当字符串太长时，用“...”从文本块中中断文本答案

【问题标题】：Interrupt text from a textblock with "..." when string is too long当字符串太长时，用“...”从文本块中中断文本
【发布时间】：2014-05-08 16:39:44
【问题描述】：

我在 windows phone 8 应用程序中使用了一个包含许多元素的长列表选择器。每个项目都有一个文本块，每个项目的文本可以从几个字母到多个单词。我想将文本保留为一行，因此我将 TextWrapping 属性设置为“NoWrap”。我想添加“...”并裁剪文本，如果它太长而不适合屏幕。到目前为止，我尝试使用每个 TextBlock 的加载事件并减少文本，直到它适合屏幕。但是，当列表有很多元素时，加载事件不会为所有文本块激活。有没有合适的方法来解决这个问题？

    private void TextBlock_Loaded_1(object sender, RoutedEventArgs e)
    {
        TextBlock txt = sender as TextBlock;
        if (txt == null)
            return;

        if (txt.ActualWidth > 300)
        {
            while (txt.Text.Length > 4 && txt.ActualWidth > 290)
                txt.Text = txt.Text.Substring(0, txt.Text.Length - 4);
            txt.Text = txt.Text.Substring(0, txt.Text.Length - 3);

            txt.Text = txt.Text.Trim(new Char[] { ' ', ',' }) + "...";

        }
    }

【问题讨论】：

TextTrimming
如果文本太长，您应该使用转换器来转换文本。

标签： c# xaml windows-phone-8 windows-phone

【解决方案1】：

这是一个如何实现此目的的转换器示例：

using System;
using System.Globalization;
using System.Windows.Data;

namespace PhoneApp2
{
    public class TextLengthConverter: IValueConverter
    {
        #region Implementation of IValueConverter

        /// <summary>
        /// Modifies the source data before passing it to the target for display in the UI.
        /// </summary>
        /// <returns>
        /// The value to be passed to the target dependency property.
        /// </returns>
        /// <param name="value">The source data being passed to the target.</param><param name="targetType">The <see cref="T:System.Type"/> of data expected by the target dependency property.</param><param name="parameter">An optional parameter to be used in the converter logic.</param><param name="culture">The culture of the conversion.</param>
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            if (value is string)
            {
                int desiredLength;
                if (int.TryParse(parameter.ToString(), out desiredLength))
                {
                    if (desiredLength > 0)
                    {
                        string textIn = value as string;
                        if (textIn.Length > desiredLength // Make sure the truncation is actually needed.
                            && textIn.Length > 3) // Make sure the length if the textIn is longer than the dots so 'something' is shown before the dots.
                        {
                            return textIn.Substring(0, desiredLength - 3) + "...";
                        }
                    }
                }
            }
            return value;
        }

        /// <summary>
        /// Modifies the target data before passing it to the source object.  This method is called only in <see cref="F:System.Windows.Data.BindingMode.TwoWay"/> bindings.
        /// </summary>
        /// <returns>
        /// The value to be passed to the source object.
        /// </returns>
        /// <param name="value">The target data being passed to the source.</param><param name="targetType">The <see cref="T:System.Type"/> of data expected by the source object.</param><param name="parameter">An optional parameter to be used in the converter logic.</param><param name="culture">The culture of the conversion.</param>
        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }

        #endregion
    }
}

要在页面中使用它，请像这样添加资源条目：

<phone:PhoneApplicationPage.Resources>
    <PhoneApp2:TextLengthConverter x:Key="TextLengthConverter"/>
</phone:PhoneApplicationPage.Resources>

并将其附加到您的绑定文本：

<TextBlock Text="{Binding BoundText, Converter={StaticResource TextLengthConverter}, ConverterParameter=4}"/>

一个不错的、可重复使用的解决方案，您可以将其添加到您的转换器集合中。

【讨论】：