,文本是否靠右侧显示
 3         /// </summary>
 4         public static readonly DependencyProperty ScrollEndWhenTextTrimmedProperty = DependencyProperty.RegisterAttached(
 5         "ScrollEndWhenTextTrimmed", typeof(bool), typeof(TextBoxHelper),
 6         new PropertyMetadata(default(bool), OnScrollEndWhenTextTrimmedChanged));
 7 
 8         private static void OnScrollEndWhenTextTrimmedChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
 9         {
10             var textBox = (TextBox)d;
11             textBox.TextChanged -= TextBoxOnTextChanged;
12             if ((bool)e.NewValue)
13             {
14                 textBox.FlowDirection = IsTextTrimmed(textBox) ? FlowDirection.RightToLeft : FlowDirection.LeftToRight;
15                 textBox.TextChanged += TextBoxOnTextChanged;
16             }
17             void TextBoxOnTextChanged(object sender, TextChangedEventArgs args)
18             {
19                 textBox.FlowDirection = IsTextTrimmed(textBox) ? FlowDirection.RightToLeft : FlowDirection.LeftToRight;
20             }
21         }
22 
23         public static void SetScrollEndWhenTextTrimmed(DependencyObject element, bool value)
24         {
25             element.SetValue(ScrollEndWhenTextTrimmedProperty, value);
26         }
27 
28         public static bool GetScrollEndWhenTextTrimmed(DependencyObject element)
29         {
30             return (bool)element.GetValue(ScrollEndWhenTextTrimmedProperty);
31         }

在需要设置文本超出时居右显示的TextBox控件中,添加附加属性ScrollEndWhenTextTrimmed即可。

2.ScrollToEnd

类似方案FlowDirection,文本超出时,通过滚动到文本末尾后,文本靠右显示。

如方案FlowDirection,可以在添加附加属性更改事件中,订阅TextBox的TextChanged。

1     textBox.SelectionStart = textBox.Text.Length;
2     textBox.ScrollToEnd();

But,此方案有缺陷。当TextBox设置IsEnabled=false时,就无法滚动到了。即使如下设置依然无效:

1     textBox.IsEnabled = true;
2     textBox.SelectionStart = textBox.Text.Length;
3     textBox.ScrollToEnd();
4     textBox.IsEnabled = false;

当然,如果文本框不设置IsEnabled时,此方案是可行的。

注:如上方案,本来通过SelectionStart直接绑定TextBox自身的Text.Length就行。然而SelectionStart不是依赖属性,只能直接赋值~

 

作者:唐宋元明清2188